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Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
High-Speed Mixed-Signal ISP FLASH MCU
ANALOG PERIPHERALS - SAR ADC * 12-Bit (C8051F120/1/4/5) * 10-Bit (C8051F122/3/6/7) * 1 LSB INL * Programmable Throughput up to 100 ksps * Up to 8 External Inputs; Programmable as Single-Ended or * * * * * * *
Differential Programmable Amplifier Gain: 16, 8, 4, 2, 1, 0.5 Data-Dependent Windowed Interrupt Generator Built-in Temperature Sensor Programmable Throughput up to 500 ksps 8 External Inputs (Single-Ended or Differential) Programmable Amplifier Gain: 4, 2, 1, 0.5 Can Synchronize Outputs to Timers for Jitter-Free Waveform Generation
HIGH SPEED 8051 C CORE - Pipelined Instruction Architecture; Executes 70% of Instruction Set in 1 or 2 System Clocks Up to 100 MIPS (C8051F120/1/2/3) or 50 MIPS (C8051F124/5/6/7) Throughput using Integrated PLL Flexible Interrupt Sources
MEMORY - 8448 Bytes Internal Data RAM (8k + 256) - 128k Bytes Banked FLASH; In-System programmable in 1024-byte Sectors External 64k Byte Data Memory Interface (programmable multiplexed or non-multiplexed modes)
8-bit ADC
Two 12-bit DACs
DIGITAL PERIPHERALS - 8 Byte-Wide Port I/O (C8051F120/2/4/6); 5V tolerant - 4 Byte-Wide Port I/O (C8051F121/3/5/7); 5V tolerant - Hardware SMBusTM (I2CTM Compatible), SPITM, and Two UART Serial Ports Available Concurrently Programmable 16-bit Counter/Timer Array with 6 Capture/Compare Modules 5 General Purpose 16-bit Counter/Timers Dedicated Watch-Dog Timer; Bi-directional Reset Pin
- Two Analog Comparators - Voltage Reference - VDD Monitor/Brown-Out Detector ON-CHIP JTAG DEBUG & BOUNDARY SCAN - On-Chip Debug Circuitry Facilitates Full- Speed, NonIntrusive In-Circuit/In-System Debugging Provides Breakpoints, Single-Stepping, Watchpoints, Stack Monitor; Inspect/Modify Memory and Registers Superior Performance to Emulation Systems Using ICEChips, Target Pods, and Sockets IEEE1149.1 Compliant Boundary Scan Complete Development Kit
CLOCK SOURCES - Internal Precision Oscillator: 24.5 MHz - Flexible PLL technology - External Oscillator: Crystal, RC, C, or Clock - Real-Time Clock Mode using Timers or PCA SUPPLY VOLTAGE .......................... 2.7V TO 3.6V - Typical Operating Current: 25 mA @ 50 MHz - Multiple Power Saving Sleep and Shutdown Modes 100-Pin TQFP and 64-Pin TQFP Packages Available Temperature Range: -40C to +85C
ANALOG PERIPHERALS
TEMP SENSOR
DIGITAL I/O
UART0 UART1 SMBus SPI Bus PCA Timer 0 Timer 1 Timer 2 Timer 3 Timer 4 CROSSBAR
Port 0
External Memory Interface
AMUX
PGA VREF
10/12-bit 100ksps
Port 1 Port 2 Port 3 Port 4 Port 5 Port 6 Port 7
ADC
8-bit 500ksps ADC
+ -
AMUX
+ -
PGA
12-Bit DAC
12-Bit DAC
VOLTAGE COMPARATORS
64 pin 100 pin
HIGH-SPEED CONTROLLER CORE
8051 CPU 128KB 8448 B JTAG (50 or 100MIPS) ISP FLASH SRAM 20 DEBUG CLOCK / PLL SANITY INTERRUPTS CIRCUITRY CIRCUIT CONTROL
DS008-0.8-AUG02
CYGNAL Integrated Products, Inc. (c) 2002
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C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
Notes
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
TABLE OF CONTENTS
1. SYSTEM OVERVIEW .........................................................................................................19 1.1. CIP-51TM Microcontroller Core ......................................................................................25 1.1.1. Fully 8051 Compatible ..........................................................................................25 1.1.2. Improved Throughput ............................................................................................25 1.1.3. Additional Features................................................................................................26 1.2. On-Chip Memory ............................................................................................................27 1.3. JTAG Debug and Boundary Scan ...................................................................................28 1.4. Programmable Digital I/O and Crossbar .........................................................................29 1.5. Programmable Counter Array .........................................................................................30 1.6. Serial Ports.......................................................................................................................31 1.7. 12-Bit Analog to Digital Converter.................................................................................32 1.8. 8-Bit Analog to Digital Converter...................................................................................33 1.9. Comparators and DACs...................................................................................................34 2. ABSOLUTE MAXIMUM RATINGS ..................................................................................35 3. GLOBAL DC ELECTRICAL CHARACTERISTICS ......................................................36 4. PINOUT AND PACKAGE DEFINITIONS........................................................................38 5. ADC0 (12-BIT ADC, C8051F120/1/4/5 ONLY) ..................................................................47 5.1. Analog Multiplexer and PGA..........................................................................................47 5.2. ADC Modes of Operation ...............................................................................................49 5.2.1. Starting a Conversion.............................................................................................49 5.2.2. Tracking Modes .....................................................................................................50 5.2.3. Settling Time Requirements ..................................................................................51 5.3. ADC0 Programmable Window Detector.........................................................................58 6. ADC0 (10-BIT ADC, C8051F122/3/6/7 ONLY) ..................................................................65 6.1. Analog Multiplexer and PGA..........................................................................................65 6.2. ADC Modes of Operation ...............................................................................................67 6.2.1. Starting a Conversion.............................................................................................67 6.2.2. Tracking Modes .....................................................................................................68 6.2.3. Settling Time Requirements ..................................................................................69 6.3. ADC0 Programmable Window Detector.........................................................................76 7. ADC2 (8-BIT ADC) ...............................................................................................................83 7.1. Analog Multiplexer and PGA..........................................................................................83 7.2. ADC2 Modes of Operation .............................................................................................84 7.2.1. Starting a Conversion.............................................................................................84 7.2.2. Tracking Modes .....................................................................................................84 7.2.3. Settling Time Requirements ..................................................................................86 7.3. ADC2 Programmable Window Detector.........................................................................92 7.3.1. Window Detector In Single-Ended Mode .............................................................92 7.3.2. Window Detector In Differential Mode.................................................................93 8. DACS, 12-BIT VOLTAGE MODE ......................................................................................97 8.1. DAC Output Scheduling..................................................................................................97 8.1.1. Update Output On-Demand ...................................................................................97
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Preliminary
8.1.2. Update Output Based on Timer Overflow .............................................................98 8.2. DAC Output Scaling/Justification...................................................................................98 9. VOLTAGE REFERENCE (C8051F120/2/4/6) .................................................................105 10. VOLTAGE REFERENCE (C8051F121/3/5/7) .................................................................107 11. COMPARATORS................................................................................................................109 12. CIP-51 MICROCONTROLLER........................................................................................117 12.1.Instruction Set................................................................................................................118 12.1.1. Instruction and CPU Timing................................................................................118 12.1.2. MOVX Instruction and Program Memory...........................................................118 12.2.Memory Organization ...................................................................................................123 12.2.1. Program Memory .................................................................................................123 12.2.2. Data Memory .......................................................................................................125 12.2.3. General Purpose Registers ...................................................................................125 12.2.4. Bit Addressable Locations ...................................................................................125 12.2.5. Stack .................................................................................................................125 12.2.6. Special Function Registers...................................................................................126 12.2.6.1. SFR Paging..................................................................................................126 12.2.6.2.Interrupts and SFR Paging...........................................................................126 12.2.6.3.SFR Page Stack Example ............................................................................128 12.2.7. Register Descriptions ...........................................................................................141 12.3.Interrupt Handler ...........................................................................................................144 12.3.1. MCU Interrupt Sources and Vectors ...................................................................144 12.3.2. External Interrupts ...............................................................................................144 12.3.3. Interrupt Priorities................................................................................................146 12.3.4. Interrupt Latency..................................................................................................146 12.3.5. Interrupt Register Descriptions ............................................................................147 12.4.Power Management Modes ...........................................................................................153 12.4.1. Idle Mode .............................................................................................................153 12.4.2. Stop Mode............................................................................................................153 13. RESET SOURCES ..............................................................................................................155 13.1.Power-on Reset..............................................................................................................156 13.2.Power-fail Reset ............................................................................................................156 13.3.External Reset................................................................................................................156 13.4.Missing Clock Detector Reset .......................................................................................157 13.5.Comparator0 Reset ........................................................................................................157 13.6.External CNVSTR0 Pin Reset.......................................................................................157 13.7.Watchdog Timer Reset ..................................................................................................157 13.7.1. Enable/Reset WDT ..............................................................................................157 13.7.2. Disable WDT .......................................................................................................158 13.7.3. Disable WDT Lockout.........................................................................................158 13.7.4. Setting WDT Interval...........................................................................................158 14. OSCILLATORS...................................................................................................................161 14.1.Programmable Internal Oscillator .................................................................................161 14.2.External Oscillator Drive Circuit...................................................................................163 14.3.System Clock Selection.................................................................................................163
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14.4.External Crystal Example..............................................................................................166 14.5.External RC Example ....................................................................................................166 14.6.External Capacitor Example..........................................................................................166 14.7.Phase-Locked Loop (PLL) ............................................................................................167 14.7.1. PLL Input Clock and Pre-divider.........................................................................167 14.7.2. PLL Multiplication and Output Clock .................................................................167 14.7.3. Powering on and Initializing the PLL..................................................................168 15. FLASH MEMORY ..............................................................................................................173 15.1.Programming The Flash Memory .................................................................................173 15.1.1. Non-volatile Data Storage ...................................................................................173 15.1.2. Erasing FLASH Pages From Software ................................................................174 15.1.3. Writing FLASH Memory From Software ...........................................................175 15.2.Security Options ............................................................................................................176 16. BRANCH TARGET CACHE.............................................................................................181 16.1.Cache and Prefetch Operation .......................................................................................181 16.2.Cache and Prefetch Optimization..................................................................................182 17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM.......................187 17.1.Accessing XRAM..........................................................................................................187 17.1.1. 16-Bit MOVX Example.......................................................................................187 17.1.2. 8-Bit MOVX Example.........................................................................................187 17.2.Configuring the External Memory Interface .................................................................187 17.3.Port Selection and Configuration ..................................................................................188 17.4.Multiplexed and Non-multiplexed Selection.................................................................190 17.4.1. Multiplexed Configuration ..................................................................................190 17.4.2. Non-multiplexed Configuration...........................................................................191 17.5.Memory Mode Selection ...............................................................................................192 17.5.1. Internal XRAM Only ...........................................................................................192 17.5.2. Split Mode without Bank Select ..........................................................................192 17.5.3. Split Mode with Bank Select ...............................................................................193 17.5.4. External Only .......................................................................................................193 17.6.Timing .......................................................................................................................194 17.6.1. Non-multiplexed Mode........................................................................................195 17.6.1.1.16-bit MOVX: EMI0CF[4:2] = `101', `110', or `111'................................195 17.6.1.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = `101' or `111'............196 17.6.1.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = `110'. ..............................197 17.6.2. Multiplexed Mode................................................................................................198 17.6.2.1.16-bit MOVX: EMI0CF[4:2] = `001', `010', or `011'................................198 17.6.2.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = `001' or `011'............199 17.6.2.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = `010'. ..............................200 18. PORT INPUT/OUTPUT .....................................................................................................203 18.1.Ports 0 through 3 and the Priority Crossbar Decoder....................................................205 18.1.1. Crossbar Pin Assignment and Allocation ............................................................205 18.1.2. Configuring the Output Modes of the Port Pins ..................................................206 18.1.3. Configuring Port Pins as Digital Inputs ...............................................................207 18.1.4. Weak Pull-ups......................................................................................................207
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Preliminary
18.1.5. Configuring Port 1 Pins as Analog Inputs ...........................................................207 18.1.6. External Memory Interface Pin Assignments ......................................................208 18.1.7. Crossbar Pin Assignment Example......................................................................210 18.2.Ports 4 through 7 (C8051F120/2/4/6 only) ...................................................................219 18.2.1. Configuring Ports which are not Pinned Out.......................................................219 18.2.2. Configuring the Output Modes of the Port Pins ..................................................219 18.2.3. Configuring Port Pins as Digital Inputs ...............................................................220 18.2.4. Weak Pull-ups......................................................................................................220 18.2.5. External Memory Interface ..................................................................................220 19. SYSTEM MANAGEMENT BUS / I2C BUS (SMBUS0) .................................................225 19.1.Supporting Documents ..................................................................................................227 19.2.SMBus Protocol.............................................................................................................227 19.2.1. Arbitration............................................................................................................227 19.2.2. Clock Low Extension...........................................................................................228 19.2.3. SCL Low Timeout ...............................................................................................228 19.2.4. SCL High (SMBus Free) Timeout.......................................................................228 19.3.SMBus Transfer Modes.................................................................................................229 19.3.1. Master Transmitter Mode ....................................................................................229 19.3.2. Master Receiver Mode.........................................................................................229 19.3.3. Slave Transmitter Mode.......................................................................................230 19.3.4. Slave Receiver Mode ...........................................................................................230 19.4.SMBus Special Function Registers ...............................................................................231 19.4.1. Control Register ...................................................................................................231 19.4.2. Clock Rate Register .............................................................................................233 19.4.3. Data Register........................................................................................................234 19.4.4. Address Register ..................................................................................................234 19.4.5. Status Register .....................................................................................................235 20. ENHANCED SERIAL PERIPHERAL INTERFACE (SPI0) .........................................239 20.1.Signal Descriptions........................................................................................................240 20.1.1. Master Out, Slave In (MOSI) ..............................................................................240 20.1.2. Master In, Slave Out (MISO) ..............................................................................240 20.1.3. Serial Clock (SCK) ..............................................................................................240 20.1.4. Slave Select (NSS)...............................................................................................240 20.2.SPI0 Master Mode Operation........................................................................................241 20.3.SPI0 Slave Mode Operation ..........................................................................................243 20.4.SPI0 Interrupt Sources...................................................................................................244 20.5.Serial Clock Timing ......................................................................................................245 20.6.SPI Special Function Registers .....................................................................................246 21. UART0 ..................................................................................................................................253 21.1.UART0 Operational Modes ..........................................................................................254 21.1.1. Mode 0: Synchronous Mode................................................................................254 21.1.2. Mode 1: 8-Bit UART, Variable Baud Rate .........................................................255 21.1.3. Mode 2: 9-Bit UART, Fixed Baud Rate ..............................................................256 21.1.4. Mode 3: 9-Bit UART, Variable Baud Rate .........................................................257 21.2.Multiprocessor Communications...................................................................................258
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21.2.1. Configuration of a Masked Address ....................................................................258 21.2.2. Broadcast Addressing ..........................................................................................258 21.3.Frame and Transmission Error Detection......................................................................259 22. UART1 ..................................................................................................................................265 22.1.Enhanced Baud Rate Generation...................................................................................266 22.2.Operational Modes ........................................................................................................267 22.2.1. 8-Bit UART .........................................................................................................267 22.2.2. 9-Bit UART .........................................................................................................268 22.3.Multiprocessor Communications...................................................................................269 23. TIMERS................................................................................................................................275 23.1.Timer 0 and Timer 1......................................................................................................275 23.1.1. Mode 0: 13-bit Counter/Timer.............................................................................275 23.1.2. Mode 1: 16-bit Counter/Timer.............................................................................276 23.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload .................................................277 23.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only) ...........................................278 23.2.Timer 2, Timer 3, and Timer 4 ......................................................................................283 23.2.1. Configuring Timer 2, 3, and 4 to Count Down....................................................283 23.2.2. Capture Mode ......................................................................................................284 23.2.3. Auto-Reload Mode ..............................................................................................285 23.2.4. Toggle Output Mode (Timer 2 and Timer 4 Only)..............................................285 24. PROGRAMMABLE COUNTER ARRAY .......................................................................291 24.1.PCA Counter/Timer.......................................................................................................292 24.2.Capture/Compare Modules............................................................................................293 24.2.1. Edge-triggered Capture Mode .............................................................................294 24.2.2. Software Timer (Compare) Mode........................................................................295 24.2.3. High Speed Output Mode ....................................................................................296 24.2.4. Frequency Output Mode ......................................................................................297 24.2.5. 8-Bit Pulse Width Modulator Mode ....................................................................298 24.2.6. 16-Bit Pulse Width Modulator Mode ..................................................................299 24.3.Register Descriptions for PCA0 ....................................................................................300 25. JTAG (IEEE 1149.1)............................................................................................................305 25.1.Boundary Scan...............................................................................................................306 25.1.1. EXTEST Instruction ............................................................................................307 25.1.2. SAMPLE Instruction ...........................................................................................307 25.1.3. BYPASS Instruction ............................................................................................307 25.1.4. IDCODE Instruction ............................................................................................307 25.2.Flash Programming Commands ....................................................................................308 25.3.Debug Support...............................................................................................................312
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Notes
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
LIST OF FIGURES
1. SYSTEM OVERVIEW .........................................................................................................19 Figure 1.1. C8051F120/124 Block Diagram..........................................................................21 Figure 1.2. C8051F121/125 Block Diagram..........................................................................22 Figure 1.3. C8051F122/126 Block Diagram..........................................................................23 Figure 1.4. C8051F123/127 Block Diagram..........................................................................24 Figure 1.5. On-Board Clock and Reset..................................................................................26 Figure 1.6. On-Chip Memory Map ........................................................................................27 Figure 1.7. Development/In-System Debug Diagram ...........................................................28 Figure 1.8. Digital Crossbar Diagram....................................................................................29 Figure 1.9. PCA Block Diagram............................................................................................30 Figure 1.10. 12-Bit ADC Block Diagram................................................................................32 Figure 1.11. 8-Bit ADC Diagram ............................................................................................33 Figure 1.12. Comparator and DAC Diagram...........................................................................34 2. ABSOLUTE MAXIMUM RATINGS ..................................................................................35 3. GLOBAL DC ELECTRICAL CHARACTERISTICS ......................................................36 4. PINOUT AND PACKAGE DEFINITIONS........................................................................38 Figure 4.1. TQFP-100 Pinout Diagram..................................................................................43 Figure 4.2. TQFP-100 Package Drawing...............................................................................44 Figure 4.3. TQFP-64 Pinout Diagram....................................................................................45 Figure 4.4. TQFP-64 Package Drawing.................................................................................46 5. ADC0 (12-BIT ADC, C8051F120/1/4/5 ONLY) ..................................................................47 Figure 5.1. 12-Bit ADC0 Functional Block Diagram............................................................47 Figure 5.2. Typical Temperature Sensor Transfer Function..................................................48 Figure 5.3. ADC0 Track and Conversion Example Timing ..................................................50 Figure 5.4. ADC0 Equivalent Input Circuits .........................................................................51 Figure 5.5. AMX0CF: AMUX0 Configuration Register.......................................................52 Figure 5.6. AMX0SL: AMUX0 Channel Select Register .....................................................53 Figure 5.7. ADC0CF: ADC0 Configuration Register ...........................................................54 Figure 5.8. ADC0CN: ADC0 Control Register .....................................................................55 Figure 5.9. ADC0H: ADC0 Data Word MSB Register.........................................................56 Figure 5.10. ADC0L: ADC0 Data Word LSB Register ..........................................................56 Figure 5.11. ADC0 Data Word Example.................................................................................57 Figure 5.12. ADC0GTH: ADC0 Greater-Than Data High Byte Register...............................58 Figure 5.13. ADC0GTL: ADC0 Greater-Than Data Low Byte Register ................................58 Figure 5.14. ADC0LTH: ADC0 Less-Than Data High Byte Register ....................................59 Figure 5.15. ADC0LTL: ADC0 Less-Than Data Low Byte Register .....................................59 Figure 5.16. 12-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data .60 Figure 5.17. 12-Bit ADC0 Window Interrupt Example: Right Justified Differential Data.....61 Figure 5.18. 12-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data....62 Figure 5.19. 12-Bit ADC0 Window Interrupt Example: Left Justified Differential Data.......63 6. ADC0 (10-BIT ADC, C8051F122/3/6/7 ONLY) ..................................................................65 Figure 6.1. 10-Bit ADC0 Functional Block Diagram............................................................65
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Figure 6.2. Typical Temperature Sensor Transfer Function..................................................66 Figure 6.3. ADC0 Track and Conversion Example Timing ..................................................68 Figure 6.4. ADC0 Equivalent Input Circuits .........................................................................69 Figure 6.5. AMX0CF: AMUX0 Configuration Register.......................................................70 Figure 6.6. AMX0SL: AMUX0 Channel Select Register .....................................................71 Figure 6.7. ADC0CF: ADC0 Configuration Register ...........................................................72 Figure 6.8. ADC0CN: ADC0 Control Register .....................................................................73 Figure 6.9. ADC0H: ADC0 Data Word MSB Register.........................................................74 Figure 6.10. ADC0L: ADC0 Data Word LSB Register ..........................................................74 Figure 6.11. ADC0 Data Word Example.................................................................................75 Figure 6.12. ADC0GTH: ADC0 Greater-Than Data High Byte Register...............................76 Figure 6.13. ADC0GTL: ADC0 Greater-Than Data Low Byte Register ................................76 Figure 6.14. ADC0LTH: ADC0 Less-Than Data High Byte Register ....................................77 Figure 6.15. ADC0LTL: ADC0 Less-Than Data Low Byte Register .....................................77 Figure 6.16. 10-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data .78 Figure 6.17. 10-Bit ADC0 Window Interrupt Example: Right Justified Differential Data.....79 Figure 6.18. 10-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data....80 Figure 6.19. 10-Bit ADC0 Window Interrupt Example: Left Justified Differential Data.......81 7. ADC2 (8-BIT ADC) ...............................................................................................................83 Figure 7.1. ADC2 Functional Block Diagram .......................................................................83 Figure 7.2. ADC2 Track and Conversion Example Timing ..................................................85 Figure 7.3. ADC2 Equivalent Input Circuit...........................................................................86 Figure 7.4. AMX2CF: AMUX2 Configuration Register.......................................................87 Figure 7.5. AMX2SL: AMUX2 Channel Select Register .....................................................88 Figure 7.6. ADC2CF: ADC2 Configuration Register ...........................................................89 Figure 7.7. ADC2CN: ADC2 Control Register .....................................................................90 Figure 7.8. ADC2: ADC2 Data Word Register .....................................................................91 Figure 7.9. ADC2 Data Word Example.................................................................................91 Figure 7.10. ADC2 Window Compare Examples, Single-Ended Mode .................................92 Figure 7.11. ADC2 Window Compare Examples, Differential Mode ....................................93 Figure 7.12. ADC2GT: ADC2 Greater-Than Data Byte Register...........................................94 Figure 7.13. ADC2LT: ADC2 Less-Than Data Byte Register................................................94 8. DACS, 12-BIT VOLTAGE MODE ......................................................................................97 Figure 8.1. DAC Functional Block Diagram .........................................................................97 Figure 8.2. DAC0H: DAC0 High Byte Register ...................................................................99 Figure 8.3. DAC0L: DAC0 Low Byte Register ....................................................................99 Figure 8.4. DAC0CN: DAC0 Control Register ...................................................................100 Figure 8.5. DAC1H: DAC1 High Byte Register .................................................................101 Figure 8.6. DAC1L: DAC1 Low Byte Register ..................................................................101 Figure 8.7. DAC1CN: DAC1 Control Register ...................................................................102 9. VOLTAGE REFERENCE (C8051F120/2/4/6) .................................................................105 Figure 9.1. Voltage Reference Functional Block Diagram..................................................105 Figure 9.2. REF0CN: Reference Control Register ..............................................................106 10. VOLTAGE REFERENCE (C8051F121/3/5/7) .................................................................107 Figure 10.1. Voltage Reference Functional Block Diagram .................................................107
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Figure 10.2. REF0CN: Reference Control Register ..............................................................108 11. COMPARATORS................................................................................................................109 Figure 11.1. Comparator Functional Block Diagram ............................................................109 Figure 11.2. Comparator Hysteresis Plot...............................................................................111 Figure 11.3. CPT0CN: Comparator0 Control Register .........................................................112 Figure 11.4. CPT0MD: Comparator0 Mode Selection Register ...........................................113 Figure 11.5. CPT1CN: Comparator1 Control Register .........................................................114 Figure 11.6. CPT1MD: Comparator1 Mode Selection Register ...........................................115 12. CIP-51 MICROCONTROLLER........................................................................................117 Figure 12.1. CIP-51 Block Diagram .....................................................................................117 Figure 12.2. Memory Map .....................................................................................................123 Figure 12.3. PSBANK: Program Space Bank Select Register ..............................................124 Figure 12.4. Address Memory Map for Instruction Fetches..................................................124 Figure 12.5. SFR Page Stack .................................................................................................127 Figure 12.6. SFR Page Stack While Using SFR Page 0x0F To Access Port 5 .....................128 Figure 12.7. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs ..............129 Figure 12.8. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR...........130 Figure 12.9. SFR Page Stack Upon Return From PCA Interrupt ..........................................131 Figure 12.10. SFR Page Stack Upon Return From ADC2 Window Interrupt.......................132 Figure 12.11. SFRPGCN: SFR Page Control Register..........................................................133 Figure 12.12. SFRPAGE: SFR Page Register .......................................................................133 Figure 12.13. SFRNEXT: SFR Next Register .......................................................................134 Figure 12.14. SFRLAST: SFR Last Register ........................................................................134 Figure 12.15. SP: Stack Pointer .............................................................................................141 Figure 12.16. DPL: Data Pointer Low Byte ..........................................................................141 Figure 12.17. DPH: Data Pointer High Byte .........................................................................141 Figure 12.18. PSW: Program Status Word ............................................................................142 Figure 12.19. ACC: Accumulator..........................................................................................143 Figure 12.20. B: B Register ...................................................................................................143 Figure 12.21. IE: Interrupt Enable .........................................................................................147 Figure 12.22. IP: Interrupt Priority ........................................................................................148 Figure 12.23. EIE1: Extended Interrupt Enable 1 .................................................................149 Figure 12.24. EIE2: Extended Interrupt Enable 2 .................................................................150 Figure 12.25. EIP1: Extended Interrupt Priority 1.................................................................151 Figure 12.26. EIP2: Extended Interrupt Priority 2.................................................................152 Figure 12.27. PCON: Power Control.....................................................................................154 13. RESET SOURCES ..............................................................................................................155 Figure 13.1. Reset Sources ....................................................................................................155 Figure 13.2. Reset Timing .....................................................................................................156 Figure 13.3. WDTCN: Watchdog Timer Control Register ...................................................158 Figure 13.4. RSTSRC: Reset Source Register.......................................................................159 14. OSCILLATORS...................................................................................................................161 Figure 14.1. Oscillator Diagram ............................................................................................161 Figure 14.2. OSCICL: Internal Oscillator Calibration Register ............................................162 Figure 14.3. OSCICN: Internal Oscillator Control Register .................................................162
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Preliminary
Figure 14.4. CLKSEL: System Clock Selection Register .....................................................164 Figure 14.5. OSCXCN: External Oscillator Control Register...............................................165 Figure 14.6. PLL Block Diagram ..........................................................................................167 Figure 14.7. PLL0CN: PLL Control Register........................................................................169 Figure 14.8. PLL0DIV: PLL Pre-divider Register ................................................................169 Figure 14.9. PLL0MUL: PLL Clock Scaler Register ............................................................170 Figure 14.10. PLL0FLT: PLL Filter Register........................................................................170 15. FLASH MEMORY ..............................................................................................................173 Figure 15.1. FLASH Memory Map for MOVC Read and MOVX Write Operations...........174 Figure 15.2. FLASH Program Memory Map and Security Bytes .........................................177 Figure 15.3. FLACL: FLASH Access Limit .........................................................................178 Figure 15.4. FLSCL: FLASH Memory Control ....................................................................179 Figure 15.5. PSCTL: Program Store Read/Write Control .....................................................180 16. BRANCH TARGET CACHE.............................................................................................181 Figure 16.1. Branch Target Cache Data Flow .......................................................................181 Figure 16.2. Branch Target Cache Organiztion .....................................................................182 Figure 16.3. Cache Lock Operation.......................................................................................183 Figure 16.4. CCH0CN: Cache Control Register....................................................................184 Figure 16.5. CCH0TN: Cache Tuning Register ....................................................................185 Figure 16.6. CCH0LC: Cache Lock Control Register...........................................................185 Figure 16.7. CCH0MA: Cache Miss Accumulator................................................................186 Figure 16.8. FLSTAT: FLASH Status...................................................................................186 17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM.......................187 Figure 17.1. EMI0CN: External Memory Interface Control .................................................189 Figure 17.2. EMI0CF: External Memory Configuration .......................................................189 Figure 17.3. Multiplexed Configuration Example.................................................................190 Figure 17.4. Non-multiplexed Configuration Example .........................................................191 Figure 17.5. EMIF Operating Modes.....................................................................................192 Figure 17.6. EMI0TC: External Memory Timing Control ....................................................194 Figure 17.7. Non-multiplexed 16-bit MOVX Timing ...........................................................195 Figure 17.8. Non-multiplexed 8-bit MOVX without Bank Select Timing............................196 Figure 17.9. Non-multiplexed 8-bit MOVX with Bank Select Timing.................................197 Figure 17.10. Multiplexed 16-bit MOVX Timing .................................................................198 Figure 17.11. Multiplexed 8-bit MOVX without Bank Select Timing .................................199 Figure 17.12. Multiplexed 8-bit MOVX with Bank Select Timing.......................................200 18. PORT INPUT/OUTPUT .....................................................................................................203 Figure 18.1. Port I/O Cell Block Diagram.............................................................................203 Figure 18.2. Port I/O Functional Block Diagram ..................................................................204 Figure 18.3. Priority Crossbar Decode Table ........................................................................205 Figure 18.4. Priority Crossbar Decode Table ........................................................................208 Figure 18.5. Priority Crossbar Decode Table ........................................................................209 Figure 18.6. Crossbar Example: ............................................................................................211 Figure 18.7. XBR0: Port I/O Crossbar Register 0 .................................................................212 Figure 18.8. XBR1: Port I/O Crossbar Register 1 .................................................................213 Figure 18.9. XBR2: Port I/O Crossbar Register 2 .................................................................214
Page 12 DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Figure 18.10. P0: Port0 Data Register ...................................................................................215 Figure 18.11. P0MDOUT: Port0 Output Mode Register.......................................................215 Figure 18.12. P1: Port1 Data Register ...................................................................................216 Figure 18.13. P1MDIN: Port1 Input Mode Register .............................................................216 Figure 18.14. P1MDOUT: Port1 Output Mode Register.......................................................217 Figure 18.15. P2: Port2 Data Register ...................................................................................217 Figure 18.16. P2MDOUT: Port2 Output Mode Register.......................................................218 Figure 18.17. P3: Port3 Data Register ...................................................................................218 Figure 18.18. P3MDOUT: Port3 Output Mode Register.......................................................219 Figure 18.19. P4: Port4 Data Register ...................................................................................221 Figure 18.20. P4MDOUT: Port4 Output Mode Register.......................................................221 Figure 18.21. P5: Port5 Data Register ...................................................................................222 Figure 18.22. P5MDOUT: Port5 Output Mode Register.......................................................222 Figure 18.23. P6: Port6 Data Register ...................................................................................223 Figure 18.24. P6MDOUT: Port6 Output Mode Register.......................................................223 Figure 18.25. P7: Port7 Data Register ...................................................................................224 Figure 18.26. P7MDOUT: Port7 Output Mode Register.......................................................224 19. SYSTEM MANAGEMENT BUS / I2C BUS (SMBUS0) .................................................225 Figure 19.1. SMBus0 Block Diagram ...................................................................................225 Figure 19.2. Typical SMBus Configuration ..........................................................................226 Figure 19.3. SMBus Transaction ...........................................................................................227 Figure 19.4. Typical Master Transmitter Sequence...............................................................229 Figure 19.5. Typical Master Receiver Sequence ...................................................................229 Figure 19.6. Typical Slave Transmitter Sequence .................................................................230 Figure 19.7. Typical Slave Receiver Sequence .....................................................................230 Figure 19.8. SMB0CN: SMBus0 Control Register ...............................................................232 Figure 19.9. SMB0CR: SMBus0 Clock Rate Register..........................................................233 Figure 19.10. SMB0DAT: SMBus0 Data Register ...............................................................234 Figure 19.11. SMB0ADR: SMBus0 Address Register..........................................................234 Figure 19.12. SMB0STA: SMBus0 Status Register..............................................................235 20. ENHANCED SERIAL PERIPHERAL INTERFACE (SPI0) .........................................239 Figure 20.1. SPI Block Diagram............................................................................................239 Figure 20.2. Multiple-Master Mode Connection Diagram ....................................................242 Figure 20.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram ...242 Figure 20.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram ....242 Figure 20.5. Data/Clock Timing Diagram .............................................................................245 Figure 20.6. SPI0CFG: SPI0 Configuration Register............................................................246 Figure 20.7. SPI0CN: SPI0 Control Register ........................................................................247 Figure 20.8. SPI0CKR: SPI0 Clock Rate Register ................................................................248 Figure 20.9. SPI0DAT: SPI0 Data Register ..........................................................................249 Figure 20.10. SPI Slave Timing (Mode 0 and Mode 2) ........................................................250 Figure 20.11. SPI Slave Timing (Mode 1 and Mode 3) ........................................................250 21. UART0 ..................................................................................................................................253 Figure 21.1. UART0 Block Diagram.....................................................................................253 Figure 21.2. UART0 Mode 0 Timing Diagram .....................................................................254
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Preliminary
Figure 21.3. UART0 Mode 0 Interconnect............................................................................254 Figure 21.4. UART0 Mode 1 Timing Diagram .....................................................................255 Figure 21.5. UART0 Modes 2 and 3 Timing Diagram..........................................................256 Figure 21.6. UART0 Modes 1, 2, and 3 Interconnect Diagram ............................................257 Figure 21.7. UART Multi-Processor Mode Interconnect Diagram .......................................259 Figure 21.8. SCON0: UART0 Control Register....................................................................261 Figure 21.9. SSTA0: UART0 Status and Clock Selection Register ......................................262 Figure 21.10. SBUF0: UART0 Data Buffer Register............................................................263 Figure 21.11. SADDR0: UART0 Slave Address Register ....................................................263 Figure 21.12. SADEN0: UART0 Slave Address Enable Register ........................................263 22. UART1 ..................................................................................................................................265 Figure 22.1. UART1 Block Diagram.....................................................................................265 Figure 22.2. UART1 Baud Rate Logic ..................................................................................266 Figure 22.3. UART Interconnect Diagram ............................................................................267 Figure 22.4. 8-Bit UART Timing Diagram ...........................................................................267 Figure 22.5. 9-Bit UART Timing Diagram ...........................................................................268 Figure 22.6. UART Multi-Processor Mode Interconnect Diagram .......................................269 Figure 22.7. SCON1: Serial Port 1 Control Register.............................................................270 Figure 22.8. SBUF1: Serial (UART1) Port Data Buffer Register .........................................271 23. TIMERS................................................................................................................................275 Figure 23.1. T0 Mode 0 Block Diagram................................................................................276 Figure 23.2. T0 Mode 2 Block Diagram................................................................................277 Figure 23.3. T0 Mode 3 Block Diagram................................................................................278 Figure 23.4. TCON: Timer Control Register.........................................................................279 Figure 23.5. TMOD: Timer Mode Register...........................................................................280 Figure 23.6. CKCON: Clock Control Register......................................................................281 Figure 23.7. TL0: Timer 0 Low Byte ....................................................................................282 Figure 23.8. TL1: Timer 1 Low Byte ....................................................................................282 Figure 23.9. TH0: Timer 0 High Byte ...................................................................................282 Figure 23.10. TH1: Timer 1 High Byte .................................................................................282 Figure 23.11. T2, 3, and 4 Capture Mode Block Diagram ....................................................284 Figure 23.12. T2, 3, and 4 Auto-reload Mode Block Diagram..............................................285 Figure 23.13. TMRnCN: Timer 2, 3, and 4 Control Registers ..............................................287 Figure 23.14. TMRnCF: Timer 2, 3, and 4 Configuration Registers ....................................288 Figure 23.15. RCAPnL: Timer 2, 3, and 4 Capture Register Low Byte................................289 Figure 23.16. RCAPnH: Timer 2, 3, and 4 Capture Register High Byte ..............................289 Figure 23.17. TMRnL: Timer 2, 3, and 4 Low Byte .............................................................289 Figure 23.18. TMRnH Timer 2, 3, and 4 High Byte .............................................................290 24. PROGRAMMABLE COUNTER ARRAY .......................................................................291 Figure 24.1. PCA Block Diagram..........................................................................................291 Figure 24.2. PCA Counter/Timer Block Diagram .................................................................292 Figure 24.3. PCA Interrupt Block Diagram...........................................................................293 Figure 24.4. PCA Capture Mode Diagram ............................................................................294 Figure 24.5. PCA Software Timer Mode Diagram................................................................295 Figure 24.6. PCA High Speed Output Mode Diagram ..........................................................296
Page 14 DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Figure 24.7. PCA Frequency Output Mode ...........................................................................297 Figure 24.8. PCA 8-Bit PWM Mode Diagram ......................................................................298 Figure 24.9. PCA 16-Bit PWM Mode ...................................................................................299 Figure 24.10. PCA0CN: PCA Control Register ....................................................................300 Figure 24.11. PCA0MD: PCA0 Mode Register ....................................................................301 Figure 24.12. PCA0CPMn: PCA0 Capture/Compare Mode Registers .................................302 Figure 24.13. PCA0L: PCA0 Counter/Timer Low Byte .......................................................303 Figure 24.14. PCA0H: PCA0 Counter/Timer High Byte ......................................................303 Figure 24.15. PCA0CPLn: PCA0 Capture Module Low Byte ..............................................304 Figure 24.16. PCA0CPHn: PCA0 Capture Module High Byte .............................................304 25. JTAG (IEEE 1149.1)............................................................................................................305 Figure 25.1. IR: JTAG Instruction Register ..........................................................................305 Figure 25.2. DEVICEID: JTAG Device ID Register ............................................................307 Figure 25.3. FLASHCON: JTAG Flash Control Register.....................................................309 Figure 25.4. FLASHDAT: JTAG Flash Data Register..........................................................310 Figure 25.5. FLASHADR: JTAG Flash Address Register ....................................................310 Figure 25.6. FLASHSCL: JTAG Flash Scale Register .........................................................311
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
Notes
Page 16
DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
LIST OF TABLES
1. SYSTEM OVERVIEW ........................................................................................................19 Table 1.1. Product Selection Guide .......................................................................................20 2. ABSOLUTE MAXIMUM RATINGS .................................................................................35 Table 2.1. Absolute Maximum Ratings* ...............................................................................35 3. GLOBAL DC ELECTRICAL CHARACTERISTICS .....................................................36 Table 3.1. Global DC Electrical Characteristics (C8051F120/1/2/3) ....................................36 Table 3.2. Global DC Electrical Characteristics (C8051F124/5/6/7) ....................................37 4. PINOUT AND PACKAGE DEFINITIONS .......................................................................38 Table 4.1. Pin Definitions ......................................................................................................38 5. ADC0 (12-BIT ADC, C8051F120/1/4/5 ONLY) .................................................................47 Table 5.1. 12-Bit ADC0 Electrical Characteristics (C8051F120/1/4/5) ................................64 6. ADC0 (10-BIT ADC, C8051F122/3/6/7 ONLY) .................................................................65 Table 6.1. 10-Bit ADC0 Electrical Characteristics (C8051F122/3/6/7) ................................82 7. ADC2 (8-BIT ADC) ..............................................................................................................83 Table 7.1. ADC2 Electrical Characteristics ...........................................................................95 8. DACS, 12-BIT VOLTAGE MODE .....................................................................................97 Table 8.1. DAC Electrical Characteristics ...........................................................................103 9. VOLTAGE REFERENCE (C8051F120/2/4/6) ................................................................105 Table 9.1. Voltage Reference Electrical Characteristics .....................................................106 10. VOLTAGE REFERENCE (C8051F121/3/5/7) ................................................................107 Table 10.1.Voltage Reference Electrical Characteristics .....................................................108 11. COMPARATORS ...............................................................................................................109 Table 11.1.Comparator Electrical Characteristics ................................................................116 12. CIP-51 MICROCONTROLLER .......................................................................................117 Table 12.1.CIP-51 Instruction Set Summary ........................................................................119 Table 12.2.Special Function Register (SFR) Memory Map .................................................135 Table 12.3.Special Function Registers .................................................................................137 Table 12.4.Interrupt Summary ..............................................................................................145 13. RESET SOURCES .............................................................................................................155 Table 13.1.Reset Electrical Characteristics ..........................................................................160 14. OSCILLATORS ..................................................................................................................161 Table 14.1.Internal Oscillator Electrical Characteristics ......................................................163 Table 14.2.PLL Frequency Characteristics ...........................................................................171 Table 14.3.PLL Lock Timing Characteristics ......................................................................171 15. FLASH MEMORY .............................................................................................................173 Table 15.1.FLASH Electrical Characteristics .......................................................................176 16. BRANCH TARGET CACHE ............................................................................................181 17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM ......................187 Table 17.1.AC Parameters for External Memory Interface ..................................................201 18. PORT INPUT/OUTPUT ....................................................................................................203 Table 18.1.Port I/O DC Electrical Characteristics ................................................................203 19. SYSTEM MANAGEMENT BUS / I2C BUS (SMBUS0) ................................................225
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
Table 19.1.SMB0STA Status Codes and States ...................................................................236 20. ENHANCED SERIAL PERIPHERAL INTERFACE (SPI0) ........................................239 Table 20.1.SPI Slave Timing Parameters .............................................................................251 21. UART0 .................................................................................................................................253 Table 21.1.UART0 Modes ....................................................................................................254 Table 21.2.Oscillator Frequencies for Standard Baud Rates ................................................260 22. UART1 .................................................................................................................................265 Table 22.1.Timer Settings for Standard Baud Rates Using The Internal Oscillator ............272 Table 22.2.Timer Settings for Standard Baud Rates Using an External Oscillator ..............272 Table 22.3.Timer Settings for Standard Baud Rates Using an External Oscillator ..............273 Table 22.4.Timer Settings for Standard Baud Rates Using the PLL ....................................273 Table 22.5.Timer Settings for Standard Baud Rates Using the PLL ....................................274 23. TIMERS ...............................................................................................................................275 24. PROGRAMMABLE COUNTER ARRAY ......................................................................291 Table 24.1.PCA Timebase Input Options .............................................................................292 Table 24.2.PCA0CPM Register Settings for PCA Capture/Compare Modules ...................293 25. JTAG (IEEE 1149.1) ...........................................................................................................305 Table 25.1.Boundary Data Register Bit Definitions .............................................................306
Page 18
DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
1.
SYSTEM OVERVIEW
The C8051F12x devices are fully integrated mixed-signal System-on-a-Chip MCUs with 64 digital I/O pins (C8051F120/2/4/6) or 32 digital I/O pins (C8051F121/3/5/7). Highlighted features are listed below; refer to Table 1.1 for specific product feature selection. * * * * * * * * * * * * High-Speed pipelined 8051-compatible CIP-51 microcontroller core (up to 100 MIPS for C8051F120/1/2/3 and 50 MIPS for C8051F124/5/6/7) In-system, full-speed, non-intrusive debug interface (on-chip) True 12-bit (C8051F120/1/4/5) or 10-bit (C8051F122/3/6/7) 100 ksps ADC with PGA and 8-channel analog multiplexer True 8-bit 500 ksps ADC with PGA and 8-channel analog multiplexer Two 12-bit DACs with programmable update scheduling 128k bytes of in-system programmable FLASH memory 8448 (8k + 256) bytes of on-chip RAM External Data Memory Interface with 64k byte address space SPI, SMBus/I2C, and (2) UART serial interfaces implemented in hardware Five general purpose 16-bit Timers Programmable Counter/Timer Array with 6 capture/compare modules On-chip Watchdog Timer, VDD Monitor, and Temperature Sensor
With on-chip VDD monitor, Watchdog Timer, and clock oscillator, the C8051F12x devices are truly stand-alone System-on-a-Chip solutions. All analog and digital peripherals are enabled/disabled and configured by user firmware. The FLASH memory can be reprogrammed even in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. On-board JTAG debug circuitry allows non-intrusive (uses no on-chip resources), full speed, in-circuit debugging using the production MCU installed in the final application. This debug system supports inspection and modification of memory and registers, setting breakpoints, watchpoints, single stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging using JTAG. Each MCU is specified for 2.7 V-to-3.6 V operation over the industrial temperature range (-45 C to +85 C). The Port I/Os, /RST, and JTAG pins are tolerant for input signals up to 5 V. The C8051F120/2/4/6 are available in a 100pin TQFP package (see block diagrams in Figure 1.1 and Figure 1.3). The C8051F121/3/5/7 are available in a 64-pin TQFP package (see block diagrams in Figure 1.2 and Figure 1.4).
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Preliminary
Table 1.1. Product Selection Guide
Programmable Counter Array 12-bit 100ksps ADC Inputs 10-bit 100ksps ADC Inputs External Memory Interface 8-bit 500ksps ADC Inputs DAC Resolution (bits) Analog Comparators 2 2 2 2 Temperature Sensor
Voltage Reference
Digital Port I/O's
FLASH Memory
Timers (16-bit)
DAC Outputs
MIPS (Peak)
SMBus/I2C
C8051F120 100 128k 8448 ! C8051F121 100 128k 8448 ! C8051F122 100 128k 8448 ! C8051F123 100 128k 8448 ! C8051F124 C8051F125 C8051F126 C8051F127 50 50 50 50 128k 8448 ! 128k 8448 ! 128k 8448 ! 128k 8448 !
!! !! !! !! !! !! !! !!
2 2 2 2 2 2 2 2
5 5 5 5 5 5 5 5
! ! ! ! ! ! ! !
64 32 64 32 64 32 64 32
8 8 8 8 -
8 8 8 8
8 8 8 8 8 8 8 8
!! !! !! !! !! !! !! !!
12 12 12 12 12 12 12 12
2 2 2 2 2 2 2 2
2 100TQFP 64TQFP
2 100TQFP 64TQFP
2 100TQFP 64TQFP
2 100TQFP 64TQFP
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Package
UARTS
RAM
SPI
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Figure 1.1. C8051F120/124 Block Diagram
VDD VDD VDD DGND DGND DGND AV+ AV+ AGND AGND TCK TMS TDI TDO /RST
Digital Power
Port I/O Config. UART0 P0 Drv
P0.0 P0.7
SFR Bus
Analog Power
UART1 SMBus
JTAG Logic
Boundary Scan Debug HW
Reset
MONEN
VDD Monitor
WDT
8 0 5 1 C o r e
SPI Bus
256 byte RAM 8kbyte XRAM
PCA Timers 0, 1, 2, 4 Timer 3/ RTC P0, P1, P2, P3 Latches Crossbar Config.
C R O S S B A R
P1 Drv
P1.0/AIN2.0 P1.7/AIN2.7
P2 Drv
P2.0 P2.7
XTAL1 XTAL2
External Oscillator Circuit PLL Circuitry Calibrated Internal Oscillator
System Clock
External Data Memory Bus
P3 Drv
P3.0 P3.7
128kbyte FLASH
VREF2
VREF VREFD DAC1
VREF
ADC 500ksps (8-Bit)
Prog Gain
A M U X
8:1
DAC1 (12-Bit) DAC0 (12-Bit)
64x4 byte cache
P4.0
Bus Control
DAC0 VREF0 AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 CP0+
CP0
C T L
P4 Latch
P4 DRV
P4.4 P4.5/ALE P4.6/RD P4.7/WR P5.0/A8 P5.7/A15 P6.0/A0 P6.7/A7
A M U X
Prog Gain
ADC 100ksps (12-Bit)
Address Bus
A d d r
P5 Latch P6 Latch
P5 DRV P6 DRV
TEMP SENSOR
Data Bus
CP0CP1+
CP1
D a t a
P7 Latch
P7 DRV
P7.0/D0 P7.7/D7
CP1-
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Preliminary
Figure 1.2. C8051F121/125 Block Diagram
VDD VDD VDD DGND DGND DGND AV+ AGND TCK TMS TDI TDO /RST
Digital Power
Port I/O Config. UART0 P0 Drv
P0.0 P0.7
SFR Bus
Analog Power
UART1 SMBus
JTAG Logic
Boundary Scan Debug HW
Reset
MONEN
VDD Monitor
WDT
8 0 5 1 C o r e
SPI Bus
256 byte RAM 8kbyte XRAM
PCA Timers 0, 1, 2, 4 Timer 3/ RTC P0, P1, P2, P3 Latches Crossbar Config.
C R O S S B A R
P1 Drv
P1.0/AIN2.0 P1.7/AIN2.7
P2 Drv
P2.0 P2.7
XTAL1 XTAL2
External Oscillator Circuit PLL Circuitry Calibrated Internal Oscillator
System Clock
External Data Memory Bus
P3 Drv
P3.0 P3.7
128kbyte FLASH
VREF
VREF
ADC 500ksps (8-Bit)
Prog Gain
A M 8:1 U X
AV+ VREFA
DAC1
DAC1 (12-Bit) DAC0 (12-Bit)
64x4 byte cache
Bus Control
DAC0 VREFA AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 CP0+ CP0CP1+ CP1-
C T L
P4 Latch
P4 DRV
A M U X
Prog Gain
ADC 100ksps (12-Bit)
Address Bus
A d d r
P5 Latch P6 Latch
P5 DRV P6 DRV
TEMP SENSOR
Data Bus
CP0
D a t a
P7 Latch
P7 DRV
CP1
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Figure 1.3. C8051F122/126 Block Diagram
VDD VDD VDD DGND DGND DGND AV+ AV+ AGND AGND TCK TMS TDI TDO /RST
Digital Power
Port I/O Config. UART0 P0 Drv
P0.0 P0.7
SFR Bus
Analog Power
UART1 SMBus
JTAG Logic
Boundary Scan Debug HW
Reset
MONEN
VDD Monitor
WDT
8 0 5 1 C o r e
SPI Bus
256 byte RAM 8kbyte XRAM
PCA Timers 0, 1, 2, 4 Timer 3/ RTC P0, P1, P2, P3 Latches Crossbar Config.
C R O S S B A R
P1 Drv
P1.0/AIN2.0 P1.7/AIN2.7
P2 Drv
P2.0 P2.7
XTAL1 XTAL2
External Oscillator Circuit PLL Circuitry Calibrated Internal Oscillator
System Clock
External Data Memory Bus
P3 Drv
P3.0 P3.7
128kbyte FLASH
VREF2
VREF VREFD DAC1
VREF
ADC 500ksps (8-Bit)
Prog Gain
A M U X
8:1
DAC1 (12-Bit) DAC0 (12-Bit)
64x4 byte cache
P4.0
Bus Control
DAC0 VREF0 AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 CP0+
CP0
C T L
P4 Latch
P4 DRV
P4.4 P4.5/ALE P4.6/RD P4.7/WR P5.0/A8 P5.7/A15 P6.0/A0 P6.7/A7
A M U X
Prog Gain
ADC 100ksps (10-Bit)
Address Bus
A d d r
P5 Latch P6 Latch
P5 DRV P6 DRV
TEMP SENSOR
Data Bus
CP0CP1+
CP1
D a t a
P7 Latch
P7 DRV
P7.0/D0 P7.7/D7
CP1-
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
Figure 1.4. C8051F123/127 Block Diagram
VDD VDD VDD DGND DGND DGND AV+ AGND TCK TMS TDI TDO /RST
Digital Power
Port I/O Config. UART0 P0 Drv
P0.0 P0.7
SFR Bus
Analog Power
UART1 SMBus
JTAG Logic
Boundary Scan Debug HW
Reset
MONEN
VDD Monitor
WDT
8 0 5 1 C o r e
SPI Bus
256 byte RAM 8kbyte XRAM
PCA Timers 0, 1, 2, 4 Timer 3/ RTC P0, P1, P2, P3 Latches Crossbar Config.
C R O S S B A R
P1 Drv
P1.0/AIN2.0 P1.7/AIN2.7
P2 Drv
P2.0 P2.7
XTAL1 XTAL2
External Oscillator Circuit PLL Circuitry Calibrated Internal Oscillator
System Clock
External Data Memory Bus
P3 Drv
P3.0 P3.7
128kbyte FLASH
VREF
VREF
ADC 500ksps (8-Bit)
Prog Gain
A M 8:1 U X
AV+ VREFA
DAC1
DAC1 (12-Bit) DAC0 (12-Bit)
64x4 byte cache
Bus Control
DAC0 VREFA AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 CP0+ CP0CP1+ CP1-
C T L
P4 Latch
P4 DRV
A M U X
Prog Gain
ADC 100ksps (10-Bit)
Address Bus
A d d r
P5 Latch P6 Latch
P5 DRV P6 DRV
TEMP SENSOR
Data Bus
CP0
D a t a
P7 Latch
P7 DRV
CP1
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
1.1.
1.1.1.
CIP-51TM Microcontroller Core
Fully 8051 Compatible
The C8051F12x family utilizes Cygnal's proprietary CIP-51 microcontroller core. The CIP-51 is fully compatible with the MCS-51TM instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The core has all the peripherals included with a standard 8052, including five 16-bit counter/timers, two full-duplex UARTs, 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space, and 8/4 byte-wide I/O Ports.
1.1.2.
Improved Throughput
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than four system clock cycles. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute Number of Instructions 1 26 2 50 2/3 5 3 14 3/4 7 4 3 4/5 1 5 2 8 1
With the CIP-51's maximum system clock at 100 MHz, the C8051F120/1/2/3 have a peak throughput of 100 MIPS (the C8051F124/5/6/7 have a peak throughput of 50 MIPS).
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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1.1.3. Additional Features
Preliminary
The C8051F12x MCU family includes several key enhancements to the CIP-51 core and peripherals to improve overall performance and ease of use in end applications. The extended interrupt handler provides 20 interrupt sources into the CIP-51 (as opposed to 7 for the standard 8051), allowing the numerous analog and digital peripherals to interrupt the controller. An interrupt driven system requires less intervention by the MCU, giving it more effective throughput. The extra interrupt sources are very useful when building multi-tasking, real-time systems. There are up to seven reset sources for the MCU: an on-board VDD monitor, a Watchdog Timer, a missing clock detector, a voltage level detection from Comparator0, a forced software reset, the CNVSTR0 input pin, and the /RST pin. The /RST pin is bi-directional, accommodating an external reset, or allowing the internally generated POR to be output on the /RST pin. Each reset source except for the VDD monitor and Reset Input pin may be disabled by the user in software; the VDD monitor is enabled/disabled via the MONEN pin. The Watchdog Timer may be permanently enabled in software after a power-on reset during MCU initialization. The MCU has an internal, stand alone clock generator which is used by default as the system clock after any reset. If desired, the clock source may be switched on the fly to the external oscillator, which can use a crystal, ceramic resonator, capacitor, RC, or external clock source to generate the system clock. This can be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) external crystal source, while periodically switching to the 24.5 MHz internal oscillator as needed. Additionally, an on-chip PLL is provided to achieve higher system clock speeds for increased throughput.
Figure 1.5. On-Board Clock and Reset
VDD
(Port I/O)
CNVSTR Crossbar
(CNVSTR reset enable)
Supply Monitor
+ Supply Reset Timeout (wired-OR)
/RST
CP0+ CP0-
Comparator0
+ (CP0 reset enable)
Missing Clock Detector (oneshot)
EN
WDT
Reset Funnel
EN
MCD Enable
WDT Enable
PLL Circuitry
System Clock
XTAL1
OSC Clock Select
CIP-51 Microcontroller Core
Extended Interrupt Handler
XTAL2
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WDT Strobe Software Reset System Reset
Internal Clock Generator
PRE
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
1.2.
On-Chip Memory
The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of general purpose registers, and the next 16 bytes can be byte addressable or bit addressable. The CIP-51 in the C8051F12x MCUs additionally has an on-chip 8k byte RAM block and an external memory interface (EMIF) for accessing off-chip data memory. The on-chip 8k byte block can be addressed over the entire 64k external data memory address range (overlapping 8k boundaries). External data memory address space can be mapped to on-chip memory only, off-chip memory only, or a combination of the two (addresses up to 8k directed to on-chip, above 8k directed to EMIF). The EMIF is also configurable for multiplexed or non-multiplexed address/data lines. The MCU's program memory consists of 128k bytes of banked FLASH memory. This memory may be reprogrammed in-system in 1024 byte sectors, and requires no special off-chip programming voltage. The 1024 bytes from addresses 0x1FC00 to 0x1FFFF are reserved. There are also two 128 byte sectors at addresses 0x20000 to 0x200FF, which may be used by software. See Figure 1.6 for the MCU system memory map.
Figure 1.6. On-Chip Memory Map
PROGRAM/DATA MEMORY (FLASH)
0x200FF 0x20000 0x1FFFF 0x1FC00 0x1FBFF 0x30 0x2F 0x20 0x1F 0x00 Scrachpad Memory (DATA only) RESERVED 0xFF 0x80 0x7F
DATA MEMORY (RAM) INTERNAL DATA ADDRESS SPACE
Upper 128 RAM (Indirect Addressing Only) (Direct and Indirect Addressing) Special Function Registers (Direct Addressing Only)
0
1
2
3
FLASH (In-System Programmable in 1024 Byte Sectors)
Bit Addressable General Purpose Registers
Lower 128 RAM (Direct and Indirect Addressing)
Up To 256 SFR Pages
EXTERNAL DATA ADDRESS SPACE
0x00000 0xFFFF
Off-chip XRAM space
0x2000 0x1FFF 0x0000
XRAM - 8192 Bytes
(accessable using MOVX instruction)
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1.3.
Preliminary
JTAG Debug and Boundary Scan
The C8051F12x device family has on-chip JTAG boundary scan and debug circuitry that provides non-intrusive, full speed, in-circuit debugging using the production part installed in the end application, via the four-pin JTAG interface. The JTAG port is fully compliant to IEEE 1149.1, providing full boundary scan for test and manufacturing purposes. Cygnal's debugging system supports inspection and modification of memory and registers, breakpoints, watchpoints, a stack monitor, and single stepping. No additional target RAM, program memory, timers, or communications channels are required. All the digital and analog peripherals are functional and work correctly while debugging. All the peripherals (except for the ADC and SMBus) are stalled when the MCU is halted, during single stepping, or at a breakpoint in order to keep them synchronized. The C8051F120DK development kit provides all the hardware and software necessary to develop application code and perform in-circuit debugging with the C8051F12x MCUs. The kit includes software with a developer's studio and debugger, an integrated 8051 assembler, and an RS-232 to JTAG serial adapter. It also has a target application board with the associated MCU installed, plus the RS-232 and JTAG cables, and wall-mount power supply. The Development Kit requires a Windows 95/98/NT/ME computer with one available RS-232 serial port. As shown in Figure 1.7, the PC is connected via RS-232 to the Serial Adapter. A six-inch ribbon cable connects the Serial Adapter to the user's application board, picking up the four JTAG pins and VDD and GND. The Serial Adapter takes its power from the application board. For applications where there is not sufficient power available from the target system, the provided power supply can be connected directly to the Serial Adapter. Cygnal's debug environment is a vastly superior configuration for developing and debugging embedded applications compared to standard MCU emulators, which use on-board "ICE Chips" and target cables and require the MCU in the application board to be socketed. Cygnal's debug environment both increases ease of use and preserves the performance of the precision analog peripherals.
Figure 1.7. Development/In-System Debug Diagram
CYGNAL Integrated Development Environment WINDOWS 95/98/NT/ME/2000
RS-232
Serial Adapter
JTAG (x4), VDD, GND
VDD
GND
TARGET PCB
C8051 F12x
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1.4.
Programmable Digital I/O and Crossbar
The standard 8051 Ports (0, 1, 2, and 3) are available on the MCUs. The C8051F120/2/4/6 have 4 additional ports (4, 5, 6, and 7) for a total of 64 general-purpose port I/O. The Port I/O behave like the standard 8051 with a few enhancements. Each Port I/O pin can be configured as either a push-pull or open-drain output. Also, the "weak pull-ups" which are normally fixed on an 8051 can be globally disabled, providing additional power saving capabilities for low-power applications. Perhaps the most unique enhancement is the Digital Crossbar. This is a large digital switching network that allows mapping of internal digital system resources to Port I/O pins on P0, P1, P2, and P3. (See Figure 1.8) Unlike microcontrollers with standard multiplexed digital I/O, all combinations of functions are supported. The on-chip counter/timers, serial buses, HW interrupts, ADC Start of Conversion inputs, comparator outputs, and other digital signals in the controller can be configured to appear on the Port I/O pins specified in the Crossbar Control registers. This allows the user to select the exact mix of general purpose Port I/O and digital resources needed for the particular application.
Figure 1.8. Digital Crossbar Diagram
Highest Priority UART0 SPI SMBus UART1 (Internal Digital Signals) PCA Comptr. Outputs 2 4 2 2 7 2 XBR0, XBR1, XBR2, P1MDIN Registers P0MDOUT, P1MDOUT, P2MDOUT, P3MDOUT Registers External Pins P0.0 P0.7 Highest Priority
Priority Decoder
8 P0 I/O Cells
Digital Crossbar
8
T0, T1, T2, T2EX, T4,T4EX /INT0, /INT1
P1 I/O Cells
P1.0 P1.7
8 P2 I/O Cells P2.0 P2.7
8
Lowest Priority
/SYSCLK divided by 1,2,4, or 8 2 CNVSTR0/2 8 P0 (P0.0-P0.7) 8 P1 (P1.0-P1.7) 8 P2 (P2.0-P2.7) 8 P3 (P3.0-P3.7) To External Memory Interface (EMIF) 8 P3 I/O Cells
P3.0 P3.7 Lowest Priority
Port Latches
To ADC2 Input
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1.5.
Preliminary
Programmable Counter Array
The C8051F12x MCU family includes an on-board Programmable Counter/Timer Array (PCA) in addition to the five 16-bit general purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with 6 programmable capture/compare modules. The timebase is clocked from one of six sources: the system clock divided by 12, the system clock divided by 4, Timer 0 overflow, an External Clock Input (ECI pin), the system clock, or the external oscillator source divided by 8. Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit Pulse Width Modulator. The PCA Capture/Compare Module I/O and External Clock Input are routed to the MCU Port I/O via the Digital Crossbar.
Figure 1.9. PCA Block Diagram
SYSCLK/12 SYSCLK/4 Timer 0 Overflow ECI SYSCLK External Clock/8 PCA CLOCK MUX 16-Bit Counter/Timer
Capture/Compare Module 0
Capture/Compare Module 1
Capture/Compare Module 2
Capture/Compare Module 3
Capture/Compare Module 4
Capture/Compare Module 5
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
ECI
Crossbar
Port I/O
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1.6.
Serial Ports
The C8051F12x MCU Family includes two Enhanced Full-Duplex UARTs, SPI Bus, and SMBus/I2C. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's interrupts, thus requiring very little intervention by the CPU. The serial buses do not "share" resources such as timers, interrupts, or Port I/O, so any or all of the serial buses may be used together with any other.
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1.7.
Preliminary
12-Bit Analog to Digital Converter
The C8051F120/1/4/5 have an on-chip 12-bit SAR ADC (ADC0) with a 9-channel input multiplexer and programmable gain amplifier. With a maximum throughput of 100 ksps, the ADC offers true 12-bit linearity with an INL of 1LSB. C8051F122/3/6/7 devices include a 10-bit SAR ADC with similar specifications and configuration options. The ADC0 voltage reference is selected between the DAC0 output and an external VREF pin. On C8051F120/2/4/6 devices, ADC0 has its own dedicated VREF0 input pin; on C8051F121/3/5/7 devices, the ADC0 shares the VREFA input pin with the 8-bit ADC2. The on-chip 15 ppm/C voltage reference may generate the voltage reference for other system components or the on-chip ADCs via the VREF output pin. The ADC is under full control of the CIP-51 microcontroller via its associated Special Function Registers. One input channel is tied to an internal temperature sensor, while the other eight channels are available externally. Each pair of the eight external input channels can be configured as either two single-ended inputs or a single differential input. The system controller can also put the ADC into shutdown mode to save power. A programmable gain amplifier follows the analog multiplexer. The gain can be set in software from 0.5 to 16 in powers of 2. The gain stage can be especially useful when different ADC input channels have widely varied input voltage signals, or when it is necessary to "zoom in" on a signal with a large DC offset (in differential mode, a DAC could be used to provide the DC offset). Conversions can be started in four ways; a software command, an overflow of Timer 2, an overflow of Timer 3, or an external signal input. This flexibility allows the start of conversion to be triggered by software events, external HW signals, or a periodic timer overflow signal. Conversion completions are indicated by a status bit and an interrupt (if enabled). The resulting 10 or 12-bit data word is latched into two SFRs upon completion of a conversion. The data can be right or left justified in these registers under software control. Window Compare registers for the ADC data can be configured to interrupt the controller when ADC data is within or outside of a specified range. The ADC can monitor a key voltage continuously in background mode, but not interrupt the controller unless the converted data is within the specified window.
Figure 1.10. 12-Bit ADC Block Diagram
Analog Multiplexer Configuration, Control, and Data Registers Window Compare Logic Window Compare Interrupt
AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7
TEMP SENSOR
+ + + + Programmable Gain Amplifier
9-to-1 AMUX (SE or DIFF)
AV+
X
+ -
12-Bit SAR
12
ADC Data Registers
ADC
Conversion Complete Interrupt VREF Start Conversion Write to AD0BUSY Timer 3 Overflow CNVSTR0 Timer 2 Overflow
External VREF Pin AGND DAC0 Output
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1.8.
8-Bit Analog to Digital Converter
The C8051F12x Family have an on-board 8-bit SAR ADC (ADC2) with an 8-channel input multiplexer and programmable gain amplifier. This ADC features a 500 ksps maximum throughput and true 8-bit linearity with an INL of 1LSB. Eight input pins are available for measurement. The ADC is under full control of the CIP-51 microcontroller via the Special Function Registers. The ADC2 voltage reference is selected between the analog power supply (AV+) and an external VREF pin. On C8051F120/2/4/6 devices, ADC2 has its own dedicated VREF2 input pin; on C8051F121/3/5/7 devices, ADC2 shares the VREFA input pin with the 12/10-bit ADC0. User software may put ADC2 into shutdown mode to save power. A programmable gain amplifier follows the analog multiplexer. The gain stage can be especially useful when different ADC input channels have widely varied input voltage signals, or when it is necessary to "zoom in" on a signal with a large DC offset (in differential mode, a DAC could be used to provide the DC offset). The PGA gain can be set in software to 0.5, 1, 2, or 4. A flexible conversion scheduling system allows ADC2 conversions to be initiated by software commands, timer overflows, or an external input signal. ADC2 conversions may also be synchronized with ADC0 software-commanded conversions. Conversion completions are indicated by a status bit and an interrupt (if enabled), and the resulting 8-bit data word is latched into an SFR upon completion.
Figure 1.11. 8-Bit ADC Diagram
Analog Multiplexer Configuration, Control, and Data Registers Window Compare Logic Window Compare Interrupt
AIN2.0 AIN2.1 AIN2.2 AIN2.3 AIN2.4 AIN2.5 AIN2.6 AIN2.7 8-to-1 AMUX
Programmable Gain Amplifier AV+
X
+ -
8-Bit SAR
8
ADC Data Register Conversion Complete Interrupt
ADC
VREF Start Conversion
Write to AD2BUSY External VREF Pin AV+ Timer 3 Overflow CNVSTR2 Input Timer 2 Overflow Write to AD0BUSY (synchronized with ADC0)
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1.9. Comparators and DACs
Preliminary
Each C8051F12x MCU has two 12-bit DACs and two comparators on chip. The MCU data and control interface to each comparator and DAC is via the Special Function Registers. The MCU can place any DAC or comparator in low power shutdown mode. The comparators have software programmable hysteresis and response time. The response time of the comparators can be adjusted to minimize power consumption, or to maximize speed. Each comparator can generate an interrupt on its rising edge, falling edge, or both; these interrupts are capable of waking up the MCU from sleep mode. The comparators' output state can also be polled in software. The comparator outputs can be programmed to appear on the Port I/O pins via the Crossbar. The DACs are voltage output mode, and include a flexible output scheduling mechanism. This scheduling mechanism allows DAC output updates to be forced by a software write or a Timer 2, 3, or 4 overflow. The DAC voltage reference is supplied via the dedicated VREFD input pin on C8051F120/2/4/6 devices or via the internal voltage reference on C8051F121/3/5/7 devices. The DACs are useful as references for the comparators or offsets for the differential inputs of the ADC.
Figure 1.12. Comparator and DAC Diagram
CP0
(Port I/O)
CP1 CROSSBAR
(Port I/O)
CP0+ CP0-
+
CP0
-
CP1+ CP1-
+
CP0 CP1 SFR's (Data and Cntrl) REF
CP1
-
CIP-51 and Interrupt Handler
DAC0
DAC0
REF
DAC1
DAC1
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2.
ABSOLUTE MAXIMUM RATINGS
Table 2.1. Absolute Maximum Ratings*
PARAMETER CONDITIONS MIN -55 -65 -0.3 -0.3 -0.3 TYP MAX 125 150 VDD + 0.3 5.8 4.2 800 100 50 100 50 UNITS C C V V V mA mA mA mA mA
Ambient temperature under bias Storage Temperature Voltage on any Pin (except VDD and Port I/O) with respect to DGND Voltage on any Port I/O Pin or /RST with respect to DGND Voltage on VDD with respect to DGND Maximum Total current through VDD, AV+, DGND, and AGND Maximum output current sunk by any Port pin Maximum output current sunk by any other I/O pin Maximum output current sourced by any Port pin Maximum output current sourced by any other I/O pin
*
Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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3.
Preliminary
GLOBAL DC ELECTRICAL CHARACTERISTICS
Table 1.1. Global DC Electrical Characteristics (C8051F120/1/2/3)
-40C TO +85C, 100 MHZ SYSTEM CLOCK UNLESS OTHERWISE SPECIFIED. PARAMETER Analog Supply Voltage Analog Supply Current Analog Supply Current with analog sub-systems inactive Analog-to-Digital Supply Delta (|VDD - AV+|) Digital Supply Voltage Digital Supply Current with CPU active VDD=TBD V, Clock=100 MHz VDD=2.7 V, Clock=50 MHz VDD=2.7 V, Clock=1 MHz VDD=2.7 V, Clock=32 kHz VDD=TBD V, Clock=100 MHz VDD=2.7 V, Clock=50 MHz VDD=2.7 V, Clock=1 MHz VDD=2.7 V, Clock=32 kHz Oscillator not running 2.7 3.0 TBD 25 0.7 16 TBD TBD TBD TBD TBD 1.5 -40 +85 (Note 1) Internal REF, ADC, DAC, Comparators all active Internal REF, ADC, DAC, Comparators all disabled, oscillator disabled CONDITIONS MIN 2.7 TYP 3.0 1.7 40 MAX 3.6 TBD TBD 0.5 3.6 UNITS V mA A V V mA mA A mA mA A A V C
Digital Supply Current with CPU inactive (not accessing FLASH) Digital Supply Current (shutdown) Digital Supply RAM Data Retention Voltage Specified Operating Temperature Range
Note 1: Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
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Table 1.2. Global DC Electrical Characteristics (C8051F124/5/6/7)
-40C TO +85C, 50 MHZ SYSTEM CLOCK UNLESS OTHERWISE SPECIFIED. PARAMETER Analog Supply Voltage Analog Supply Current Analog Supply Current with analog sub-systems inactive Analog-to-Digital Supply Delta (|VDD - AV+|) Digital Supply Voltage Digital Supply Current with CPU active Digital Supply Current with CPU inactive (not accessing FLASH) Digital Supply Current (shutdown) Digital Supply RAM Data Retention Voltage Specified Operating Temperature Range -40 VDD=2.7 V, Clock=50 MHz VDD=2.7 V, Clock=1 MHz VDD=2.7 V, Clock=32 kHz VDD=2.7 V, Clock=50 MHz VDD=2.7 V, Clock=1 MHz VDD=2.7 V, Clock=32 kHz Oscillator not running 2.7 3.0 25 0.7 16 TBD TBD TBD TBD 1.5 +85 (Note 1) Internal REF, ADC, DAC, Comparators all active Internal REF, ADC, DAC, Comparators all disabled, oscillator disabled CONDITIONS MIN 2.7 TYP 3.0 1.7 40 MAX 3.6 TBD TBD 0.5 3.6 UNITS V mA A V V mA mA A mA mA A A V C
Note 1: Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
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4.
Preliminary
PINOUT AND PACKAGE DEFINITIONS
Table 4.1. Pin Definitions
Pin Numbers Name F120/ 2/4/6 F121/ 3/5/7 Type Description Digital Supply Voltage. Must be tied to +2.7 to +3.6 V. Digital Ground. Must be tied to Ground. Analog Supply Voltage. Must be tied to +2.7 to +3.6 V. Analog Ground. Must be tied to Ground. D In D In D In JTAG Test Mode Select with internal pull-up. JTAG Test Clock with internal pull-up. JTAG Test Data Input with internal pull-up. TDI is latched on the rising edge of TCK.
VDD DGND AV+ AGND TMS TCK TDI TDO /RST
37, 64, 24, 41, 90 57 38, 63, 25, 40, 89 56 11, 14 10, 13 1 2 3 4 5 6 5 58 59 60 61 62
D Out JTAG Test Data Output with internal pull-up. Data is shifted out on TDO on the falling edge of TCK. TDO output is a tri-state driver. D I/O Device Reset. Open-drain output of internal VDD monitor. Is driven low when VDD is < VRST and MONEN is high. An external source can initiate a system reset by driving this pin low. A In Crystal Input. This pin is the return for the internal oscillator circuit for a crystal or ceramic resonator. For a precision internal clock, connect a crystal or ceramic resonator from XTAL1 to XTAL2. If overdriven by an external CMOS clock, this becomes the system clock.
XTAL1
26
17
XTAL2 MONEN
27 28
18 19
A Out Crystal Output. This pin is the excitation driver for a crystal or ceramic resonator. D In VDD Monitor Enable. When tied high, this pin enables the internal VDD monitor, which forces a system reset when VDD is < VRST. When tied low, the internal VDD monitor is disabled. This pin must be tied high or low.
VREF VREFA VREF0 VREF2 VREFD
12
7 8
A I/O Bandgap Voltage Reference Output (all devices). DAC Voltage Reference Input (C8051F121/3/5/7 only). A In A In A In A In ADC0 and ADC2 Voltage Reference Input. ADC0 Voltage Reference Input. ADC2 Voltage Reference Input. DAC Voltage Reference Input.
16 17 15
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Table 4.1. Pin Definitions
Pin Numbers Name F120/ 2/4/6 18 19 20 21 22 23 24 25 9 8 7 6 100 99 62 61 60 59 58 57 F121/ 3/5/7 9 10 11 12 13 14 15 16 4 3 2 1 64 63 55 54 53 52 51 50 A In A In A In A In A In A In A In A In A In A In A In A In Type Description ADC0 Input Channel 0 (See ADC0 Specification for complete description). ADC0 Input Channel 1 (See ADC0 Specification for complete description). ADC0 Input Channel 2 (See ADC0 Specification for complete description). ADC0 Input Channel 3 (See ADC0 Specification for complete description). ADC0 Input Channel 4 (See ADC0 Specification for complete description). ADC0 Input Channel 5 (See ADC0 Specification for complete description). ADC0 Input Channel 6 (See ADC0 Specification for complete description). ADC0 Input Channel 7 (See ADC0 Specification for complete description). Comparator 0 Non-Inverting Input. Comparator 0 Inverting Input. Comparator 1 Non-Inverting Input. Comparator 1 Inverting Input.
AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 CP0+ CP0CP1+ CP1DAC0 DAC1 P0.0 P0.1 P0.2 P0.3 P0.4 ALE/P0.5
A Out Digital to Analog Converter 0 Voltage Output. (See DAC Specification for complete description). A Out Digital to Analog Converter 1 Voltage Output. (See DAC Specification for complete description). D I/O Port 0.0. See Port Input/Output section for complete description. D I/O Port 0.1. See Port Input/Output section for complete description. D I/O Port 0.2. See Port Input/Output section for complete description. D I/O Port 0.3. See Port Input/Output section for complete description. D I/O Port 0.4. See Port Input/Output section for complete description. D I/O ALE Strobe for External Memory Address bus (multiplexed mode) Port 0.5 See Port Input/Output section for complete description.
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Pin Numbers Name F120/ 2/4/6 56 F121/ 3/5/7 49
Preliminary
Table 4.1. Pin Definitions
Type Description D I/O /RD Strobe for External Memory Address bus Port 0.6 See Port Input/Output section for complete description. D I/O /WR Strobe for External Memory Address bus Port 0.7 See Port Input/Output section for complete description. A In ADC2 Input Channel 0 (See ADC2 Specification for complete D I/O description). Bit 8 External Memory Address bus (Non-multiplexed mode) Port 1.0 See Port Input/Output section for complete description. A In Port 1.1. See Port Input/Output section for complete description. D I/O A In Port 1.2. See Port Input/Output section for complete description. D I/O A In Port 1.3. See Port Input/Output section for complete description. D I/O A In Port 1.4. See Port Input/Output section for complete description. D I/O A In Port 1.5. See Port Input/Output section for complete description. D I/O A In Port 1.6. See Port Input/Output section for complete description. D I/O A In Port 1.7. See Port Input/Output section for complete description. D I/O D I/O Bit 8 External Memory Address bus (Multiplexed mode) Bit 0 External Memory Address bus (Non-multiplexed mode) Port 2.0 See Port Input/Output section for complete description. D I/O Port 2.1. See Port Input/Output section for complete description. D I/O Port 2.2. See Port Input/Output section for complete description. D I/O Port 2.3. See Port Input/Output section for complete description. D I/O Port 2.4. See Port Input/Output section for complete description. D I/O Port 2.5. See Port Input/Output section for complete description. D I/O Port 2.6. See Port Input/Output section for complete description.
/RD/P0.6
/WR/P0.7
55
48
AIN2.0/A8/P1.0
36
29
AIN2.1/A9/P1.1 AIN2.2/A10/P1.2 AIN2.3/A11/P1.3 AIN2.4/A12/P1.4 AIN2.5/A13/P1.5 AIN2.6/A14/P1.6 AIN2.7/A15/P1.7 A8m/A0/P2.0
35 34 33 32 31 30 29 46
28 27 26 23 22 21 20 37
A9m/A1/P2.1 A10m/A2/P2.2 A11m/A3/P2.3 A12m/A4/P2.4 A13m/A5/P2.5 A14m/A6/P2.6
45 44 43 42 41 40
36 35 34 33 32 31
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Table 4.1. Pin Definitions
Pin Numbers Name F120/ 2/4/6 39 54 F121/ 3/5/7 30 47 Type Description D I/O Port 2.7. See Port Input/Output section for complete description. D I/O Bit 0 External Memory Address/Data bus (Multiplexed mode) Bit 0 External Memory Data bus (Non-multiplexed mode) Port 3.0 See Port Input/Output section for complete description. D I/O Port 3.1. See Port Input/Output section for complete description. D I/O Port 3.2. See Port Input/Output section for complete description. D I/O Port 3.3. See Port Input/Output section for complete description. D I/O Port 3.4. See Port Input/Output section for complete description. D I/O Port 3.5. See Port Input/Output section for complete description. D I/O Port 3.6. See Port Input/Output section for complete description. D I/O Port 3.7. See Port Input/Output section for complete description. D I/O Port 4.0. See Port Input/Output section for complete description. D I/O Port 4.1. See Port Input/Output section for complete description. D I/O Port 4.2. See Port Input/Output section for complete description. D I/O Port 4.3. See Port Input/Output section for complete description. D I/O Port 4.4. See Port Input/Output section for complete description. D I/O ALE Strobe for External Memory Address bus (multiplexed mode) Port 4.5 See Port Input/Output section for complete description. D I/O /RD Strobe for External Memory Address bus Port 4.6 See Port Input/Output section for complete description. D I/O /WR Strobe for External Memory Address bus Port 4.7 See Port Input/Output section for complete description. D I/O Bit 8 External Memory Address bus (Non-multiplexed mode) Port 5.0 See Port Input/Output section for complete description. D I/O Port 5.1. See Port Input/Output section for complete description. D I/O Port 5.2. See Port Input/Output section for complete description. D I/O Port 5.3. See Port Input/Output section for complete description.
A15m/A7/P2.7 AD0/D0/P3.0
AD1/D1/P3.1 AD2/D2/P3.2 AD3/D3/P3.3 AD4/D4/P3.4 AD5/D5/P3.5 AD6/D6/P3.6 AD7/D7/P3.7 P4.0 P4.1 P4.2 P4.3 P4.4 ALE/P4.5
53 52 51 50 49 48 47 98 97 96 95 94 93
46 45 44 43 42 39 38
/RD/P4.6
92
/WR/P4.7
91
A8/P5.0
88
A9/P5.1 A10/P5.2 A11/P5.3
87 86 85
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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C8051F120/1/2/3 C8051F124/5/6/7
Pin Numbers Name F120/ 2/4/6 84 83 82 81 80 F121/ 3/5/7
Preliminary
Table 4.1. Pin Definitions
Type Description D I/O Port 5.4. See Port Input/Output section for complete description. D I/O Port 5.5. See Port Input/Output section for complete description. D I/O Port 5.6. See Port Input/Output section for complete description. D I/O Port 5.7. See Port Input/Output section for complete description. D I/O Bit 8 External Memory Address bus (Multiplexed mode) Bit 0 External Memory Address bus (Non-multiplexed mode) Port 6.0 See Port Input/Output section for complete description. D I/O Port 6.1. See Port Input/Output section for complete description. D I/O Port 6.2. See Port Input/Output section for complete description. D I/O Port 6.3. See Port Input/Output section for complete description. D I/O Port 6.4. See Port Input/Output section for complete description. D I/O Port 6.5. See Port Input/Output section for complete description. D I/O Port 6.6. See Port Input/Output section for complete description. D I/O Port 6.7. See Port Input/Output section for complete description. D I/O Bit 0 External Memory Address/Data bus (Multiplexed mode) Bit 0 External Memory Data bus (Non-multiplexed mode) Port 7.0 See Port Input/Output section for complete description. D I/O Port 7.1. See Port Input/Output section for complete description. D I/O Port 7.2. See Port Input/Output section for complete description. D I/O Port 7.3. See Port Input/Output section for complete description. D I/O Port 7.4. See Port Input/Output section for complete description. D I/O Port 7.5. See Port Input/Output section for complete description. D I/O Port 7.6. See Port Input/Output section for complete description. D I/O Port 7.7. See Port Input/Output section for complete description.
A12/P5.4 A13/P5.5 A14/P5.6 A15/P5.7 A8m/A0/P6.0
A9m/A1/P6.1 A10m/A2/P6.2 A11m/A3/P6.3 A12m/A4/P6.4 A13m/A5/P6.5 A14m/A6/P6.6 A15m/A7/P6.7 AD0/D0/P7.0
79 78 77 76 75 74 73 72
AD1/D1/P7.1 AD2/D2/P7.2 AD3/D3/P7.3 AD4/D4/P7.4 AD5/D5/P7.5 AD6/D6/P7.6 AD7/D7/P7.7
71 70 69 68 67 66 65
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Figure 4.1. TQFP-100 Pinout Diagram
A10m/A2/P6.2 78 A11m/A3/P6.3 77 A12m/A4/P6.4 76 A8m/A0/P6.0 80 A9m/A1/P6.1 79
/WR/P4.7
ALE/P4.5
A10/P5.2
A11/P5.3
A12/P5.4 84
A13/P5.5 83
100 DAC0
99
98
97 96
95
94
93
92
91
90 89
88
87
86
85
TMS TCK TDI TDO /RST CP1CP1+ CP0CP0+ AGND AV+ VREF AGND AV+ VREFD VREF0 VREF2 AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
82 81
A14/P5.6 A15/P5.7
/RD/P4.6
A8/P5.0
A9/P5.1
VDD DGND
DAC1
P4.0
P4.1 P4.2
P4.3
P4.4
C8051F120 C8051F122 C8051F124 C8051F126
75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51
A13m/A5/P6.5 A14m/A6/P6.6 A15m/A7/P6.7 AD0/D0/P7.0 AD1/D1/P7.1 AD2/D2/P7.2 AD3/D3/P7.3 AD4/D4/P7.4 AD5/D5/P7.5 AD6/D6/P7.6 AD7/D7/P7.7 VDD DGND P0.0 P0.1 P0.2 P0.3 P0.4 ALE/P0.5 /RD/P0.6 /WR/P0.7 AD0/D0/P3.0 AD1/D1/P3.1 AD2/D2/P3.2 AD3/D3/P3.3
26
27
28
29 30
31
32
33
34
35
36 37
38
39
40
41
42
43
44 45
46
47
48 AD6/D6/P3.6
49 AD5/D5/P3.5
XTAL1
XTAL2
AIN2.7/A15/P1.7 AIN2.6/A14/P1.6
AIN2.5/A13/P1.5
AIN2.4/A12/P1.4
AIN2.3/A11/P1.3
AIN2.2/A10/P1.2
AIN2.1/A9/P1.1
AIN2.0/A8/P1.0 VDD
AD7/D7/P3.7
A15m/A7/P2.7
A14m/A6/P2.6
A13m/A5/P2.5
A12m/A4/P2.4
A11m/A3/P2.3
A10m/A2/P2.2 A9m/A1/P2.1
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
A8m/A0/P2.0
AD4/D4/P3.4
MONEN
DGND
50
Page 43
C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
Figure 4.2. TQFP-100 Package Drawing
D D1
MIN NOM MAX (mm) (mm) (mm) A 1.20 0.15
A1 0.05
A2 0.95 1.00 1.05 b D
E1 E
0.17 0.22 0.27 16.00 14.00 0.50 16.00 14.00 -
D1 e E E1
100 PIN 1 DESIGNATOR 1
A2
e A b A1
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Figure 4.3. TQFP-64 Pinout Diagram
ALE/P0.5 50 /RD/P0.6 49 DGND
DAC0
DAC1
/RST
VDD
TDO
TMS
P0.0
P0.1
P0.2
P0.3 52
64
63
62
61
60
59
58
57
56
55
54
53
CP1CP1+ CP0CP0+ AGND AV+ VREF VREFA AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
51
P0.4
TCK
TDI
48 47 46 45 44
/WR/P0.7 AD0/D0/P3.0 AD1/D1/P3.1 AD2/D2/P3.2 AD3/D3/P3.3 AD4/D4/P3.4 AD5/D5/P3.5 VDD DGND AD6/D6/P3.6 AD7/D7/P3.7 A8m/A0/P2.0 A9m/A1/P2.1 A10m/A2/P2.2 A11m/A3/P2.3 A12m/A4/P2.4
C8051F121 C8051F123 C8051F125 C8051F127
43 42 41 40 39 38 37 36 35 34 33
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31 A14m/A6/P2.6
MONEN
AIN2.7/A15/P1.7
AIN2.6/A14/P1.6
AIN2.5/A13/P1.5
AIN2.4/A12/P1.4
DGND
VDD
AIN2.3/A11/P1.3
AIN2.2/A10/P1.2
AIN2.1/A9/P1.1
AIN2.0/A8/P1.0
XTAL1
XTAL2
A15m/A7/P2.7
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
A13m/A5/P2.5
32
Page 45
C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
Figure 4.4. TQFP-64 Package Drawing
D D1
MIN NOM MAX (mm) (mm) (mm) A 1.20 0.15 1.05
A1 0.05
E1 E
A2 0.95 b D
0.17 0.22 0.27 12.00 10.00 0.50 12.00 10.00 -
64 PIN 1 DESIGNATOR 1 A2 e A b A1
D1 e E E1
Page 46
DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
5.
ADC0 (12-BIT ADC, C8051F120/1/4/5 ONLY)
The ADC0 subsystem for the C8051F120/1/4/5 consists of a 9-channel, configurable analog multiplexer (AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 12-bit successive-approximation-register ADC with integrated track-and-hold and Programmable Window Detector (see block diagram in Figure 5.1). The AMUX0, PGA0, Data Conversion Modes, and Window Detector are all configurable under software control via the Special Function Registers shown in Figure 5.1. The voltage reference used by ADC0 is selected as described in Section "9. VOLTAGE REFERENCE (C8051F120/2/4/6)" on page 105 for C8051F120/2/4/6 devices, or Section "10. VOLTAGE REFERENCE (C8051F121/3/5/7)" on page 107 for C8051F121/3/5/7 devices. The ADC0 subsystem (ADC0, trackand-hold and PGA0) is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
Figure 5.1. 12-Bit ADC0 Functional Block Diagram
ADC0GTH ADC0GTL ADC0LTH ADC0LTL
24 Comb. Logic 12
AD0WINT
AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7
TEMP SENSOR
+
AD0EN AV+
SYSCLK REF
AIN0.0
+
AV+
9-to-1 AMUX + (SE or - DIFF)
+ -
X
+ AGND
12-Bit SAR
12
AD0CM
ADC0L
ADC
ADC0H
00
Start Conversion 01
AD0BUSY (W) Timer 3 Overflow CNVSTR0 Timer 2 Overflow
AGND AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 AD0EN AD0TM AD0INT AD0BUSY AD0CM1 AD0CM0 AD0WINT AD0LJST AIN67IC AIN45IC AIN23IC AIN01IC
10 11 AD0CM
AMX0CF
AMX0SL
ADC0CF
ADC0CN
5.1.
Analog Multiplexer and PGA
Eight of the AMUX channels are available for external measurements while the ninth channel is internally connected to an on-chip temperature sensor (temperature transfer function is shown in Figure 5.2). AMUX input pairs can be programmed to operate in either differential or single-ended mode. This allows the user to select the best measurement technique for each input channel, and even accommodates mode changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are two registers associated with the AMUX: the Channel Selection register AMX0SL (Figure 5.6), and the Configuration register AMX0CF (Figure 5.5). The table in Figure 5.6 shows AMUX functionality by channel, for each possible configuration. The PGA amplifies the AMUX output signal by an amount determined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (Figure 5.7). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset.
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
Page 47
C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
The Temperature Sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the PGA input when the Temperature Sensor is selected by bits AMX0AD3-0 in register AMX0SL; this voltage will be amplified by the PGA according to the user-programmed PGA settings.
Figure 5.2. Typical Temperature Sensor Transfer Function
(Volts)
1.000
0.900
0.800 VTEMP = 0.00286(TEMPC) + 0.776 0.700 for PGA Gain = 1 0.600
0.500 -50 0 50 100
(Celsius)
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
5.2.
ADC Modes of Operation
ADC0 has a maximum conversion speed of 100 ksps. The ADC0 conversion clock is derived from the system clock divided by the value held in the ADCSC bits of register ADC0CF.
5.2.1.
Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start of Conversion Mode bits (AD0CM1, AD0CM0) in ADC0CN. Conversions may be initiated by: 1. 2. 3. 4. Writing a `1' to the AD0BUSY bit of ADC0CN; A Timer 3 overflow (i.e. timed continuous conversions); A rising edge detected on the external ADC convert start signal, CNVSTR0; A Timer 2 overflow (i.e. timed continuous conversions).
The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag (ADC0CN.5). Converted data is available in the ADC0 data word MSB and LSB registers, ADC0H, ADC0L. Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in Figure 5.11) depending on the programmed state of the AD0LJST bit in the ADC0CN register. When initiating conversions by writing a `1' to AD0BUSY, the AD0INT bit should be polled to determine when a conversion has completed (ADC0 interrupts may also be used). The recommended polling procedure is shown below. Step 1. Step 2. Step 3. Step 4. Write a `0' to AD0INT; Write a `1' to AD0BUSY; Poll AD0INT for `1'; Process ADC0 data.
When CNVSTR0 is used as a conversion start source, it must be enabled in the crossbar, and the corresponding pin must be set to open-drain, high-impedance mode (see Section "18. PORT INPUT/OUTPUT" on page 203 for more details on Port I/O configuration).
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
Page 49
C8051F120/1/2/3 C8051F124/5/6/7
5.2.2. Tracking Modes
Preliminary
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0 input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0 operates in lowpower track-and-hold mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR0 signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR0 is low; conversion begins on the rising edge of CNVSTR0 (see Figure 5.3). Tracking can also be disabled (shutdown) when the entire chip is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section "5.2.3. Settling Time Requirements" on page 51).
Figure 5.3. ADC0 Track and Conversion Example Timing
A. ADC Timing for External Trigger Source
CNVSTR0 (AD0STM[1:0]=10)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
SAR Clocks Low Power or Convert
ADC0TM=1 ADC0TM=0
Track
Convert Convert
Low Power Mode Track
Track Or Convert
B. ADC Timing for Internal Trigger Sources
Timer 2, Timer 3 Overflow; Write '1' to AD0BUSY (AD0STM[1:0]=00, 01, 11) SAR Clocks Low Power or Convert
1
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19
ADC0TM=1
Track
2 3 4 5 6 7 8 9
Convert
10 11 12 13 14 15 16
Low Power Mode
SAR Clocks Track or Convert
ADC0TM=0
Convert
Track
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
5.2.3.
Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different MUX or PGA selection is made), a minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Figure 5.4 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice that the equivalent time constant for both input circuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature Sensor output, RTOTAL reduces to RMUX. An absolute minimum settling time of 1.5 s is required after any MUX or PGA selection. Note that in low-power tracking mode, three SAR clocks are used for tracking at the start of every conversion. For most applications, these three SAR clocks will meet the tracking requirements.
Equation 5.1. ADC0 Settling Time Requirements 2 t = ln ------ x R TOTAL C SAMPLE SA
n
Where: SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB) t is the required settling time in seconds RTOTAL is the sum of the ADC0 MUX resistance and any external source resistance. n is the ADC resolution in bits (12).
Figure 5.4. ADC0 Equivalent Input Circuits
Differential Mode
MUX Select
Single-Ended Mode
MUX Select
AIN0.x RMUX = 5k CSAMPLE = 10pF RCInput= RMUX * CSAMPLE CSAMPLE = 10pF AIN0.y RMUX = 5k MUX Select
AIN0.x RMUX = 5k CSAMPLE = 10pF RCInput= RMUX * CSAMPLE
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
Page 51
C8051F120/1/2/3 C8051F124/5/6/7
Preliminary
Figure 5.5. AMX0CF: AMUX0 Configuration Register
SFR Page: SFR Address: R/W
0 0xBA
R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
AIN67IC
Bit3
AIN45IC
Bit2
AIN23IC
Bit1
AIN01IC
Bit0
00000000
Bits7-4: Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 0000b; Write = don't care. AIN67IC: AIN0.6, AIN0.7 Input Pair Configuration Bit. 0: AIN0.6 and AIN0.7 are independent single-ended inputs. 1: AIN0.6, AIN0.7 are (respectively) +, - differential input pair. AIN45IC: AIN0.4, AIN0.5 Input Pair Configuration Bit. 0: AIN0.4 and AIN0.5 are independent single-ended inputs. 1: AIN0.4, AIN0.5 are (respectively) +, - differential input pair. AIN23IC: AIN0.2, AIN0.3 Input Pair Configuration Bit. 0: AIN0.2 and AIN0.3 are independent single-ended inputs. 1: AIN0.2, AIN0.3 are (respectively) +, - differential input pair. AIN01IC: AIN0.0, AIN0.1 Input Pair Configuration Bit. 0: AIN0.0 and AIN0.1 are independent single-ended inputs. 1: AIN0.0, AIN0.1 are (respectively) +, - differential input pair. The ADC0 Data Word is in 2's complement format for channels configured as differential.
NOTE:
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.
Preliminary
C8051F120/1/2/3 C8051F124/5/6/7
Figure 5.6. AMX0SL: AMUX0 Channel Select Register
SFR Page: SFR Address: R/W
0 0xBB
R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
Bit7
Bit6
Bit5
Bit4
AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000
Bits7-4: Bits3-0:
UNUSED. Read = 0000b; Write = don't care. AMX0AD3-0: AMX0 Address Bits. 0000-1111b: ADC Inputs selected per chart below. AMX0AD3-0 0000 0001
AIN0.1
0010
AIN0.2 AIN0.2
0011
AIN0.3 AIN0.3
0100
AIN0.4 AIN0.4 AIN0.4 AIN0.4
0101
AIN0.5 AIN0.5 AIN0.5 AIN0.5
0110
AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6
0111
AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7
1xxx
TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR
0000 0001 0010 0011 0100 0101 AMX0CF Bits 3-0 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
AIN0.1
AIN0.2 AIN0.2
AIN0.3 AIN0.3
+(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
AIN0.1
AIN0.2 AIN0.2
AIN0.3 AIN0.3
AIN0.4 AIN0.4 AIN0.4 AIN0.4
AIN0.5 AIN0.5 AIN0.5 AIN0.5
+(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
AIN0.1
AIN0.2 AIN0.2
AIN0.3 AIN0.3
+(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
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Figure 5.7. ADC0CF: ADC0 Configuration Register
SFR Page: SFR Address: R/W
0 0xBC
R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
AD0SC4
Bit7
AD0SC3
Bit6
AD0SC2
Bit5
AD0SC1
Bit4
AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000
Bits7-3:
AD0SC4-0: ADC0 SAR Conversion Clock Period Bits. SAR Conversion clock is derived from system clock by the following equation, where AD0SC refers to the 5-bit value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0 SAR clock (Note: the ADC0 SAR Conversion Clock should be less than or equal to 2.5 MHz).
SYSCLK AD0SC = ------------------------------- - 1 2 x C LK SAR0
Bits2-0: AMP0GN2-0: ADC0 Internal Amplifier Gain (PGA). 000: Gain = 1 001: Gain = 2 010: Gain = 4 011: Gain = 8 10x: Gain = 16 11x: Gain = 0.5
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Figure 5.8. ADC0CN: ADC0 Control Register
SFR Page: SFR Address: R/W
0 0xE8
R/W Bit6
(bit addressable)
R/W Bit5 R/W Bit4 R/W Bit3 R/W R/W R/W Bit0 Reset Value
AD0EN
Bit7
AD0TM AD0INT AD0BUSY AD0CM1
AD0CM0
Bit2
AD0WINT
Bit1
AD0LJST 00000000
Bit7:
Bit6:
Bit5:
Bit4:
Bits3-2:
Bit1:
Bit0:
AD0EN: ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. AD0TM: ADC Track Mode Bit. 0: When the ADC is enabled, tracking is continuous unless a conversion is in process. 1: Tracking Defined by ADSTM1-0 bits. AD0INT: ADC0 Conversion Complete Interrupt Flag. This flag must be cleared by software. 0: ADC0 has not completed a data conversion since the last time this flag was cleared. 1: ADC0 has completed a data conversion. AD0BUSY: ADC0 Busy Bit. Read: 0: ADC0 Conversion is complete or a conversion is not currently in progress. AD0INT is set to logic 1 on the falling edge of AD0BUSY. 1: ADC0 Conversion is in progress. Write: 0: No Effect. 1: Initiates ADC0 Conversion if AD0STM1-0 = 00b. AD0CM1-0: ADC0 Start of Conversion Mode Select. If AD0TM = 0: 00: ADC0 conversion initiated on every write of `1' to AD0BUSY. 01: ADC0 conversion initiated on overflow of Timer 3. 10: ADC0 conversion initiated on rising edge of external CNVSTR0. 11: ADC0 conversion initiated on overflow of Timer 2. If AD0TM = 1: 00: Tracking starts with the write of `1' to AD0BUSY and lasts for 3 SAR clocks, followed by conversion. 01: Tracking started by the overflow of Timer 3 and lasts for 3 SAR clocks, followed by conversion. 10: ADC0 tracks only when CNVSTR0 input is logic low; conversion starts on rising CNVSTR0 edge. 11: Tracking started by the overflow of Timer 2 and lasts for 3 SAR clocks, followed by conversion. AD0WINT: ADC0 Window Compare Interrupt Flag. This bit must be cleared by software. 0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared. 1: ADC0 Window Comparison Data match has occurred. AD0LJST: ADC0 Left Justify Select. 0: Data in ADC0H:ADC0L registers are right-justified. 1: Data in ADC0H:ADC0L registers are left-justified.
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Preliminary
Figure 5.9. ADC0H: ADC0 Data Word MSB Register
SFR Page: SFR Address: R/W Bit7
0 0xBF
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
ADC0 Data Word High-Order Bits. For AD0LJST = 0: Bits 7-4 are the sign extension of Bit3. Bits 3-0 are the upper 4 bits of the 12-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-0 are the most-significant bits of the 12-bit ADC0 Data Word.
Figure 5.10. ADC0L: ADC0 Data Word LSB Register
SFR Page: SFR Address: R/W Bit7
0 0xBE
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
ADC0 Data Word Low-Order Bits. For AD0LJST = 0: Bits 7-0 are the lower 8 bits of the 12-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-4 are the lower 4 bits of the 12-bit ADC0 Data Word. Bits3-0 will always read `0'.
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Figure 5.11. ADC0 Data Word Example
12-bit ADC0 Data Word appears in the ADC0 Data Word Registers as follows: ADC0H[3:0]:ADC0L[7:0], if AD0LJST = 0 (ADC0H[7:4] will be sign-extension of ADC0H.3 for a differential reading, otherwise = 0000b). ADC0H[7:0]:ADC0L[7:4], if AD0LJST = 1 (ADC0L[3:0] = 0000b). Example: ADC0 Data Word Conversion Map, AIN0.0 Input in Single-Ended Mode (AMX0CF = 0x00, AMX0SL = 0x00) AIN0.0-AGND ADC0H:ADC0L ADC0H:ADC0L (Volts) (AD0LJST = 0) (AD0LJST = 1) VREF * (4095/4096) 0x0FFF 0xFFF0 VREF / 2 0x0800 0x8000 VREF * (2047/4096) 0x07FF 0x7FF0 0 0x0000 0x0000 Example: ADC0 Data Word Conversion Map, AIN0.0-AIN0.1 Differential Input Pair (AMX0CF = 0x01, AMX0SL = 0x00) AIN0.0-AIN0.1 ADC0H:ADC0L ADC0H:ADC0L (Volts) (AD0LJST = 0) (AD0LJST = 1) VREF * (2047/2048) 0x07FF 0x7FF0 VREF / 2 0x0400 0x4000 VREF * (1/2048) 0x0001 0x0010 0 0x0000 0x0000 -VREF * (1/2048) 0xFFFF (-1d) 0xFFF0 -VREF / 2 0xFC00 (-1024d) 0xC000 -VREF 0xF800 (-2048d) 0x8000 For AD0LJST = 0:
Gain Code = Vin x -------------- x 2 n ; `n' = 12 for Single-Ended; `n'=11 for Differential. VREF
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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5.3.
Preliminary
ADC0 Programmable Window Detector
The ADC0 Programmable Window Detector continuously compares the ADC0 output to user-programmed limits, and notifies the system when an out-of-bound condition is detected. This is especially effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD0WINT in ADC0CN) can also be used in polled mode. The high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting on page 60. Notice that the window detector flag can be asserted when the measured data is inside or outside the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx registers.
Figure 5.12. ADC0GTH: ADC0 Greater-Than Data High Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC5
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
Bits7-0:
High byte of ADC0 Greater-Than Data Word.
Figure 5.13. ADC0GTL: ADC0 Greater-Than Data Low Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC4
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
Bits7-0:
Low byte of ADC0 Greater-Than Data Word.
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Figure 5.14. ADC0LTH: ADC0 Less-Than Data High Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC7
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
High byte of ADC0 Less-Than Data Word.
Figure 5.15. ADC0LTL: ADC0 Less-Than Data Low Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC6
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
Low byte of ADC0 Less-Than Data Word.
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Figure 5.16. 12-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data
Input Voltage (AD0.0 - AGND) REF x (4095/4096)
ADC Data Word
0x0FFF AD0WINT not affected 0x0201
Input Voltage (AD0.0 - AGND) REF x (4095/4096)
ADC Data Word
0x0FFF
AD0WINT=1
0x0201 ADC0LTH:ADC0LTL AD0WINT=1 REF x (512/4096) 0x0200 0x01FF 0x0101 ADC0GTH:ADC0GTL REF x (256/4096) 0x0100 0x00FF ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL
REF x (512/4096)
0x0200 0x01FF 0x0101
REF x (256/4096)
0x0100 0x00FF
AD0WINT not affected 0 0x0000 0 0x0000
AD0WINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x00 AD0LJST = `0', ADC0LTH:ADC0LTL = 0x0200, ADC0GTH:ADC0GTL = 0x0100. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x0200 and > 0x0100.
Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = `0', ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0x0200. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is > 0x0200 or < 0x0100.
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Figure 5.17. 12-Bit ADC0 Window Interrupt Example: Right Justified Differential Data
Input Voltage (AD0.0 - AD0.1) REF x (2047/2048)
ADC Data Word
0x07FF AD0WINT not affected 0x0101
Input Voltage (AD0.0 - AD0.1) REF x (2047/2048)
ADC Data Word
0x07FF
AD0WINT=1
0x0101 ADC0LTH:ADC0LTL AD0WINT=1 REF x (256/2048) 0x0100 0x00FF 0x0000 ADC0GTH:ADC0GTL REF x (-1/2048) 0xFFFF 0xFFFE ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL
REF x (256/2048)
0x0100 0x00FF 0x0000
REF x (-1/2048)
0xFFFF 0xFFFE
AD0WINT not affected -REF 0xF800 -REF 0xF800
AD0WINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `0', ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0xFFFF. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x0100 and > 0xFFFF. (In two's-complement math, 0xFFFF = -1.)
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `0', ADC0LTH:ADC0LTL = 0xFFFF, ADC0GTH:ADC0GTL = 0x0100. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0xFFFF or > 0x0100. (In two's-complement math, 0xFFFF = -1.)
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Figure 5.18. 12-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data
Input Voltage (AD0.0 - AGND) REF x (4095/4096)
ADC Data Word
0xFFF0 AD0WINT not affected 0x2010
Input Voltage (AD0.0 - AGND) REF x (4095/4096)
ADC Data Word
0xFFF0
AD0WINT=1
0x2010 ADC0LTH:ADC0LTL AD0WINT=1 REF x (512/4096) 0x2000 0x1FF0 0x1010 ADC0GTH:ADC0GTL REF x (256/4096) 0x1000 0x0FF0 ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL
REF x (512/4096)
0x2000 0x1FF0 0x1010
REF x (256/4096)
0x1000 0x0FF0
AD0WINT not affected 0 0x0000 0 0x0000
AD0WINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = `1', ADC0LTH:ADC0LTL = 0x2000, ADC0GTH:ADC0GTL = 0x1000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x2000 and > 0x1000.
Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = `1' ADC0LTH:ADC0LTL = 0x1000, ADC0GTH:ADC0GTL = 0x2000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x1000 or > 0x2000.
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Figure 5.19. 12-Bit ADC0 Window Interrupt Example: Left Justified Differential Data
Input Voltage (AD0.0 - AD0.1) REF x (2047/2048)
ADC Data Word
0x7FF0 AD0WINT not affected 0x1010
Input Voltage (AD0.0 - AD0.1) REF x (2047/2048)
ADC Data Word
0x7FF0
AD0WINT=1
0x1010 ADC0LTH:ADC0LTL AD0WINT=1 REF x (256/2048) 0x1000 0x0FF0 0x0000 ADC0GTH:ADC0GTL REF x (-1/2048) 0xFFF0 0xFFE0 ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL
REF x (256/2048)
0x1000 0x0FF0 0x0000
REF x (-1/2048)
0xFFF0 0xFFE0
AD0WINT not affected -REF 0x8000 -REF 0x8000
AD0WINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `1', ADC0LTH:ADC0LTL = 0x1000, ADC0GTH:ADC0GTL = 0xFFF0. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x1000 and > 0xFFF0. (Two's-complement math.)
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `1', ADC0LTH:ADC0LTL = 0xFFF0, ADC0GTH:ADC0GTL = 0x1000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0xFFF0 or > 0x1000. (Two's-complement math.)
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Table 5.1. 12-Bit ADC0 Electrical Characteristics (C8051F120/1/4/5)
VDD = 3.0V, AV+ = 3.0V, VREF = 2.40V (REFBE=0), PGA Gain = 1, -40C to +85C unless otherwise specified PARAMETER DC ACCURACY Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Full Scale Error Offset Temperature Coefficient Signal-to-Noise Plus Distortion Total Harmonic Distortion Spurious-Free Dynamic Range CONVERSION RATE SAR Clock Frequency Conversion Time in SAR Clocks Track/Hold Acquisition Time Throughput Rate ANALOG INPUTS Input Voltage Range *Common-mode Voltage Range Input Capacitance TEMPERATURE SENSOR Linearity Gain Offset POWER SPECIFICATIONS Power Supply Current (AV+ supplied to ADC) Power Supply Rejection Note 1: Includes ADC offset, gain, and linearity variations. Note 2: Represents one standard deviation from the mean. Operating Mode, 100 ksps 450 0.3 900 A mV/V Note 1 Note 2 Note 1, Note 2, (Temp = 0 C) 0.2 2.86 776 8.5 C mV / C mV Single-ended operation Differential operation 0 AGND 10 VREF AV+ V V pF 16 1.5 100 2.5 MHz clocks s ksps Up to the 5th harmonic 66 -75 80 Differential mode Guaranteed Monotonic -31 -73 0.25 12 1 1 bits LSB LSB LSB LSB ppm/C dB dB dB CONDITIONS MIN TYP MAX UNITS
DYNAMIC PERFORMANCE (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps
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6.
ADC0 (10-BIT ADC, C8051F122/3/6/7 ONLY)
The ADC0 subsystem for the C8051F122/3/6/7 consists of a 9-channel, configurable analog multiplexer (AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 10-bit successive-approximation-register ADC with integrated track-and-hold and Programmable Window Detector (see block diagram in Figure 6.1). The AMUX0, PGA0, Data Conversion Modes, and Window Detector are all configurable under software control via the Special Function Registers shown in Figure 6.1. The voltage reference used by ADC0 is selected as described in Section "9. VOLTAGE REFERENCE (C8051F120/2/4/6)" on page 105 for C8051F120/2/4/6 devices, or Section "10. VOLTAGE REFERENCE (C8051F121/3/5/7)" on page 107 for C8051F121/3/5/7 devices. The ADC0 subsystem (ADC0, trackand-hold and PGA0) is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
Figure 6.1. 10-Bit ADC0 Functional Block Diagram
ADC0GTH ADC0GTL ADC0LTH ADC0LTL
20 Comb. Logic 10
AD0WINT
AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7
TEMP SENSOR
+
AD0EN AV+
SYSCLK REF
AIN0.0
+
AV+
9-to-1 AMUX + (SE or - DIFF)
+ -
X
+ AGND
10-Bit SAR
10
AD0CM
ADC0L
ADC
ADC0H
00
Start Conversion 01
AD0BUSY (W) Timer 3 Overflow CNVSTR0 Timer 2 Overflow
AGND AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 AD0EN AD0TM AD0INT AD0BUSY AD0CM1 AD0CM0 AD0WINT AD0LJST AIN67IC AIN45IC AIN23IC AIN01IC
10 11 AD0CM
AMX0CF
AMX0SL
ADC0CF
ADC0CN
6.1.
Analog Multiplexer and PGA
Eight of the AMUX channels are available for external measurements while the ninth channel is internally connected to an on-chip temperature sensor (temperature transfer function is shown in Figure 6.2). AMUX input pairs can be programmed to operate in either differential or single-ended mode. This allows the user to select the best measurement technique for each input channel, and even accommodates mode changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are two registers associated with the AMUX: the Channel Selection register AMX0SL (Figure 6.6), and the Configuration register AMX0CF (Figure 6.5). The table in Figure 6.6 shows AMUX functionality by channel, for each possible configuration. The PGA amplifies the AMUX output signal by an amount determined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (Figure 6.7). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset.
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The Temperature Sensor transfer function is shown in Figure 6.2. The output voltage (VTEMP) is the PGA input when the Temperature Sensor is selected by bits AMX0AD3-0 in register AMX0SL; this voltage will be amplified by the PGA according to the user-programmed PGA settings.
Figure 6.2. Typical Temperature Sensor Transfer Function
(Volts)
1.000
0.900
0.800 VTEMP = 0.00286(TEMPC) + 0.776 0.700 for PGA Gain = 1 0.600
0.500 -50 0 50 100
(Celsius)
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6.2.
ADC Modes of Operation
ADC0 has a maximum conversion speed of 100 ksps. The ADC0 conversion clock is derived from the system clock divided by the value held in the ADCSC bits of register ADC0CF.
6.2.1.
Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start of Conversion Mode bits (AD0CM1, AD0CM0) in ADC0CN. Conversions may be initiated by: 1. 2. 3. 4. Writing a `1' to the AD0BUSY bit of ADC0CN; A Timer 3 overflow (i.e. timed continuous conversions); A rising edge detected on the external ADC convert start signal, CNVSTR0; A Timer 2 overflow (i.e. timed continuous conversions).
The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag (ADC0CN.5). Converted data is available in the ADC0 data word MSB and LSB registers, ADC0H, ADC0L. Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in Figure 6.11) depending on the programmed state of the AD0LJST bit in the ADC0CN register. When initiating conversions by writing a `1' to AD0BUSY, the AD0INT bit should be polled to determine when a conversion has completed (ADC0 interrupts may also be used). The recommended polling procedure is shown below. Step 1. Step 2. Step 3. Step 4. Write a `0' to AD0INT; Write a `1' to AD0BUSY; Poll AD0INT for `1'; Process ADC0 data.
When CNVSTR0 is used as a conversion start source, it must be enabled in the crossbar, and the corresponding pin must be set to open-drain, high-impedance mode (see Section "18. PORT INPUT/OUTPUT" on page 203 for more details on Port I/O configuration).
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6.2.2. Tracking Modes
Preliminary
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0 input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0 operates in lowpower track-and-hold mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR0 signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR0 is low; conversion begins on the rising edge of CNVSTR0 (see Figure 6.3). Tracking can also be disabled (shutdown) when the entire chip is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section "6.2.3. Settling Time Requirements" on page 69).
Figure 6.3. ADC0 Track and Conversion Example Timing
A. ADC Timing for External Trigger Source
CNVSTR0 (AD0STM[1:0]=10)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
SAR Clocks Low Power or Convert
ADC0TM=1 ADC0TM=0
Track
Convert Convert
Low Power Mode Track
Track Or Convert
B. ADC Timing for Internal Trigger Sources
Timer 2, Timer 3 Overflow; Write '1' to AD0BUSY (AD0STM[1:0]=00, 01, 11) SAR Clocks Low Power or Convert
1
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19
ADC0TM=1
Track
2 3 4 5 6 7 8 9
Convert
10 11 12 13 14 15 16
Low Power Mode
SAR Clocks Track or Convert
ADC0TM=0
Convert
Track
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6.2.3.
Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different MUX or PGA selection is made), a minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Figure 6.4 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice that the equivalent time constant for both input circuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by Equation 6.1. When measuring the Temperature Sensor output, RTOTAL reduces to RMUX. An absolute minimum settling time of 1.5 s is required after any MUX or PGA selection. Note that in low-power tracking mode, three SAR clocks are used for tracking at the start of every conversion. For most applications, these three SAR clocks will meet the tracking requirements.
Equation 6.1. ADC0 Settling Time Requirements 2 t = ln ------ x R TOTAL C SAMPLE SA
n
Where: SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB) t is the required settling time in seconds RTOTAL is the sum of the ADC0 MUX resistance and any external source resistance. n is the ADC resolution in bits (10).
Figure 6.4. ADC0 Equivalent Input Circuits
Differential Mode
MUX Select
Single-Ended Mode
MUX Select
AIN0.x RMUX = 5k CSAMPLE = 10pF RCInput= RMUX * CSAMPLE CSAMPLE = 10pF AIN0.y RMUX = 5k MUX Select
AIN0.x RMUX = 5k CSAMPLE = 10pF RCInput= RMUX * CSAMPLE
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Figure 6.5. AMX0CF: AMUX0 Configuration Register
SFR Page: SFR Address: R/W
0 0xBA
R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
AIN67IC
Bit3
AIN45IC
Bit2
AIN23IC
Bit1
AIN01IC
Bit0
00000000
Bits7-4: Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 0000b; Write = don't care. AIN67IC: AIN0.6, AIN0.7 Input Pair Configuration Bit. 0: AIN0.6 and AIN0.7 are independent single-ended inputs. 1: AIN0.6, AIN0.7 are (respectively) +, - differential input pair. AIN45IC: AIN0.4, AIN0.5 Input Pair Configuration Bit. 0: AIN0.4 and AIN0.5 are independent single-ended inputs. 1: AIN0.4, AIN0.5 are (respectively) +, - differential input pair. AIN23IC: AIN0.2, AIN0.3 Input Pair Configuration Bit. 0: AIN0.2 and AIN0.3 are independent single-ended inputs. 1: AIN0.2, AIN0.3 are (respectively) +, - differential input pair. AIN01IC: AIN0.0, AIN0.1 Input Pair Configuration Bit. 0: AIN0.0 and AIN0.1 are independent single-ended inputs. 1: AIN0.0, AIN0.1 are (respectively) +, - differential input pair. The ADC0 Data Word is in 2's complement format for channels configured as differential.
NOTE:
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Figure 6.6. AMX0SL: AMUX0 Channel Select Register
SFR Page: SFR Address: R/W
0 0xBB
R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
Bit7
Bit6
Bit5
Bit4
AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000
Bits7-4: Bits3-0:
UNUSED. Read = 0000b; Write = don't care. AMX0AD3-0: AMX0 Address Bits. 0000-1111b: ADC Inputs selected per chart below. AMX0AD3-0 0000 0001
AIN0.1
0010
AIN0.2 AIN0.2
0011
AIN0.3 AIN0.3
0100
AIN0.4 AIN0.4 AIN0.4 AIN0.4
0101
AIN0.5 AIN0.5 AIN0.5 AIN0.5
0110
AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6 AIN0.6
0111
AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7 AIN0.7
1xxx
TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR TEMP SENSOR
0000 0001 0010 0011 0100 0101 AMX0CF Bits 3-0 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1) AIN0.0 +(AIN0.0) -(AIN0.1)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
AIN0.1
AIN0.2 AIN0.2
AIN0.3 AIN0.3
+(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
AIN0.1
AIN0.2 AIN0.2
AIN0.3 AIN0.3
AIN0.4 AIN0.4 AIN0.4 AIN0.4
AIN0.5 AIN0.5 AIN0.5 AIN0.5
+(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7) +(AIN0.6) -(AIN0.7)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
AIN0.1
AIN0.2 AIN0.2
AIN0.3 AIN0.3
+(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5) +(AIN0.4) -(AIN0.5)
AIN0.1
+(AIN0.2) -(AIN0.3) +(AIN0.2) -(AIN0.3)
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Figure 6.7. ADC0CF: ADC0 Configuration Register
SFR Page: SFR Address: R/W
0 0xBC
R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
AD0SC4
Bit7
AD0SC3
Bit6
AD0SC2
Bit5
AD0SC1
Bit4
AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000
Bits7-3:
AD0SC4-0: ADC0 SAR Conversion Clock Period Bits. SAR Conversion clock is derived from system clock by the following equation, where AD0SC refers to the 5-bit value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0 SAR clock (Note: the ADC0 SAR Conversion Clock should be less than or equal to 2.5 MHz).
SYSCLK AD0SC = ------------------------------- - 1 2 x C LK SAR0
Bits2-0: AMP0GN2-0: ADC0 Internal Amplifier Gain (PGA). 000: Gain = 1 001: Gain = 2 010: Gain = 4 011: Gain = 8 10x: Gain = 16 11x: Gain = 0.5
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Figure 6.8. ADC0CN: ADC0 Control Register
SFR Page: SFR Address: R/W
0 0xE8
R/W Bit6
(bit addressable)
R/W Bit5 R/W Bit4 R/W Bit3 R/W R/W R/W Bit0 Reset Value
AD0EN
Bit7
AD0TM AD0INT AD0BUSY AD0CM1
AD0CM0
Bit2
AD0WINT
Bit1
AD0LJST 00000000
Bit7:
Bit6:
Bit5:
Bit4:
Bits3-2:
Bit1:
Bit0:
AD0EN: ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. AD0TM: ADC Track Mode Bit. 0: When the ADC is enabled, tracking is continuous unless a conversion is in process. 1: Tracking Defined by ADSTM1-0 bits. AD0INT: ADC0 Conversion Complete Interrupt Flag. This flag must be cleared by software. 0: ADC0 has not completed a data conversion since the last time this flag was cleared. 1: ADC0 has completed a data conversion. AD0BUSY: ADC0 Busy Bit. Read: 0: ADC0 Conversion is complete or a conversion is not currently in progress. AD0INT is set to logic 1 on the falling edge of AD0BUSY. 1: ADC0 Conversion is in progress. Write: 0: No Effect. 1: Initiates ADC0 Conversion if AD0STM1-0 = 00b. AD0CM1-0: ADC0 Start of Conversion Mode Select. If AD0TM = 0: 00: ADC0 conversion initiated on every write of `1' to AD0BUSY. 01: ADC0 conversion initiated on overflow of Timer 3. 10: ADC0 conversion initiated on rising edge of external CNVSTR0. 11: ADC0 conversion initiated on overflow of Timer 2. If AD0TM = 1: 00: Tracking starts with the write of `1' to AD0BUSY and lasts for 3 SAR clocks, followed by conversion. 01: Tracking started by the overflow of Timer 3 and lasts for 3 SAR clocks, followed by conversion. 10: ADC0 tracks only when CNVSTR0 input is logic low; conversion starts on rising CNVSTR0 edge. 11: Tracking started by the overflow of Timer 2 and lasts for 3 SAR clocks, followed by conversion. AD0WINT: ADC0 Window Compare Interrupt Flag. This bit must be cleared by software. 0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared. 1: ADC0 Window Comparison Data match has occurred. AD0LJST: ADC0 Left Justify Select. 0: Data in ADC0H:ADC0L registers are right-justified. 1: Data in ADC0H:ADC0L registers are left-justified.
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Figure 6.9. ADC0H: ADC0 Data Word MSB Register
SFR Page: SFR Address: R/W Bit7
0 0xBF
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
ADC0 Data Word High-Order Bits. For AD0LJST = 0: Bits 7-4 are the sign extension of Bit3. Bits 3-0 are the upper 4 bits of the 10-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-0 are the most-significant bits of the 10-bit ADC0 Data Word.
Figure 6.10. ADC0L: ADC0 Data Word LSB Register
SFR Page: SFR Address: R/W Bit7
0 0xBE
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
ADC0 Data Word Low-Order Bits. For AD0LJST = 0: Bits 7-0 are the lower 8 bits of the 10-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-4 are the lower 4 bits of the 10-bit ADC0 Data Word. Bits3-0 will always read `0'.
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Figure 6.11. ADC0 Data Word Example
10-bit ADC0 Data Word appears in the ADC0 Data Word Registers as follows: ADC0H[1:0]:ADC0L[7:0], if AD0LJST = 0 (ADC0H[7:2] will be sign-extension of ADC0H.1 for a differential reading, otherwise = 000000b). ADC0H[7:0]:ADC0L[7:6], if AD0LJST = 1 (ADC0L[5:0] = 00b). Example: ADC0 Data Word Conversion Map, AIN0.0 Input in Single-Ended Mode (AMX0CF = 0x00, AMX0SL = 0x00) AIN0.0-AGND ADC0H:ADC0L ADC0H:ADC0L (Volts) (AD0LJST = 0) (AD0LJST = 1) VREF * (1023/1024) 0x03FF 0xFFC0 VREF / 2 0x0800 0x8000 VREF * (511/1024) 0x01FF 0x7FC0 0 0x0000 0x0000 Example: ADC0 Data Word Conversion Map, AIN0.0-AIN0.1 Differential Input Pair (AMX0CF = 0x01, AMX0SL = 0x00) AIN0.0-AIN0.1 ADC0H:ADC0L ADC0H:ADC0L (Volts) (AD0LJST = 0) (AD0LJST = 1) VREF * (511/512) 0x01FF 0x7FC0 VREF / 2 0x0100 0x4000 VREF * (1/512) 0x0001 0x0040 0 0x0000 0x0000 -VREF * (1/512) 0xFFFF (-1d) 0xFFC0 -VREF / 2 0xFF00 (-256d) 0xC000 -VREF 0xFE00 (-512d) 0x8000 For AD0LJST = 0:
Gain Code = Vin x -------------- x 2 n ; `n' = 10 for Single-Ended; `n'= 9 for Differential. VREF
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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6.3.
Preliminary
ADC0 Programmable Window Detector
The ADC0 Programmable Window Detector continuously compares the ADC0 output to user-programmed limits, and notifies the system when an out-of-bound condition is detected. This is especially effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD0WINT in ADC0CN) can also be used in polled mode. The high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting on page 78. Notice that the window detector flag can be asserted when the measured data is inside or outside the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx registers.
Figure 6.12. ADC0GTH: ADC0 Greater-Than Data High Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC5
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
Bits7-0:
High byte of ADC0 Greater-Than Data Word.
Figure 6.13. ADC0GTL: ADC0 Greater-Than Data Low Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC4
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
Bits7-0:
Low byte of ADC0 Greater-Than Data Word.
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Figure 6.14. ADC0LTH: ADC0 Less-Than Data High Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC7
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
High byte of ADC0 Less-Than Data Word.
Figure 6.15. ADC0LTL: ADC0 Less-Than Data Low Byte Register
SFR Page: SFR Address: R/W Bit7
0 0xC6
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
Low byte of ADC0 Less-Than Data Word.
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Figure 6.16. 10-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data
Input Voltage (AD0.0 - AGND) REF x (1023/1024)
ADC Data Word
0x03FF ADWINT not affected 0x0201
Input Voltage (AD0.0 - AGND) REF x (1023/1024)
ADC Data Word
0x03FF
ADWINT=1
0x0201 ADC0LTH:ADC0LTL ADWINT=1 REF x (512/1024) 0x0200 0x01FF 0x0101 ADC0GTH:ADC0GTL REF x (256/1024) 0x0100 0x00FF ADC0GTH:ADC0GTL ADWINT not affected ADC0LTH:ADC0LTL
REF x (512/1024)
0x0200 0x01FF 0x0101
REF x (256/1024)
0x0100 0x00FF
ADWINT not affected 0 0x0000 0 0x0000
ADWINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x00 AD0LJST = `0', ADC0LTH:ADC0LTL = 0x0200, ADC0GTH:ADC0GTL = 0x0100. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x0200 and > 0x0100.
Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = `0', ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0x0200. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is > 0x0200 or < 0x0100.
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Figure 6.17. 10-Bit ADC0 Window Interrupt Example: Right Justified Differential Data
Input Voltage (AD0.0 - AD0.1) REF x (511/512)
ADC Data Word
0x01FF ADWINT not affected 0x0101
Input Voltage (AD0.0 - AD0.1) REF x (511/512)
ADC Data Word
0x01FF
ADWINT=1
0x0101 ADC0LTH:ADC0LTL ADWINT=1 REF x (256/512) 0x0100 0x00FF 0x0000 ADC0GTH:ADC0GTL REF x (-1/512) 0xFFFF 0xFFFE ADC0GTH:ADC0GTL ADWINT not affected ADC0LTH:ADC0LTL
REF x (256/512)
0x0100 0x00FF 0x0000
REF x (-1/512)
0xFFFF 0xFFFE
ADWINT not affected -REF 0xFE00 -REF 0xFE00
ADWINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `0', ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0xFFFF. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x0100 and > 0xFFFF. (In two's-complement math, 0xFFFF = -1.)
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `0', ADC0LTH:ADC0LTL = 0xFFFF, ADC0GTH:ADC0GTL = 0x0100. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0xFFFF or > 0x0100. (In two's-complement math, 0xFFFF = -1.)
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Figure 6.18. 10-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data
Input Voltage (AD0.0 - AGND) REF x (1023/1024)
ADC Data Word
0xFFC0 ADWINT not affected 0x8040
Input Voltage (AD0.0 - AGND) REF x (1023/1024)
ADC Data Word
0xFFC0
ADWINT=1
0x8040 ADC0LTH:ADC0LTL ADWINT=1 REF x (512/1024) 0x8000 0x7FC0 0x4040 ADC0GTH:ADC0GTL REF x (256/1024) 0x4000 0x3FC0 ADC0GTH:ADC0GTL ADWINT not affected ADC0LTH:ADC0LTL
REF x (512/1024)
0x8000 0x7FC0 0x4040
REF x (256/1024)
0x4000 0x3FC0
ADWINT not affected 0 0x0000 0 0x0000
ADWINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = `1', ADC0LTH:ADC0LTL = 0x2000, ADC0GTH:ADC0GTL = 0x1000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x2000 and > 0x1000.
Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = `1' ADC0LTH:ADC0LTL = 0x1000, ADC0GTH:ADC0GTL = 0x2000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x1000 or > 0x2000.
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Figure 6.19. 10-Bit ADC0 Window Interrupt Example: Left Justified Differential Data
Input Voltage (AD0.0 - AD0.1) REF x (511/512)
ADC Data Word
0x7FC0 ADWINT not affected 0x2040
Input Voltage (AD0.0 - AD0.1) REF x (511/512)
ADC Data Word
0x7FC0
ADWINT=1
0x2040 ADC0LTH:ADC0LTL ADWINT=1 REF x (128/512) 0x2000 0x1FC0 0x0000 ADC0GTH:ADC0GTL REF x (-1/512) 0xFFC0 0xFF80 ADC0GTH:ADC0GTL ADWINT not affected ADC0LTH:ADC0LTL
REF x (128/512)
0x2000 0x1FC0 0x0000
REF x (-1/512)
0xFFC0 0xFF80
ADWINT not affected -REF 0x8000 -REF 0x8000
ADWINT=1
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `1', ADC0LTH:ADC0LTL = 0x2000, ADC0GTH:ADC0GTL = 0xFFC0. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0x2000 and > 0xFFC0. (Two's-complement math.)
Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = `1', ADC0LTH:ADC0LTL = 0xFFC0, ADC0GTH:ADC0GTL = 0x2000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = `1') if the resulting ADC0 Data Word is < 0xFFC0 or > 0x2000. (Two's-complement math.)
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Table 6.1. 10-Bit ADC0 Electrical Characteristics (C8051F122/3/6/7)
VDD = 3.0V, AV+ = 3.0V, VREF = 2.40V (REFBE=0), PGA Gain = 1, -40C to +85C unless otherwise specified PARAMETER DC ACCURACY Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Full Scale Error Offset Temperature Coefficient Signal-to-Noise Plus Distortion Total Harmonic Distortion Spurious-Free Dynamic Range CONVERSION RATE SAR Clock Frequency Conversion Time in SAR Clocks Track/Hold Acquisition Time Throughput Rate ANALOG INPUTS Input Voltage Range *Common-mode Voltage Range Input Capacitance TEMPERATURE SENSOR Linearity Gain Offset POWER SPECIFICATIONS Power Supply Current (AV+ supplied to ADC) Power Supply Rejection Note 1: Includes ADC offset, gain, and linearity variations. Note 2: Represents one standard deviation from the mean. Operating Mode, 100 ksps 450 0.3 900 A mV/V Note 1 Note 2 Note 1, Note 2, (Temp = 0 C) 0.2 2.86 776 8.5 C mV / C mV Single-ended operation Differential operation 0 AGND 10 VREF AV+ V V pF 16 1.5 100 2.5 MHz clocks s ksps Up to the 5th harmonic 59 -70 80 Differential mode Guaranteed Monotonic 0.5 -1.50.5 0.25 10 1 1 bits LSB LSB LSB LSB ppm/C dB dB dB CONDITIONS MIN TYP MAX UNITS
DYNAMIC PERFORMANCE (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps
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7.
ADC2 (8-BIT ADC)
The ADC2 subsystem for the C8051F120/1/2/3/4/5/6/7 consists of an 8-channel, configurable analog multiplexer (AMUX2), a programmable gain amplifier (PGA2), and a 500 ksps, 8-bit successive-approximation-register ADC with integrated track-and-hold (see block diagram in Figure 7.1). The AMUX2, PGA2, and Data Conversion Modes are all configurable under software control via the Special Function Registers shown in Figure 7.1. The ADC2 subsystem (8-bit ADC, track-and-hold and PGA) is enabled only when the AD2EN bit in the ADC2 Control register (ADC2CN) is set to logic 1. The ADC2 subsystem is in low power shutdown when this bit is logic 0. The voltage reference used by ADC2 is selected as described in Section "9. VOLTAGE REFERENCE (C8051F120/2/4/6)" on page 105 for C8051F120/2/4/6 devices, or Section "10. VOLTAGE REFERENCE (C8051F121/3/5/7)" on page 107 for C8051F121/3/5/7 devices.
Figure 7.1. ADC2 Functional Block Diagram
ADC2GTH ADC2LTH
16 SYSCLK REF Dig Comp
AV+
AIN2.0 (P1.0) AIN2.1 (P1.1) AIN2.2 (P1.2) AIN2.3 (P1.3) AIN2.4 (P1.4) AIN2.5 (P1.5) AIN2.6 (P1.6) AIN2.7 (P1.7)
+ + + +
AD2EN AV+
AD2WINT 8
8-to-1 AMUX
X
+ AGND
8
ADC2
8-Bit SAR
8
ADC
AD2CM
000 001
Start Conversion
Write to AD2BUSY Timer 3 Overflow CNVSTR2 Timer 2 Overflow Write to AD0BUSY (synchronized with ADC0)
010 011 1xx
AMX2AD2 AMX2AD1 AMX2AD0
AMP2GN1 AMP2GN0
AD2EN AD2TM AD2INT AD2BUSY AD2CM2 AD2CM1 AD2CM0 AD2WINT
PIN67IC PIN45IC PIN23IC PIN01IC
AD2SC4 AD2SC3 AD2SC2 AD2SC1 AD2SC0
AMX2CF
AMX2SL
ADC2CF
ADC2CN
7.1.
Analog Multiplexer and PGA
Eight ADC2 channels are available for measurement, as selected by the AMX2SL register (see Figure 7.5). The PGA amplifies the ADC2 output signal by an amount determined by the states of the AMP2GN2-0 bits in the ADC2 Configuration register, ADC2CF (Figure 7.6). The PGA can be software-programmed for gains of 0.5, 1, 2, or 4. Gain defaults to 0.5 on reset. Important Note: AIN2 pins also function as Port 1 I/O pins, and must be configured as analog inputs when used as ADC2 inputs. To configure an AIN2 pin for analog input, set to `1' the corresponding bit in register P1MDIN. Port 1 pins selected as analog inputs are skipped by the Digital I/O Crossbar. See Section "18.1.5. Configuring Port 1 Pins as Analog Inputs" on page 207 for more information on configuring the AIN2 pins.
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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7.2. ADC2 Modes of Operation
Preliminary
ADC2 has a maximum conversion speed of 500 ksps. The ADC2 conversion clock (SAR2 clock) is a divided version of the system clock, determined by the AD2SC bits in the ADC2CF register. The maximum ADC2 conversion clock is 7.5 MHz.
7.2.1.
Starting a Conversion
A conversion can be initiated in one of five ways, depending on the programmed states of the ADC2 Start of Conversion Mode bits (AD2STM1, AD2STM0) in ADC2CN. Conversions may be initiated by: 1. Writing a `1' to the AD2BUSY bit of ADC2CN; 2. A Timer 3 overflow (i.e. timed continuous conversions); 3. A rising edge detected on the external ADC convert start signal, CNVSTR2; 4. A Timer 2 overflow (i.e. timed continuous conversions); 5. Writing a `1' to the AD0BUSY of register ADC0CN (initiate conversion of ADC2 and ADC0 with a single software command). During conversion, the AD2BUSY bit is set to logic 1 and restored to 0 when conversion is complete. The falling edge of AD2BUSY triggers an interrupt (when enabled) and sets the interrupt flag in ADC2CN. Converted data is available in the ADC2 data word, ADC2. When a conversion is initiated by writing a `1' to AD2BUSY, it is recommended to poll AD2INT to determine when the conversion is complete. The recommended procedure is: Step 1. Step 2. Step 3. Step 4. Write a `0' to AD2INT; Write a `1' to AD2BUSY; Poll AD2INT for `1'; Process ADC2 data.
When CNVSTR2 is used as a conversion start source, it must be enabled in the crossbar, and the corresponding pin must be set to open-drain, high-impedance mode (see Section "18. PORT INPUT/OUTPUT" on page 203 for more details on Port I/O configuration).
7.2.2.
Tracking Modes
The AD2TM bit in register ADC2CN controls the ADC2 track-and-hold mode. In its default state, the ADC2 input is continuously tracked, except when a conversion is in progress. When the AD2TM bit is logic 1, ADC2 operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR2 signal is used to initiate conversions in low-power tracking mode, ADC2 tracks only when CNVSTR2 is low; conversion begins on the rising edge of CNVSTR2 (see Figure 7.2). Tracking can also be disabled (shutdown) when the entire chip is in low power standby or sleep modes. Low-power Track-and-Hold mode is also useful when AMUX or PGA settings are frequently changed, due to the settling time requirements described in Section "7.2.3. Settling Time Requirements" on page 86.
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Figure 7.2. ADC2 Track and Conversion Example Timing
A. ADC Timing for External Trigger Source
CNVSTR2 (AD2CM[2:0]=010)
1 2 3 4 5 6 7 8 9
SAR Clocks Low Power or Convert
AD2TM=1
Track
Convert
Low Power Mode
AD2TM=0
Track or Convert
Convert
Track
B. ADC Timing for Internal Trigger Source
Write '1' to AD2BUSY, Timer 3 Overflow, Timer 2 Overflow, Write '1' to AD0BUSY (AD2CM[2:0]=000, 001, 011, 1xx)
1 2 3 4 5 6 7 8 9 10 11 12
SAR Clocks AD2TM=1 Low Power or Convert
1
Track
2 3 4 5 6
Convert
7 8 9
Low Power Mode
SAR Clocks AD2TM=0 Track or Convert Convert Track
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7.2.3. Settling Time Requirements
Preliminary
When the ADC2 input configuration is changed (i.e., a different MUX or PGA selection), a minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the ADC2 MUX resistance, the ADC2 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Figure 7.3 shows the equivalent ADC2 input circuit. The required ADC2 settling time for a given settling accuracy (SA) may be approximated by Equation 7.1. Note: An absolute minimum settling time of 800 ns required after any MUX selection. Note that in low-power tracking mode, three SAR2 clocks are used for tracking at the start of every conversion. For most applications, these three SAR2 clocks will meet the tracking requirements.
Equation 7.1. ADC2 Settling Time Requirements 2 t = ln ------ x R TOTAL C SAMPLE SA
Where: SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB) t is the required settling time in seconds RTOTAL is the sum of the ADC2 MUX resistance and any external source resistance. n is the ADC resolution in bits (8).
n
Figure 7.3. ADC2 Equivalent Input Circuit
Differential Mode
MUX Select
Single-Ended Mode
MUX Select
AIN2.x RMUX = 5k CSAMPLE = 5pF RCInput= RMUX * CSAMPLE CSAMPLE = 5pF AIN2.y RMUX = 5k MUX Select
AIN2.x RMUX = 5k CSAMPLE = 5pF RCInput= RMUX * CSAMPLE
Note: When the PGA gain is set to 0.5, CSAMPLE = 3pF
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Figure 7.4. AMX2CF: AMUX2 Configuration Register
SFR Page: SFR Address: R/W
2 0xBA
R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
PIN67IC
Bit3
PIN45IC
Bit2
PIN23IC
Bit1
PIN01IC
Bit0
00000000
Bits7-4: Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 0000b; Write = don't care. PIN67IC: AIN2.6, AIN2.7 Input Pair Configuration Bit. 0: AIN2.6 and AIN2.7 are independent single-ended inputs. 1: AIN2.6 and AIN2.7 are (respectively) +, - differential input pair. PIN45IC: AIN2.4, AIN2.5 Input Pair Configuration Bit. 0: AIN2.4 and AIN2.5 are independent single-ended inputs. 1: AIN2.4 and AIN2.5 are (respectively) +, - differential input pair. PIN23IC: AIN2.2, AIN2.3 Input Pair Configuration Bit. 0: AIN2.2 and AIN2.3 are independent single-ended inputs. 1: AIN2.2 and AIN2.3 are (respectively) +, - differential input pair. PIN01IC: AIN2.0, AIN2.1 Input Pair Configuration Bit. 0: AIN2.0 and AIN2.1 are independent single-ended inputs. 1: AIN2.0 and AIN2.1 are (respectively) +, - differential input pair. The ADC2 Data Word is in 2's complement format for channels configured as differential.
NOTE:
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Figure 7.5. AMX2SL: AMUX2 Channel Select Register
SFR Page: SFR Address: R/W
2 0xBB
R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
Bit7
Bit6
Bit5
Bit4
AMX2AD2 AMX2AD1 AMX2AD0 00000000
Bits7-3: Bits2-0:
UNUSED. Read = 00000b; Write = don't care. AMX2AD2-0: AMX2 Address Bits. 000-111b: ADC Inputs selected per chart below. AMX2AD2-0 000 001
AIN2.1
010
AIN2.2 AIN2.2
011
AIN2.3 AIN2.3
100
AIN2.4 AIN2.4 AIN2.4 AIN2.4
101
AIN2.5 AIN2.5 AIN2.5 AIN2.5
110
AIN2.6 AIN2.6 AIN2.6 AIN2.6 AIN2.6 AIN2.6 AIN2.6 AIN2.6
111
AIN2.7 AIN2.7 AIN2.7 AIN2.7 AIN2.7 AIN2.7 AIN2.7 AIN2.7
0000 0001 0010 0011 0100 0101 AMX2CF Bits 3-0 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
AIN2.0 +(AIN2.0) -(AIN2.1) AIN2.0 +(AIN2.0) -(AIN2.1) AIN2.0 +(AIN2.0) -(AIN2.1) AIN2.0 +(AIN2.0) -(AIN2.1) AIN2.0 +(AIN2.0) -(AIN2.1) AIN2.0 +(AIN2.0) -(AIN2.1) AIN2.0 +(AIN2.0) -(AIN2.1) AIN2.0 +(AIN2.0) -(AIN2.1)
AIN2.1
+(AIN2.2) -(AIN2.3) +(AIN2.2) -(AIN2.3)
AIN2.1
AIN2.2 AIN2.2
AIN2.3 AIN2.3
+(AIN2.4) -(AIN2.5) +(AIN2.4) -(AIN2.5) +(AIN2.4) -(AIN2.5) +(AIN2.4) -(AIN2.5)
AIN2.1
+(AIN2.2) -(AIN2.3) +(AIN2.2) -(AIN2.3)
AIN2.1
AIN2.2 AIN2.2
AIN2.3 AIN2.3
AIN2.4 AIN2.4 AIN2.4 AIN2.4
AIN2.5 AIN2.5 AIN2.5 AIN2.5
+(AIN2.6) -(AIN2.7) +(AIN2.6) -(AIN2.7) +(AIN2.6) -(AIN2.7) +(AIN2.6) -(AIN2.7) +(AIN2.6) -(AIN2.7) +(AIN2.6) -(AIN2.7) +(AIN2.6) -(AIN2.7) +(AIN2.6) -(AIN2.7)
AIN2.1
+(AIN2.2) -(AIN2.3) +(AIN2.2) -(AIN2.3)
AIN2.1
AIN2.2 AIN2.2
AIN2.3 AIN2.3
+(AIN2.4) -(AIN2.5) +(AIN2.4) -(AIN2.5) +(AIN2.4) -(AIN2.5) +(AIN2.4) -(AIN2.5)
AIN2.1
+(AIN2.2) -(AIN2.3) +(AIN2.2) -(AIN2.3)
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Figure 7.6. ADC2CF: ADC2 Configuration Register
SFR Page: SFR Address: R/W
2 0xBC
R/W R/W R/W R/W R/W R/W Bit1 R/W Bit0 Reset Value
AD2SC4
Bit7
AD2SC3
Bit6
AD2SC2
Bit5
AD2SC1
Bit4
AD2SC0
Bit3
Bit2
AMP2GN1 AMP2GN0 11111000
Bits7-3:
AD2SC4-0: ADC2 SAR Conversion Clock Period Bits. SAR Conversion clock is derived from system clock by the following equation, where AD2SC refers to the 5-bit value held in AD2SC4-0, and CLKSAR2 refers to the desired ADC2 SAR clock (Note: the ADC2 SAR Conversion Clock should be less than or equal to 7.5 MHz).
SYSCLK AD2SC = ---------------------- - 1 CLK SAR2
Bit2: Bits1-0: UNUSED. Read = 0b; Write = don't care. AMP2GN1-0: ADC2 Internal Amplifier Gain (PGA). 00: Gain = 0.5 01: Gain = 1 10: Gain = 2 11: Gain = 4
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Figure 7.7. ADC2CN: ADC2 Control Register
SFR Page: SFR Address: R/W
2 0xE8
R/W
(bit addressable)
R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W R/W Bit0 Reset Value
AD2EN
Bit7
AD2TM
Bit6
AD2INT AD2BUSY AD2CM2 AD2CM1
AD2CM0
Bit1
AD2WINT 00000000
Bit7:
Bit6:
Bit5:
Bit4:
Bits3-1:
Bit0:
AD2EN: ADC2 Enable Bit. 0: ADC2 Disabled. ADC2 is in low-power shutdown. 1: ADC2 Enabled. ADC2 is active and ready for data conversions. AD2TM: ADC2 Track Mode Bit. 0: Normal Track Mode: When ADC2 is enabled, tracking is continuous unless a conversion is in process. 1: Low-power Track Mode: Tracking Defined by AD2STM2-0 bits (see below). AD2INT: ADC2 Conversion Complete Interrupt Flag. This flag must be cleared by software. 0: ADC2 has not completed a data conversion since the last time this flag was cleared. 1: ADC2 has completed a data conversion. AD2BUSY: ADC2 Busy Bit. Read: 0: ADC2 Conversion is complete or a conversion is not currently in progress. AD2INT is set to logic 1 on the falling edge of AD2BUSY. 1: ADC2 Conversion is in progress. Write: 0: No Effect. 1: Initiates ADC2 Conversion if AD2STM2-0 = 000b AD2CM2-0: ADC2 Start of Conversion Mode Select. AD2TM = 0: 000: ADC2 conversion initiated on every write of `1' to AD2BUSY. 001: ADC2 conversion initiated on overflow of Timer 3. 010: ADC2 conversion initiated on rising edge of external CNVSTR2. 011: ADC2 conversion initiated on overflow of Timer 2. 1xx: ADC2 conversion initiated on write of `1' to AD0BUSY (synchronized with ADC0 softwarecommanded conversions). AD2TM = 1: 000: Tracking initiated on write of `1' to AD2BUSY and lasts 3 SAR2 clocks, followed by conversion. 001: Tracking initiated on overflow of Timer 3 and lasts 3 SAR2 clocks, followed by conversion. 010: ADC2 tracks only when CNVSTR2 input is logic low; conversion starts on rising CNVSTR2 edge. 011: Tracking initiated on overflow of Timer 2 and lasts 3 SAR2 clocks, followed by conversion. 1xx: Tracking initiated on write of `1' to AD0BUSY and lasts 3 SAR2 clocks, followed by conversion. AD2WINT: ADC2 Window Compare Interrupt Flag. This bit must be cleared by software. 0: ADC2 Window Comparison Data match has not occurred since this flag was last cleared. 1: ADC2 Window Comparison Data match has occurred.
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Figure 7.8. ADC2: ADC2 Data Word Register
SFR Page: SFR Address: R/W Bit7
2 0xBE
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0:
ADC2 Data Word.
Figure 7.9. ADC2 Data Word Example
Single-Ended Example: 8-bit ADC Data Word appears in the ADC2 Data Word Register as follows: Example: ADC2 Data Word Conversion Map, Single-Ended AIN2.0 Input (AMX2CF = 0x00; AMX2SL = 0x00) AIN2.0-AGND ADC2 (Volts) VREF * (255/256) 0xFF VREF * (128/256) 0x80 VREF * (64/256) 0x40 0 0x00
Gain Code = Vin x -------------- x 256 VREF
Differential Example: 8-bit ADC Data Word appears in the ADC2 Data Word Register as follows: Example: ADC2 Data Word Conversion Map, Differential AIN2.0-AIN2.1 Input (AMX2CF = 0x01; AMX2SL = 0x00) AIN2.0-AIN2.1 ADC2 (Volts) VREF * (127/128) 0x7F VREF * (64/128) 0x40 0 0x00 -VREF * (64/128) 0xC0 (-64d) -VREF * (128/128) 0x80 (-128d)
Gain Code = Vin x ------------------------ x 256 2 x V REF
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7.3.
Preliminary
ADC2 Programmable Window Detector
The ADC2 Programmable Window Detector continuously compares the ADC2 output to user-programmed limits, and notifies the system when a desired condition is detected. This is especially effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD2WINT in register ADC2CN) can also be used in polled mode. The ADC2 Greater-Than (ADC2GT) and Less-Than (ADC2LT) registers hold the comparison values. Example comparisons for Differential and Single-ended modes are shown in Figure 7.11 and Figure 7.10, respectively. Notice that the window detector flag can be programmed to indicate when measured data is inside or outside of the user-programmed limits, depending on the contents of the ADC2LT and ADC2GT registers.
7.3.1.
Window Detector In Single-Ended Mode
Figure 7.10 shows two example window comparisons for Single-ended mode, with ADC2LT = 0x20 and ADC2GT = 0x10. Notice that in Single-ended mode, the codes vary from 0 to VREF*(255/256) and are represented as 8-bit unsigned integers. In the left example, an AD2WINT interrupt will be generated if the ADC2 conversion word (ADC2) is within the range defined by ADC2GT and ADC2LT (if 0x10 < ADC2 < 0x20). In the right example, and AD2WINT interrupt will be generated if ADC2 is outside of the range defined by ADC2GT and ADC2LT (if ADC2 < 0x10 or ADC2 > 0x20).
Figure 7.10. ADC2 Window Compare Examples, Single-Ended Mode
ADC2 Input Voltage (AIN2.x - AGND) REF x (255/256) 0xFF AD2WINT not affected 0x21 REF x (32/256) 0x20 0x1F 0x11 0x10 0x0F ADC2LT AD2WINT=1 REF x (16/256) ADC2GT REF x (16/256) 0x11 0x10 0x0F REF x (32/256) 0x21 0x20 0x1F ADC2GT AD2WINT not affected ADC2LT Input Voltage (AIN2.x - AGND) REF x (255/256) 0xFF ADC2
AD2WINT=1
AD2WINT not affected 0 0x00 0 0x00
AD2WINT=1
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7.3.2.
Window Detector In Differential Mode
Figure 7.11 shows two example window comparisons for differential mode, with ADC2LT = 0x10 (+16d) and ADC2GT = 0xFF (-1d). Notice that in Differential mode, the codes vary from -VREF to VREF*(127/128) and are represented as 8-bit 2's complement signed integers. In the left example, an AD2WINT interrupt will be generated if the ADC2 conversion word (ADC2L) is within the range defined by ADC2GT and ADC2LT (if 0xFF (-1d) < ADC2 < 0x0F (16d)). In the right example, an AD2WINT interrupt will be generated if ADC2 is outside of the range defined by ADC2GT and ADC2LT (if ADC2 < 0xFF (-1d) or ADC2 > 0x10 (+16d)).
Figure 7.11. ADC2 Window Compare Examples, Differential Mode
ADC2 Input Voltage (AIN2.x - AIN2.y) REF x (127/128) 0x7F (127d) AD2WINT not affected 0x11 (17d) REF x (16/128) 0x10 (16d) 0x0F (15d) 0x00 (0d) 0xFF (-1d) 0xFE (-2d) ADC2LT AD2WINT=1 REF x (-1/256) ADC2GT REF x (-1/256) 0x00 (0d) 0xFF (-1d) 0xFE (-2d) REF x (16/128) 0x11 (17d) 0x10 (16d) 0x0F (15d) ADC2GT AD2WINT not affected ADC2LT Input Voltage (AIN2.x - AIN2.y) REF x (127/128) 0x7F (127d) ADC2
AD2WINT=1
AD2WINT not affected -REF 0x80 (-128d) -REF 0x80 (-128d)
AD2WINT=1
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Figure 7.12. ADC2GT: ADC2 Greater-Than Data Byte Register
SFR Page: SFR Address: R/W Bit7
2 0xC4
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
11111111
Bits7-0: ADC2 Greater-Than Data Word.
Figure 7.13. ADC2LT: ADC2 Less-Than Data Byte Register
SFR Page: SFR Address: R/W Bit7
2 0xC6
R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
Bits7-0: ADC2 Less-Than Data Word.
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Table 7.1. ADC2 Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, VREF2 = 2.40 V (REFBE=0), PGA gain = 1, -40C to +85C unless otherwise specified PARAMETER DC ACCURACY Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Full Scale Error Offset Temperature Coefficient Signal-to-Noise Plus Distortion Total Harmonic Distortion Spurious-Free Dynamic Range CONVERSION RATE SAR Clock Frequency Conversion Time in SAR Clocks Track/Hold Acquisition Time Throughput Rate ANALOG INPUTS Input Voltage Range Input Capacitance POWER SPECIFICATIONS Power Supply Current (AV+ supplied to ADC2) Power Supply Rejection Operating Mode, 500 ksps 420 0.3 TBD A mV/V 0 5 VREF V pF 8 800 500 7.5 MHz clocks ns ksps Up to the 5 harmonic
th
CONDITIONS
MIN
TYP 8
MAX
UNITS bits
1 Guaranteed Monotonic 0.50.3 Differential mode -10.2 TBD TBD 47 51 52 1
LSB LSB LSB LSB ppm/C dB dB dB
DYNAMIC PERFORMANCE (10 kHz sine-wave input, 1 dB below Full Scale, 500 ksps
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8.
DACS, 12-BIT VOLTAGE MODE
Each C8051F12x device includes two on-chip 12-bit voltage-mode Digital-to-Analog Converters (DACs). Each DAC has an output swing of 0 V to (VREF-1LSB) for a corresponding input code range of 0x000 to 0xFFF. The DACs may be enabled/disabled via their corresponding control registers, DAC0CN and DAC1CN. While disabled, the DAC output is maintained in a high-impedance state, and the DAC supply current falls to 1 A or less. The voltage reference for each DAC is supplied at the VREFD pin (C8051F120/2/4/6 devices) or the VREF pin (C8051F121/ 3/5/7 devices). Note that the VREF pin on C8051F121/3/5/7 devices may be driven by the internal voltage reference or an external source. If the internal voltage reference is used it must be enabled in order for the DAC outputs to be valid. See Section "9. VOLTAGE REFERENCE (C8051F120/2/4/6)" on page 105 or Section "10. VOLTAGE REFERENCE (C8051F121/3/5/7)" on page 107 for more information on configuring the voltage reference for the DACs.
8.1.
DAC Output Scheduling
Each DAC features a flexible output update mechanism which allows for seamless full-scale changes and supports jitter-free updates for waveform generation. The following examples are written in terms of DAC0, but DAC1 operation is identical.
8.1.1.
Update Output On-Demand
In its default mode (DAC0CN.[4:3] = `00') the DAC0 output is updated "on-demand" on a write to the high-byte of the DAC0 data register (DAC0H). It is important to note that writes to DAC0L are held, and have no effect on the DAC0 output until a write to DAC0H takes place. If writing a full 12-bit word to the DAC data registers, the 12-bit data word is written to the low byte (DAC0L) and high byte (DAC0H) data registers. Data is latched into DAC0 after
Figure 8.1. DAC Functional Block Diagram
DAC0H Timer 3 Timer 4 DAC0EN DAC0CN DAC0MD1 DAC0MD0 DAC0DF2 DAC0DF1 DAC0DF0 DAC0H Dig. MUX 8 Latch 8 Timer 2
REF AV+
12
DAC0 DAC0
DAC0L
8
Latch
8 AGND
DAC1H
Timer 3
Timer 4
DAC1EN DAC1CN DAC1MD1 DAC1MD0 DAC1DF2 DAC1DF1 DAC1DF0 DAC1H
Timer 2
REF AV+ Dig. MUX 8 Latch 8
12
DAC1 DAC1
DAC1L
8
Latch
8 AGND
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a write to the corresponding DAC0H register, so the write sequence should be DAC0L followed by DAC0H if the full 12-bit resolution is required. The DAC can be used in 8-bit mode by initializing DAC0L to the desired value (typically 0x00), and writing data to only DAC0H (also see Section 8.2 for information on formatting the 12-bit DAC data word within the 16-bit SFR space).
8.1.2.
Update Output Based on Timer Overflow
Similar to the ADC operation, in which an ADC conversion can be initiated by a timer overflow independently of the processor, the DAC outputs can use a Timer overflow to schedule an output update event. This feature is useful in systems where the DAC is used to generate a waveform of a defined sampling rate by eliminating the effects of variable interrupt latency and instruction execution on the timing of the DAC output. When the DAC0MD bits (DAC0CN.[4:3]) are set to `01', `10', or `11', writes to both DAC data registers (DAC0L and DAC0H) are held until an associated Timer overflow event (Timer 3, Timer 4, or Timer 2, respectively) occurs, at which time the DAC0H:DAC0L contents are copied to the DAC input latches allowing the DAC output to change to the new value.
8.2.
DAC Output Scaling/Justification
In some instances, input data should be shifted prior to a DAC0 write operation to properly justify data within the DAC input registers. This action would typically require one or more load and shift operations, adding software overhead and slowing DAC throughput. To alleviate this problem, the data-formatting feature provides a means for the user to program the orientation of the DAC0 data word within data registers DAC0H and DAC0L. The three DAC0DF bits (DAC0CN.[2:0]) allow the user to specify one of five data word orientations as shown in the DAC0CN register definition. DAC1 is functionally the same as DAC0 described above. The electrical specifications for both DAC0 and DAC1 are given in Table 8.1.
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Figure 8.2. DAC0H: DAC0 High Byte Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xD3 SFR Page: 0 Reset Value
00000000
Bits7-0:
DAC0 Data Word Most Significant Byte.
Figure 8.3. DAC0L: DAC0 Low Byte Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xD2 SFR Page: 0 Reset Value
00000000
Bits7-0:
DAC0 Data Word Least Significant Byte.
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Figure 8.4. DAC0CN: DAC0 Control Register
R/W R/W R/W R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xD4 SFR Page: 0 Reset Value
DAC0EN
Bit7
Bit6
Bit5
DAC0MD1 DAC0MD0 DAC0DF2 DAC0DF1 DAC0DF0 00000000
Bit7:
Bits6-5: Bits4-3:
Bits2-0:
DAC0EN: DAC0 Enable Bit. 0: DAC0 Disabled. DAC0 Output pin is disabled; DAC0 is in low-power shutdown mode. 1: DAC0 Enabled. DAC0 Output pin is active; DAC0 is operational. UNUSED. Read = 00b; Write = don't care. DAC0MD1-0: DAC0 Mode Bits. 00: DAC output updates occur on a write to DAC0H. 01: DAC output updates occur on Timer 3 overflow. 10: DAC output updates occur on Timer 4 overflow. 11: DAC output updates occur on Timer 2 overflow. DAC0DF2-0: DAC0 Data Format Bits: 000: The most significant nibble of the DAC0 Data Word is in DAC0H[3:0], while the least significant byte is in DAC0L. DAC0H DAC0L
MSB LSB
001:
The most significant 5-bits of the DAC0 Data Word is in DAC0H[4:0], while the least significant 7-bits are in DAC0L[7:1]. DAC0H DAC0L
MSB LSB
010:
The most significant 6-bits of the DAC0 Data Word is in DAC0H[5:0], while the least significant 6-bits are in DAC0L[7:2]. DAC0H DAC0L
LSB
MSB
011:
The most significant 7-bits of the DAC0 Data Word is in DAC0H[6:0], while the least significant 5-bits are in DAC0L[7:3]. DAC0H DAC0L
LSB
MSB
1xx:
The most significant 8-bits of the DAC0 Data Word is in DAC0H[7:0], while the least significant 4-bits are in DAC0L[7:4]. DAC0H DAC0L
LSB
MSB
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Figure 8.5. DAC1H: DAC1 High Byte Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xD3 SFR Page: 1 Reset Value
00000000
Bits7-0:
DAC1 Data Word Most Significant Byte.
Figure 8.6. DAC1L: DAC1 Low Byte Register
R/W Bit7
R/W Bit6
R/W Bit5
R/W Bit4
R/W Bit3
R/W Bit2
R/W Bit1
R/W Bit0
Reset Value
00000000
SFR Address: 0xD2 SFR Page: 1
Bits7-0:
DAC1 Data Word Least Significant Byte.
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Figure 8.7. DAC1CN: DAC1 Control Register
R/W R/W R/W R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xD4 SFR Page: 1 Reset Value
DAC1EN
Bit7
Bit6
Bit5
DAC1MD1 DAC1MD0 DAC1DF2 DAC1DF1 DAC1DF0 00000000
Bit7:
Bits6-5: Bits4-3:
Bits2-0:
DAC1EN: DAC1 Enable Bit. 0: DAC1 Disabled. DAC1 Output pin is disabled; DAC1 is in low-power shutdown mode. 1: DAC1 Enabled. DAC1 Output pin is active; DAC1 is operational. UNUSED. Read = 00b; Write = don't care. DAC1MD1-0: DAC1 Mode Bits: 00: DAC output updates occur on a write to DAC1H. 01: DAC output updates occur on Timer 3 overflow. 10: DAC output updates occur on Timer 4 overflow. 11: DAC output updates occur on Timer 2 overflow. DAC1DF2: DAC1 Data Format Bits: 000: The most significant nibble of the DAC1 Data Word is in DAC1H[3:0], while the least significant byte is in DAC1L. DAC1H DAC1L
MSB LSB
001:
The most significant 5-bits of the DAC1 Data Word is in DAC1H[4:0], while the least significant 7-bits are in DAC1L[7:1]. DAC1H DAC1L
MSB LSB
010:
The most significant 6-bits of the DAC1 Data Word is in DAC1H[5:0], while the least significant 6-bits are in DAC1L[7:2]. DAC1H DAC1L
LSB
MSB
011:
The most significant 7-bits of the DAC1 Data Word is in DAC1H[6:0], while the least significant 5-bits are in DAC1L[7:3]. DAC1H DAC1L
LSB
MSB
1xx:
The most significant 8-bits of the DAC1 Data Word is in DAC1H[7:0], while the least significant 4-bits are in DAC1L[7:4]. DAC1H DAC1L
LSB
MSB
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.
Table 8.1. DAC Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), No Output Load unless otherwise specified PARAMETER STATIC PERFORMANCE Resolution Integral Nonlinearity Differential Nonlinearity Output Noise No Output Filter 100 kHz Output Filter 10 kHz Output Filter Data Word = 0x014 250 128 41 3 6 20 10 -60 DACnEN = 0 100 300 Data Word = 0xFFF Load = 40pF Load = 40pF, Output swing from code 0xFFF to 0x014 0 10 IL = 0.01mA to 0.3mA at code 0xFFF Data Word = 0x7FF 60 110 400 15 0.44 10 VREF1LSB 60 30 12 1.5 1 bits LSB LSB Vrms CONDITIONS MIN TYP MAX UNITS
Offset Error Offset Tempco Gain Error Gain-Error Tempco VDD Power Supply Rejection Ratio Output Impedance in Shutdown Mode Output Sink Current Output Short-Circuit Current DYNAMIC PERFORMANCE Voltage Output Slew Rate Output Settling Time to 1/2 LSB Output Voltage Swing Startup Time ANALOG OUTPUTS Load Regulation Power Supply Current (AV+ supplied to DAC)
mV ppm/C mV ppm/C dB k A mA V/s s V s ppm A
POWER CONSUMPTION (each DAC)
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Notes
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9.
VOLTAGE REFERENCE (C8051F120/2/4/6)
The voltage reference circuit offers full flexibility in operating the ADC and DAC modules. Three voltage reference input pins allow each ADC and the two DACs to reference an external voltage reference or the on-chip voltage reference output. ADC0 may also reference the DAC0 output internally, and ADC2 may reference the analog power supply voltage, via the VREF multiplexers shown in Figure 9.1. The internal voltage reference circuit consists of a 1.2 V, 15 ppm/C (typical) bandgap voltage reference generator and a gain-of-two output buffer amplifier. The internal reference may be routed via the VREF pin to external system components or to the voltage reference input pins shown in Figure 9.1. The maximum load seen by the VREF pin must be less than 200 A to AGND. Bypass capacitors of 0.1 F and 4.7 F are recommended from the VREF pin to AGND, as shown in Figure 9.1. The Reference Control Register, REF0CN (defined in Figure 9.2) enables/disables the internal reference generator and selects the reference inputs for ADC0 and ADC2. The BIASE bit in REF0CN enables the on-board reference generator while the REFBE bit enables the gain-of-two buffer amplifier which drives the VREF pin. When disabled, the supply current drawn by the bandgap and buffer amplifier falls to less than 1 A (typical) and the output of the buffer amplifier enters a high impedance state. If the internal bandgap is used as the reference voltage generator, BIASE and REFBE must both be set to logic 1. If the internal reference is not used, REFBE may be set to logic 0. Note that the BIASE bit must be set to logic 1 if either DAC or ADC is used, regardless of whether the voltage reference is derived from the on-chip reference or supplied by an off-chip source. If neither the ADC nor the DAC are being used, both of these bits can be set to logic 0 to conserve power. Bits AD0VRS and AD2VRS select the ADC0 and ADC2 voltage reference sources, respectively. The electrical specifications for the Voltage Reference are given in Table 9.1.
Figure 9.1. Voltage Reference Functional Block Diagram
REF0CN AD0VRS AD2VRS TEMPE BIASE REFBE
ADC2
AV+ 1 VREF2 VDD External Voltage Reference Circuit R1 0 Ref
ADC0
DGND VREF0 0 1 Ref
DAC0
VREFD Ref
DAC1
BIASE Bias to ADCs, DACs
EN VREF
x2
+ 4.7F 0.1F REFBE Recommended Bypass Capacitors
1.2V Band-Gap
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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The temperature sensor connects to the highest order input of the ADC0 input multiplexer (see Section "5.1. Analog Multiplexer and PGA" on page 47 for C8051F120/1/4/5 devices, or Section "6.1. Analog Multiplexer and PGA" on page 65 for C8051F122/3/6/7 devices). The TEMPE bit within REF0CN enables and disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any A/D measurements performed on the sensor while disabled result in undefined data.
Figure 9.2. REF0CN: Reference Control Register
SFR Page: SFR Address: R/W
0 0xD1
R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
AD0VRS
Bit4
AD2VRS
Bit3
TEMPE
Bit2
BIASE
Bit1
REFBE
Bit0
00000000
Bits7-5: Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 000b; Write = don't care. AD0VRS: ADC0 Voltage Reference Select. 0: ADC0 voltage reference from VREF0 pin. 1: ADC0 voltage reference from DAC0 output. AD2VRS: ADC2 Voltage Reference Select. 0: ADC2 voltage reference from VREF2 pin. 1: ADC2 voltage reference from AV+. TEMPE: Temperature Sensor Enable Bit. 0: Internal Temperature Sensor Off. 1: Internal Temperature Sensor On. BIASE: ADC/DAC Bias Generator Enable Bit. (Must be `1' if using ADC or DAC). 0: Internal Bias Generator Off. 1: Internal Bias Generator On. REFBE: Internal Reference Buffer Enable Bit. 0: Internal Reference Buffer Off. 1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
Table 9.1. Voltage Reference Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, -40C to +85C unless otherwise specified PARAMETER INTERNAL REFERENCE (REFBE = 1) Output Voltage VREF Short-Circuit Current VREF Temperature Coefficient Load Regulation VREF Turn-on Time 1 VREF Turn-on Time 2 VREF Turn-on Time 3 Input Voltage Range Input Current Load = 0 to 200 A to AGND 4.7F tantalum, 0.1F ceramic bypass 0.1F ceramic bypass no bypass cap 1.00 0 15 0.5 2 20 10 (AV+) 0.3 1 25C ambient 2.36 2.43 2.48 30 V mA ppm/C ppm/A ms s s V A CONDITIONS MIN TYP MAX UNITS
EXTERNAL REFERENCE (REFBE = 0)
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10.
VOLTAGE REFERENCE (C8051F121/3/5/7)
The internal voltage reference circuit consists of a 1.2 V, 15 ppm/C (typical) bandgap voltage reference generator and a gain-of-two output buffer amplifier. The internal reference may be routed via the VREF pin to external system components or to the VREFA input pin shown in Figure 10.1. The maximum load seen by the VREF pin must be less than 200 A to AGND. Bypass capacitors of 0.1 F and 4.7 F are recommended from the VREF pin to AGND, as shown in Figure 10.1. The VREFA pin provides a voltage reference input for ADC0 and ADC2. ADC0 may also reference the DAC0 output internally, and ADC2 may reference the analog power supply voltage, via the VREF multiplexers shown in Figure 10.1. The Reference Control Register, REF0CN (defined in Figure 10.2) enables/disables the internal reference generator and selects the reference inputs for ADC0 and ADC2. The BIASE bit in REF0CN enables the on-board reference generator while the REFBE bit enables the gain-of-two buffer amplifier which drives the VREF pin. When disabled, the supply current drawn by the bandgap and buffer amplifier falls to less than 1 A (typical) and the output of the buffer amplifier enters a high impedance state. If the internal bandgap is used as the reference voltage generator, BIASE and REFBE must both be set to 1 (this includes any time a DAC is used). If the internal reference is not used, REFBE may be set to logic 0. Note that the BIASE bit must be set to logic 1 if either ADC is used, regardless of whether the voltage reference is derived from the on-chip reference or supplied by an off-chip source. If neither the ADC nor the DAC are being used, both of these bits can be set to logic 0 to conserve power. Bits AD0VRS and AD2VRS select the ADC0 and ADC2 voltage reference sources, respectively. The electrical specifications for the Voltage Reference are given in Table 10.1.
Figure 10.1. Voltage Reference Functional Block Diagram
REF0CN AD0VRS AD2VRS TEMPE BIASE REFBE
ADC2
AV+ VDD 1 External Voltage Reference Circuit R1 0 Ref
DGND
VREFA
ADC0
0 1 Ref
DAC0
Ref
DAC1
BIASE Bias to ADCs, DACs
EN VREF
x2
+ 4.7F 0.1F REFBE Recommended Bypass Capacitors
1.2V Band-Gap
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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The temperature sensor connects to the highest order input of the ADC0 input multiplexer (see Section "5.1. Analog Multiplexer and PGA" on page 47 for C8051F120/1/4/5 devices, or Section "6.1. Analog Multiplexer and PGA" on page 65 for C8051F122/3/6/7 devices). The TEMPE bit within REF0CN enables and disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any A/D measurements performed on the sensor while disabled result in undefined data.
Figure 10.2. REF0CN: Reference Control Register
SFR Page: SFR Address: R/W
0 0xD1
R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
AD0VRS
Bit4
AD2VRS
Bit3
TEMPE
Bit2
BIASE
Bit1
REFBE
Bit0
00000000
Bits7-5: Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 000b; Write = don't care. AD0VRS: ADC0 Voltage Reference Select. 0: ADC0 voltage reference from VREFA pin. 1: ADC0 voltage reference from DAC0 output. AD2VRS: ADC2 Voltage Reference Select. 0: ADC2 voltage reference from VREFA pin. 1: ADC2 voltage reference from AV+. TEMPE: Temperature Sensor Enable Bit. 0: Internal Temperature Sensor Off. 1: Internal Temperature Sensor On. BIASE: ADC/DAC Bias Generator Enable Bit. (Must be `1' if using ADC or DAC). 0: Internal Bias Generator Off. 1: Internal Bias Generator On. REFBE: Internal Reference Buffer Enable Bit. 0: Internal Reference Buffer Off. 1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
Table 10.1. Voltage Reference Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, -40C to +85C unless otherwise specified PARAMETER INTERNAL REFERENCE (REFBE = 1) Output Voltage VREF Short-Circuit Current VREF Temperature Coefficient Load Regulation VREF Turn-on Time 1 VREF Turn-on Time 2 VREF Turn-on Time 3 Input Voltage Range Input Current Load = 0 to 200 A to AGND 4.7F tantalum, 0.1F ceramic bypass 0.1F ceramic bypass no bypass cap 1.00 0 15 0.5 2 20 10 (AV+) 0.3 1 25C ambient 2.36 2.43 2.48 30 V mA ppm/C ppm/A ms s s V A CONDITIONS MIN TYP MAX UNITS
EXTERNAL REFERENCE (REFBE = 0)
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11.
COMPARATORS
C8051F120/1/2/3/4/5/6/7 devices include two on-chip programmable voltage comparators as shown in Figure 11.1. The inputs of each Comparator are available at dedicated pins. The output of each comparator is optionally available at the package pins via the I/O crossbar. When assigned to package pins, each comparator output can be programmed to operate in open drain or push-pull modes. See Section "18.1. Ports 0 through 3 and the Priority Crossbar Decoder" on page 205 for Crossbar and port initialization details.
Figure 11.1. Comparator Functional Block Diagram
CPT0MD
CP0MD1 CP0MD0 CP0EN CP0OUT CP0RIF CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0
CP0MD
CPT0CN
AV+
CP0+ CP0-
+ -
CP0MD
Reset Decision Tree
D
SET
Q
D
SET
Q
Crossbar Interrupt Handler
CLR
Q
CLR
Q
AGND
(SYNCHRONIZER)
CPT1MD
CP1MD1 CP1MD0 CP1EN CP1OUT CP1RIF CP1FIF CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0
CP1MD
CPT1CN
AV+
CP1+ CP1-
+ -
CP1MD
D
SET
Q
D
SET
Q
Crossbar Interrupt Handler
CLR
Q
CLR
Q
AGND
(SYNCHRONIZER)
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Comparator interrupts can be generated on rising-edge and/or falling-edge output transitions. (For interrupt enable and priority control, see Section "12.7. Interrupt Handler" on page 144). The CP0FIF flag is set upon a Comparator0 falling-edge interrupt, and the CP0RIF flag is set upon the Comparator0 rising-edge interrupt. Once set, these bits remain set until cleared by software. The Output State of Comparator0 can be obtained at any time by reading the CP0OUT bit. Comparator0 is enabled by setting the CP0EN bit to logic 1, and is disabled by clearing this bit to logic 0. Comparator0 can also be programmed as a reset source; for details, see Section "13.5. Comparator0 Reset" on page 157. Note that after being enabled, there is a Power-Up time (listed in Table 11.1) during which the comparator outputs stabilize. The states of the Rising-Edge and Falling-Edge flags are indeterminant after comparator Power-Up and should be explicitly cleared before the comparator interrupts are enabled or the comparators are configured as a reset source. Comparator0 response time may be configured in software via the CP0MD1-0 bits in register CPT0MD (see Figure 11.4). Selecting a longer response time reduces the amount of current consumed by Comparator0. See Table 11.1 for complete timing and current consumption specifications. The hysteresis of each comparator is software-programmable via its respective Comparator control register (CPT0CN and CPT1CN for Comparator0 and Comparator1, respectively). The user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive and negative-going symmetry of this hysteresis around the threshold voltage. The output of the comparator can be polled in software, or can be used as an interrupt source. Each comparator can be individually enabled or disabled (shutdown). When disabled, the comparator output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic low state, its interrupt capability is suspended and its supply current falls to less than 100 nA. Comparator inputs can be externally driven from -0.25 V to (AV+) + 0.25 V without damage or upset. Comparator0 hysteresis is programmed using bits 3-0 in the Comparator0 Control Register CPT0CN (shown in Figure 11.3). The amount of negative hysteresis voltage is determined by the settings of the CP0HYN bits. As shown in Figure 11.3, the negative hysteresis can be programmed to three different settings, or negative hysteresis can be disabled. In a similar way, the amount of positive hysteresis is determined by the setting the CP0HYP bits. The operation of Comparator1 is identical to that of Comparator0, though Comparator1 may not be configured as a reset source. Comparator1 is controlled by the CPT1CN Register (Figure 11.5) and the CPT1MD Register (Figure 11.6). The complete electrical specifications for the Comparators are given in Table 11.1.
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Figure 11.2. Comparator Hysteresis Plot
CP0+ CP0-
VIN+ VIN-
+ CP0 _ OUT
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage (Programmed with CP0HYP Bits)
VIN-
INPUTS
VIN+
Negative Hysteresis Voltage (Programmed by CP0HYN Bits)
VOH
OUTPUT
VOL
Negative Hysteresis Disabled Positive Hysteresis Disabled Maximum Positive Hysteresis Maximum Negative Hysteresis
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Figure 11.3. CPT0CN: Comparator0 Control Register
SFR Page: SFR Address: R/W
1 0x88
R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
CP0EN
Bit7
CP0OUT
Bit6
CP0RIF
Bit5
CP0FIF
Bit4
CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit7:
Bit6:
Bit5:
Bit4:
Bits3-2:
Bits1-0:
CP0EN: Comparator0 Enable Bit. 0: Comparator0 Disabled. 1: Comparator0 Enabled. CP0OUT: Comparator0 Output State Flag. 0: Voltage on CP0+ < CP0-. 1: Voltage on CP0+ > CP0-. CP0RIF: Comparator0 Rising-Edge Interrupt Flag. 0: No Comparator0 Rising Edge Interrupt has occurred since this flag was last cleared. 1: Comparator0 Rising Edge Interrupt has occurred. CP0FIF: Comparator0 Falling-Edge Interrupt Flag. 0: No Comparator0 Falling-Edge Interrupt has occurred since this flag was last cleared. 1: Comparator0 Falling-Edge Interrupt has occurred. CP0HYP1-0: Comparator0 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 15 mV. CP0HYN1-0: Comparator0 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 15 mV.
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Figure 11.4. CPT0MD: Comparator0 Mode Selection Register
SFR Page: SFR Address: R/W
1 0x89
R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
1
Bit5
1
Bit4
Bit3
Bit2
CP0MD1
Bit1
CP0MD0
Bit0
00110000
Bits7-6: Bits5-4: Bits3-2: Bits1-0:
UNUSED. Read = 00b, Write = don't care. Must be set to 11b. UNUSED. Read = 00b, Write = don't care. CP0MD1-CP0MD0: Comparator0 Mode Select These bits select the response time for Comparator0. Mode 0 1 2 3 CP0MD1 0 0 1 1 CP0MD0 0 1 0 1 Notes Fastest Response Time Lowest Power Consumption
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Figure 11.5. CPT1CN: Comparator1 Control Register
SFR Page: SFR Address: R/W
2 0x88
R/W R/W R/W R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
CP1EN
Bit7
CP1OUT
Bit6
CP1RIF
Bit5
CP1FIF
Bit4
CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000
Bit7:
Bit6:
Bit5:
Bit4:
Bits3-2:
Bits1-0:
CP1EN: Comparator1 Enable Bit. 0: Comparator1 Disabled. 1: Comparator1 Enabled. CP1OUT: Comparator1 Output State Flag. 0: Voltage on CP1+ < CP1-. 1: Voltage on CP1+ > CP1-. CP1RIF: Comparator1 Rising-Edge Interrupt Flag. 0: No Comparator1 Rising Edge Interrupt has occurred since this flag was last cleared. 1: Comparator1 Rising Edge Interrupt has occurred. CP1FIF: Comparator1 Falling-Edge Interrupt Flag. 0: No Comparator1 Falling-Edge Interrupt has occurred since this flag was last cleared. 1: Comparator1 Falling-Edge Interrupt has occurred. CP1HYP1-0: Comparator1 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 15 mV. CP1HYN1-0: Comparator1 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 15 mV.
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Figure 11.6. CPT1MD: Comparator1 Mode Selection Register
SFR Page: SFR Address: R/W
2 0x89
R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
1
Bit5
1
Bit4
Bit3
Bit2
CP1MD1
Bit1
CP1MD0
Bit0
00110000
Bits7-6: Bits5-4: Bits3-2: Bits1-0:
UNUSED. Read = 00b, Write = don't care. Must be set to 11b. UNUSED. Read = 00b, Write = don't care. CP1MD1-CP1MD0: Comparator1 Mode Select These bits select the response time for Comparator1. Mode 0 1 2 3 CP0MD1 0 0 1 1 CP0MD0 0 1 0 1 Notes Fastest Response Time Lowest Power Consumption
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Table 11.1. Comparator Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, -40C to +85C unless otherwise specified PARAMETER Response Time: Mode 0, Vcm = 1.5 V Response Time: Mode 1, Vcm = 1.5 V Response Time: Mode 2, Vcm = 1.5 V Response Time: Mode 3, Vcm = 1.5 V Common-Mode Rejection Ratio Positive Hysteresis 1 Positive Hysteresis 2 Positive Hysteresis 3 Positive Hysteresis 4 Negative Hysteresis 1 Negative Hysteresis 2 Negative Hysteresis 3 Negative Hysteresis 4 Inverting or Non-Inverting Input Voltage Range Input Capacitance Input Bias Current Input Offset Voltage POWER SUPPLY Power-up Time Power Supply Rejection Mode 0 Supply Current at DC (each comparator) Mode 1 Mode 2 Mode 3
CONDITIONS CPn+ - CPn- = 100 mV CPn+ - CPn- = -100 mV CPn+ - CPn- = 100 mV CPn+ - CPn- = -100 mV CPn+ - CPn- = 100 mV CPn+ - CPn- = -100 mV CPn+ - CPn- = 100 mV CPn+ - CPn- = -100 mV CPnHYP1-0 = 00 CPnHYP1-0 = 01 CPnHYP1-0 = 10 CPnHYP1-0 = 11 CPnHYN1-0 = 00 CPnHYN1-0 = 01 CPnHYN1-0 = 10 CPnHYN1-0 = 11
MIN
TYP 100 250 175 500 320 1100 1050 5200 1.5 0
MAX
UNITS ns ns ns ns ns ns ns ns
4 1 7 13 25 1 7 13 25 (AV+) + 0.25
mV/V mV mV mV mV mV mV mV mV V pF
2 4 10 2 4 10 -0.25
4.5 9 17 0 4.5 9 17
7 -5 -10 CPnEN from 0 to 1 20 0.1 7.6 3.2 1.3 0.4 1 0.001 +5 +10
nA mV s mV/V A A A A
VCM is the common-mode voltage on CPn+ and CPn-.
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12.
CIP-51 MICROCONTROLLER
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the MCS-51TM instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The MCU family has a superset of all the peripherals included with a standard 8051. Included are five 16-bit counter/timers (see description in Section 23), two full-duplex UARTs (see description in Section 21 and Section 22), 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space (see Section 12.2.6), and 8/4 byte-wide I/O Ports (see description in Section 18). The CIP-51 also includes on-chip debug hardware (see description in Section 25), and interfaces directly with the MCU's analog and digital subsystems providing a complete data acquisition or controlsystem solution in a single integrated circuit. The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as additional custom peripherals and functions to extend its capability (see Figure 12.1 for a block diagram). The CIP-51 includes the following features: Fully Compatible with MCS-51 Instruction Set 100 or 50 MIPS Peak Using the On-Chip PLL 256 Bytes of Internal RAM 8/4 Byte-Wide I/O Ports Extended Interrupt Handler Reset Input Power Management Modes On-chip Debug Logic Program and Data Memory Security
Figure 12.1. CIP-51 Block Diagram
DATA BUS
D8 D8 D8 D8 D8
ACCUMULATOR
B REGISTER
STACK POINTER
DATA BUS
TMP1
TMP2
PSW
ALU
D8 D8
SRAM ADDRESS REGISTER
D8
SRAM (256 X 8)
D8
DATA BUS
SFR_ADDRESS BUFFER
D8
DATA POINTER
D8 D8
SFR BUS INTERFACE
SFR_CONTROL SFR_WRITE_DATA SFR_READ_DATA
PC INCREMENTER
DATA BUS
PROGRAM COUNTER (PC)
D8
MEM_ADDRESS MEM_CONTROL
PRGM. ADDRESS REG.
A16
MEMORY INTERFACE
MEM_WRITE_DATA MEM_READ_DATA
PIPELINE RESET CLOCK STOP IDLE POWER CONTROL REGISTER
D8
D8
CONTROL LOGIC INTERRUPT INTERFACE
SYSTEM_IRQs EMULATION_IRQ
D8
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Performance The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more than eight system clock cycles. With the CIP-51's system clock running at 100 MHz, it has a peak throughput of 100 MIPS. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute Number of Instructions 1 26 2 50 2/3 5 3 14 3/4 7 4 3 4/5 1 5 2 8 1
Programming and Debugging Support A JTAG-based serial interface is provided for in-system programming of the FLASH program memory and communication with on-chip debug support logic. The re-programmable FLASH can also be read and changed by the application software using the MOVC and MOVX instructions. This feature allows program memory to be used for nonvolatile data storage as well as updating program code under software control. The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware breakpoints and watch points, starting, stopping and single stepping through program execution (including interrupt service routines), examination of the program's call stack, and reading/writing the contents of registers and memory. This method of on-chip debug is completely non-intrusive and non-invasive, requiring no RAM, Stack, timers, or other on-chip resources. The CIP-51 is supported by development tools from Cygnal Integrated Products and third party vendors. Cygnal provides an integrated development environment (IDE) including editor, macro assembler, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51 via its JTAG interface to provide fast and efficient insystem device programming and debugging. Third party macro assemblers and C compilers are also available.
12.1.
Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51TM instruction set; standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51 instructions are the binary and functional equivalent of their MCS-51TM counterparts, including opcodes, addressing modes and effect on PSW flags. However, instruction timing is different than that of the standard 8051.
12.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based solely on clock cycle timing. All instruction timings are specified in terms of clock cycles. Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 12.1 is the CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock cycles for each instruction.
12.1.2. MOVX Instruction and Program Memory
In the CIP-51, the MOVX instruction serves three purposes: accessing on-chip XRAM, accessing off-chip XRAM, and accessing on-chip program FLASH memory. The FLASH access feature provides a mechanism for user software to update program code and use the program memory space for non-volatile data storage (see Section "15. FLASH
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MEMORY" on page 173). The External Memory Interface provides a fast access to off-chip XRAM (or memorymapped peripherals) via the MOVX instruction. Refer to Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for details.
Table 12.1. CIP-51 Instruction Set Summary
Mnemonic ADD A, Rn ADD A, direct ADD A, @Ri ADD A, #data ADDC A, Rn ADDC A, direct ADDC A, @Ri ADDC A, #data SUBB A, Rn SUBB A, direct SUBB A, @Ri SUBB A, #data INC A INC Rn INC direct INC @Ri DEC A DEC Rn DEC direct DEC @Ri INC DPTR MUL AB DIV AB DA A ANL A, Rn ANL A, direct ANL A, @Ri ANL A, #data ANL direct, A ANL direct, #data ORL A, Rn ORL A, direct ORL A, @Ri ORL A, #data ORL direct, A ORL direct, #data XRL A, Rn XRL A, direct XRL A, @Ri Description ARITHMETIC OPERATIONS Add register to A Add direct byte to A Add indirect RAM to A Add immediate to A Add register to A with carry Add direct byte to A with carry Add indirect RAM to A with carry Add immediate to A with carry Subtract register from A with borrow Subtract direct byte from A with borrow Subtract indirect RAM from A with borrow Subtract immediate from A with borrow Increment A Increment register Increment direct byte Increment indirect RAM Decrement A Decrement register Decrement direct byte Decrement indirect RAM Increment Data Pointer Multiply A and B Divide A by B Decimal adjust A LOGICAL OPERATIONS AND Register to A AND direct byte to A AND indirect RAM to A AND immediate to A AND A to direct byte AND immediate to direct byte OR Register to A OR direct byte to A OR indirect RAM to A OR immediate to A OR A to direct byte OR immediate to direct byte Exclusive-OR Register to A Exclusive-OR direct byte to A Exclusive-OR indirect RAM to A Bytes 1 2 1 2 1 2 1 2 1 2 1 2 1 1 2 1 1 1 2 1 1 1 1 1 1 2 1 2 2 3 1 2 1 2 2 3 1 2 1 Clock Cycles 1 2 2 2 1 2 2 2 1 2 2 2 1 1 2 2 1 1 2 2 1 4 8 1 1 2 2 2 2 3 1 2 2 2 2 3 1 2 2
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Mnemonic XRL A, #data XRL direct, A XRL direct, #data CLR A CPL A RL A RLC A RR A RRC A SWAP A MOV A, Rn MOV A, direct MOV A, @Ri MOV A, #data MOV Rn, A MOV Rn, direct MOV Rn, #data MOV direct, A MOV direct, Rn MOV direct, direct MOV direct, @Ri MOV direct, #data MOV @Ri, A MOV @Ri, direct MOV @Ri, #data MOV DPTR, #data16 MOVC A, @A+DPTR MOVC A, @A+PC MOVX A, @Ri MOVX @Ri, A MOVX A, @DPTR MOVX @DPTR, A PUSH direct POP direct XCH A, Rn XCH A, direct XCH A, @Ri XCHD A, @Ri CLR C CLR bit SETB C SETB bit CPL C Description
Preliminary
Table 12.1. CIP-51 Instruction Set Summary
Bytes 2 2 3 1 1 1 1 1 1 1 1 2 1 2 1 2 2 2 2 3 2 3 1 2 2 3 1 1 1 1 1 1 2 2 1 2 1 1 1 2 1 2 1 Clock Cycles 2 2 3 1 1 1 1 1 1 1 1 2 2 2 1 2 2 2 2 3 2 3 2 2 2 3 3 3 3 3 3 3 2 2 1 2 2 2 1 2 1 2 1
Exclusive-OR immediate to A Exclusive-OR A to direct byte Exclusive-OR immediate to direct byte Clear A Complement A Rotate A left Rotate A left through Carry Rotate A right Rotate A right through Carry Swap nibbles of A DATA TRANSFER Move Register to A Move direct byte to A Move indirect RAM to A Move immediate to A Move A to Register Move direct byte to Register Move immediate to Register Move A to direct byte Move Register to direct byte Move direct byte to direct byte Move indirect RAM to direct byte Move immediate to direct byte Move A to indirect RAM Move direct byte to indirect RAM Move immediate to indirect RAM Load DPTR with 16-bit constant Move code byte relative DPTR to A Move code byte relative PC to A Move external data (8-bit address) to A Move A to external data (8-bit address) Move external data (16-bit address) to A Move A to external data (16-bit address) Push direct byte onto stack Pop direct byte from stack Exchange Register with A Exchange direct byte with A Exchange indirect RAM with A Exchange low nibble of indirect RAM with A BOOLEAN MANIPULATION Clear Carry Clear direct bit Set Carry Set direct bit Complement Carry
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Bytes 2 2 2 2 2 2 2 2 2 3 3 3 2 3 1 1 2 3 2 1 2 2 3 3 3 3 2 3 1 Clock Cycles 2 2 2 2 2 2 2 2/3 2/3 3/4 3/4 3/4 3 4 5 5 3 4 3 3 2/3 2/3 3/4 3/4 3/4 4/5 2/3 3/4 1
Table 12.1. CIP-51 Instruction Set Summary
Mnemonic CPL bit ANL C, bit ANL C, /bit ORL C, bit ORL C, /bit MOV C, bit MOV bit, C JC rel JNC rel JB bit, rel JNB bit, rel JBC bit, rel ACALL addr11 LCALL addr16 RET RETI AJMP addr11 LJMP addr16 SJMP rel JMP @A+DPTR JZ rel JNZ rel CJNE A, direct, rel CJNE A, #data, rel CJNE Rn, #data, rel CJNE @Ri, #data, rel DJNZ Rn, rel DJNZ direct, rel NOP Description Complement direct bit AND direct bit to Carry AND complement of direct bit to Carry OR direct bit to carry OR complement of direct bit to Carry Move direct bit to Carry Move Carry to direct bit Jump if Carry is set Jump if Carry is not set Jump if direct bit is set Jump if direct bit is not set Jump if direct bit is set and clear bit PROGRAM BRANCHING Absolute subroutine call Long subroutine call Return from subroutine Return from interrupt Absolute jump Long jump Short jump (relative address) Jump indirect relative to DPTR Jump if A equals zero Jump if A does not equal zero Compare direct byte to A and jump if not equal Compare immediate to A and jump if not equal Compare immediate to Register and jump if not equal Compare immediate to indirect and jump if not equal Decrement Register and jump if not zero Decrement direct byte and jump if not zero No operation
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Notes on Registers, Operands and Addressing Modes: Rn - Register R0-R7 of the currently selected register bank. @Ri - Data RAM location addressed indirectly through R0 or R1. rel - 8-bit, signed (two's complement) offset relative to the first byte of the following instruction. Used by SJMP and all conditional jumps. direct - 8-bit internal data location's address. This could be a direct-access Data RAM location (0x00-0x7F) or an SFR (0x80-0xFF). #data - 8-bit constant #data16 - 16-bit constant bit - Direct-accessed bit in Data RAM or SFR addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same 2K-byte page of program memory as the first byte of the following instruction. addr16 - 16-bit destination address used by LCALL and LJMP. The destination may be anywhere within the 64Kbyte program memory space. There is one unused opcode (0xA5) that performs the same function as NOP. All mnemonics copyrighted (c) Intel Corporation 1980.
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12.2.
Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are two separate memory spaces: program memory and data memory. Program and data memory share the same address space but are accessed via different instruction types. There are 256 bytes of internal data memory and 128k bytes of internal program memory address space implemented within the CIP-51. The CIP-51 memory organization is shown in Figure 12.2.
Figure 12.2. Memory Map
PROGRAM/DATA MEMORY (FLASH)
0x200FF 0x20000 0x1FFFF 0x1FC00 0x1FBFF Scrachpad Memory (DATA only) RESERVED 0xFF 0x80 0x7F
DATA MEMORY (RAM) INTERNAL DATA ADDRESS SPACE
Upper 128 RAM (Indirect Addressing Only) (Direct and Indirect Addressing) Special Function Registers (Direct Addressing Only)
0
1
2
3
FLASH (In-System Programmable in 1024 Byte Sectors)
0x30 0x2F 0x20 0x1F 0x00
Bit Addressable General Purpose Registers
Lower 128 RAM (Direct and Indirect Addressing)
Up To 256 SFR Pages
EXTERNAL DATA ADDRESS SPACE
0x00000 0xFFFF
Off-chip XRAM space
0x2000 0x1FFF 0x0000
XRAM - 8192 Bytes
(accessable using MOVX instruction)
12.2.1. Program Memory
The CIP-51 has a 128k byte program memory space. The MCU implements 131072 bytes of this program memory space as in-system re-programmable FLASH memory in four 32k byte code banks. A common code bank (Bank 0) of 32k bytes is always accessible from addresses 0x0000 to 0x7FFF. The three upper code banks (Bank 1, Bank 2, and Bank 3) are each mapped to addresses 0x8000 to 0xFFFF, depending on the selection of bits in the PSBANK register, as described in Figure 12.3. The IFBANK bits select which of the upper banks are used for code execution, while the COBANK bits select the bank to be used for direct writes and reads of the FLASH memory. Note: 1024 bytes of the memory in Bank 3 (0x1FC00 to 0x1FFFF) are reserved and are not available for user program or data storage. Program memory is normally assumed to be read-only. However, the CIP-51 can write to program memory by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature provides a mechanism for the CIP-51 to update program code and use the program memory space for non-volatile data storage. Refer to Section "15. FLASH MEMORY" on page 173 for further details.
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Figure 12.3. PSBANK: Program Space Bank Select Register
R/W R/W R/W Bit5 R/W Bit4 R/W R/W R/W Bit1 R/W Bit0 SFR Address: 0xB1 SFR Page: All Pages Reset Value
Bit7
Bit6
COBANK
Bit3
Bit2
IFBANK
00010001
Bits 7-6: Bits 5-4:
Bits 3-2: Bits 1-0:
Reserved. COBANK: Constant Operations Bank Select. These bits select which FLASH bank is targeted during constant operations (MOVC and FLASH MOVX) involving addresses 0x8000 to 0xFFFF. These bits are ignored when accessing the Scratchpad memory areas (see Section "15. FLASH MEMORY" on page 173). 00: Constant Operations Target Bank 0 (note that Bank 0 is also mapped between 0x0000 to 0x7FFF). 01: Constant Operations Target Bank 1. 10: Constant Operations Target Bank 2. 11: Constant Operations Target Bank 3. Reserved. IFBANK: Instruction Fetch Operations Bank Select. These bits select which FLASH bank is used for instruction fetches involving addresses 0x8000 to 0xFFFF. These bits can only be changed from code in Bank 0 (see Figure 12.4). 00: Instructions Fetch From Bank 0 (note that Bank 0 is also mapped between 0x0000 to 0x7FFF). 01: Instructions Fetch From Bank 1. 10: Instructions Fetch From Bank 2. 11: Instructions Fetch From Bank 3.
Figure 12.4. Address Memory Map for Instruction Fetches
Internal Address 0xFFFF IFBANK = 0 IFBANK = 1 IFBANK = 2 IFBANK = 3
Bank 0
Bank 1
Bank 2
Bank 3
0x8000 0x7FFF
Bank 0
Bank 0
Bank 0
Bank 0
0x0000
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12.2.2. Data Memory
The CIP-51 implements 256 bytes of internal RAM mapped into the data memory space from 0x00 through 0xFF. The lower 128 bytes of data memory are used for general purpose registers and memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or as 128 bit locations accessible with the direct addressing mode. The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the same address space as the Special Function Registers (SFR) but is physically separate from the SFR space. The addressing mode used by an instruction when accessing locations above 0x7F determines whether the CPU accesses the upper 128 bytes of data memory space or the SFR's. Instructions that use direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the upper 128 bytes of data memory. Figure 12.2 illustrates the data memory organization of the CIP-51.
12.2.3. General Purpose Registers
The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of general-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and RS1 (PSW.4), select the active register bank (see description of the PSW in Figure 12.18). This allows fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes use registers R0 and R1 as index registers.
12.2.4. Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20 through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from 0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit 7 of the byte at 0x20 has bit address 0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by the type of instruction used (bit source or destination operands as opposed to a byte source or destination). The MCS-51TM assembly language allows an alternate notation for bit addressing of the form XX.B where XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
12.2.5. Stack
A programmer's stack can be located anywhere in the 256 byte data memory. The stack area is designated using the Stack Pointer (SP, address 0x81) SFR. The SP will point to the last location used. The next value pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to location 0x07; therefore, the first value pushed on the stack is placed at location 0x08, which is also the first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be initialized to a location in the data memory not being used for data storage. The stack depth can extend up to 256 bytes. The MCUs also have built-in hardware for a stack record which is accessed by the debug logic. The stack record is a 32-bit shift register, where each PUSH or increment SP pushes one record bit onto the register, and each CALL pushes two record bits onto the register. (A POP or decrement SP pops one record bit, and a RET pops two record bits, also.) The stack record circuitry can also detect an overflow or underflow on the 32-bit shift register, and can notify the debug software even with the MCU running at speed.
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12.2.6. Special Function Registers
Preliminary
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers (SFR's). The SFR's provide control and data exchange with the CIP-51's resources and peripherals. The CIP-51 duplicates the SFR's found in a typical 8051 implementation as well as implementing additional SFR's used to configure and access the sub-systems unique to the MCU. This allows the addition of new functionality while retaining compatibility with the MCS-51TM instruction set. Table 12.2 lists the SFR's implemented in the CIP-51 System Controller. The SFR registers are accessed whenever the direct addressing mode is used to access memory locations from 0x80 to 0xFF. SFR's with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, P1, SCON, IE, etc.) are bit-addressable as well as byte-addressable. All other SFR's are byte-addressable only. Unoccupied addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate effect and should be avoided. Refer to the corresponding pages of the datasheet, as indicated in Table 12.3, for a detailed description of each register. 12.2.6.1. SFR Paging The CIP-51 features SFR paging, allowing the device to map many SFR's into the 0x80 to 0xFF memory address space. The SFR memory space has 256 pages. In this way, each memory location from 0x80 to 0xFF can access up to 256 SFR's. The C8051F12x family of devices utilizes five SFR pages: 0, 1, 2, 3, and F. SFR pages are selected using the Special Function Register Page Selection register, SFRPAGE (see Figure 12.12). The procedure for reading and writing an SFR is as follows: 1. 2. Select the appropriate SFR page number using the SFRPAGE register. Use direct accessing mode to read or write the special function register (MOV instruction).
12.2.6.2. Interrupts and SFR Paging When an interrupt occurs, the SFR Page Register will automatically switch to the SFR page containing the flag bit that caused the interrupt. The automatic SFR Page switch function conveniently removes the burden of switching SFR pages from the interrupt service routine. Upon execution of the RETI instruction, the SFR page is automatically restored to the SFR Page in use prior to the interrupt. This is accomplished via a three-byte SFR Page Stack. The top byte of the stack is SFRPAGE, the current SFR Page. The second byte of the SFR Page Stack is SFRNEXT. The third, or bottom byte of the SFR Page Stack is SFRLAST. On interrupt, the current SFRPAGE value is pushed to the SFRNEXT byte, and the value of SFRNEXT is pushed to SFRLAST. Hardware then loads SFRPAGE with the SFR Page containing the flag bit associated with the interrupt. On a return from interrupt, the SFR Page Stack is popped resulting in the value of SFRNEXT returning to the SFRPAGE register, thereby restoring the SFR page context without software intervention. The value in SFRLAST (0x00 if there is no SFR Page value in the bottom of the stack) of the stack is placed in SFRNEXT register. If desired, the values stored in SFRNEXT and SFRLAST may be modified during an interrupt, enabling the CPU to return to a different SFR Page upon execution of the RETI instruction (on interrupt exit). Modifying registers in the SFR Page Stack does not cause a push or pop of the stack. Only interrupt calls and returns will cause push/pop operations on the SFR Page Stack.
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Figure 12.5. SFR Page Stack
SFRPGCN Bit
Interrupt Logic
SFRPAGE
CIP-51
SFRNEXT
SFRLAST
Automatic hardware switching of the SFR Page on interrupts may be enabled or disabled as desired using the SFR Automatic Page Control Enable Bit located in the SFR Page Control Register (SFRPGCN). This function defaults to `enabled' upon reset. In this way, the autoswitching function will be enabled unless disabled in software. A summary of the SFR locations (address and SFR page) is provided in Table 12.2. in the form of an SFR memory map. Each memory location in the map has an SFR page row, denoting the page in which that SFR resides. Note that certain SFR's are accessible from ALL SFR pages, and are denoted by the "(ALL PAGES)" designation. For example, the Port I/O registers P0, P1, P2, and P3 all have the "(ALL PAGES)" designation, indicating these SFR's are accessible from all SFR pages regardless of the SFRPAGE register value.
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12.2.6.3. SFR Page Stack Example
Preliminary
The following is an example that shows the operation of the SFR Page Stack during interrupts. In this example, the SFR Page Control is left in the default enabled state (i.e., SFRPGEN = 1), and the CIP-51 is executing in-line code that is writing values to Port 5 (SFR "P5", located at address 0xD8 on SFR Page 0x0F). The device is also using the Programmable Counter Array (PCA) and the 10-bit ADC (ADC2) window comparator to monitor a voltage. The PCA is timing a critical control function in its interrupt service routine (ISR), so its interrupt is enabled and is set to high priority. The ADC2 is monitoring a voltage that is less important, but to minimize the software overhead its window comparator is being used with an associated ISR that is set to low priority. At this point, the SFR page is set to access the Port 5 SFR (SFRPAGE = 0x0F). See Figure 12.6 below.
Figure 12.6. SFR Page Stack While Using SFR Page 0x0F To Access Port 5
SFR Page Stack SFR's
0x0F SFRPAGE (Port 5) SFRNEXT
SFRLAST
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While CIP-51 executes in-line code (writing values to Port 5 in this example), ADC2 Window Comparator Interrupt occurs. The CIP-51 vectors to the ADC2 Window Comparator ISR and pushes the current SFR Page value (SFR Page 0x0F) into SFRNEXT in the SFR Page Stack. The SFR page needed to access ADC2's SFR's is then automatically placed in the SFRPAGE register (SFR Page 0x02). SFRPAGE is considered the "top" of the SFR Page Stack. Software can now access the ADC2 SFR's. Software may switch to any SFR Page by writing a new value to the SFRPAGE register at any time during the ADC2 ISR to access SFR's that are not on SFR Page 0x02. See Figure 12.7 below.
Figure 12.7. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs
SFR Page 0x02 Automatically pushed on stack in SFRPAGE on ADC2 interrupt
0x02 SFRPAGE
SFRPAGE pushed to SFRNEXT
(ADC2) 0x0F SFRNEXT (Port 5) SFRLAST
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While in the ADC2 ISR, a PCA interrupt occurs. Recall the PCA interrupt is configured as a high priority interrupt, while the ADC2 interrupt is configured as a low priority interrupt. Thus, the CIP-51 will now vector to the high priority PCA ISR. Upon doing so, the CIP-51 will automatically place the SFR page needed to access the PCA's special function registers into the SFRPAGE register, SFR Page 0x00. The value that was in the SFRPAGE register before the PCA interrupt (SFR Page 2 for ADC2) is pushed down the stack into SFRNEXT. Likewise, the value that was in the SFRNEXT register before the PCA interrupt (in this case SFR Page 0x0F for Port 5) is pushed down to the SFRLAST register, the "bottom" of the stack. Note that a value stored in SFRLAST (via a previous software write to the SFRLAST register) will be overwritten. See Figure 12.8 below.
Figure 12.8. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR
SFR Page 0x00 Automatically pushed on stack in SFRPAGE on PCA interrupt
0x00 SFRPAGE
SFRPAGE pushed to SFRNEXT
(PCA) 0x02 SFRNEXT (ADC2) 0x0F SFRLAST (Port 5)
SFRNEXT pushed to SFRLAST
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On exit from the PCA interrupt service routine, the CIP-51 will return to the ADC2 Window Comparator ISR. On execution of the RETI instruction, SFR Page 0x00 used to access the PCA registers will be automatically popped off of the SFR Page Stack, and the contents of the SFRNEXT register will be moved to the SFRPAGE register. Software in the ADC2 ISR can continue to access SFR's as it did prior to the PCA interrupt. Likewise, the contents of SFRLAST are moved to the SFRNEXT register. Recall this was the SFR Page value 0x0F being used to access Port 5 before the ADC2 interrupt occurred. See Figure 12.9 below.
Figure 12.9. SFR Page Stack Upon Return From PCA Interrupt
SFR Page 0x00 Automatically popped off of the stack on return from interrupt
0x02 SFRPAGE
SFRNEXT popped to SFRPAGE
(ADC2) 0x0F SFRNEXT (Port 5) SFRLAST
SFRLAST popped to SFRNEXT
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On the execution of the RETI instruction in the ADC2 Window Comparator ISR, the value in SFRPAGE register is overwritten with the contents of SFRNEXT. The CIP-51 may now access the Port 5 SFR bits as it did prior to the interrupts occurring. See Figure 12.10 below.
Figure 12.10. SFR Page Stack Upon Return From ADC2 Window Interrupt
SFR Page 0x02 Automatically popped off of the stack on return from interrupt
0x0F SFRPAGE
SFRNEXT popped to SFRPAGE
(Port 5) SFRNEXT
SFRLAST
Note that in the above example, all three bytes in the SFR Page Stack are accessible via the SFRPAGE, SFRNEXT, and SFRLAST special function registers. If the stack is altered while servicing an interrupt, it is possible to return to a different SFR Page upon interrupt exit than selected prior to the interrupt call. Direct access to the SFR Page stack can be useful to enable real-time operating systems to control and manage context switching between multiple tasks. Push operations on the SFR Page Stack only occur on interrupt service, and pop operations only occur on interrupt exit (execution on the RETI instruction). The automatic switching of the SFRPAGE and operation of the SFR Page Stack as described above can be disabled in software by clearing the SFR Automatic Page Enable Bit (SFRPGEN) in the SFR Page Control Register (SFRPGCN). See Figure 12.11.
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Figure 12.11. SFRPGCN: SFR Page Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Bit0 SFR Address: 0x96 SFR Page: F Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
SFRPGEN 00000001
Bits7-1: Bit0:
Reserved. SFRPGEN: SFR Automatic Page Control Enable. Upon interrupt, the C8051 Core will vector to the specified interrupt service routine and automatically switch the SFR page to the corresponding peripheral or function's SFR page. This bit is used to control this autopaging function. 0: SFR Automatic Paging disabled. C8051 core will not automatically change to the appropriate SFR page (i.e., the SFR page that contains the SFR's for the peripheral/function that was the source of the interrupt). 1: SFR Automatic Paging enabled. Upon interrupt, the C8051 will switch the SFR page to the page that contains the SFR's for the peripheral or function that is the source of the interrupt.
Figure 12.12. SFRPAGE: SFR Page Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x84 SFR Page: All Pages Reset Value
00000000
Bits7-0:
SFR Page Bits: Byte Represents the SFR Page the C8051 MCU uses when reading or modifying SFR's. Write: Sets the SFR Page. Read: Byte is the SFR page the C8051 MCU is using. When enabled in the SFR Page Control Register (SFRPGEN), the C8051 will automatically switch to the SFR Page that contains the SFR's of the corresponding peripheral/function that caused the interrupt, and return to the previous SFR page upon return from interrupt (unless SFR Stack was altered before a returning from the interrupt). SFRPAGE is the top byte of the SFR Page Stack, and push/pop events of this stack are caused by interrupts (and not by reading/writing to the SFRPAGE register)
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Figure 12.13. SFRNEXT: SFR Next Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x85 SFR Page: All Pages Reset Value
00000000
Bits7-0:
SFR Page Stack Bits: SFR page context is retained upon interrupts/return from interrupts in a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFRLAST is the third entry. The SFR stack bytes may be used alter the context in the SFR Page Stack, and will not cause the stack to `push' or `pop'. Only interrupts and return from interrupts cause pushes and pops of the SFR Page Stack. Write: Sets the SFR Page contained in the second byte of the SFR Stack. This will cause the SFRPAGE SFR to have this SFR page value upon a return from interrupt. Read: Returns the value of the SFR page contained in the second byte of the SFR stack. This is the value that will go to the SFR Page register upon a return from interrupt.
Figure 12.14. SFRLAST: SFR Last Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x86 SFR Page: All Pages Reset Value
00000000
Bits7-0:
SFR Page Stack Bits: SFR page context is retained upon interrupts/return from interrupts in a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFRLAST is the third entry. The SFR stack bytes may be used alter the context in the SFR Page Stack, and will not cause the stack to `push' or `pop'. Only interrupts and return from interrupts cause pushes and pops of the SFR Page Stack. Write: Sets the SFR Page in the last entry of the SFR Stack. This will cause the SFRNEXT SFR to have this SFR page value upon a return from interrupt. Read: Returns the value of the SFR page contained in the last entry of the SFR stack.
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Table 12.2. Special Function Register (SFR) Memory Map
ADDRESS SFR Page 0(8)
SPI0CN
1(9)
PCA0L
2(A)
PCA0H
3(B)
PCA0CPL0
4(C)
PCA0CPH0
5(D)
PCA0CPL1
6(E)
PCA0CPH1
7(F)
F8
F0
E8
E0
D8
D0
C8
0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F
WDTCN (ALL PAGES) P7 B (ALL PAGES) EIP1 (ALL PAGES) EIP2 (ALL PAGES)
ADC0CN ADC2CN
PCA0CPL2
PCA0CPH2
PCA0CPL3
PCA0CPH3
PCA0CPL4
PCA0CPH4
RSTSRC
P6 PCA0CPL5 ACC (ALL PAGES) XBR0 PCA0MD PCA0CPH5 EIE1 (ALL PAGES) EIE2 (ALL PAGES)
PCA0CN
XBR1 XBR2 PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0CPM5
P5 REF0CN PSW (ALL PAGES) DAC0L DAC1L DAC0H DAC1H DAC0CN DAC1CN
TMR2CN TMR3CN TMR4CN
TMR2CF TMR3CF TMR4CF
RCAP2L RCAP3L RCAP4L
RCAP2H RCAP3H RCAP4H
TMR2L TMR3L TMR4L
TMR2H TMR3H TMR4H
SMB0CR
P4
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
7(F)
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0 1 2 3 4 F FF 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F 0 1 2 3 4 F SMB0CN SMB0STA
Preliminary
Table 12.2. Special Function Register (SFR) Memory Map
SMB0DAT SMB0ADR ADC0GTL ADC2GT ADC0GTH ADC0LTL ADC2LT ADC0LTH
C0
SADEN0 IP (ALL PAGES)
AMX0CF AMX2CF
AMX0SL AMX2SL
ADC0CF ADC2CF
ADC0L ADC2
ADC0H
B8
FLSCL P3 (ALL PAGES) PSBANK (ALL PAGES) FLACL SADDR0 IE (ALL PAGES) P1MDIN EMI0TC P2 (ALL PAGES) CCH0CN SBUF0 SBUF1 CCH0TN SPI0CFG CCH0LC SPI0DAT P0MDOUT P1MDOUT SPI0CKR P2MDOUT P3MDOUT EMI0CN EMI0CF
B0
A8
A0
SCON0 SCON1
98
CCH0MA SSTA0 P1 (ALL PAGES)
P4MDOUT
P5MDOUT
P6MDOUT
P7MDOUT
90
88
TCON CPT0CN CPT1CN
TMOD CPT0MD CPT1MD
TL0
TL1
VDDMON TH0
TH1
SFRPGCN CKCON
CLKSEL PSCTL
FLSTAT
PLL0CN
OSCICN
OSCICL
OSCXCN
PLL0DIV
PLL0MUL
PLL0FLT
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
7(F)
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Table 12.2. Special Function Register (SFR) Memory Map
0 1 2 3 4 F P0 (ALL PAGES) SP (ALL PAGES) DPL (ALL PAGES) DPH (ALL PAGES) SFRPAGE (ALL PAGES) SFRNEXT (ALL PAGES) SFRLAST (ALL PAGES) PCON (ALL PAGES)
80
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
7(F)
Table 12.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved. SFR Register Address Description Page ACC 0xE0 All Pages Accumulator ADC0CF 0xBC 0 ADC0 Configuration ADC0CN 0xE8 0 ADC0 Control ADC0GTH 0xC5 0 ADC0 Greater-Than High Byte ADC0GTL 0xC4 0 ADC0 Greater-Than Low Byte ADC0H 0xBF 0 ADC0 Data Word High Byte ADC0L 0xBE 0 ADC0 Data Word Low Byte ADC0LTH 0xC7 0 ADC0 Less-Than High Byte ADC0LTL 0xC6 0 ADC0 Less-Than Low Byte ADC2 0xBE 2 ADC2 Data Word ADC2CF 0xBC 2 ADC2 Configuration ADC2CN 0xE8 2 ADC2 Control ADC2GT 0xC4 2 ADC2 Greater-Than ADC2LT 0xC6 2 ADC2 Less-Than AMX0CF 0xBA 0 ADC0 Multiplexer Configuration AMX0SL 0xBB 0 ADC0 Multiplexer Channel Select AMX2CF 0xBA 2 ADC2 Multiplexer Configuration AMX2SL 0xBB 2 ADC2 Multiplexer Channel Select B 0xF0 All Pages B Register CCH0CN 0xA1 F Cache Control CCH0LC 0xA3 F Cache Lock CCH0MA 0x9A F Cache Miss Accumulator CCH0TN 0xA2 F Cache Tuning CKCON 0x8E 0 Clock Control CLKSEL 0x97 F System Clock Select CPT0CN 0x88 1 Comparator 0 Control CPT0MD 0x89 1 Comparator 0 Configuration CPT1CN 0x88 2 Comparator 1 Control CPT1MD 0x89 2 Comparator 1 Configuration DAC0CN 0xD4 0 DAC0 Control DAC0H 0xD3 0 DAC0 High Byte DAC0L 0xD2 0 DAC0 Low Byte DAC1CN 0xD4 1 DAC1 Control Page No. page 143 page 54*, page 72** page 55*, page 73** page 58*, page 76** page 58*, page 76** page 56*, page 74** page 56*, page 74** page 59*, page 77** page 59*, page 77** page 91 page 89 page 90 page 94 page 94 page 52*, page 70** page 53*, page 71** page 87 page 88 page 143 page 184 page 185 page 186 page 185 page 281 page 164 page 112 page 113 page 114 page 115 page 100 page 99 page 99 page 102
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Table 12.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved. SFR Register Address Description Page DAC1H 0xD3 1 DAC1 High Byte DAC1L 0xD2 1 DAC1 Low Byte DPH 0x83 All Pages Data Pointer High Byte DPL 0x82 All Pages Data Pointer Low Byte EIE1 0xE6 All Pages Extended Interrupt Enable 1 EIE2 0xE7 All Pages Extended Interrupt Enable 2 EIP1 0xF6 All Pages Extended Interrupt Priority 1 EIP2 0xF7 All Pages Extended Interrupt Priority 2 EMI0CF 0xA3 0 EMIF Configuration EMI0CN 0xA2 0 EMIF Control EMI0TC 0xA1 0 EMIF Timing Control FLACL 0xB7 F FLASH Access Limit FLSCL 0xB7 0 FLASH Scale FLSTAT 0x88 1 FLASH Status IE 0xA8 All Pages Interrupt Enable IP 0xB8 All Pages Interrupt Priority OSCICL 0x8B F Internal Oscillator Calibration OSCICN 0x8A F Internal Oscillator Control OSCXCN 0x8C F External Oscillator Control P0 0x80 All Pages Port 0 Latch P0MDOUT 0xA4 F Port 0 Output Mode Configuration P1 0x90 All Pages Port 1 Latch P1MDIN 0xAD F Port 1 Input Mode P1MDOUT 0xA5 F Port 1 Output Mode Configuration P2 0xA0 All Pages Port 2 Latch P2MDOUT 0xA6 F Port 2 Output Mode Configuration P3 0xB0 All Pages Port 3 Latch P3MDOUT 0xA7 F Port 3 Output Mode Configuration P4 0xC8 F Port 4 Latch P4MDOUT 0x9C F Port 4 Output Mode Configuration P5 0xD8 F Port 5 Latch P5MDOUT 0x9D F Port 5 Output Mode Configuration P6 0xE8 F Port 6 Latch P6MDOUT 0x9E F Port 6 Output Mode Configuration P7 0xF8 F Port 7 Latch P7MDOUT 0x9F F Port 7 Output Mode Configuration PCA0CN 0xD8 0 PCA Control PCA0CPH0 0xFC 0 PCA Module 0 Capture/Compare High Byte PCA0CPH1 0xFE 0 PCA Module 1 Capture/Compare High Byte PCA0CPH2 0xEA 0 PCA Module 2 Capture/Compare High Byte PCA0CPH3 0xEC 0 PCA Module 3 Capture/Compare High Byte PCA0CPH4 0xEE 0 PCA Module 4 Capture/Compare High Byte PCA0CPH5 0xE2 0 PCA Module 5 Capture/Compare High Byte PCA0CPL0 0xFB 0 PCA Module 0 Capture/Compare Low Byte Page No. page 101 page 101 page 141 page 141 page 149 page 150 page 151 page 152 page 189 page 189 page 194 page 178 page 179 page 186 page 147 page 148 page 162 page 162 page 165 page 215 page 215 page 216 page 216 page 217 page 217 page 218 page 218 page 219 page 221 page 221 page 222 page 222 page 223 page 223 page 224 page 224 page 300 page 304 page 304 page 304 page 304 page 304 page 304 page 304
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Table 12.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved. SFR Register Address Description Page PCA0CPL1 0xFD 0 PCA Module 1 Capture/Compare Low Byte PCA0CPL2 0xE9 0 PCA Module 2 Capture/Compare Low Byte PCA0CPL3 0xEB 0 PCA Module 3 Capture/Compare Low Byte PCA0CPL4 0xED 0 PCA Module 4 Capture/Compare Low Byte PCA0CPL5 0xE1 0 PCA Module 5 Capture/Compare Low Byte PCA0CPM0 0xDA 0 PCA Module 0 Mode PCA0CPM1 0xDB 0 PCA Module 1 Mode PCA0CPM2 0xDC 0 PCA Module 2 Mode PCA0CPM3 0xDD 0 PCA Module 3 Mode PCA0CPM4 0xDE 0 PCA Module 4 Mode PCA0CPM5 0xDF 0 PCA Module 5 Mode PCA0H 0xFA 0 PCA Counter High Byte PCA0L 0xF9 0 PCA Counter Low Byte PCA0MD 0xD9 0 PCA Mode PCON 0x87 All Pages Power Control PLL0CN 0x89 F PLL Control PLL0DIV 0x8D F PLL Divider PLL0FLT 0x8F F PLL Filter PLL0MUL 0x8E F PLL Multiplier PSBANK 0xB1 All Pages FLASH Bank Select PSCTL 0x8F 0 FLASH Write/Erase Control PSW 0xD0 All Pages Program Status Word RCAP2H 0xCB 0 Timer/Counter 2 Capture/Reload High Byte RCAP2L 0xCA 0 Timer/Counter 2 Capture/Reload Low Byte RCAP3H 0xCB 1 Timer 3 Capture/Reload High Byte RCAP3L 0xCA 1 Timer 3 Capture/Reload Low Byte RCAP4H 0xCB 2 Timer/Counter 4 Capture/Reload High Byte RCAP4L 0xCA 2 Timer/Counter 4 Capture/Reload Low Byte REF0CN 0xD1 0 Voltage Reference Control RSTSRC 0xEF 0 Reset Source SADDR0 0xA9 0 UART 0 Slave Address SADEN0 0xB9 0 UART 0 Slave Address Mask SBUF0 0x99 0 UART 0 Data Buffer SBUF1 0x99 1 UART 1 Data Buffer SCON0 0x98 0 UART 0 Control SCON1 0x98 1 UART 1 Control SFRLAST 0x86 All Pages SFR Stack Last Page SFRNEXT 0x85 All Pages SFR Stack Next Page SFRPAGE 0x84 All Pages SFR Page Select SFRPGCN 0x96 F SFR Page Control SMB0ADR 0xC3 0 SMBus Slave Address SMB0CN 0xC0 0 SMBus Control SMB0CR 0xCF 0 SMBus Clock Rate SMB0DAT 0xC2 0 SMBus Data Page No. page 304 page 304 page 304 page 304 page 304 page 302 page 302 page 302 page 302 page 302 page 302 page 303 page 303 page 301 page 154 page 169 page 169 page 170 page 170 page 124 page 180 page 142 page 289 page 289 page 289 page 289 page 289 page 289 page 106, page 108 page 159 page 263 page 263 page 263 page 271 page 261 page 270 page 134 page 134 page 133 page 133 page 234 page 232 page 233 page 234
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Table 12.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved. SFR Register Address Description Page SMB0STA 0xC1 0 SMBus Status SP 0x81 All Pages Stack Pointer SPI0CFG 0x9A 0 SPI Configuration SPI0CKR 0x9D 0 SPI Clock Rate Control SPI0CN 0xF8 0 SPI Control SPI0DAT 0x9B 0 SPI Data SSTA0 0x91 0 UART 0 Status TCON 0x88 0 Timer/Counter Control TH0 0x8C 0 Timer/Counter 0 High Byte TH1 0x8D 0 Timer/Counter 1 High Byte TL0 0x8A 0 Timer/Counter 0 Low Byte TL1 0x8B 0 Timer/Counter 1 Low Byte TMOD 0x89 0 Timer/Counter Mode TMR2CF 0xC9 0 Timer/Counter 2 Configuration TMR2CN 0xC8 0 Timer/Counter 2 Control TMR2H 0xCD 0 Timer/Counter 2 High Byte TMR2L 0xCC 0 Timer/Counter 2 Low Byte TMR3CF 0xC9 1 Timer 3 Configuration TMR3CN 0xC8 1 Timer 3 Control TMR3H 0xCD 1 Timer 3 High Byte TMR3L 0xCC 1 Timer 3 Low Byte TMR4CF 0xC9 2 Timer/Counter 4 Configuration TMR4CN 0xC8 2 Timer/Counter 4 Control TMR4H 0xCD 2 Timer/Counter 4 High Byte TMR4L 0xCC 2 Timer/Counter 4 Low Byte WDTCN 0xFF All Pages Watchdog Timer Control XBR0 0xE1 F Port I/O Crossbar Control 0 XBR1 0xE2 F Port I/O Crossbar Control 1 XBR2 0xE3 F Port I/O Crossbar Control 2 * Refers to a register in the C8051F120/1/4/5 only. ** Refers to a register in the C8051F122/3/6/7 only. Refers to a register in the C8051F120/2/4/6 only. Refers to a register in the C8051F121/3/5/7 only. Page No. page 235 page 141 page 246 page 248 page 247 page 249 page 262 page 279 page 282 page 282 page 282 page 282 page 280 page 288 page 288 page 290 page 289 page 288 page 288 page 290 page 289 page 288 page 288 page 290 page 289 page 158 page 212 page 213 page 214
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12.6.4. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits should not be set to logic l. Future product versions may use these bits to implement new features in which case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of the remaining SFRs are included in the sections of the datasheet associated with their corresponding system function.
Figure 12.15. SP: Stack Pointer
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x81 SFR Page: All Pages Reset Value
00000111
Bits7-0:
SP: Stack Pointer. The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented before every PUSH operation. The SP register defaults to 0x07 after reset.
Figure 12.16. DPL: Data Pointer Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x82 SFR Page: All Pages Reset Value
00000000
Bits7-0:
DPL: Data Pointer Low. The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly addressed XRAM and FLASH memory.
Figure 12.17. DPH: Data Pointer High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x83 SFR Page: All Pages Reset Value
00000000
Bits7-0:
DPH: Data Pointer High. The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly addressed XRAM and FLASH memory.
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Figure 12.18. PSW: Program Status Word
R/W R/W R/W R/W R/W R/W R/W R Reset Value
CY
Bit7
AC
Bit6
F0
Bit5
RS1
Bit4
RS0
Bit3
OV
Bit2
F1
Bit1
PARITY
Bit0
00000000
Bit Addressable
SFR Address: 0xD0 SFR Page: All Pages
Bit7:
Bit6:
Bit5: Bits4-3:
CY: Carry Flag. This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow (subtraction). It is cleared to 0 by all other arithmetic operations. AC: Auxiliary Carry Flag This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow from (subtraction) the high order nibble. It is cleared to 0 by all other arithmetic operations. F0: User Flag 0. This is a bit-addressable, general purpose flag for use under software control. RS1-RS0: Register Bank Select. These bits select which register bank is used during register accesses. RS1 0 0 1 1 RS0 0 1 0 1 Register Bank 0 1 2 3 Address 0x00 - 0x07 0x08 - 0x0F 0x10 - 0x17 0x18 - 0x1F
Bit2:
Bit1: Bit0:
OV: Overflow Flag. This bit is set to 1 if the last arithmetic operation resulted in a carry (addition), borrow (subtraction), or overflow (multiply or divide). It is cleared to 0 by all other arithmetic operations. F1: User Flag 1. This is a bit-addressable, general purpose flag for use under software control. PARITY: Parity Flag. This bit is set to 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum is even.
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Figure 12.19. ACC: Accumulator
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ACC.7
Bit7
ACC.6
Bit6
ACC.5
Bit5
ACC.4
Bit4
ACC.3
Bit3
ACC.2
Bit2
ACC.1
Bit1
ACC.0
Bit0
00000000
Bit Addressable
SFR Address: 0xE0 SFR Page: All Pages
Bits7-0:
ACC: Accumulator. This register is the accumulator for arithmetic operations.
Figure 12.20. B: B Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
B.7
Bit7
B.6
Bit6
B.5
Bit5
B.4
Bit4
B.3
Bit3
B.2
Bit2
B.1
Bit1
B.0
Bit0
00000000
Bit Addressable
SFR Address: 0xF0 SFR Page: All Pages
Bits7-0:
B: B Register. This register serves as a second accumulator for certain arithmetic operations.
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12.7. Interrupt Handler
Preliminary
The CIP-51 includes an extended interrupt system supporting a total of 20 interrupt sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and external input pins varies according to the specific version of the device. Each interrupt source has one or more associated interrupt-pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition, the associated interrupt-pending flag is set to logic 1. If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a predetermined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI instruction, which returns program execution to the next instruction that would have been executed if the interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regardless of the interrupt's enable/disable state.) Each interrupt source can be individually enabled or disabled through the use of an associated interrupt enable bit in an SFR (IE-EIE2). However, interrupts must first be globally enabled by setting the EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interrupt-enable settings. Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR. However, most are not cleared by the hardware and must be cleared by software before returning from the ISR. If an interruptpending flag remains set after the CPU completes the return-from-interrupt (RETI) instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after the completion of the next instruction.
12.7.1. MCU Interrupt Sources and Vectors
The MCUs support 20 interrupt sources. Software can simulate an interrupt event by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources, associated vector addresses, priority order and control bits are summarized in Table 12.4. Refer to the datasheet section associated with a particular onchip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
12.7.2. External Interrupts
Two of the external interrupt sources (/INT0 and /INT1) are configurable as active-low level-sensitive or active-low edge-sensitive inputs depending on the setting of bits IT0 (TCON.0) and IT1 (TCON.2). IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flag for the /INT0 and /INT1 external interrupts, respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When configured as level sensitive, the interrupt-pending flag follows the state of the external interrupt's input pin. The external interrupt source must hold the input active until the interrupt request is recognized. It must then deactivate the interrupt request before execution of the ISR completes or another interrupt request will be generated.
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Cleared by HW? Bit addressable?
Table 12.4. Interrupt Summary
Interrupt Source
Interrupt Vector
Priority Pending Flag Order
Enable Flag
Priority Control
Reset External Interrupt 0 (/INT0) Timer 0 Overflow External Interrupt 1 (/INT1) Timer 1 Overflow UART0 Timer 2 Serial Peripheral Interface SMBus Interface ADC0 Window Comparator PCA 0 Comparator 0 Comparator 0 Comparator 1 Comparator 1 Timer 3 ADC0 End of Conversion Timer 4 ADC2 Window Comparator ADC2 End of Conversion UART1
0x0000 0x0003 0x000B 0x0013 0x001B 0x0023 0x002B 0x0033 0x003B 0x0043 0x004B 0x0053 0x005B 0x0063 0x006B 0x0073 0x007B 0x0083 0x008B 0x0093 0x00A3
Top 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20
None IE0 (TCON.1) TF0 (TCON.5) IE1 (TCON.3) TF1 (TCON.7) RI0 (SCON0.0) TI0 (SCON0.1) TF2 (TMR2CN.7) EXF2 (TMR2CN.6) SPIF (SPI0CN.7) SI (SMB0CN.3) AD0WINT (ADC0CN.1) CF (PCA0CN.7) CCFn (PCA0CN.n) CP0FIF (CPT0CN.4) CP0RIF (CPT0CN.5) CP1FIF (CPT1CN.4) CP1RIF (CPT1CN.5) TF3 (TMR3CN.7) EXF3 (TMR3CN.6) AD0INT (ADC0CN.5) TF4 (TMR4CN.7) EXF4 (TMR4CN.7) AD2WINT (ADC2CN.0) AD2INT (ADC2CN.5) RI1 (SCON1.0) TI1 (SCON1.1)
N/A N/A Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
Always Enabled EX0 (IE.0) ET0 (IE.1) EX1 (IE.2) ET1 (IE.3) ES0 (IE.4) ET2 (IE.5) ESPI0 (EIE1.0) ESMB0 (EIE1.1) EWADC0 (EIE1.2) EPCA0 (EIE1.3) ECP0F (EIE1.4) ECP0R (EIE1.5) ECP1F (EIE1.6) ECP1R (EIE1.7) ET3 (EIE2.0) EADC0 (EIE2.1) ET4 (EIE2.2) EWADC2 (EIE2.3) EADC2 (EIE2.4) ES1 (EIE2.6)
Always Highest PX0 (IP.0) PT0 (IP.1) PX1 (IP.2) PT1 (IP.3) PS0 (IP.4) PT2 (IP.5) PSPI0 (EIP1.0) PSMB0 (EIP1.1) PWADC0 (EIP1.2) PPCA0 (EIP1.3) PCP0F (EIP1.4) PCP0R (EIP1.5) PCP1F (EIP1.6) PCP1F (EIP1.7) PT3 (EIP2.0) PADC0 (EIP2.1) PT4 (EIP2.2) PWADC2 (EIP2.3) PADC2 (EIP2.4) PS1 (EIP2.6)
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12.7.3. Interrupt Priorities
Preliminary
Each interrupt source can be individually programmed to one of two priority levels: low or high. A low priority interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP-EIP2) used to configure its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is used to arbitrate, given in Table 12.4.
12.7.4. Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5 system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is 18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI and following instruction.
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12.7.5. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
Figure 12.21. IE: Interrupt Enable
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
EA
Bit7
IEGF0
Bit6
ET2
Bit5
ES0
Bit4
ET1
Bit3
EX1
Bit2
ET0
Bit1
EX0
Bit0
00000000
Bit Addressable
SFR Address: 0xA8 SFR Page: All Pages
Bit7:
Bit6: Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
EA: Enable All Interrupts. This bit globally enables/disables all interrupts. It overrides the individual interrupt mask settings. 0: Disable all interrupt sources. 1: Enable each interrupt according to its individual mask setting. IEGF0: General Purpose Flag 0. This is a general purpose flag for use under software control. ET2: Enabler Timer 2 Interrupt. This bit sets the masking of the Timer 2 interrupt. 0: Disable Timer 2 interrupt. 1: Enable Timer 2 interrupt. ES0: Enable UART0 Interrupt. This bit sets the masking of the UART0 interrupt. 0: Disable UART0 interrupt. 1: Enable UART0 interrupt. ET1: Enable Timer 1 Interrupt. This bit sets the masking of the Timer 1 interrupt. 0: Disable Timer 1 interrupt. 1: Enable Timer 1 interrupt. EX1: Enable External Interrupt 1. This bit sets the masking of External Interrupt 1. 0: Disable External Interrupt 1. 1: Enable External Interrupt 1. ET0: Enable Timer 0 Interrupt. This bit sets the masking of the Timer 0 interrupt. 0: Disable Timer 0 interrupts. 1: Enable Timer 0 interrupts. EX0: Enable External Interrupt 0. This bit sets the masking of External Interrupt 0. 0: Disable External Interrupt 0. 1: Enable External Interrupt 0.
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Figure 12.22. IP: Interrupt Priority
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
PT2
Bit5
PS0
Bit4
PT1
Bit3
PX1
Bit2
PT0
Bit1
PX0
Bit0
11000000
Bit Addressable
SFR Address: 0xB8 SFR Page: All Pages
Bits7-6: Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 11b, Write = don't care. PT2: Timer 2 Interrupt Priority Control. This bit sets the priority of the Timer 2 interrupt. 0: Timer 2 interrupt set to low priority. 1: Timer 2 interrupt set to high priority. PS0: UART0 Interrupt Priority Control. This bit sets the priority of the UART0 interrupt. 0: UART0 interrupt set to low priority. 1: UART0 interrupts set to high priority. PT1: Timer 1 Interrupt Priority Control. This bit sets the priority of the Timer 1 interrupt. 0: Timer 1 interrupt set to low priority. 1: Timer 1 interrupts set to high priority. PX1: External Interrupt 1 Priority Control. This bit sets the priority of the External Interrupt 1 interrupt. 0: External Interrupt 1 set to low priority. 1: External Interrupt 1 set to high priority. PT0: Timer 0 Interrupt Priority Control. This bit sets the priority of the Timer 0 interrupt. 0: Timer 0 interrupt set to low priority. 1: Timer 0 interrupt set to high priority. PX0: External Interrupt 0 Priority Control. This bit sets the priority of the External Interrupt 0 interrupt. 0: External Interrupt 0 set to low priority. 1: External Interrupt 0 set to high priority.
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Figure 12.23. EIE1: Extended Interrupt Enable 1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ECP1R
Bit7
ECP1F
Bit6
ECP0R
Bit5
ECP0F
Bit4
EPCA0
Bit3
EWADC0
Bit2
ESMB0
Bit1
ESPI0
Bit0
00000000
SFR Address: 0xE6 SFR Page: All Pages
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
ECP1R: Enable Comparator1 (CP1) Rising Edge Interrupt. This bit sets the masking of the CP1 rising edge interrupt. 0: Disable CP1 rising edge interrupts. 1: Enable CP1 rising edge interrupts. ECP1F: Enable Comparator1 (CP1) Falling Edge Interrupt. This bit sets the masking of the CP1 falling edge interrupt. 0: Disable CP1 falling edge interrupts. 1: Enable CP1 falling edge interrupts. ECP0R: Enable Comparator0 (CP0) Rising Edge Interrupt. This bit sets the masking of the CP0 rising edge interrupt. 0: Disable CP0 rising edge interrupts. 1: Enable CP0 rising edge interrupts. ECP0F: Enable Comparator0 (CP0) Falling Edge Interrupt. This bit sets the masking of the CP0 falling edge interrupt. 0: Disable CP0 falling edge interrupts. 1: Enable CP0 falling edge interrupts. EPCA0: Enable Programmable Counter Array (PCA0) Interrupt. This bit sets the masking of the PCA0 interrupts. 0: Disable PCA0 interrupts. 1: Enable PCA0 interrupts. EWADC0: Enable Window Comparison ADC0 Interrupt. This bit sets the masking of ADC0 Window Comparison interrupt. 0: Disable ADC0 Window Comparison Interrupt. 1: Enable ADC0 Window Comparison Interrupt. ESMB0: Enable System Management Bus (SMBus0) Interrupt. This bit sets the masking of the SMBus interrupt. 0: Disable SMBus interrupts. 1: Enable SMBus interrupts. ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt. This bit sets the masking of SPI0 interrupt. 0: Disable SPI0 interrupts. 1: Enable SPI0 interrupts.
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Figure 12.24. EIE2: Extended Interrupt Enable 2
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
ES1
Bit6
Bit5
EADC2
Bit4
EWADC2
Bit3
ET4
Bit2
EADC0
Bit1
ET3
Bit0
00000000
SFR Address: 0xE7 SFR Page: All Pages
Bit7: Bit6:
Bit5: Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 0b, Write = don't care. ES1: Enable UART1 Interrupt. This bit sets the masking of the UART1 interrupt. 0: Disable UART1 interrupts. 1: Enable UART1 interrupts. UNUSED. Read = 0b, Write = don't care. EADC2: Enable ADC2 End Of Conversion Interrupt. This bit sets the masking of the ADC2 End of Conversion interrupt. 0: Disable ADC2 End of Conversion interrupts. 1: Enable ADC2 End of Conversion Interrupts. EWADC2: Enable Window Comparison ADC2 Interrupt. This bit sets the masking of ADC2 Window Comparison interrupt. 0: Disable ADC2 Window Comparison Interrupts. 1: Enable ADC2 Window Comparison Interrupts. ET4: Enable Timer 4 Interrupt This bit sets the masking of the Timer 4 interrupt. 0: Disable Timer 4 interrupts. 1: Enable Timer 4 interrupts. EADC0: Enable ADC0 End of Conversion Interrupt. This bit sets the masking of the ADC0 End of Conversion Interrupt. 0: Disable ADC0 End of Conversion Interrupts. 1: Enable ADC0 End of Conversion Interrupts. ET3: Enable Timer 3 Interrupt. This bit sets the masking of the Timer 3 interrupt. 0: Disable Timer 3 interrupts. 1: Enable Timer 3 interrupts.
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Figure 12.25. EIP1: Extended Interrupt Priority 1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PCP1R
Bit7
PCP1F
Bit6
PCP0R
Bit5
PCP0F
Bit4
PPCA0
Bit3
PWADC0
Bit2
PSMB0
Bit1
PSPI0
Bit0
00000000
SFR Address: 0xF6 SFR Page: All Pages
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
PCP1R: Comparator1 (CP1) Rising Interrupt Priority Control. This bit sets the priority of the CP1 interrupt. 0: CP1 rising interrupt set to low priority. 1: CP1 rising interrupt set to high priority. PCP1F: Comparator1 (CP1) Falling Interrupt Priority Control. This bit sets the priority of the CP1 interrupt. 0: CP1 falling interrupt set to low priority. 1: CP1 falling interrupt set to high priority. PCP0R: Comparator0 (CP0) Rising Interrupt Priority Control. This bit sets the priority of the CP0 interrupt. 0: CP0 rising interrupt set to low priority. 1: CP0 rising interrupt set to high priority. PCP0F: Comparator0 (CP0) Falling Interrupt Priority Control. This bit sets the priority of the CP0 interrupt. 0: CP0 falling interrupt set to low priority. 1: CP0 falling interrupt set to high priority. PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control. This bit sets the priority of the PCA0 interrupt. 0: PCA0 interrupt set to low priority. 1: PCA0 interrupt set to high priority. PWADC0: ADC0 Window Comparator Interrupt Priority Control. This bit sets the priority of the ADC0 Window interrupt. 0: ADC0 Window interrupt set to low priority. 1: ADC0 Window interrupt set to high priority. PSMB0: System Management Bus (SMBus0) Interrupt Priority Control. This bit sets the priority of the SMBus0 interrupt. 0: SMBus interrupt set to low priority. 1: SMBus interrupt set to high priority. PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control. This bit sets the priority of the SPI0 interrupt. 0: SPI0 interrupt set to low priority. 1: SPI0 interrupt set to high priority.
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Figure 12.26. EIP2: Extended Interrupt Priority 2
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
PS1
Bit6
Bit5
PADC2
Bit4
PWADC2
Bit3
PT4
Bit2
PADC0
Bit1
PT3
Bit0
00000000
SFR Address: 0xF7 SFR Page: All Pages
Bit7: Bit6:
Bit5: Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 0b, Write = don't care. ES1: UART1 Interrupt Priority Control. This bit sets the priority of the UART1 interrupt. 0: UART1 interrupt set to low priority. 1: UART1 interrupt set to high priority. UNUSED. Read = 0b, Write = don't care. PADC2: ADC2 End Of Conversion Interrupt Priority Control. This bit sets the priority of the ADC2 End of Conversion interrupt. 0: ADC2 End of Conversion interrupt set to low priority. 1: ADC2 End of Conversion interrupt set to high priority. PWADC2: ADC2 Window Compare Interrupt Priority Control. This bit sets the priority of the ADC2 Window Compare interrupt. 0: ADC2 Window Compare interrupt set to low priority. 1: ADC2 Window Compare interrupt set to high priority. PT4: Timer 4 Interrupt Priority Control. This bit sets the priority of the Timer 4 interrupt. 0: Timer 4 interrupt set to low priority. 1: Timer 4 interrupt set to high priority. PADC0: ADC0 End of Conversion Interrupt Priority Control. This bit sets the priority of the ADC0 End of Conversion Interrupt. 0: ADC0 End of Conversion interrupt set to low priority. 1: ADC0 End of Conversion interrupt set to high priority. PT3: Timer 3 Interrupt Priority Control. This bit sets the priority of the Timer 3 interrupts. 0: Timer 3 interrupt set to low priority. 1: Timer 3 interrupt set to high priority.
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12.8. Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode halts the CPU while leaving the external peripherals and internal clocks active. In Stop mode, the CPU is halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the system clock is stopped. Since clocks are running in Idle mode, power consumption is dependent upon the system clock frequency and the number of peripherals left in active mode before entering Idle. Stop mode consumes the least power. Figure 12.27 describes the Power Control Register (PCON) used to control the CIP-51's power management modes. Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power management of the entire MCU is better accomplished by enabling/disabling individual peripherals as needed. Each analog peripheral can be disabled when not in use and put into low power mode. Digital peripherals, such as timers or serial buses, draw little power whenever they are not in use. Turning off the Flash memory saves power, similar to entering Idle mode. Turning off the oscillator saves even more power, but requires a reset to restart the MCU.
12.8.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon as the instruction that sets the bit completes. All internal registers and memory maintain their original data. All analog and digital peripherals can remain active during Idle mode. Idle mode is terminated when an enabled interrupt or /RST is asserted. The assertion of an enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume operation. The pending interrupt will be serviced and the next instruction to be executed after the return from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit. If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins program execution at address 0x0000. If enabled, the WDT will eventually cause an internal watchdog reset and thereby terminate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This provides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for an external stimulus to wake up the system. Refer to Section 13 for more information on the use and configuration of the WDT.
12.8.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruction that sets the bit completes. In Stop mode, the CPU and oscillators are stopped, effectively shutting down all digital peripherals. Each analog peripheral must be shut down individually prior to entering Stop Mode. Stop mode can only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset sequence and begins program execution at address 0x0000. If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode. The Missing Clock Detector should be disabled if the CPU is to be put to sleep for longer than the MCD timeout of 100 s.
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Figure 12.27. PCON: Power Control
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
STOP
Bit1
IDLE
Bit0
00000000
SFR Address: 0x87 SFR Page: All Pages
Bits7-3: Bit1:
Bit0:
Reserved. STOP: STOP Mode Select. Writing a `1' to this bit will place the CIP-51 into STOP mode. This bit will always read `0'. 1: CIP-51 forced into power-down mode. (Turns off oscillator). IDLE: IDLE Mode Select. Writing a `1' to this bit will place the CIP-51 into IDLE mode. This bit will always read `0'. 1: CIP-51 forced into IDLE mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, and all peripherals remain active.)
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13.
RESET SOURCES
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this reset state, the following occur: * * * * CIP-51 halts program execution. Special Function Registers (SFRs) are initialized to their defined reset values. External port pins are forced to a known configuration. Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal data memory are unaffected during a reset; any previously stored data is preserved. However, since the stack pointer SFR is reset, the stack is effectively lost even though the data on the stack are not altered. The I/O port latches are reset to 0xFF (all logic 1's), activating internal weak pull-ups which take the external I/O pins to a high state. The external I/O pins do not go high immediately, but will go high within four system clock cycles after entering the reset state. This allows power to be conserved while the part is held in reset. For VDD Monitor resets, the /RST pin is driven low until the end of the VDD reset timeout. On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator running at its lowest frequency. Refer to Section "14. OSCILLATORS" on page 161 for information on selecting and configuring the system clock source. The Watchdog Timer is enabled using its longest timeout interval (see Section "13.7. Watchdog Timer Reset" on page 157). Once the system clock source is stable, program execution begins at location 0x0000. There are seven sources for putting the MCU into the reset state: power-on, power-fail, external /RST pin, external CNVSTR0 signal, software command, Comparator0, Missing Clock Detector, and Watchdog Timer. Each reset source is described in the following sections.
Figure 13.1. Reset Sources
VDD
(Port I/O)
CNVSTR Crossbar
(CNVSTR reset enable)
Supply Monitor
+ Supply Reset Timeout (wired-OR)
/RST
CP0+ CP0-
Comparator0
+ (CP0 reset enable)
Missing Clock Detector (oneshot)
EN
WDT
Reset Funnel
EN
MCD Enable
WDT Enable
PLL Circuitry
System Clock
XTAL1
OSC Clock Select
CIP-51 Microcontroller Core
Extended Interrupt Handler
XTAL2
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WDT Strobe Software Reset System Reset
Internal Clock Generator
PRE
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13.1. Power-on Reset
Preliminary
The C8051F120/1/2/3/4/5/6/7 family incorporates a power supply monitor that holds the MCU in the reset state until VDD rises above the VRST level during power-up. See Figure 13.2 for timing diagram, and refer to Table 13.1 for the Electrical Characteristics of the power supply monitor circuit. The /RST pin is asserted low until the end of the 100 ms VDD Monitor timeout in order to allow the VDD supply to stabilize. The VDD Monitor reset is enabled and disabled using the external VDD monitor enable pin (MONEN). On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. All of the other reset flags in the RSTSRC Register are indeterminate. PORSF is cleared by all other resets. Since all resets cause program execution to begin at the same location (0x0000) software can read the PORSF flag to determine if a power-up was the cause of reset. The contents of internal data memory should be assumed to be undefined after a power-on reset.
Figure 13.2. Reset Timing
volts 2.70 2.55 2.0
VRST
1.0
VD D
t
Logic HIGH
/RST
100ms 100ms
Logic LOW
Power-On Reset
VDD Monitor Reset
13.2.
Power-fail Reset
When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply monitor will drive the /RST pin low and return the CIP-51 to the reset state. When VDD returns to a level above VRST, the CIP-51 will leave the reset state in the same manner as that for the power-on reset (see Figure 13.2). Note that even though internal data memory contents are not altered by the power-fail reset, it is impossible to determine if VDD dropped below the level required for data retention. If the PORSF flag is set to logic 1, the data may no longer be valid.
13.3.
External Reset
The external /RST pin provides a means for external circuitry to force the MCU into a reset state. Asserting the /RST pin low will cause the MCU to enter the reset state. It may be desirable to provide an external pull-up and/or decoupling of the /RST pin to avoid erroneous noise-induced resets. The MCU will remain in reset until at least 12 clock cycles after the active-low /RST signal is removed. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
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13.4. Missing Clock Detector Reset
The Missing Clock Detector is essentially a one-shot circuit that is triggered by the MCU system clock. If the system clock goes away for more than 100 s, the one-shot will time out and generate a reset. After a Missing Clock Detector reset, the MCDRSF flag (RSTSRC.2) will be set, signifying the MSD as the reset source; otherwise, this bit reads `0'. The state of the /RST pin is unaffected by this reset. Setting the MCDRSF bit, RSTSRC.2 (see Section "14. OSCILLATORS" on page 161) enables the Missing Clock Detector.
13.5.
Comparator0 Reset
Comparator0 can be configured as a reset input by writing a `1' to the C0RSEF flag (RSTSRC.5). Comparator0 should be enabled using CPT0CN.7 (see Section "11. COMPARATORS" on page 109) prior to writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting input voltage (CP0+ pin) is less than the inverting input voltage (CP0- pin), the MCU is put into the reset state. After a Comparator0 Reset, the C0RSEF flag (RSTSRC.5) will read `1' signifying Comparator0 as the reset source; otherwise, this bit reads `0'. The state of the /RST pin is unaffected by this reset.
13.6.
External CNVSTR0 Pin Reset
The external CNVSTR0 signal can be configured as a reset input by writing a `1' to the CNVRSEF flag (RSTSRC.6). The CNVSTR0 signal can appear on any of the P0, P1, P2 or P3 I/O pins as described in Section "18.1. Ports 0 through 3 and the Priority Crossbar Decoder" on page 205. Note that the Crossbar must be configured for the CNVSTR0 signal to be routed to the appropriate Port I/O. The Crossbar should be configured and enabled before the CNVRSEF is set. When configured as a reset, CNVSTR0 is active-low and level sensitive. CNVSTR0 cannot be used to start ADC0 conversions when it is configured as a reset source. After a CNVSTR0 reset, the CNVRSEF flag (RSTSRC.6) will read `1' signifying CNVSTR0 as the reset source; otherwise, this bit reads `0'. The state of the RST pin is unaffected by this reset.
13.7.
Watchdog Timer Reset
The MCU includes a programmable Watchdog Timer (WDT) running off the system clock. A WDT overflow will force the MCU into the reset state. To prevent the reset, the WDT must be restarted by application software before overflow. If the system experiences a software or hardware malfunction preventing the software from restarting the WDT, the WDT will overflow and cause a reset. This should prevent the system from running out of control. Following a reset the WDT is automatically enabled and running with the default maximum time interval. If desired the WDT can be disabled by system software or locked on to prevent accidental disabling. Once locked, the WDT cannot be disabled until the next system reset. The state of the /RST pin is unaffected by this reset. The WDT consists of a 21-bit timer running from the programmed system clock. The timer measures the period between specific writes to its control register. If this period exceeds the programmed limit, a WDT reset is generated. The WDT can be enabled and disabled as needed in software, or can be permanently enabled if desired. Watchdog features are controlled via the Watchdog Timer Control Register (WDTCN) shown in Figure 13.3.
13.7.1. Enable/Reset WDT
The watchdog timer is both enabled and reset by writing 0xA5 to the WDTCN register. The user's application software should include periodic writes of 0xA5 to WDTCN as needed to prevent a watchdog timer overflow. The WDT is enabled and reset as a result of any system reset.
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13.7.2. Disable WDT
Preliminary
Writing 0xDE followed by 0xAD to the WDTCN register disables the WDT. The following code segment illustrates disabling the WDT:
CLR MOV MOV SETB EA WDTCN,#0DEh WDTCN,#0ADh EA ; disable all interrupts ; disable software watchdog timer ; re-enable interrupts
The writes of 0xDE and 0xAD must occur within 4 clock cycles of each other, or the disable operation is ignored. Interrupts should be disabled during this procedure to avoid delay between the two writes.
13.7.3. Disable WDT Lockout
Writing 0xFF to WDTCN locks out the disable feature. Once locked out, the disable operation is ignored until the next system reset. Writing 0xFF does not enable or reset the watchdog timer. Applications always intending to use the watchdog should write 0xFF to WDTCN in the initialization code.
13.7.4. Setting WDT Interval
WDTCN.[2:0] control the watchdog timeout interval. The interval is given by the following equation:
4
3 + WDTCN [ 2 - 0 ]
x T sysclk ; where Tsysclk is the system clock period.
For a 3 MHz system clock, this provides an interval range of 0.021 ms to 349.5 ms. WDTCN.7 must be logic 0 when setting this interval. Reading WDTCN returns the programmed interval. WDTCN.[2:0] reads 111b after a system reset.
Figure 13.3. WDTCN: Watchdog Timer Control Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xFF SFR Page: All Pages Reset Value
xxxxx111
Bits7-0:
Bit4:
Bits2-0:
WDT Control Writing 0xA5 both enables and reloads the WDT. Writing 0xDE followed within 4 system clocks by 0xAD disables the WDT. Writing 0xFF locks out the disable feature. Watchdog Status Bit (when Read) Reading the WDTCN.[4] bit indicates the Watchdog Timer Status. 0: WDT is inactive 1: WDT is active Watchdog Timeout Interval Bits The WDTCN.[2:0] bits set the Watchdog Timeout Interval. When writing these bits, WDTCN.7 must be set to 0.
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Figure 13.4. RSTSRC: Reset Source Register
R R/W Bit6 R/W Bit5 R/W R Bit3 R/W Bit2 R R/W Reset Value
Bit7
CNVRSEF C0RSEF
SWRSEF
Bit4
WDTRSF MCDRSF
PORSF
Bit1
PINRSF
Bit0
00000000
SFR Address: 0xEF SFR Page: 0
Bit7: Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
Reserved. CNVRSEF: Convert Start 0 Reset Source Enable and Flag Write: 0: CNVSTR0 is not a reset source. 1: CNVSTR0 is a reset source (active low). Read: 0: Source of prior reset was not CNVSTR0. 1: Source of prior reset was CNVSTR0. C0RSEF: Comparator0 Reset Enable and Flag. Write: 0: Comparator0 is not a reset source. 1: Comparator0 is a reset source (active low). Read: 0: Source of last reset was not Comparator0. 1: Source of last reset was Comparator0. SWRSF: Software Reset Force and Flag. Write: 0: No effect. 1: Forces an internal reset. /RST pin is not effected. Read: 0: Source of last reset was not a write to the SWRSF bit. 1: Source of last reset was a write to the SWRSF bit. WDTRSF: Watchdog Timer Reset Flag. 0: Source of last reset was not WDT timeout. 1: Source of last reset was WDT timeout. MCDRSF: Missing Clock Detector Flag. Write: 0: Missing Clock Detector disabled. 1: Missing Clock Detector enabled; triggers a reset if a missing clock condition is detected. Read: 0: Source of last reset was not a Missing Clock Detector timeout. 1: Source of last reset was a Missing Clock Detector timeout. PORSF: Power-On Reset Flag. This bit is set anytime a power-on reset occurs. This may be due to a true power-on reset or a VDD monitor reset. In either case, data memory should be considered indeterminate following the reset. This reset is enabled/disabled using the external VDD monitor enable pin. 0: Source of last reset was not a power-on or VDD monitor reset. 1: Source of last reset was a power-on or VDD monitor reset. Note: When this flag is set, all other reset flags indeterminate. PINRSF: HW Pin Reset Flag. Write: 0: No effect. 1: Forces a Power-On Reset. /RST is driven low. Read: 0: Source of prior reset was not /RST pin. 1: Source of prior reset was /RST pin.
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Table 13.1. Reset Electrical Characteristics
-40C to +85C unless otherwise specified. PARAMETER CONDITIONS IOL = 8.5 mA, VDD = 2.7 V to 3.6 V /RST Output Low Voltage /RST Input High Voltage /RST Input Low Voltage /RST Input Leakage Current VDD for /RST Output Valid AV+ for /RST Output Valid VDD POR Threshold (VRST) Minimum /RST Low Time to Generate a System Reset Reset Time Delay Missing Clock Detector Timeout /RST = 0.0 V 1.0 1.0 2.40 10 /RST rising edge after VDD crosses VRST threshold Time from last system clock to reset initiation 80 100 100 220 120 500 50 MIN 0.7 x VDD 0.3 x VDD A V V V ns ms s TYP MAX 0.6 UNITS V V
2.55
2.70
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14.
OSCILLATORS
C8051F120/1/2/3/4/5/6/7 devices include a programmable internal oscillator and an external oscillator drive circuit. The internal oscillator can be enabled, disabled and calibrated using the OSCICN and OSCICL registers, as shown in Figure 14.1. The system clock can be sourced by the external oscillator circuit, the internal oscillator, or the on-chip phase-locked loop (PLL). The internal oscillator's electrical specifications are given in Table 14.1 on page 163.
Figure 14.1. Oscillator Diagram
OSCICL
IOSCEN IFRDY Option 3 XTAL1 XTAL2 Option 4 XTAL1
EN
OSCICN
IFCN1 IFCN0
CLKSEL
CLKDIV1 CLKDIV0 00 CLKSL1 CLKSL0 SYSCLK 01 10
Calibrated Internal Oscillator Option 2 VDD Option 1 XTAL1 Input Circuit XTAL1 XTAL2 OSC
n
PLL
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
OSCXCN
14.1.
Programmable Internal Oscillator
All C8051F12x devices include a programmable internal oscillator that defaults as the system clock after a system reset. The internal oscillator period can be adjusted via the OSCICL register as defined by Figure 14.2. OSCICL is factory calibrated to obtain a 24.5 MHz frequency. Electrical specifications for the precision internal oscillator are given in Table 14.1. Note that the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the IFCN bits in register OSCICN.
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XFCN2 XFCN1 XFCN0
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Figure 14.2. OSCICL: Internal Oscillator Calibration Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x8B SFR Page: F Reset Value
Variable
Bits 7-0:
OSCICL: Internal Oscillator Calibration Register. This register calibrates the internal oscillator period. The reset value for OSCICL defines the internal oscillator base frequency. The reset value is factory calibrated to generate an internal oscillator frequency of 24.5 MHz.
Figure 14.3. OSCICN: Internal Oscillator Control Register
R/W R R/W R R/W R/W R/W R/W Reset Value
IOSCEN
Bit7
IFRDY
Bit6
Bit5
Bit4
Bit3
Bit2
IFCN1
Bit1
IFCN0
Bit0
11000000
SFR Address: 0x8A SFR Page: F
Bit 7:
Bit 6:
Bits 5-2: Bits 1-0:
IOSCEN: Internal Oscillator Enable Bit. 0: Internal Oscillator Disabled. 1: Internal Oscillator Enabled. IFRDY: Internal Oscillator Frequency Ready Flag. 0: Internal Oscillator not running at programmed frequency. 1: Internal Oscillator running at programmed frequency. Reserved. IFCN1-0: Internal Oscillator Frequency Control Bits. 00: Internal Oscillator is divided by 8. 01: Internal Oscillator is divided by 4. 10: Internal Oscillator is divided by 2. 11: Internal Oscillator is divided by 1.
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Table 14.1. Internal Oscillator Electrical Characteristics
-40C to +85C unless otherwise specified PARAMETER CONDITIONS Calibrated Internal Oscillator Frequency Internal Oscillator Supply Current OSCICN.7 = 1 (from VDD) MIN 24 TYP 24.5 TBD MAX 25 UNITS MHz A
14.2.
External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crystal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 14.1. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 and/or XTAL1 pin(s) as shown in Option 2, 3, or 4 of Figure 14.1. The type of external oscillator must be selected in the OSCXCN register, and the frequency control bits (XFCN) must be selected appropriately (see Figure 14.5).
14.3.
System Clock Selection
The CLKSL1-0 bits in register CLKSEL select which oscillator source generates the system clock. CLKSL1-0 must be set to `01' for the system clock to run from the external oscillator; however the external oscillator may still clock certain peripherals, such as the timers and PCA, when the internal oscillator or the PLL is selected as the system clock. The system clock may be switched on-the-fly between the internal and external oscillators or the PLL, so long as the selected oscillator source is enabled and settled. The internal oscillator requires little start-up time, and may be enabled and selected as the system clock in the same write to OSCICN. External crystals and ceramic resonators typically require a start-up time before they are settled and ready for use as the system clock. The Crystal Valid Flag (XTLVLD in register OSCXCN) is set to `1' by hardware when the external oscillator is settled. To avoid reading a false XTLVLD, in crystal mode software should delay at least 1 ms between enabling the external oscillator and checking XTLVLD. RC and C modes typically require no startup time. The PLL also requires time to lock onto the desired frequency, and the PLL Lock Flag (PLLLCK in register PLL0CN) is set to `1' by hardware once the PLL is locked on the correct frequency.
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Figure 14.4. CLKSEL: System Clock Selection Register
R/W R/W R/W Bit5 R/W Bit4 R/W R/W R/W R/W Reset Value
Bit7
Bit6
CLKDIV1 CLKDIV0
Bit3
Bit2
CLKSL1
Bit1
CLKSL0
Bit0
00000000
SFR Address: 0x97 SFR Page: F
Bits 7-6: Bits 5-4:
Bits 3-2: Bits 1-0:
Reserved. CLKDIV1-0: Output SYSCLK Divide Factor. These bits can be used to pre-divide SYSCLK before it is output to a port pin through the crossbar. 00: Output will be SYSCLK. 01: Output will be SYSCLK/2. 10: Output will be SYSCLK/4. 11: Output will be SYSCLK/8. See Section "18. PORT INPUT/OUTPUT" on page 203 for more details about routing this output to a port pin. Reserved. CLKSL1-0: System Clock Source Select Bits. 00: SYSCLK derived from the Internal Oscillator, and scaled as per the IFCN bits in OSCICN. 01: SYSCLK derived from the External Oscillator circuit. 10: SYSCLK derived from the PLL. 11: Reserved.
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Figure 14.5. OSCXCN: External Oscillator Control Register
R Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R R/W R/W R/W Reset Value
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
Bit3
XFCN2
Bit2
XFCN1
Bit1
XFCN0
Bit0
00000000
SFR Address: 0x8C SFR Page: F
Bit7:
Bits6-4:
Bit3: Bits2-0:
XTLVLD: Crystal Oscillator Valid Flag. (Valid only when XOSCMD = 11x.) 0: Crystal Oscillator is unused or not yet stable. 1: Crystal Oscillator is running and stable. XOSCMD2-0: External Oscillator Mode Bits. 00x: External Oscillator circuit off. 010: External CMOS Clock Mode (External CMOS Clock input on XTAL1 pin). 011: External CMOS Clock Mode with divide by 2 stage (External CMOS Clock input on XTAL1 pin). 10x: RC/C Oscillator Mode with divide by 2 stage. 110: Crystal Oscillator Mode. 111: Crystal Oscillator Mode with divide by 2 stage. RESERVED. Read = 0, Write = don't care. XFCN2-0: External Oscillator Frequency Control Bits. 000-111: see table below: XFCN 000 001 010 011 100 101 110 111 Crystal (XOSCMD = 11x) f 32kHz 32kHz < f 84kHz 84kHz < f 225kHz 225kHz < f 590kHz 590kHz < f 1.5MHz 1.5MHz < f 4MHz 4MHz < f 10MHz 10MHz < f 30MHz RC (XOSCMD = 10x) f 25kHz 25kHz < f 50kHz 50kHz < f 100kHz 100kHz < f 200kHz 200kHz < f 400kHz 400kHz < f 800kHz 800kHz < f 1.6MHz 1.6MHz < f 3.2MHz C (XOSCMD = 10x) K Factor = 0.87 K Factor = 2.6 K Factor = 7.7 K Factor = 22 K Factor = 65 K Factor = 180 K Factor = 664 K Factor = 1590
CRYSTAL MODE (Circuit from Figure 14.1, Option 1; XOSCMD = 11x) Choose XFCN value to match crystal frequency. RC MODE (Circuit from Figure 14.1, Option 2; XOSCMD = 10x) Choose XFCN value to match frequency range: f = 1.23(103) / (R * C), where f = frequency of oscillation in MHz C = capacitor value in pF R = Pull-up resistor value in k C MODE (Circuit from Figure 14.1, Option 3; XOSCMD = 10x) Choose K Factor (KF) for the oscillation frequency desired: f = KF / (C * VDD), where f = frequency of oscillation in MHz C = capacitor value on XTAL1, XTAL2 pins in pF
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14.4. External Crystal Example
Preliminary
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 14.1, Option 1. The External Oscillator Frequency Control value (XFCN) should be chosen from the Crystal column of the table in Figure 14.5 (OSCXCN register). For example, an 11.0592 MHz crystal requires an XFCN setting of 111b. When the crystal oscillator is enabled, the oscillator amplitude detection circuit requires a settle time to achieve proper bias. Waiting at least 1 ms between enabling the oscillator and checking the XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure is: Step 1. Step 2. Step 3. Step 4. Enable the external oscillator. Wait at least 1 ms. Poll for XTLVLD => `1'. Switch the system clock to the external oscillator.
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as short as possible and shielded with ground plane from any other traces which could introduce noise or interference.
14.5.
External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 14.1, Option 2. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first select the RC network value to produce the desired frequency of oscillation. If the frequency desired is 100 kHz, let R = 246 k and C = 50 pF: f = 1.23( 103 ) / RC = 1.23 ( 103 ) / [ 246 * 50 ] = 0.1 MHz = 100 kHz Referring to the table in Figure 14.5, the required XFCN setting is 010.
14.6.
External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in Figure 14.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capacitor to be used and find the frequency of oscillation from the equations below. Assume VDD = 3.0 V and C = 50 pF: f = KF / ( C * VDD ) = KF / ( 50 * 3 ) f = KF / 150 If a frequency of roughly 50 kHz is desired, select the K Factor from the table in Figure 14.5 as KF = 7.7: f = 7.7 / 150 = 0.051 MHz, or 51 kHz Therefore, the XFCN value to use in this example is 010.
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14.7.
Phase-Locked Loop (PLL)
The C8051F12x Family include a Phase-Locked-Loop (PLL), which is used to multiply the internal oscillator or an external clock source to achieve higher CPU operating frequencies. The PLL circuitry is designed to produce an output frequency between 25 MHz and 100 MHz, from a divided reference frequency between 5 MHz and 30 MHz. A block diagram of the PLL is shown in Figure 14.6.
Figure 14.6. PLL Block Diagram
PLL0CN
PLLSRC PLLEN PLLPWR PLLLCK
PLL0FLT
PLLICO1 PLLICO0 PLLLP3 PLLLP2 PLLLP1 PLLLP0
Internal Oscillator
0
External Oscillator
/
1
Divided Reference Clock
Phase / Frequency Detection
Loop Filter
Current Controlled Oscillator
PLL Clock Output
/
PLLM4 PLLM3 PLLM2 PLLM1 PLLM0 PLLN7 PLLN6 PLLN5 PLLN4 PLLN3 PLLN2 PLLN1 PLLN0
PLL0DIV
PLL0MUL
14.7.1. PLL Input Clock and Pre-divider
The PLL circuitry can derive its reference clock from either the internal oscillator or an external clock source. The PLLSRC bit (PLL0CN.2) controls which clock source is used for the reference clock (see Figure 14.7). If PLLSRC is set to `0', the internal oscillator source is used. Note that the internal oscillator divide factor (as specified by bits IFCN1-0 in register OSCICN) will also apply to this clock. When PLLSRC is set to `1', an external oscillator source will be used. The external oscillator should be active and settled before it is selected as a reference clock for the PLL circuit. The reference clock is divided down prior to the PLL circuit, according to the contents of the PLLM4-0 bits in the PLL Pre-divider Register (PLL0DIV), shown in Figure 14.8.
14.7.2. PLL Multiplication and Output Clock
The PLL circuitry will multiply the divided reference clock by the multiplication factor stored in the PLL0MUL register shown in Figure 14.9. To accomplish this, it uses a feedback loop consisting of a phase/frequency detector, a loop filter, and a current-controlled oscillator (ICO). It is important to configure the loop filter and the ICO for the correct frequency ranges. The PLLLP3-0 bits (PLL0FLT.3-0) should be set according to the divided reference clock frequency. Likewise, the PLLICO1-0 bits (PLL0FLT.5-4) should be set according to the desired output frequency range. Figure 14.10 describes the proper settings to use for the PLLLP3-0 and PLLICO1-0 bits. When the PLL is locked and stable at the desired frequency, the PLLLCK bit (PLL0CN.5) will be set to a `1'. The resulting PLL frequency will be set according to the equation:
PLLN PLL Frequency = Reference Frequency x --------------PLLM
Where "Reference Frequency" is the selected source clock frequency, PLLN is the PLL Multiplier, and PLLM is the PLL Pre-divider.
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14.7.3. Powering on and Initializing the PLL
To set up and use the PLL as the system clock after power-up of the device, the following procedure should be implemented: Step 1. Ensure that the reference clock to be used (internal or external) is running and stable. Step 2. Set the PLLSRC bit (PLL0CN.2) to select the desired clock source for the PLL. Step 3. Program the FLASH read timing bits, FLRT (FLSCL.5-4) to the appropriate value for the new clock rate (see Section "15. FLASH MEMORY" on page 173). Step 4. Enable power to the PLL by setting PLLPWR (PLL0CN.0) to `1'. Step 5. Program the PLL0DIV register to produce the divided reference frequency to the PLL. Step 6. Program the PLLLP3-0 bits (PLL0FLT.3-0) to the appropriate range for the divided reference frequency. Step 7. Program the PLLICO1-0 bits (PLL0FLT.5-4) to the appropriate range for the PLL output frequency. Step 8. Program the PLL0MUL register to the desired clock multiplication factor. Step 9. Wait at least 5 s, to provide a fast frequency lock. Step 10. Enable the PLL by setting PLLEN (PLL0CN.1) to `1'. Step 11. Poll PLLLCK (PLL0CN.4) until it changes from `0' to `1'. Step 12. Switch the System Clock source to the PLL using the CLKSEL register.
If the PLL characteristics need to be changed when the PLL is already running, the following procedure should be implemented: Step 1. The system clock should first be switched to either the internal oscillator or an external clock source that is running and stable, using the CLKSEL register. Step 2. Ensure that the reference clock to be used for the new PLL setting (internal or external) is running and stable. Step 3. Set the PLLSRC bit (PLL0CN.2) to select the new clock source for the PLL. Step 4. If moving to a faster frequency, program the FLASH read timing bits, FLRT (FLSCL.5-4) to the appropriate value for the new clock rate (see Section "15. FLASH MEMORY" on page 173). Step 5. Disable the PLL by setting PLLEN (PLL0CN.1) to `0'. Step 6. Program the PLL0DIV register to produce the divided reference frequency to the PLL. Step 7. Program the PLLLP3-0 bits (PLL0FLT.3-0) to the appropriate range for the divided reference frequency. Step 8. Program the PLLICO1-0 bits (PLL0FLT.5-4) to the appropriate range for the PLL output frequency. Step 9. Program the PLL0MUL register to the desired clock multiplication factor. Step 10. Enable the PLL by setting PLLEN (PLL0CN.1) to `1'. Step 11. Poll PLLLCK (PLL0CN.4) until it changes from `0' to `1'. Step 12. Switch the System Clock source to the PLL using the CLKSEL register. Step 13. If moving to a slower frequency, program the FLASH read timing bits, FLRT (FLSCL.5-4) to the appropriate value for the new clock rate (see Section "15. FLASH MEMORY" on page 173).
To shut down the PLL, the system clock should be switched to the internal oscillator or a stable external clock source, using the CLKSEL register. Next, disable the PLL by setting PLLEN (PLL0CN.1) to `0'. Finally, the PLL can be powered off, by setting PLLPWR (PLL0CN.0) to `0'. Note that the PLLEN and PLLPWR bits can be cleared at the same time.
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Figure 14.7. PLL0CN: PLL Control Register
R/W R/W R/W R R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
PLLLCK
Bit4
0
Bit3
PLLSRC
Bit2
PLLEN
Bit1
PLLPWR
Bit0
00000000
SFR Address: 0x89 SFR Page: F
Bits 7-5: Bit 4:
Bit 3: Bit 2:
Bit 1:
Bit 0:
UNUSED: Read = 000b; Write = don't care. PLLCK: PLL Lock Flag. 0: PLL Frequency is not locked. 1: PLL Frequency is locked. RESERVED. Must write to `0'. PLLSRC: PLL Reference Clock Source Select Bit. 0: PLL Reference Clock Source is Internal Oscillator. 1: PLL Reference Clock Source is External Oscillator. PLLEN: PLL Enable Bit. 0: PLL is held in reset. 1: PLL is enabled. PLLPWR must be `1'. PLLPWR: PLL Power Enable. 0: PLL bias generator is de-activated. No static power is consumed. 1: PLL bias generator is active. Must be set for PLL to operate.
Figure 14.8. PLL0DIV: PLL Pre-divider Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
PLLM4
Bit4
PLLM3
Bit3
PLLM2
Bit2
PLLM1
Bit1
PLLM0
Bit0
00000001
SFR Address: 0x8D SFR Page: F
Bits 7-5: Bits 4-0:
UNUSED: Read = 000b; Write = don't care. PLLM4-0: PLL Reference Clock Pre-divider. These bits select the pre-divide value of the PLL reference clock. When set to any non-zero value, the reference clock will be divided by the value in PLLM4-0. When set to `00000b', the reference clock will be divided by 32.
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Figure 14.9. PLL0MUL: PLL Clock Scaler Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PLLN7
Bit7
PLLN6
Bit6
PLLN5
Bit5
PLLN4
Bit4
PLLN3
Bit3
PLLN2
Bit2
PLLN1
Bit1
PLLN0
Bit0
00000001
SFR Address: 0x8E SFR Page: F
Bits 7-0:
PLLN7-0: PLL Multiplier. These bits select the multiplication factor of the divided PLL reference clock. When set to any nonzero value, the multiplication factor will be equal to the value in PLLN7-0. When set to `00000000b', the multiplication factor will be equal to 256.
Figure 14.10. PLL0FLT: PLL Filter Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
PLLICO1
Bit5
PLLICO0
Bit4
PLLLP3
Bit3
PLLLP2
Bit2
PLLLP1
Bit1
PLLLP0
Bit0
00110001
SFR Address: 0x8F SFR Page: F
Bits 7-6: Bits 5-4:
UNUSED: Read = 000b; Write = don't care. PLLICO1-0: PLL Current-Controlled Oscillator Control Bits. Selection is based on the desired output frequency, according to the following table:
PLL Output Clock 65 - 100 MHz 45 - 80 MHz 30 - 60 MHz 25 - 50 MHz
PLLICO1-0 00 01 10 11
Bits 3-0:
PLLLP3-0: PLL Loop Filter Control Bits. Selection is based on the divided PLL reference clock, according to the following table:
Divided PLL Reference Clock 19 - 30 MHz 12.2 - 19.5 MHz 7.8 - 12.5 MHz 5 - 8 MHz
PLLLP3-0 0001 0011 0111 1111
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Table 14.2. PLL Frequency Characteristics
-40C to +85C unless otherwise specified PARAMETER Input Frequency (Divided Reference Frequency) PLL Output Frequency (C8051F120/1/2/3) PLL Output Frequency (C8051F124/5/6/7) CONDITIONS MIN 5 25 25 TYP MAX 30 100 50 UNITS MHz MHz MHz
Table 14.3. PLL Lock Timing Characteristics
-40C to +85C unless otherwise specified INPUT MULTIPLIER PLL0FLT FREQUENCY (PLL0MUL) SETTING 20 0x0F 13 0x0F 16 0x1F 9 0x1F 5 MHz 12 0x2F 6 0x2F 10 0x3F 5 0x3F 4 0x01 2 0x01 3 0x11 2 0x11 25 MHz 2 0x21 1 0x21 2 0x31 1 0x31 OUTPUT FREQUENCY 100 MHz 65 MHz 80 MHz 45 MHz 60 MHz 30 MHz 50 MHz 25 MHz 100 MHz 50 MHz 75 MHz 50 MHz 50 MHz 25 MHz 50 MHz 25 MHz MIN TYP 202 115 241 116 258 112 263 113 42 33 48 17 42 33 60 25 MAX UNITS s s s s s s s s s s s s s s s s
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Notes
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15.
FLASH MEMORY
The C8051F12x family includes 128k + 256 bytes of on-chip, reprogrammable FLASH memory for program code and non-volatile data storage. The FLASH memory can be programmed in-system through the JTAG interface, or by software using the MOVX write instructions. Once cleared to logic 0, a FLASH bit must be erased to set it back to logic 1. Bytes should be erased (set to 0xFF) before being reprogrammed. FLASH write and erase operations are automatically timed by hardware for proper execution. During a FLASH erase or write, the FLBUSY bit in the FLSTAT register is set to `1' (see Figure 16.8). During this time, instructions that are located in the prefetch buffer or the branch target cache can be executed, but the processor will stall until the erase or write is completed if instruction data must be fetched from FLASH memory. Interrupts that have been pre-loaded into the branch target cache can also be serviced at this time, if the current code is also executing from the prefetch engine or cache memory. Any interrupts that are not pre-loaded into cache, or that occur while the core is halted, will be held in a pending state during the FLASH write/erase operation, and serviced in priority order once the FLASH operation has completed. Refer to Table 15.1 for the electrical characteristics of the FLASH memory.
15.1.
Programming The Flash Memory
The simplest means of programming the FLASH memory is through the JTAG interface using programming tools provided by Cygnal or a third party vendor. This is the only means for programming a non-initialized device. For details on the JTAG commands to program FLASH memory, see Section "25. JTAG (IEEE 1149.1)" on page 305. The FLASH memory can be programmed from software using the MOVX write instruction with the address and data byte to be programmed provided as normal operands. Before writing to FLASH memory using MOVX, FLASH write operations must be enabled by setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic 1. This directs the MOVX writes to FLASH memory instead of to XRAM, which is the default target. The PSWE bit remains set until cleared by software. To avoid errant FLASH writes, it is recommended that interrupts be disabled while the PSWE bit is logic 1. FLASH memory is read using the MOVC instruction. MOVX reads are always directed to XRAM, regardless of the state of PSWE. The COBANK bits in the PSBANK register (Figure 12.3) determine which of the upper three FLASH banks are mapped to the address range 0x08000 to 0x0FFFF for FLASH writes, reads and erases. NOTE: To ensure the integrity of FLASH memory contents, it is strongly recommended that the on-chip VDD monitor be enabled by connecting the VDD monitor enable pin (MONEN) to VDD in any system that writes and/or erases FLASH memory from software. See "RESET SOURCES" on page 155 for more information. A write to FLASH memory can clear bits but cannot set them; only an erase operation can set bits in FLASH. A byte location to be programmed must be erased before a new value can be written.
15.1.1. Non-volatile Data Storage
The FLASH memory can be used for non-volatile data storage as well as program code. This allows data such as calibration coefficients to be calculated and stored at run time. Data is written and erased using the MOVX write instruction (as described in Section 15.1.2 and Section 15.1.3) and read using the MOVC instruction. The COBANK bits in register PSBANK (Figure 12.3) control which portion of the FLASH memory is targeted by writes and erases of addresses above 0x07FFF. Two additional 128-byte sectors (256 bytes total) of FLASH memory are included for non-volatile data storage. The smaller sector size makes them particularly well suited as general purpose, non-volatile scratchpad memory. Even though FLASH memory can be written a single byte at a time, an entire sector must be erased first. In order to change a single byte of a multi-byte data set, the data must be moved to temporary storage. The 128-byte sector-size facili-
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tates updating data without wasting program memory or RAM space. The 128-byte sectors are double-mapped over the 128k byte FLASH memory for MOVC reads and MOVX writes only; their addresses range from 0x00 to 0x7F and from 0x80 to 0xFF (see Figure 15.2). To access the 128-byte sectors, the SFLE bit in PSCTL must be set to logic 1. Code execution from the 128-byte Scratchpad areas is not possible. The 128-byte sectors can be erased individually, or both at the same time. To erase both sectors simultaneously, the address 0x0400 should be targeted during the erase operation with SFLE set to `1'. See Figure 15.1 for the memory map under different COBANK and SFLE settings.
Figure 15.1. FLASH Memory Map for MOVC Read and MOVX Write Operations
SFLE = 0 COBANK = 0 COBANK = 1 COBANK = 2 COBANK = 3 SFLE = 1 Internal Address 0xFFFF
Bank 0
Bank 1
Bank 2
Bank 3 Undefined 0x8000 0x7FFF
Bank 0
Bank 0
Bank 0
Bank 0 Scratchpad Areas (2) 0x00FF 0x0000
15.1.2. Erasing FLASH Pages From Software
When erasing FLASH memory, an entire page is erased (all bytes in the page are set to 0xFF). The 128k byte FLASH memory is organized in 1024-byte pages. The 256 bytes of Scratchpad area (addresses 0x20000 to 0x200FF) consists of two 128 byte pages. To erase any FLASH page, the FLWE, PSWE, and PSEE bits must be set to `1', and a byte must be written using a MOVX instruction to any address within that page. The following is the recommended procedure for erasing a FLASH page from software: Step 1. Disable interrupts. Step 2. If erasing a page in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for the appropriate bank. Step 3. If erasing a page in the Scratchpad area, set the SFLE bit (PSCTL.2). Step 4. Set FLWE (FLSCL.0) to enable FLASH writes/erases via user software. Step 5. Set PSEE (PSCTL.1) to enable FLASH erases. Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to FLASH. Step 7. Use the MOVX instruction to write a data byte to any location within the page to be erased. Step 8. Clear PSEE to disable FLASH erases. Step 9. Clear the PSWE bit to redirect MOVX commands to the XRAM data space. Step 10. Clear the FLWE bit, to disable FLASH writes/erases. Step 11. If erasing a page in the Scratchpad area, clear the SFLE bit. Step 12. Re-enable interrupts.
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15.1.3. Writing FLASH Memory From Software
Bytes in FLASH memory can be written one byte at a time, or in small blocks. The CHBLKW bit in register CCH0CN (Figure 16.4) controls whether a single byte or a block of bytes is written to FLASH during a write operation. When CHBLKW is cleared to `0', the FLASH will be written one byte at a time. When CHBLKW is set to `1', the FLASH will be written in blocks of four bytes for addresses in code space, or blocks of two bytes for addresses in the Scratchpad area. Block writes are performed in the same amount of time as single byte writes, which can save time when storing large amounts of data to FLASH memory. For single-byte writes to FLASH, bytes are written individually, and the FLASH write is performed after each MOVX write instruction. The recommended procedure for writing FLASH in single bytes is: Step 1. Disable interrupts. Step 2. Clear CHBLKW (CCH0CN.0) to select single-byte write mode. Step 3. If writing to bytes in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for the appropriate bank. Step 4. If writing to bytes in the Scratchpad area, set the SFLE bit (PSCTL.2). Step 5. Set FLWE (FLSCL.0) to enable FLASH writes/erases via user software. Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to FLASH. Step 7. Use the MOVX instruction to write a data byte to the desired location (repeat as necessary). Step 8. Clear the PSWE bit to redirect MOVX commands to the XRAM data space. Step 9. Clear the FLWE bit, to disable FLASH writes/erases. Step 10. If writing to bytes in the Scratchpad area, clear the SFLE bit. Step 11. Re-enable interrupts. For block FLASH writes, the FLASH write procedure is only performed after the last byte of each block is written with the MOVX write instruction. When writing to addresses located in any of the four code banks, a FLASH write block is four bytes long, from addresses ending in 00b to addresses ending in 11b. Writes must be performed sequentially (i.e. addresses ending in 00b, 01b, 10b, and 11b must be written in order). The FLASH write will be performed following the MOVX write that targets the address ending in 11b. When writing to addresses located in the FLASH Scratchpad area, a FLASH block is two bytes long, from addresses ending in 0b to addresses ending in 1b. The FLASH write will be performed following the MOVX write that targets the address ending in 1b. If any bytes in the block do not need to be updated in FLASH, they should be written to 0xFF. The recommended procedure for writing FLASH in blocks is: Step 1. Disable interrupts. Step 2. Set CHBLKW (CCH0CN.0) to select block write mode. Step 3. If writing to bytes in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for the appropriate bank. Step 4. If writing to bytes in the Scratchpad area, set the SFLE bit (PSCTL.2). Step 5. Set FLWE (FLSCL.0) to enable FLASH writes/erases via user software. Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to FLASH. Step 7. Use the MOVX instruction to write data bytes to the desired block. The data bytes must be written sequentially, and the last byte written must be the high byte of the block (see text for details, repeat as necessary). Step 8. Clear the PSWE bit to redirect MOVX commands to the XRAM data space. Step 9. Clear the FLWE bit, to disable FLASH writes/erases. Step 10. If writing to bytes in the Scratchpad area, clear the SFLE bit. Step 11. Re-enable interrupts.
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Table 15.1. FLASH Electrical Characteristics
VDD = 2.7 to 3.6 V; -40C to +85C PARAMETER CONDITIONS Endurance Erase Cycle Time Write Cycle Time MIN 20k 10 40 TYP 100k 12 50 MAX 14 60 UNITS Erase/Write ms s
15.2.
Security Options
The CIP-51 provides security options to protect the FLASH memory from inadvertent modification by software as well as prevent the viewing of proprietary program code and constants. The Program Store Write Enable (PSCTL.0), Program Store Erase Enable (PSCTL.1), and Flash Write/Erase Enable (FLACL.0) bits protect the FLASH memory from accidental modification by software. These bits must be explicitly set to logic 1 before software can write or erase the FLASH memory. Additional security features prevent proprietary program code and data constants from being read or altered across the JTAG interface or by software running on the system controller. A set of security lock bytes stored at 0x1FBFF and 0x1FBFE protect the FLASH program memory from being read or altered across the JTAG interface. Each bit in a security lock-byte protects one 16k-byte block of memory. Access to the scratchpad area can only be locked by locking all other FLASH blocks. Clearing a bit to logic 0 in a Read Lock Byte prevents the corresponding block of FLASH memory from being read across the JTAG interface. Clearing a bit in the Write/Erase Lock Byte protects the block from JTAG erasures and/or writes. The Read Lock Byte is at location 0x1FBFF. The Write/Erase Lock Byte is located at 0x1FBFE. Figure 15.2 shows the location and bit definitions of the security bytes. The 1024-byte sector containing the lock bytes can be written to, but not erased by software. An attempted read of a read-locked byte returns undefined data. Debugging code in a read-locked sector is not possible through the JTAG interface. To ensure protection from external access, the block containing the lock bytes (1C000-1BFFF) must be write/erase locked by clearing the MSB of byte 0x1FBFE.
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Figure 15.2. FLASH Program Memory Map and Security Bytes
Read and Write/Erase Security Bits. (Bit 7 is MSB.)
SFLE = 0
0x1FFFF
SFLE = 1
Scratchpad Memory (Data only)
0x00FF 0x0000
Bit
7 6 5 4 3 2 1 0
Memory Block
0x1C000 - 0x1FBFD 0x18000 - 0x1BFFF 0x14000 - 0x17FFF 0x10000 - 0x13FFF 0x0C000 - 0x0FFFF 0x08000 - 0x0BFFF 0x04000 - 0x07FFF 0x00000 - 0x03FFF
Reserved
0x1FC00
Read Lock Byte Write/Erase Lock Byte
0x1FBFF 0x1FBFE 0x1FBFD
Program/Data Memory Space
Software Read Limit
0x00000
FLASH Read Lock Byte Bits7-0: Each bit locks a corresponding block of memory. (Bit7 is MSB). 0: Read operations are locked (disabled) for corresponding block across the JTAG interface. 1: Read operations are unlocked (enabled) for corresponding block across the JTAG interface. FLASH Write/Erase Lock Byte Bits7-0: Each bit locks a corresponding block of memory. 0: Write/Erase operations are locked (disabled) for corresponding block across the JTAG interface. 1: Write/Erase operations are unlocked (enabled) for corresponding block across the JTAG interface. NOTE: When the highest block is locked, the security bytes may be written but not erased. FLASH access Limit Register (FLACL) The content of this register is used as the 8 MSBs of the 17-bit software read limit address. Software running at or above this address is prohibited from using the MOVX and MOVC instructions to read, write, or erase FLASH locations below this address. Any attempts to read locations below this limit will return indeterminate data.
The lock bits can always be read and cleared to logic 0 regardless of the security setting applied to the block containing the security bytes. This allows additional blocks to be protected after the block containing the security bytes has been locked. Important Note: The only means of removing a lock once set is to erase the entire program memory space by performing a JTAG erase operation (i.e. cannot be done in user firmware). Addressing either security byte while performing a JTAG erase operation will automatically initiate erasure of the entire program memory space (except for the reserved area). This erasure can only be performed via JTAG. If a nonsecurity byte in the 0x1F800-0x1FBFF page is addressed during the JTAG erasure, only that page (including the security bytes) will be erased.
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The FLASH Access Limit security feature (see Figure 15.2) protects proprietary program code and data from being read by software running on the C8051F120/1/2/3/4/5/6/7. This feature provides support for OEMs that wish to program the MCU with proprietary value-added firmware before distribution. The value-added firmware can be protected while allowing additional code to be programmed in remaining program memory space later. The Software Read Limit (SRL) is a 17-bit address that establishes two logical partitions in the program memory space. The first is an upper partition consisting of all the program memory locations at or above the SRL address, and the second is a lower partition consisting of all the program memory locations starting at 0x00000 up to (but excluding) the SRL address. Software in the upper partition can execute code in the lower partition, but is prohibited from reading locations in the lower partition using the MOVC instruction. (Executing a MOVC instruction from the upper partition with a source address in the lower partition will return indeterminate data.) Software running in the lower partition can access locations in both the upper and lower partition without restriction. The Value-added firmware should be placed in the lower partition. On reset, control is passed to the value-added firmware via the reset vector. Once the value-added firmware completes its initial execution, it branches to a predetermined location in the upper partition. If entry points are published, software running in the upper partition may execute program code in the lower partition, but it cannot read or change the contents of the lower partition. Parameters may be passed to the program code running in the lower partition either through the typical method of placing them on the stack or in registers before the call or by placing them in prescribed memory locations in the upper partition. The SRL address is specified using the contents of the FLASH Access Register. The 8 MSBs of the 17-bit SRL address are determined by the setting of the FLACL register. Thus, the SRL can be located on 512-byte boundaries anywhere in program memory space. However, the 1024-byte erase sector size essentially requires that a 1024 boundary be used. The contents of a non-initialized FLACL security byte are 0x00, thereby setting the SRL address to 0x00000 and allowing read access to all locations in program memory space by default.
Figure 15.3. FLACL: FLASH Access Limit
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address: SFR Address: 0xB7 SFR Page: F
Bits 7-0:
FLACL: FLASH Access Limit. This register holds the most significant 8 bits of the 17-bit program memory read/write/erase limit address. The lower 9 bits of the read/write/erase limit are always set to 0. A write to this register sets the FLASH Access Limit. This register can only be written once after any reset. Any subsequent writes are ignored until the next reset. To fully protect all addresses below this limit, bit 0 of FLACL should be set to `0'.
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Figure 15.4. FLSCL: FLASH Memory Control
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6 Bit5
FLRT
Bit4
Reserved
Bit3
Reserved
Bit2
Reserved
Bit1
FLWE
Bit0
10000000
SFR Address:
SFR Address: 0xB7 SFR Page: 0
Bits 7-6: Bits 5-4:
Bits 3-1: Bit 0:
Unused. FLRT: FLASH Read Time. These bits should be programmed to the smallest allowed value, according to the system clock speed. 00: SYSCLK <= 25 MHz. 01: SYSCLK <= 50 MHz. 10: SYSCLK <= 75 MHz. 11: SYSCLK <= 100 MHz. RESERVED. Read = 000b. Must Write 000b. FLWE: FLASH Write/Erase Enable. This bit must be set to allow FLASH writes/erasures from user software. 0: FLASH writes/erases disabled. 1: FLASH writes/erases enabled.
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Figure 15.5. PSCTL: Program Store Read/Write Control
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
SFLE
Bit2
PSEE
Bit1
PSWE
Bit0
00000000
SFR Address:
SFR Address: 0x8F SFR Page: 0
Bits 7-3: Bit 2:
Bit 1:
Bit 0:
UNUSED. Read = 00000b, Write = don't care. SFLE: Scratchpad FLASH Memory Access Enable When this bit is set, FLASH MOVC reads and writes from user software are directed to the two 128byte Scratchpad FLASH sectors. When SFLE is set to logic 1, FLASH accesses out of the address range 0x00-0xFF should not be attempted (with the exception of address 0x400, which can be used to simultaneously erase both Scratchpad areas). Reads/Writes out of this range will yield undefined results. 0: FLASH access from user software directed to the 128k byte Program/Data FLASH sector. 1: FLASH access from user software directed to the two 128 byte Scratchpad sectors. PSEE: Program Store Erase Enable. Setting this bit allows an entire page of the FLASH program memory to be erased provided the PSWE bit is also set. After setting this bit, a write to FLASH memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter. Note: The FLASH page containing the Read Lock Byte and Write/Erase Lock Byte cannot be erased by software. 0: FLASH program memory erasure disabled. 1: FLASH program memory erasure enabled. PSWE: Program Store Write Enable. Setting this bit allows writing a byte of data to the FLASH program memory using the MOVX write instruction. The location must be erased prior to writing data. 0: Write to FLASH program memory disabled. MOVX write operations target External RAM. 1: Write to FLASH program memory enabled. MOVX write operations target FLASH memory.
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16.
BRANCH TARGET CACHE
The C8051F12x family of devices incorporate a 63x4 byte branch target cache with a 4-byte prefetch engine. Because the access time of the FLASH memory is 40ns, and the minimum instruction time is 10ns (C8051F120/1/2/ 3) or 20ns (C8051F124/5/6/7), the branch target cache and prefetch engine are necessary for full-speed code execution. Instructions are read from FLASH memory four bytes at a time by the prefetch engine, and given to the CIP-51 processor core to execute. When running linear code (code without any jumps or branches), the prefetch engine alone allows instructions to be executed at full speed. When a code branch occurs, a search is performed for the branch target (destination address) in the cache. If the branch target information is found in the cache (called a "cache hit"), the instruction data is read from the cache and immediately returned to the CIP-51 with no delay in code execution. If the branch target is not found in the cache (called a "cache miss"), the processor may be stalled for up to four clock cycles while the next set of four instructions is retrieved from FLASH memory. Each time a cache miss occurs, the requested instruction data is written to the cache if allowed by the current cache settings. A data flow diagram of the interaction between the CIP-51 and the Branch Target Cache and Prefetch Engine is shown in Figure 16.1.
Figure 16.1. Branch Target Cache Data Flow
Instruction Data CIP-51 FLASH Memory
Prefetch Engine
Branch Target Cache Instruction Address
16.1.
Cache and Prefetch Operation
The branch target cache maintains two sets of memory locations: "slots" and "tags". A slot is where the cached instruction data from FLASH is stored. Each slot holds four consecutive code bytes. A tag contains the 15 most significant bits of the corresponding FLASH address for each four-byte slot. Thus, instruction data is always cached along four-byte boundaries in code space. A tag also contains a "valid bit", which indicates whether a cache location contains valid instruction data. A special cache location (called the linear tag and slot), is reserved for use by the prefetch engine. The cache organization is shown in Figure 16.2. Each time a FLASH read is requested, the address is compared with all valid cache tag locations (including the linear tag). If any of the tag locations match the requested address, the data from that slot is immediately provided to the CIP-51. If the requested address matches a location that is currently being read by the prefetch engine, the CIP-51 will be stalled until the read is complete. If a match is not found, the current prefetch operation is abandoned, and a new prefetch operation is initiated for the requested instruction data. When the prefetch operation is finished, the CIP-51 begins executing the instructions that were retrieved, and the prefetch engine begins reading the next four-byte word from FLASH memory. If the newly-fetched data also meets the criteria necessary to be cached, it will be written to the cache in the slot indicated by the current replacement algorithm. The replacement algorithm is selected with the Cache Algorithm bit, CHALGM (CCH0TN.3). When CHALGM is cleared to `0', the cache will use the rebound algorithm to replace cache locations. The rebound algorithm replaces locations in order from the beginning of cache memory to the end, and then from the end of cache memory to the
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beginning. When CHALGM is set to `1', the cache will use the pseudo-random algorithm to replace cache locations. The pseudo-random algorithm uses a pseudo-random number to determine which cache location to replace. The cache can be manually emptied by writing a `1' to the CHFLUSH bit (CCH0CN.4).
Figure 16.2. Branch Target Cache Organiztion
Valid Bit Prefetch Data VL V0 V1 V2 Address LINEAR TAG TAG 0 TAG 1 TAG 2 Data LINEAR SLOT SLOT 0 SLOT 1 SLOT 2
Cache Data V58 V59 V60 V61 V62 TAG 58 TAG 59 TAG 60 TAG 61 TAG 62 SLOT 58 SLOT 59 SLOT 60 SLOT 61 SLOT 62
A16
A2
A1 A0 0 0 1 0 1
Byte 0 Byte 1 Byte 2 Byte 3 SLOT = 4 Instruction Data Bytes
TAG = 15 MSBs of Absolute FLASH Address
0 1 1
16.2. Cache and Prefetch Optimization
By default, the branch target cache is configured to provide code speed improvements for a broad range of circumstances. In most applications, the cache control registers should be left in their reset states. Sometimes it is desirable to optimize the execution time of a specific routine or critical timing loop. The branch target cache includes options to exclude caching of certain types of data, as well as the ability to pre-load and lock time-critical branch locations to optimize execution speed. The most basic level of cache control is implemented with the Cache Miss Penalty Threshold bits, CHMSTH (CCH0TN.1-0). If the processor is stalled during a prefetch operation for more clock cycles than the number stored in CHMSTH, the requested data will be cached when it becomes available. The CHMSTH bits are set to zero by default, meaning that any time the processor is stalled, the new data will be cached. If, for example, CHMSTH is equal to 2, any cache miss causing a delay of 3 or 4 clock cycles will be cached, while a cache miss causing a delay of 1-2 clock cycles will not be cached. Certain types of instruction data or certain blocks of code can also be excluded from caching. The destinations of RETI instructions are, by default, excluded from caching. To enable caching of RETI destinations, the CHRETI bit (CCH0CN.3) can be set to `1'. It is generally not beneficial to cache RETI destinations unless the same instruction is
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likely to be interrupted repeatedly (such as a code loop that is waiting for an interrupt to happen). Instructions that are part of an interrupt service routine (ISR) can also be excluded from caching. By default, ISR instructions are cached, but this can be disabled by clearing the CHISR bit (CCH0CN.2) to `0'. The other information that can be explicitly excluded from caching are the data returned by MOVC instructions. Clearing the CHMOV bit (CCH0CN.1) to `0' will disable caching of MOVC data. If MOVC caching is allowed, it can be restricted to only use slot 0 for the MOVC information (excluding cache push operations). The CHFIXM bit (CCH0TN.2) controls this behavior. Further cache control can be implemented by disabling all cache writes. Cache writes can be disabled by clearing the CHWREN bit (CCH0CN.7) to `0'. Although normal cache writes (such as those after a cache miss) are disabled, data can still be written to the cache with a cache push operation. Disabling cache writes can be used to prevent a non-critical section of code from changing the cache contents. Note that regardless of the value of CHWREN, a FLASH write or erase operation automatically removes the affected bytes from the cache. Cache reads and the prefetch engine can also be individually disabled. Disabling cache reads forces all instructions data to execute from FLASH memory or from the prefetch engine. To disable cache reads, the CHRDEN bit (CCH0CN.6) can be cleared to `0'. Note that when cache reads are disabled, cache writes will still occur (if CHWREN is set to `1'). Disabling the prefetch engine is accomplished using the CHPFEN bit (CCH0CN.5). When this bit is cleared to `0', the prefetch engine will be disabled. If both CHPFEN and CHRDEN are `0', code will execute at a fixed rate, as instructions become available from the FLASH memory. Cache locations can also be pre-loaded and locked with time-critical branch destinations. For example, in a system with an ISR that must respond as fast as possible, the entry point for the ISR can be locked into a cache location to minimize the response latency of the ISR. Up to 61 locations can be locked into the cache at one time. Instructions are locked into cache by enabling cache push operations with the CHPUSH bit (CCH0LC.7). When CHPUSH is set to `1', a MOVC instruction will cause the four-byte segment containing the data byte to be written to the cache slot location indicated by CHSLOT (CCH0LC.5-0). CHSLOT is them decremented to point to the next lockable cache location. This process is called a cache push operation. Cache locations that are above CHSLOT are "locked", and cannot be changed by the processor core, as shown in Figure 16.3. Cache locations can be unlocked by using a cache pop operation. A cache pop is performed by writing a `1' to the CHPOP bit (CCH0LC.6). When a cache pop is initiated, the value of CHSLOT is incremented. This unlocks the most recently locked cache location, but does not remove the information from the cache. Note that a cache pop should not be initiated if CHSLOT is equal to 111110b. Doing so may have an adverse effect on cache performance. Important: Although locking cache location 1 is not explicitly disabled by hardware, the entire cache will be unlocked when CHSLOT is equal to 000000b. Therefore, cache locations 1 and 0 must remain unlocked at all times.
Figure 16.3. Cache Lock Operation
TAG 0 Cache Push Operations Decrement CHSLOT TAG 1 TAG 2 SLOT 0 SLOT 1 SLOT 2 Lock Status UNLOCKED UNLOCKED UNLOCKED UNLOCKED
TAG 57 CHSLOT = 58 TAG 58 TAG 59 TAG 60 TAG 61 TAG 62
SLOT 57 SLOT 58 SLOT 59 SLOT 60 SLOT 61 SLOT 62
UNLOCKED UNLOCKED LOCKED LOCKED LOCKED LOCKED
Cache Pop Operations Increment CHSLOT
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Figure 16.4. CCH0CN: Cache Control Register
R/W Bit7 R/W Bit6 R/W R/W R/W R/W R/W Bit1 R/W Bit0 SFR Address: 0xA1 SFR Page: F Reset Value
CHWREN CHRDEN
CHPFEN
Bit5
CHFLSH
Bit4
CHRETI
Bit3
CHISR
Bit2
CHMOVC CHBLKW 11100110
Bit 7:
Bit 6:
Bit 5:
Bit 4: Bit 3:
Bit 2:
Bit 1:
Bit 0:
CHWREN: Cache Write Enable. This bit enables the processor to write to the cache memory. 0: Cache contents are not allowed to change, except during FLASH writes/erasures or cache locks. 1: Writes to cache memory are allowed. CHRDEN: Cache Read Enable. This bit enables the processor to read instructions from the cache memory. 0: All instruction data comes from FLASH memory or the prefetch engine. 1: Instruction data is obtained from cache (when available). CHPFEN: Cache Prefetch Enable. This bit enables the prefetch engine. 0: Prefetch engine is disabled. 1: Prefetch engine is enabled. CHFLSH: Cache Flush. When written to a `1', this bit clears the cache contents. This bit always reads `0'. CHRETI: Cache RETI Destination Enable. This bit enables the destination of a RETI address to be cached. 0: Destinations of RETI instructions will not be cached. 1: RETI destinations will be cached. CHISR: Cache ISR Enable. This bit allows instructions which are part of an Interrupt Service Rountine (ISR) to be cached. 0: Instructions in ISRs will not be loaded into cache memory. 1: Instructions in ISRs can be cached. CHMOVC: Cache MOVC Enable. This bit allows data requested by a MOVC instruction to be loaded into the cache memory. 0: Data requested by MOVC instructions will not be cached. 1: Data requested by MOVC instructions will be loaded into cache memory. CHBLKW: Block Write Enable. This bit allows block writes to FLASH memory from software. 0: Each byte of a software FLASH write is written individually. 1: FLASH bytes are written in groups of four (for code space writes) or two (for scratchpad writes).
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Figure 16.5. CCH0TN: Cache Tuning Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xA2 SFR Page: F Reset Value
CHMSCTL
CHALGM CHFIXM
CHMSTH
00000100
Bits 7-4: Bit 3:
Bit 2:
Bits 1-0:
CHMSCTL: Cache Miss Penalty Accumulator (Bits 4-1). These are bits 4-1 of the Cache Miss Penalty Accumulator (See Figure 16.7). CHALGM: Cache Algorithm Select. This bit selects the cache replacement algorithm. 0: Cache uses Rebound algorithm. 1: Cache uses Pseudo-random algorithm. CHFIXM: Cache Fix MOVC Enable. This bit forces MOVC writes to the cache memory to use slot 0. 0: MOVC data is written according to the current algorithm selected by the CHALGM bit. 1: MOVC data is always written to cache slot 0. CHMSTH: Cache Miss Penalty Threshold. These bits determine when missed instruction data will be cached. If data takes longer than CHMSTH clocks to obtain, it will be cached.
Figure 16.6. CCH0LC: Cache Lock Control Register
R/W R/W R Bit5 R Bit4 R R R Bit1 R Bit0 SFR Address: 0xA3 SFR Page: F Reset Value
CHPUSH
Bit7
CHPOP
Bit6
CHSLOT
Bit3 Bit2
00111110
Bit 7:
Bit 6:
Bits 5-0:
CHPUSH: Cache Push Enable. This bit enables cache push operations, which will lock information in cache slots using MOVC instructions. 0: Cache push operations are disabled. 1: Cache push operations are enabled. When a MOVC read is executed, the requested 4-byte segment containing the data is locked into the cache at the location indicated by CHSLOT, and CHSLOT is decremented. Note that no more than 61 cache slots should be locked at one time, since the entire cache will be unlocked when CHSLOT is equal to 0. CHPOP: Cache Pop. Writing a `1' to this bit will increment CHSLOT and then unlock that location. This bit always reads `0'. Note that Cache Pop operations should not be performed while CHSLOT = 111110b. CHSLOT: Cache Slot Pointer. These read-only bits are the pointer into the cache lock stack. Locations above CHSLOT are locked, and will not be changed by the processor, except when CHSLOT equals 0.
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Figure 16.7. CCH0MA: Cache Miss Accumulator
R R/W Bit6 R/W Bit5 R/W Bit4 R/W R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x9A SFR Page: F Reset Value
CHMSOV
Bit7
CHMSCTH
Bit3
00000000
Bit 7:
Bits 6-0:
CHMSOV: Cache Miss Penalty Overflow. This bit indicates when the Cache Miss Penalty Accumulator has overflowed since it was last written. 0: The Cache Miss Penalty Accumulator has not overflowed since it was last written. 1: An overflow of the Cache Miss Penalty Accumulator has occurred since it was last written. CHMSCTH: Cache Miss Penalty Accumulator (bits 11-5) These are bits 11-5 of the Cache Miss Penalty Accumulator. The next four bits (bits 4-1) are stored in CHMSCTL in the CCH0TN register. The Cache Miss Penalty Accumulator is incremented every clock cycle that the processor is delayed due to a cache miss. This is primarily used as a diagnostic feature, when optimizing code for execution speed. Writing to CHMSCTH clears the lower 5 bits of the Cache Miss Penalty Accumulator. Reading from CHMSCTH returns the current value of CHMSTCH, and latches bits 4-1 into CHMSTCL so that they can be read. Because bit 0 of the Cache Miss Penalty Accumulator is not available, the Cumulative Miss Penalty is equal to 2 * (CCHMSTCH:CCHMSTCL).
Figure 16.8. FLSTAT: FLASH Status
R R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
FLBUSY
Bit0
00000000
SFR Address: 0x88 SFR Page: 1
Bit 7-1: Bit 0:
Reserved. FLBUSY: FLASH Busy This bit indicates when a FLASH write or erase operation is in progress. 0: FLASH is idle or reading. 1: FLASH write/erase operation is currently in progress.
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17.
EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM
The C8051F12x MCUs include 8k bytes of on-chip RAM mapped into the external data memory space (XRAM), as well as an External Data Memory Interface which can be used to access off-chip memories and memory-mapped devices connected to the GPIO ports. The external memory space may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using the MOVX indirect addressing mode using R0 or R1. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN, shown in Figure 17.1). Note: the MOVX instruction can also be used for writing to the FLASH memory. See Section "15. FLASH MEMORY" on page 173 for details. The MOVX instruction accesses XRAM by default. The EMIF can be configured to appear on the lower GPIO Ports (P0-P3) or the upper GPIO Ports (P4-P7).
17.1.
Accessing XRAM
The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms, both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit register which contains the effective address of the XRAM location to be read from or written to. The second method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM address. Examples of both of these methods are given below.
17.1.1. 16-Bit MOVX Example
The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the accumulator A:
MOV MOVX DPTR, #1234h A, @DPTR ; load DPTR with 16-bit address to read (0x1234) ; load contents of 0x1234 into accumulator A
The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately, the DPTR can be accessed through the SFR registers DPH, which contains the upper 8-bits of DPTR, and DPL, which contains the lower 8-bits of DPTR.
17.1.2. 8-Bit MOVX Example
The 8-bit form of the MOVX instruction uses the contents of the EMI0CN SFR to determine the upper 8-bits of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the effective address to be accessed. The following series of instructions read the contents of the byte at address 0x1234 into the accumulator A.
MOV MOV MOVX EMI0CN, #12h R0, #34h a, @R0 ; load high byte of address into EMI0CN ; load low byte of address into R0 (or R1) ; load contents of 0x1234 into accumulator A
17.2.
Configuring the External Memory Interface
Configuring the External Memory Interface consists of five steps: 1. Select EMIF on Low Ports (P3, P2, P1, and P0) or High Ports (P7, P6, P5, and P4). 2. Configure the Output Modes of the port pins as either push-pull or open-drain (push-pull is most common). 3. Configure Port latches to "park" the EMIF pins in a dormant state (usually by setting them to logic `1'). 4. Select Multiplexed mode or Non-multiplexed mode.
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5. Select the memory mode (on-chip only, split mode without bank select, split mode with bank select, or off-chip only). 6. Set up timing to interface with off-chip memory or peripherals. Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed mode selection, and Mode bits are located in the EMI0CF register shown in Figure 17.2.
17.3.
Port Selection and Configuration
The External Memory Interface can appear on Ports 3, 2, 1, and 0 (C8051F120/1/2/3/4/5/6/7 devices) or on Ports 7, 6, 5, and 4 (C8051F120/2/4/6 devices only), depending on the state of the PRTSEL bit (EMI0CF.5). If the lower Ports are selected, the EMIFLE bit (XBR2.1) must be set to a `1' so that the Crossbar will skip over P0.7 (/WR), P0.6 (/ RD), and if multiplexed mode is selected P0.5 (ALE). For more information about the configuring the Crossbar, see Section "18.1. Ports 0 through 3 and the Priority Crossbar Decoder" on page 205. The External Memory Interface claims the associated Port pins for memory operations ONLY during the execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port pins reverts to the Port latches or to the Crossbar (on Ports 3, 2, 1, and 0). See Section "18. PORT INPUT/OUTPUT" on page 203 for more information about the Crossbar and Port operation and configuration. The Port latches should be explicitly configured to `park' the External Memory Interface pins in a dormant state, most commonly by setting them to a logic 1. During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the drivers on all Port pins that are acting as Inputs (Data[7:0] during a READ operation, for example). The Output mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases, the output modes of all EMIF pins should be configured for push-pull mode. See"Configuring the Output Modes of the Port Pins" on page 206.
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Figure 17.1. EMI0CN: External Memory Interface Control
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PGSEL7
Bit7
PGSEL6
Bit6
PGSEL5
Bit5
PGSEL4
Bit4
PGSEL3
Bit3
PGSEL2
Bit2
PGSEL1
Bit1
PGSEL0
Bit0
00000000
SFR Address: 0xA2 SFR Page: 0
Bits7-0:
PGSEL[7:0]: XRAM Page Select Bits. The XRAM Page Select Bits provide the high byte of the 16-bit external data memory address when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. 0x00: 0x0000 to 0x00FF 0x01: 0x0100 to 0x01FF ... 0xFE: 0xFE00 to 0xFEFF 0xFF: 0xFF00 to 0xFFFF
Figure 17.2. EMI0CF: External Memory Configuration
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
PRTSEL
Bit5
EMD2
Bit4
EMD1
Bit3
EMD0
Bit2
EALE1
Bit1
EALE0
Bit0
00000011
SFR Address: 0xA3 SFR Page: 0
Bits7-6: Bit5:
Bit4:
Bits3-2:
Bits1-0:
Unused. Read = 00b. Write = don't care. PRTSEL: EMIF Port Select. 0: EMIF active on P0-P3. 1: EMIF active on P4-P7. EMD2: EMIF Multiplex Mode Select. 0: EMIF operates in multiplexed address/data mode. 1: EMIF operates in non-multiplexed mode (separate address and data pins). EMD1-0: EMIF Operating Mode Select. These bits control the operating mode of the External Memory Interface. 00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias to on-chip memory space. 01: Split Mode without Bank Select: Accesses below the 8k boundary are directed on-chip. Accesses above the 8k boundary are directed off-chip. 8-bit off-chip MOVX operations use the current contents of the Address High port latches to resolve upper address byte. Note that in order to access off-chip space, EMI0CN must be set to a page that is not contained in the on-chip address space. 10: Split Mode with Bank Select: Accesses below the 8k boundary are directed on-chip. Accesses above the 8k boundary are directed off-chip. 8-bit off-chip MOVX operations use the contents of EMI0CN to determine the high-byte of the address. 11: External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible to the CPU. EALE1-0: ALE Pulse-Width Select Bits (only has effect when EMD2 = 1). 00: ALE high and ALE low pulse width = 1 SYSCLK cycle. 01: ALE high and ALE low pulse width = 2 SYSCLK cycles. 10: ALE high and ALE low pulse width = 3 SYSCLK cycles. 11: ALE high and ALE low pulse width = 4 SYSCLK cycles.
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17.4.
Preliminary
Multiplexed and Non-multiplexed Selection
The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode, depending on the state of the EMD2 (EMI0CF.4) bit.
17.4.1. Multiplexed Configuration
In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins: AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in Figure 17.3. In Multiplexed mode, the external MOVX operation can be broken into two phases delineated by the state of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are presented to AD[7:0]. During this phase, the address latch is configured such that the `Q' outputs reflect the states of the `D' inputs. When ALE falls, signaling the beginning of the second phase, the address latch outputs remain fixed and are no longer dependent on the latch inputs. Later in the second phase, the Data Bus controls the state of the AD[7:0] port at the time /RD or / WR is asserted. See Section "17.6.2. Multiplexed Mode" on page 198 for more information.
Figure 17.3. Multiplexed Configuration Example
A[15:8]
ADDRESS BUS 74HC373
A[15:8]
E M I F
ALE AD[7:0] ADDRESS/DATA BUS VDD
G D Q A[7:0] 64K X 8 SRAM
(Optional)
8
I/O[7:0] CE WE OE
/WR /RD
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17.4.2. Non-multiplexed Configuration
In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a Non-multiplexed Configuration is shown in Figure 17.4. See Section "17.6.1. Non-multiplexed Mode" on page 195 for more information about Non-multiplexed operation.
Figure 17.4. Non-multiplexed Configuration Example
E M I F
A[15:0]
ADDRESS BUS VDD
A[15:0]
(Optional)
8 D[7:0] DATA BUS
64K X 8 SRAM I/O[7:0] CE WE OE
/WR /RD
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17.5. Memory Mode Selection
Preliminary
The external data memory space can be configured in one of four modes, shown in Figure 17.5, based on the EMIF Mode bits in the EMI0CF register (Figure 17.2). These modes are summarized below. More information about the different modes can be found in Section "17.6. Timing" on page 194.
17.5.1. Internal XRAM Only
When EMI0CF.[3:2] are set to `00', all MOVX instructions will target the internal XRAM space on the device. Memory accesses to addresses beyond the populated space will wrap on 8k boundaries. As an example, the addresses 0x1000 and 0x2000 both evaluate to address 0x0000 in on-chip XRAM space. * * 8-bit MOVX operations use the contents of EMI0CN to determine the high-byte of the effective address and R0 or R1 to determine the low-byte of the effective address. 16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address.
17.5.2. Split Mode without Bank Select
When EMI0CF.[3:2] are set to `01', the XRAM memory map is split into two areas, on-chip space and off-chip space. * * * Effective addresses below the 8k boundary will access on-chip XRAM space. Effective addresses above the 8k boundary will access off-chip space. 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-chip or offchip. However, in the "No Bank Select" mode, an 8-bit MOVX operation will not drive the upper 8-bits A[15:8] of the Address Bus during an off-chip access. This allows the user to manipulate the upper address bits at will by setting the Port state directly via the port latches. This behavior is in contrast with "Split Mode with Bank Select" described below. The lower 8-bits of the Address Bus A[7:0] are driven, determined by R0 or R1. 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-chip or offchip, and unlike 8-bit MOVX operations, the full 16-bits of the Address Bus A[15:0] are driven during the offchip transaction.
*
Figure 17.5. EMIF Operating Modes
EMI0CF[3:2] = 00 0xFFFF On-Chip XRAM EMI0CF[3:2] = 01 0xFFFF EMI0CF[3:2] = 10 0xFFFF EMI0CF[3:2] = 11 0xFFFF
On-Chip XRAM
Off-Chip Memory (No Bank Select)
Off-Chip Memory (Bank Select) Off-Chip Memory
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM On-Chip XRAM On-Chip XRAM 0x0000 0x0000 0x0000 0x0000 On-Chip XRAM
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17.5.3. Split Mode with Bank Select
When EMI0CF.[3:2] are set to `10', the XRAM memory map is split into two areas, on-chip space and off-chip space. * * * Effective addresses below the 8k boundary will access on-chip XRAM space. Effective addresses above the 8k boundary will access off-chip space. 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-chip or offchip. The upper 8-bits of the Address Bus A[15:8] are determined by EMI0CN, and the lower 8-bits of the Address Bus A[7:0] are determined by R0 or R1. All 16-bits of the Address Bus A[15:0] are driven in "Bank Select" mode. 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-chip or offchip, and the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction.
*
17.5.4. External Only
When EMI0CF[3:2] are set to `11', all MOVX operations are directed to off-chip space. On-chip XRAM is not visible to the CPU. This mode is useful for accessing off-chip memory located between 0x0000 and the 8k boundary. * 8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are not driven (identical behavior to an off-chip access in "Split Mode without Bank Select" described above). This allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower 8-bits of the effective address A[7:0] are determined by the contents of R0 or R1. 16-bit MOVX operations use the contents of DPTR to determine the effective address A[15:0]. The full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction.
*
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17.6. Timing
Preliminary
The timing parameters of the External Memory Interface can be configured to enable connection to devices having different setup and hold time requirements. The Address Setup time, Address Hold time, /RD and /WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in units of SYSCLK periods through EMI0TC, shown in Figure 17.6, and EMI0CF[1:0]. Assuming non-multiplexed operation, the minimum execution time for an off-chip XRAM operation is 4 SYSCLK cycles: 3 cycles for the MOVX operation + 1 cycle for the /RD or /WR pulse duration. The programmable setup and hold times default to the maximum delay settings after a reset. Table 17.1 lists the AC parameters for the External Memory Interface, and Figure 17.7 through Figure 17.12 show the timing diagrams for the different External Memory Interface modes and MOVX operations.
Figure 17.6. EMI0TC: External Memory Timing Control
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
EAS1
Bit7
EAS0
Bit6
ERW3
Bit5
EWR2
Bit4
EWR1
Bit3
EWR0
Bit2
EAH1
Bit1
EAH0
Bit0
11111111
SFR Address: 0xA1 SFR Page: 0
Bits7-6:
Bits5-2:
Bits1-0:
EAS1-0: EMIF Address Setup Time Bits. 00: Address setup time = 0 SYSCLK cycles. 01: Address setup time = 1 SYSCLK cycle. 10: Address setup time = 2 SYSCLK cycles. 11: Address setup time = 3 SYSCLK cycles. EWR3-0: EMIF /WR and /RD Pulse-Width Control Bits. 0000: /WR and /RD pulse width = 1 SYSCLK cycle. 0001: /WR and /RD pulse width = 2 SYSCLK cycles. 0010: /WR and /RD pulse width = 3 SYSCLK cycles. 0011: /WR and /RD pulse width = 4 SYSCLK cycles. 0100: /WR and /RD pulse width = 5 SYSCLK cycles. 0101: /WR and /RD pulse width = 6 SYSCLK cycles. 0110: /WR and /RD pulse width = 7 SYSCLK cycles. 0111: /WR and /RD pulse width = 8 SYSCLK cycles. 1000: /WR and /RD pulse width = 9 SYSCLK cycles. 1001: /WR and /RD pulse width = 10 SYSCLK cycles. 1010: /WR and /RD pulse width = 11 SYSCLK cycles. 1011: /WR and /RD pulse width = 12 SYSCLK cycles. 1100: /WR and /RD pulse width = 13 SYSCLK cycles. 1101: /WR and /RD pulse width = 14 SYSCLK cycles. 1110: /WR and /RD pulse width = 15 SYSCLK cycles. 1111: /WR and /RD pulse width = 16 SYSCLK cycles. EAH1-0: EMIF Address Hold Time Bits. 00: Address hold time = 0 SYSCLK cycles. 01: Address hold time = 1 SYSCLK cycle. 10: Address hold time = 2 SYSCLK cycles. 11: Address hold time = 3 SYSCLK cycles.
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17.6.1. Non-multiplexed Mode
17.6.1.1. 16-bit MOVX: EMI0CF[4:2] = `101', `110', or `111'.
Figure 17.7. Non-multiplexed 16-bit MOVX Timing
Nonmuxed 16-bit WRITE ADDR[15:8] P1/P5 EMIF ADDRESS (8 MSBs) from DPH P1/P5
ADDR[7:0]
P2/P6
EMIF ADDRESS (8 LSBs) from DPL
P2/P6
DATA[7:0]
P3/P7 T T
ACS
EMIF WRITE DATA
WDS
P3/P7 T
WDH ACH
T
ACW
T
/WR
P0.7/P4.7
P0.7/P4.7
/RD
P0.6/P4.6
P0.6/P4.6
Nonmuxed 16-bit READ ADDR[15:8] P1/P5 EMIF ADDRESS (8 MSBs) from DPH P1/P5
ADDR[7:0]
P2/P6
EMIF ADDRESS (8 LSBs) from DPL
P2/P6
DATA[7:0]
P3/P7
EMIF READ DATA T T
ACS RDS
P3/P7
T
RDH
T
ACW
T
ACH
/RD
P0.6/P4.6
P0.6/P4.6
/WR
P0.7/P4.7
P0.7/P4.7
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17.6.1.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = `101' or `111'.
Figure 17.8. Non-multiplexed 8-bit MOVX without Bank Select Timing
Nonmuxed 8-bit WRITE without Bank Select ADDR[15:8] P1/P5
ADDR[7:0]
P2/P6
EMIF ADDRESS (8 LSBs) from R0 or R1
P2/P6
DATA[7:0]
P3/P7 T T
ACS
EMIF WRITE DATA
WDS
P3/P7 T
WDH ACH
T
ACW
T
/WR
P0.7/P4.7
P0.7/P4.7
/RD
P0.6/P4.6
P0.6/P4.6
Nonmuxed 8-bit READ without Bank Select ADDR[15:8] P1/P5
ADDR[7:0]
P2/P6
EMIF ADDRESS (8 LSBs) from R0 or R1
P2/P6
DATA[7:0]
P3/P7
EMIF READ DATA T T
ACS RDS
P3/P7
T
RDH
T
ACW
T
ACH
/RD
P0.6/P4.6
P0.6/P4.6
/WR
P0.7/P4.7
P0.7/P4.7
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17.6.1.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = `110'.
Figure 17.9. Non-multiplexed 8-bit MOVX with Bank Select Timing
Nonmuxed 8-bit WRITE with Bank Select ADDR[15:8] P1/P5 EMIF ADDRESS (8 MSBs) from EMI0CN P1/P5
ADDR[7:0]
P2/P6
EMIF ADDRESS (8 LSBs) from R0 or R1
P2/P6
DATA[7:0]
P3/P7 T T
ACS
EMIF WRITE DATA
WDS
P3/P7 T
WDH ACH
T
ACW
T
/WR
P0.7/P4.7
P0.7/P4.7
/RD
P0.6/P4.6
P0.6/P4.6
Nonmuxed 8-bit READ with Bank Select ADDR[15:8] P1/P5 EMIF ADDRESS (8 MSBs) from EMI0CN P1/P5
ADDR[7:0]
P2/P6
EMIF ADDRESS (8 LSBs) from R0 or R1
P2/P6
DATA[7:0]
P3/P7
EMIF READ DATA T T
ACS RDS
P3/P7
T
RDH
T
ACW
T
ACH
/RD
P0.6/P4.6
P0.6/P4.6
/WR
P0.7/P4.7
P0.7/P4.7
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Preliminary
17.6.2.1. 16-bit MOVX: EMI0CF[4:2] = `001', `010', or `011'.
Figure 17.10. Multiplexed 16-bit MOVX Timing
Muxed 16-bit WRITE ADDR[15:8] P2/P6 EMIF ADDRESS (8 MSBs) from DPH EMIF ADDRESS (8 LSBs) from DPL T
ALEH
P2/P6
AD[7:0]
P3/P7
EMIF WRITE DATA
P3/P7
T
ALEL
ALE
P0.5/P4.5 T T
ACS WDS
P0.5/P4.5 T T
ACW WDH ACH
T
/WR
P0.7/P4.7
P0.7/P4.7
/RD
P0.6/P4.6
P0.6/P4.6
Muxed 16-bit READ ADDR[15:8] P2/P6 EMIF ADDRESS (8 MSBs) from DPH EMIF ADDRESS (8 LSBs) from DPL T
ALEH
P2/P6
AD[7:0]
P3/P7
EMIF READ DATA
P3/P7
T
ALEL
T
RDS
T
RDH
ALE
P0.5/P4.5
P0.5/P4.5
T /RD P0.6/P4.6
ACS
T
ACW
T
ACH
P0.6/P4.6
/WR
P0.7/P4.7
P0.7/P4.7
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17.6.2.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = `001' or `011'.
Figure 17.11. Multiplexed 8-bit MOVX without Bank Select Timing
Muxed 8-bit WRITE Without Bank Select ADDR[15:8] EMIF ADDRESS (8 LSBs) from R0 or R1 T
ALEH
P2/P6
AD[7:0]
P3/P7
EMIF WRITE DATA
P3/P7
T
ALEL
ALE
P0.5/P4.5 T T
ACS WDS
P0.5/P4.5 T T
ACW WDH ACH
T
/WR
P0.7/P4.7
P0.7/P4.7
/RD
P0.6/P4.6
P0.6/P4.6
Muxed 8-bit READ Without Bank Select ADDR[15:8] EMIF ADDRESS (8 LSBs) from R0 or R1 T
ALEH
P2/P6
AD[7:0]
P3/P7
EMIF READ DATA
P3/P7
T
ALEL
T
RDS
T
RDH
ALE
P0.5/P4.5
P0.5/P4.5
T /RD P0.6/P4.6
ACS
T
ACW
T
ACH
P0.6/P4.6
/WR
P0.7/P4.7
P0.7/P4.7
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17.6.2.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = `010'.
Figure 17.12. Multiplexed 8-bit MOVX with Bank Select Timing
Muxed 8-bit WRITE with Bank Select ADDR[15:8] P2/P6 EMIF ADDRESS (8 MSBs) from EMI0CN EMIF ADDRESS (8 LSBs) from R0 or R1 T
ALEH
P2/P6
AD[7:0]
P3/P7
EMIF WRITE DATA
P3/P7
T
ALEL
ALE
P0.5/P4.5 T T
ACS WDS
P0.5/P4.5 T T
ACW WDH ACH
T
/WR
P0.7/P4.7
P0.7/P4.7
/RD
P0.6/P4.6
P0.6/P4.6
Muxed 8-bit READ with Bank Select ADDR[15:8] P2/P6 EMIF ADDRESS (8 MSBs) from EMI0CN EMIF ADDRESS (8 LSBs) from R0 or R1 T
ALEH
P2/P6
AD[7:0]
P3/P7
EMIF READ DATA
P3/P7
T
ALEL
T
RDS
T
RDH
ALE
P0.5/P4.5
P0.5/P4.5
T /RD P0.6/P4.6
ACS
T
ACW
T
ACH
P0.6/P4.6
/WR
P0.7/P4.7
P0.7/P4.7
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Table 17.1. AC Parameters for External Memory Interface
PARAMETER TSYSCLK TSYSCLK TACS TACW TACH TALEH TALEL TWDS TWDH TRDS TRDH DESCRIPTION System Clock Period (C8051F120/1/2/3) System Clock Period (C8051F124/5/6/7) Address / Control Setup Time Address / Control Pulse Width Address / Control Hold Time Address Latch Enable High Time Address Latch Enable Low Time Write Data Setup Time Write Data Hold Time Read Data Setup Time Read Data Hold Time MIN 10 20 0 1*TSYSCLK 0 1*TSYSCLK 1*TSYSCLK 1*TSYSCLK 0 20 0 3*TSYSCLK 16*TSYSCLK 3*TSYSCLK 4*TSYSCLK 4*TSYSCLK 19*TSYSCLK 3*TSYSCLK MAX UNITS ns ns ns ns ns ns ns ns ns ns ns
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Notes
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18.
PORT INPUT/OUTPUT
The C8051F12x family of devices are fully integrated mixed-signal System on a Chip MCUs with 64 digital I/O pins (C8051F120/2/4/6) or 32 digital I/O pins (C8051F121/3/5/7), organized as 8-bit Ports. All ports are both bit- and byte-addressable through their corresponding Port Data registers. The upper ports: P4, P5, P6, and P7 are byteaddressable. All Port pins are 5 V-tolerant, and all support configurable Open-Drain or Push-Pull output modes and weak pull-ups. A block diagram of the Port I/O cell is shown in Figure 18.1. Complete Electrical Specifications for the Port I/O pins are given in Table 18.1.
Figure 18.1. Port I/O Cell Block Diagram
/WEAK-PULLUP
PUSH-PULL /PORT-OUTENABLE
VDD
VDD
(WEAK) PORT PAD
PORT-OUTPUT
Analog Select (Ports 1, 2, and 3) ANALOG INPUT PORT-INPUT
DGND
Table 18.1. Port I/O DC Electrical Characteristics
VDD = 2.7 V to 3.6 V, -40C to +85C unless otherwise specified. PARAMETER CONDITIONS MIN VDD - 0.7 VDD - 0.1 VDD-0.8 0.6 0.1 1.0 0.7 x VDD 0.3 x VDD DGND < Port Pin < VDD, Pin Tri-state Weak Pull-up Off Weak Pull-up On A 1 10 5 pF V TYP MAX UNITS V Output High Voltage (VOH) IOH = -3 mA, Port I/O Push-Pull IOH = -10 A, Port I/O Push-Pull IOH = -10 mA, Port I/O Push-Pull Output Low Voltage (VOL) IOL = 8.5 mA IOL = 10 A IOL = 25 mA Input High Voltage (VIH) Input Low Voltage (VIL) Input Leakage Current
Input Capacitance
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The C8051F12x family of devices have a wide array of digital resources which are available through the four lower I/ O Ports: P0, P1, P2, and P3. Each of the pins on P0, P1, P2, and P3, can be defined as a General-Purpose I/O (GPIO) pin or can be controlled by a digital peripheral or function (like UART0 or /INT1 for example), as shown in Figure 18.2. The system designer controls which digital functions are assigned pins, limited only by the number of pins available. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. Note that the state of a Port I/O pin can always be read from its associated Data register regardless of whether that pin has been assigned to a digital peripheral or behaves as GPIO. The Port pins on Port 1 can be used as Analog Inputs to ADC2. An External Memory Interface which is active during the execution of an off-chip MOVX instruction can be active on either the lower Ports or the upper Ports. See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Figure 18.2. Port I/O Functional Block Diagram
Highest Priority UART0 SPI SMBus UART1 (Internal Digital Signals) PCA Comptr. Outputs 2 4 2 2 7 2 XBR0, XBR1, XBR2, P1MDIN Registers P0MDOUT, P1MDOUT, P2MDOUT, P3MDOUT Registers External Pins P0.0 P0.7 Highest Priority
Priority Decoder
8 P0 I/O Cells
Digital Crossbar
8
T0, T1, T2, T2EX, T4,T4EX /INT0, /INT1
P1 I/O Cells
P1.0 P1.7
8 P2 I/O Cells P2.0 P2.7
8
Lowest Priority
/SYSCLK divided by 1,2,4, or 8 2 CNVSTR0/2 8 P0 (P0.0-P0.7) 8 P1 (P1.0-P1.7) 8 P2 (P2.0-P2.7) 8 P3 (P3.0-P3.7) To External Memory Interface (EMIF) 8 P3 I/O Cells
P3.0 P3.7 Lowest Priority
Port Latches
To ADC2 Input
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18.1.
Ports 0 through 3 and the Priority Crossbar Decoder
The Priority Crossbar Decoder, or "Crossbar", allocates and assigns Port pins on Port 0 through Port 3 to the digital peripherals (UARTs, SMBus, PCA, Timers, etc.) on the device using a priority order. The Port pins are allocated in order starting with P0.0 and continue through P3.7 if necessary. The digital peripherals are assigned Port pins in a priority order which is listed in Figure 18.3, with UART0 having the highest priority and CNVSTR2 having the lowest priority.
18.1.1. Crossbar Pin Assignment and Allocation
The Crossbar assigns Port pins to a peripheral if the corresponding enable bits of the peripheral are set to a logic 1 in the Crossbar configuration registers XBR0, XBR1, and XBR2, shown in Figure 18.7, Figure 18.8, and Figure 18.9. For example, if the UART0EN bit (XBR0.2) is set to a logic 1, the TX0 and RX0 pins will be mapped to P0.0 and P0.1 respectively. Because UART0 has the highest priority, its pins will always be mapped to P0.0 and P0.1 when UART0EN is set to a logic 1. If a digital peripheral's enable bits are not set to a logic 1, then its ports are not accessi-
Figure 18.3. Priority Crossbar Decode Table
P0 PIN I/O 0 TX0 RX0 SCK MISO MOSI NSS SDA SCL TX1 RX1 CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI CP0 CP1 T0 /INT0 T1 /INT1 T2 T2EX T4 T4EX /SYSCLK CNVSTR0 1 2 3 4 5 6 7 0 1 2 3
P1 4 5 6 7 0 1 2 3
P2 4 5 6 7 0 1 2 3
P3 4 5 6 7
Crossbar Register Bits
G G G G G G G G G G G G G G G G G
UART0EN: XBR0.2
SPI0EN: XBR0.1
NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
SMB0EN: XBR0.0
GGGGG G GGGGG GGGGGGG GGGGGGG GGGGGGGGG GGGGGGGGG GGGGGGGGG GGGGGGGGG G G GGGGGGGGG GGGGGGGGG
UART1EN: XBR2.2
PCA0ME: XBR0.[5:3]
GGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGGGGGG
ECI0E: XBR0.6 CP0E: XBR0.7 CP1E: XBR1.0 T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 INT1E: XBR1.4 T2E: XBR1.5 T2EXE: XBR1.6 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR2.5 AD6/D6 AD7/D7
GGGGGGGGGGGGGGGGGGGGGGGGGGGGG CNVSTR2 G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G
AIN1.2/A10 AIN1.3/A11 AIN1.4/A12 AIN1.5/A13 AIN1.6/A14 AIN1.7/A15 AIN1.0/A8 AIN1.1/A9 A10m/A2 A11m/A3 A12m/A4 A13m/A5 A14m/A6 A15m/A7 A8m/A0 A9m/A1 AD0/D0 AD1/D1 AD2/D2 AD3/D3 AD4/D4 AD5/D5
/WR
ALE
/RD
AIN1 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L
Muxed Data/Non-muxed Data
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ble at the Port pins of the device. Also note that the Crossbar assigns pins to all associated functions when a serial communication peripheral is selected (i.e. SMBus, SPI, UART). It would be impossible, for example, to assign TX0 to a Port pin without assigning RX0 as well. Each combination of enabled peripherals results in a unique device pinout. All Port pins on Ports 0 through 3 that are not allocated by the Crossbar can be accessed as General-Purpose I/O (GPIO) pins by reading and writing the associated Port Data registers (See Figure 18.10, Figure 18.12, Figure 18.15, and Figure 18.17), a set of SFR's which are both byte- and bit-addressable. The output states of Port pins that are allocated by the Crossbar are controlled by the digital peripheral that is mapped to those pins. Writes to the Port Data registers (or associated Port bits) will have no effect on the states of these pins. A Read of a Port Data register (or Port bit) will always return the logic state present at the pin itself, regardless of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC, CLR, SETB, and the bitwise MOV write operation). During the read cycle of the read-modify-write instruction, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read. Because the Crossbar registers affect the pinout of the peripherals of the device, they are typically configured in the initialization code of the system before the peripherals themselves are configured. Once configured, the Crossbar registers are typically left alone. Once the Crossbar registers have been properly configured, the Crossbar is enabled by setting XBARE (XBR2.4) to a logic 1. Until XBARE is set to a logic 1, the output drivers on Ports 0 through 3 are explicitly disabled in order to prevent possible contention on the Port pins while the Crossbar registers and other registers which can affect the device pinout are being written. The output drivers on Crossbar-assigned input signals (like RX0, for example) are explicitly disabled; thus the values of the Port Data registers and the PnMDOUT registers have no effect on the states of these pins.
18.1.2. Configuring the Output Modes of the Port Pins
The output drivers on Ports 0 through 3 remain disabled until the Crossbar is enabled by setting XBARE (XBR2.4) to a logic 1. The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to GND, and writing a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will cause the Port pin to assume a high-impedance state. The Open-Drain configuration is useful to prevent contention between devices in systems where the Port pin participates in a shared interconnection in which multiple outputs are connected to the same physical wire (like the SDA signal on an SMBus connection). The output modes of the Port pins on Ports 0 through 3 are determined by the bits in the associated PnMDOUT registers (See Figure 18.11, Figure 18.14, Figure 18.16, and Figure 18.18). For example, a logic 1 in P3MDOUT.7 will configure the output mode of P3.7 to Push-Pull; a logic 0 in P3MDOUT.7 will configure the output mode of P3.7 to Open-Drain. All Port pins default to Open-Drain output. The PnMDOUT registers control the output modes of the port pins regardless of whether the Crossbar has allocated the Port pin for a digital peripheral or not. The exceptions to this rule are: the Port pins connected to SDA, SCL, RX0 (if UART0 is in Mode 0), and RX1 (if UART1 is in Mode 0) are always configured as Open-Drain outputs, regardless of the settings of the associated bits in the PnMDOUT registers.
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18.1.3. Configuring Port Pins as Digital Inputs
A Port pin is configured as a digital input by setting its output mode to "Open-Drain" and writing a logic 1 to the associated bit in the Port Data register. For example, P3.7 is configured as a digital input by setting P3MDOUT.7 to a logic 0 and P3.7 to a logic 1. If the Port pin has been assigned to a digital peripheral by the Crossbar and that pin functions as an input (for example RX0, the UART0 receive pin), then the output drivers on that pin are automatically disabled.
18.1.4. Weak Pull-ups
By default, each Port pin has an internal weak pull-up device enabled which provides a resistive connection (about 100 k) between the pin and VDD. The weak pull-up devices can be globally disabled by writing a logic 1 to the Weak Pull-up Disable bit, (WEAKPUD, XBR2.7). The weak pull-up is automatically deactivated on any pin that is driving a logic 0; that is, an output pin will not contend with its own pull-up device. The weak pull-up device can also be explicitly disabled on any Port 1 pin by configuring the pin as an Analog Input, as described below.
18.1.5. Configuring Port 1 Pins as Analog Inputs
The pins on Port 1 can serve as analog inputs to the ADC2 analog MUX. A Port pin is configured as an Analog Input by writing a logic 0 to the associated bit in the PnMDIN registers. All Port pins default to a Digital Input mode. Configuring a Port pin as an analog input: 1. Disables the digital input path from the pin. This prevents additional power supply current from being drawn when the voltage at the pin is near VDD / 2. A read of the Port Data bit will return a logic 0 regardless of the voltage at the Port pin. 2. Disables the weak pull-up device on the pin. 3. Causes the Crossbar to "skip over" the pin when allocating Port pins for digital peripherals. Note that the output drivers on a pin configured as an Analog Input are not explicitly disabled. Therefore, the associated P1MDOUT bits of pins configured as Analog Inputs should explicitly be set to logic 0 (Open-Drain output mode), and the associated Port1 Data bits should be set to logic 1 (high-impedance). Also note that it is not required to configure a Port pin as an Analog Input in order to use it as an input to ADC2, however, it is strongly recommended. See the ADC2 section in this datasheet for further information.
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18.1.6. External Memory Interface Pin Assignments
If the External Memory Interface (EMIF) is enabled on the Low ports (Ports 0 through 3), EMIFLE (XBR2.5) should be set to a logic 1 so that the Crossbar will not assign peripherals to P0.7 (/WR), P0.6 (/RD), and if the External Memory Interface is in Multiplexed mode, P0.5 (ALE). Figure 18.4 shows an example Crossbar Decode Table with EMIFLE=1 and the EMIF in Multiplexed mode. Figure 18.5 shows an example Crossbar Decode Table with EMIFLE=1 and the EMIF in Non-multiplexed mode. If the External Memory Interface is enabled on the Low ports and an off-chip MOVX operation occurs, the External Memory Interface will control the output states of the affected Port pins during the execution phase of the MOVX instruction, regardless of the settings of the Crossbar registers or the Port Data registers. The output configuration of the Port pins is not affected by the EMIF operation, except that Read operations will explicitly disable the output drivers on the Data Bus. See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Figure 18.4. Priority Crossbar Decode Table EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xFF)
P0 PIN I/O 0 TX0 RX0 SCK MISO MOSI NSS SDA SCL TX1 RX1 CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI CP0 CP1 T0 /INT0 T1 /INT1 T2 T2EX T4 T4EX /SYSCLK CNVSTR0 CNVSTR2 1 2 3 4 5 6 7 0 1 2 3 P1 4 5 6 7 0 1 2 3 P2 4 5 6 7 0 1 2 3 P3 4 5 6 7 UART0EN: XBR0.2 Crossbar Register Bits
G G G G G G G G G G G G G G NSS is not assigned to a port pin when the SPI is placed in 3-wire mode G GG GGG GGGG GGGGG GGGGGG GGGGGGG GGGGGGGG GGGGGGGGG G G GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGGGGGG GGGGGGGGG G GGG GG GGG GG GGG GG G G G
SPI0EN: XBR0.1
SMB0EN: XBR0.0
UART1EN: XBR2.2
PCA0ME: XBR0.[5:3]
GGGGGGGGGGGG GGGGGGGGGGGGG GGGGGGGGGGGGGG GGGGGGGGGGGGGGG GGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGG
AIN1.2/A10 AIN1.3/A11 AIN1.4/A12 AIN1.5/A13 AIN1.6/A14 AIN1.7/A15 AIN1.0/A8 AIN1.1/A9 A10m/A2 A11m/A3 A12m/A4 A13m/A5 A14m/A6 A15m/A7 A8m/A0 A9m/A1 AD0/D0 AD1/D1 AD2/D2 AD3/D3 AD4/D4 AD5/D5 AD6/D6 AD7/D7
ECI0E: XBR0.6 CP0E: XBR0.7 CP1E: XBR1.0 T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 INT1E: XBR1.4 T2E: XBR1.5 T2EXE: XBR1.6 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR2.5
/WR
ALE
/RD
AIN1 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L
Muxed Data/Non-muxed Data
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Figure 18.5. Priority Crossbar Decode Table
P0 PIN I/O 0 TX0 RX0 SCK MISO MOSI NSS SDA SCL TX1 RX1 CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI CP0 CP1 T0 /INT0 T1 /INT1 T2 T2EX T4 T4EX /SYSCLK CNVSTR0 1 2 3 4 5 6 7 0 1 2 3
P1 4 5 6 7 0 1 2 3
P2 4 5 6 7 0 1 2 3
P3 4 5 6 7
Crossbar Register Bits
G G G G G G G G G G G G G G G G G GG GGG GGGG GGGGG GGGGGG GGGGGGG GGGGGGGG GGGGGGGGG G GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGG GGGGGGGGG GGGGGGGGGGG GGGGGGGGGGGG GGGGGGGGGGGGG GGGGGGGGGGGGGG GGGGGGGGGGGGGGG GGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGG
AIN1.2/A10 AIN1.3/A11 AIN1.4/A12 AIN1.5/A13 AIN1.6/A14 AIN1.7/A15 AIN1.0/A8 AIN1.1/A9 A10m/A2 A11m/A3 A12m/A4 A13m/A5 A14m/A6 A15m/A7 A8m/A0 A9m/A1 AD0/D0 AD1/D1 AD2/D2 AD3/D3 AD4/D4 AD5/D5 AD6/D6 AD7/D7
UART0EN: XBR0.2
SPI0EN: XBR0.1
NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
SMB0EN: XBR0.0
GGGG GGG GGGG GGG GGGG GGG G GG G G G
UART1EN: XBR2.2
PCA0ME: XBR0.[5:3]
ECI0E: XBR0.6 CP0E: XBR0.7 CP1E: XBR1.0 T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 INT1E: XBR1.4 T2E: XBR1.5 T2EXE: XBR1.6 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR2.5
GGGGGG CNVSTR2 G G G G G G
/WR
ALE
/RD
AIN1 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L
Muxed Data/Non-muxed Data
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18.1.7. Crossbar Pin Assignment Example
In this example (Figure 18.6), we configure the Crossbar to allocate Port pins for UART0, the SMBus, UART1, / INT0, and /INT1 (8 pins total). Additionally, we configure the External Memory Interface to operate in Multiplexed mode and to appear on the Low ports. Further, we configure P1.2, P1.3, and P1.4 for Analog Input mode so that the voltages at these pins can be measured by ADC2. The configuration steps are as follows: 1. XBR0, XBR1, and XBR2 are set such that UART0EN = 1, SMB0EN = 1, INT0E = 1, INT1E = 1, and EMIFLE = 1. Thus: XBR0 = 0x05, XBR1 = 0x14, and XBR2 = 0x02. 2. We configure the External Memory Interface to use Multiplexed mode and to appear on the Low ports. PRTSEL = 0, EMD2 = 0. 3. We configure the desired Port 1 pins to Analog Input mode by setting P1MDIN to 0xE3 (P1.4, P1.3, and P1.2 are Analog Inputs, so their associated P1MDIN bits are set to logic 0). 4. We enable the Crossbar by setting XBARE = 1: XBR2 = 0x42. - UART0 has the highest priority, so P0.0 is assigned to TX0, and P0.1 is assigned to RX0. - The SMBus is next in priority order, so P0.2 is assigned to SDA, and P0.3 is assigned to SCL. - UART1 is next in priority order, so P0.4 is assigned to TX1. Because the External Memory Interface is selected on the lower Ports, EMIFLE = 1, which causes the Crossbar to skip P0.6 (/RD) and P0.7 (/WR). Because the External Memory Interface is configured in Multiplexed mode, the Crossbar will also skip P0.5 (ALE). RX1 is assigned to the next non-skipped pin, which in this case is P1.0. - /INT0 is next in priority order, so it is assigned to P1.1. - P1MDIN is set to 0xE3, which configures P1.2, P1.3, and P1.4 as Analog Inputs, causing the Crossbar to skip these pins. - /INT1 is next in priority order, so it is assigned to the next non-skipped pin, which is P1.5. - The External Memory Interface will drive Ports 2 and 3 (denoted by red dots in Figure 18.6) during the execution of an off-chip MOVX instruction. 5. We set the UART0 TX pin (TX0, P0.0) and UART1 TX pin (TX1, P0.4) outputs to Push-Pull by setting P0MDOUT = 0x11. 6. We configure all EMIF-controlled pins to push-pull output mode by setting P0MDOUT |= 0xE0; P2MDOUT = 0xFF; P3MDOUT = 0xFF. 7. We explicitly disable the output drivers on the 3 Analog Input pins by setting P1MDOUT = 0x00 (configure outputs to Open-Drain) and P1 = 0xFF (a logic 1 selects the high-impedance state).
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Figure 18.6. Crossbar Example: (EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xE3;
P0 PIN I/O 0 TX0 RX0 SCK MISO MOSI NSS SDA SCL TX1 RX1 CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI CP0 CP1 T0 /INT0 T1 /INT1 T2 T2EX T4 T4EX /SYSCLK CNVSTR0 CNVSTR2 1 2 3 4 5 6 7 0 1 2 3 P1 4 5 6 7 0 1 2 3 P2 4 5 6 7 0 1 2 3 P3 4 5 6 7 UART0EN: XBR0.2 Crossbar Register Bits
G G G G G G G G G G G G G G GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGGGG GGG G GG GGG GG GGG GG G G G G G GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG GG
AIN1.2/A10 AIN1.3/A11 AIN1.4/A12 AIN1.0/A8 AIN1.1/A9
SPI0EN: XBR0.1
G GG GGG GGGG GGGGG GGGGGG GGGGGGG GGGGGGGG GGGGGGGGG GGGGGGGGGG GGGGGGGGGGG GGGGGGGGGGGG GGGGGGGGGGGGG GGGGGGGGGGGGGG GGGGGGGGGGGGGGG GGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGG
AIN1.5/A13 AIN1.6/A14 AIN1.7/A15 A10m/A2 A11m/A3 A12m/A4 A13m/A5 A14m/A6 A15m/A7 A8m/A0 A9m/A1 AD0/D0 AD1/D1 AD2/D2 AD3/D3 AD4/D4 AD5/D5 AD6/D6 AD7/D7
SMB0EN: XBR0.0
UART1EN: XBR2.2
PCA0ME: XBR0.[5:3]
ECI0E: XBR0.6 CP0E: XBR0.7 CP1E: XBR1.0 T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 INT1E: XBR1.4 T2E: XBR1.5 T2EXE: XBR1.6 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR2.5
ALE
/WR
/RD
AIN1 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L
Muxed Data/Non-muxed Data
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Figure 18.7. XBR0: Port I/O Crossbar Register 0
R/W R/W R/W Bit5 R/W R/W Bit3 R/W R/W R/W Reset Value
CP0E
Bit7
ECI0E
Bit6
PCA0ME
Bit4
UART0EN
Bit2
SPI0EN
Bit1
SMB0EN
Bit0
00000000
SFR Address: 0xE1 SFR Page: F
Bit7:
Bit6:
Bits5-3:
Bit2:
Bit1:
Bit0:
CP0E: Comparator 0 Output Enable Bit. 0: CP0 unavailable at Port pin. 1: CP0 routed to Port pin. ECI0E: PCA0 External Counter Input Enable Bit. 0: PCA0 External Counter Input unavailable at Port pin. 1: PCA0 External Counter Input (ECI0) routed to Port pin. PCA0ME: PCA0 Module I/O Enable Bits. 000: All PCA0 I/O unavailable at port pins. 001: CEX0 routed to port pin. 010: CEX0, CEX1 routed to 2 port pins. 011: CEX0, CEX1, and CEX2 routed to 3 port pins. 100: CEX0, CEX1, CEX2, and CEX3 routed to 4 port pins. 101: CEX0, CEX1, CEX2, CEX3, and CEX4 routed to 5 port pins. 110: CEX0, CEX1, CEX2, CEX3, CEX4, and CEX5 routed to 6 port pins. UART0EN: UART0 I/O Enable Bit. 0: UART0 I/O unavailable at Port pins. 1: UART0 TX routed to P0.0, and RX routed to P0.1. SPI0EN: SPI0 Bus I/O Enable Bit. 0: SPI0 I/O unavailable at Port pins. 1: SPI0 SCK, MISO, MOSI, and NSS routed to 4 Port pins. Note that the NSS signal is not assigned to a port pin if the SPI is in 3-wire mode. See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information. SMB0EN: SMBus0 Bus I/O Enable Bit. 0: SMBus0 I/O unavailable at Port pins. 1: SMBus0 SDA and SCL routed to 2 Port pins.
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Figure 18.8. XBR1: Port I/O Crossbar Register 1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SYSCKE
Bit7
T2EXE
Bit6
T2E
Bit5
INT1E
Bit4
T1E
Bit3
INT0E
Bit2
T0E
Bit1
CP1E
Bit0
00000000
SFR Address: 0xE2 SFR Page: F
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
SYSCKE: /SYSCLK Output Enable Bit. 0: /SYSCLK unavailable at Port pin. 1: /SYSCLK (divided by 1, 2, 4, or 8) routed to Port pin. divide factor is determined by the CLKDIV1-0 bits in register CLKSEL (See Section "14. OSCILLATORS" on page 161). T2EXE: T2EX Input Enable Bit. 0: T2EX unavailable at Port pin. 1: T2EX routed to Port pin. T2E: T2 Input Enable Bit. 0: T2 unavailable at Port pin. 1: T2 routed to Port pin. INT1E: /INT1 Input Enable Bit. 0: /INT1 unavailable at Port pin. 1: /INT1 routed to Port pin. T1E: T1 Input Enable Bit. 0: T1 unavailable at Port pin. 1: T1 routed to Port pin. INT0E: /INT0 Input Enable Bit. 0: /INT0 unavailable at Port pin. 1: /INT0 routed to Port pin. T0E: T0 Input Enable Bit. 0: T0 unavailable at Port pin. 1: T0 routed to Port pin. CP1E: CP1 Output Enable Bit. 0: CP1 unavailable at Port pin. 1: CP1 routed to Port pin.
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Figure 18.9. XBR2: Port I/O Crossbar Register 2
R/W Bit7 R/W Bit6 R/W Bit5 R/W R/W R/W R/W R/W Bit0 SFR Address: 0xE3 SFR Page: F Reset Value
WEAKPUD XBARE CNVST2E
T4EXE
Bit4
T4E
Bit3
UART1E
Bit2
EMIFLE
Bit1
CNVST0E 00000000
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
WEAKPUD: Weak Pull-Up Disable Bit. 0: Weak pull-ups globally enabled. 1: Weak pull-ups globally disabled. XBARE: Crossbar Enable Bit. 0: Crossbar disabled. All pins on Ports 0, 1, 2, and 3, are forced to Input mode. 1: Crossbar enabled. CNVST2E: External Convert Start 2 Input Enable Bit. 0: CNVSTR2 unavailable at Port pin. 1: CNVSTR2 routed to Port pin. T4EXE: T4EX Input Enable Bit. 0: T4EX unavailable at Port pin. 1: T4EX routed to Port pin. T4E: T4 Input Enable Bit. 0: T4 unavailable at Port pin. 1: T4 routed to Port pin. UART1E: UART1 I/O Enable Bit. 0: UART1 I/O unavailable at Port pins. 1: UART1 TX and RX routed to 2 Port pins. EMIFLE: External Memory Interface Low-Port Enable Bit. 0: P0.7, P0.6, and P0.5 functions are determined by the Crossbar or the Port latches. 1: If EMI0CF.4 = `0' (External Memory Interface is in Multiplexed mode) P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) are `skipped' by the Crossbar and their output states are determined by the Port latches and the External Memory Interface. 1: If EMI0CF.4 = `1' (External Memory Interface is in Non-multiplexed mode) P0.7 (/WR) and P0.6 (/RD) are `skipped' by the Crossbar and their output states are determined by the Port latches and the External Memory Interface. CNVST0E: ADC0 External Convert Start Input Enable Bit.
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Figure 18.10. P0: Port0 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P0.7
Bit7
P0.6
Bit6
P0.5
Bit5
P0.4
Bit4
P0.3
Bit3
P0.2
Bit2
P0.1
Bit1
P0.0
Bit0
11111111
Bit Addressable
SFR Address: 0x80 SFR Page: All Pages
Bits7-0:
P0.[7:0]: Port0 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P0MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, and XBR2 Register settings). 0: P0.n pin is logic low. 1: P0.n pin is logic high. Note: P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) can be driven by the External Data Memory Interface. See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information. See also Figure 18.9 for information about configuring the Crossbar for External Memory accesses.
Figure 18.11. P0MDOUT: Port0 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xA4 SFR Page: F Reset Value
00000000
Bits7-0:
P0MDOUT.[7:0]: Port0 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins.
Note:
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Figure 18.12. P1: Port1 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P1.7
Bit7
P1.6
Bit6
P1.5
Bit5
P1.4
Bit4
P1.3
Bit3
P1.2
Bit2
P1.1
Bit1
P1.0
Bit0
11111111
Bit Addressable
SFR Address: 0x90 SFR Page: All Pages
Bits7-0:
P1.[7:0]: Port1 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P1MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, and XBR2 Register settings). 0: P1.n pin is logic low. 1: P1.n pin is logic high.
Notes: 1.
2.
P1.[7:0] can be configured as inputs to ADC1 as AIN1.[7:0], in which case they are `skipped' by the Crossbar assignment process and their digital input paths are disabled, depending on P1MDIN (See Figure 18.13). Note that in analog mode, the output mode of the pin is determined by the Port 1 latch and P1MDOUT (Figure 18.14). See Section "7. ADC2 (8-Bit ADC)" on page 83 for more information about ADC2. P1.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-multiplexed mode). See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Figure 18.13. P1MDIN: Port1 Input Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xAD SFR Page: F Reset Value
11111111
Bits7-0:
P1MDIN.[7:0]: Port 1 Input Mode Bits. 0: Port Pin is configured in Analog Input mode. The digital input path is disabled (a read from the Port bit will always return `0'). The weak pull-up on the pin is disabled. 1: Port Pin is configured in Digital Input mode. A read from the Port bit will return the logic level at the Pin. When configured as a digital input, the state of the weak pull-up for the port pin is determined by the WEAKPUD bit (XBR2.7, see Figure 18.9).
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Figure 18.14. P1MDOUT: Port1 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xA5 SFR Page: F Reset Value
00000000
Bits7-0:
P1MDOUT.[7:0]: Port1 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins.
Note:
Figure 18.15. P2: Port2 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P2.7
Bit7
P2.6
Bit6
P2.5
Bit5
P2.4
Bit4
P2.3
Bit3
P2.2
Bit2
P2.1
Bit1
P2.0
Bit0
11111111
Bit Addressable
SFR Address: 0xA0 SFR Page: All Pages
Bits7-0:
P2.[7:0]: Port2 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P2MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, and XBR2 Register settings). 0: P2.n pin is logic low. 1: P2.n pin is logic high. P2.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Multiplexed mode, or as Address[7:0] in Non-multiplexed mode). See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Note:
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Figure 18.16. P2MDOUT: Port2 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xA6 SFR Page: F Reset Value
00000000
Bits7-0:
P2MDOUT.[7:0]: Port2 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins.
Note:
Figure 18.17. P3: Port3 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P3.7
Bit7
P3.6
Bit6
P3.5
Bit5
P3.4
Bit4
P3.3
Bit3
P3.2
Bit2
P3.1
Bit1
P3.0
Bit0
11111111
Bit Addressable
SFR Address: 0xB0 SFR Page: All Pages
Bits7-0:
P3.[7:0]: Port3 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P3MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, and XBR2 Register settings). 0: P3.n pin is logic low. 1: P3.n pin is logic high. P3.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed mode, or as D[7:0] in Non-multiplexed mode). See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Note:
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Figure 18.18. P3MDOUT: Port3 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xA7 SFR Page: F Reset Value
00000000
Bits7-0:
P2MDOUT.[7:0]: Port3 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull.
18.2.
Ports 4 through 7 (C8051F120/2/4/6 only)
All Port pins on Ports 4 through 7 can be accessed as General-Purpose I/O (GPIO) pins by reading and writing the associated Port Data registers (See Figure 18.19, Figure 18.21, Figure 18.23, and Figure 18.25), a set of SFR's which are both bit and byte-addressable. A Read of a Port Data register (or Port bit) will always return the logic state present at the pin itself, regardless of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC, CLR, SET, and the bitwise MOV operation). During the read cycle of the read-modify-write instruction, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read.
18.2.1. Configuring Ports which are not Pinned Out
Although P4, P5, P6, and P7 are not brought out to pins on the C8051F121/3/5/7 devices, the Port Data registers are still present and can be used by software. Because the digital input paths also remain active, it is recommended that these pins not be left in a `floating' state in order to avoid unnecessary power dissipation arising from the inputs floating to non-valid logic levels. This condition can be prevented by any of the following: 1. Leave the weak pull-up devices enabled by setting WEAKPUD (XBR2.7) to a logic 0. 2. Configure the output modes of P4, P5, P6, and P7 to "Push-Pull" by writing PnOUT = 0xFF. 3. Force the output states of P4, P5, P6, and P7 to logic 0 by writing zeros to the Port Data registers: P4 = 0x00, P5 = 0x00, P6= 0x00, and P7 = 0x00.
18.2.2. Configuring the Output Modes of the Port Pins
The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull configuration, a logic 0 in the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configuration, a logic 0 in the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will cause the Port pin to assume a highimpedance state. The Open-Drain configuration is useful to prevent contention between devices in systems where the Port pin participates in a shared interconnection in which multiple outputs are connected to the same physical wire. The output modes of the Port pins on Ports 4 through 7 are determined by the bits in their respective PnMDOUT Output Mode Registers. Each bit in PnMDOUT controls the output mode of its corresponding port pin (see Figure 18.20, Figure 18.22, Figure 18.24, and Figure 18.26). For example, to place Port pin 4.3 in push-pull mode (digital output), set P4MDOUT.3 to logic 1. All port pins default to open-drain mode upon device reset.
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18.2.3. Configuring Port Pins as Digital Inputs
A Port pin is configured as a digital input by setting its output mode to "Open-Drain" and writing a logic 1 to the associated bit in the Port Data register. For example, P7.7 is configured as a digital input by setting P7MDOUT.7 to a logic 0 and P7.7 to a logic 1.
18.2.4. Weak Pull-ups
By default, each Port pin has an internal weak pull-up device enabled which provides a resistive connection (about 100 k) between the pin and VDD. The weak pull-up devices can be globally disabled by writing a logic 1 to the Weak Pull-up Disable bit, (WEAKPUD, XBR2.7). The weak pull-up is automatically deactivated on any pin that is driving a logic 0; that is, an output pin will not contend with its own pull-up device.
18.2.5. External Memory Interface
If the External Memory Interface (EMIF) is enabled on the High ports (Ports 4 through 7), EMIFLE (XBR2.5) should be set to a logic 0. If the External Memory Interface is enabled on the High ports and an off-chip MOVX operation occurs, the External Memory Interface will control the output states of the affected Port pins during the execution phase of the MOVX instruction, regardless of the settings of the Port Data registers. The output configuration of the Port pins is not affected by the EMIF operation, except that Read operations will explicitly disable the output drivers on the Data Bus during the MOVX execution. See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
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Figure 18.19. P4: Port4 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P4.7
Bit7
P4.6
Bit6
P4.5
Bit5
P4.4
Bit4
P4.3
Bit3
P4.2
Bit2
P4.1
Bit1
P4.0
Bit0
11111111
Bit Addressable
SFR Address: 0xC8 SFR Page: F
Bits7-0:
P4.[7:0]: Port4 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P4MDOUT.n bit = 0). See Figure 18.20. Read - Returns states of I/O pins. 0: P4.n pin is logic low. 1: P4.n pin is logic high. Note: P4.7 (/WR), P4.6 (/RD), and P4.5 (ALE) can be driven by the External Data Memory Interface. See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information.
Figure 18.20. P4MDOUT: Port4 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x9C SFR Page: F Reset Value
00000000
Bits7-0:
P4MDOUT.[7:0]: Port4 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull.
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Figure 18.21. P5: Port5 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P5.7
Bit7
P5.6
Bit6
P5.5
Bit5
P5.4
Bit4
P5.3
Bit3
P5.2
Bit2
P5.1
Bit1
P5.0
Bit0
11111111
Bit Addressable
SFR Address: 0xD8 SFR Page: F
Bits7-0:
P5.[7:0]: Port5 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P5MDOUT bit = 0). See Figure 18.22. Read - Returns states of I/O pins. 0: P5.n pin is logic low. 1: P5.n pin is logic high. P5.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-multiplexed mode). See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Note:
Figure 18.22. P5MDOUT: Port5 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x9D SFR Page: F Reset Value
00000000
Bits7-0:
P5MDOUT.[7:0]: Port5 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull.
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Figure 18.23. P6: Port6 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P6.7
Bit7
P6.6
Bit6
P6.5
Bit5
P6.4
Bit4
P6.3
Bit3
P6.2
Bit2
P6.1
Bit1
P6.0
Bit0
11111111
Bit Addressable
SFR Address: 0xE8 SFR Page: F
Bits7-0:
P6.[7:0]: Port6 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P6MDOUT bit = 0). See Figure 18.24. Read - Returns states of I/O pins. 0: P6.n pin is logic low. 1: P6.n pin is logic high. P6.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Multiplexed mode, or as Address[7:0] in Non-multiplexed mode). See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Note:
Figure 18.24. P6MDOUT: Port6 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x9E SFR Page: F Reset Value
00000000
Bits7-0:
P6MDOUT.[7:0]: Port6 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull.
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Figure 18.25. P7: Port7 Data Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P7.7
Bit7
P7.6
Bit6
P7.5
Bit5
P7.4
Bit4
P7.3
Bit3
P7.2
Bit2
P7.1
Bit1
P7.0
Bit0
11111111
Bit Addressable
SFR Address: 0xF8 SFR Page: F
Bits7-0:
P7.[7:0]: Port7 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P7MDOUT bit = 0). See Figure 18.26. Read - Returns states of I/O pins. 0: P7.n pin is logic low. 1: P7.n pin is logic high. P7.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed mode, or as D[7:0] in Non-multiplexed mode). See Section "17. EXTERNAL DATA MEMORY INTERFACE AND ON-CHIP XRAM" on page 187 for more information about the External Memory Interface.
Note:
Figure 18.26. P7MDOUT: Port7 Output Mode Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x9F SFR Page: F Reset Value
00000000
Bits7-0:
P7MDOUT.[7:0]: Port7 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins.
Note:
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19.
SYSTEM MANAGEMENT BUS / I2C BUS (SMBUS0)
The SMBus0 I/O interface is a two-wire, bi-directional serial bus. SMBus0 is compliant with the System Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to the interface by the system controller are byte oriented with the SMBus0 interface autonomously controlling the serial transfer of the data. A method of extending the clock-low duration is available to accommodate devices with different speed capabilities on the same bus. SMBus0 may operate as a master and/or slave, and may function on a bus with multiple masters. SMBus0 provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic, and START/STOP control and generation. Three SFR's are associated with SMBus0: SMB0CF configures SMBus0; SMB0CN controls SMBus0; and SMB0DAT is the data register, used for both transmitting and receiving.
Figure 19.1. SMBus0 Block Diagram
SFR Bus
SMB0CN
B U S Y ESSSAFT NTT IATO SAO EE M B S T A 7 S T A 6
SMB0STA
S T A 5 S T A 4 S T A 3 S T A 2 S T A 1 S T A 0
SMB0CR
CCCCCCCC RRRRRRRR 76543210
Clock Divide Logic
SYSCLK
FILTER
SCL
SMBUS CONTROL LOGIC
SMBUS IRQ
Interrupt Request Arbitration SCL Synchronization Status Generation SCL Generation (Master Mode) IRQ Generation Data Path Control
SCL Control SDA Control
N
B
A
B
A
C R O S S B A R
Port I/O
A=B
A=B 0000000b 7 MSBs 8
7
SMB0DAT 76543210
8 S L V 6 S L V 5 S L V 4 S L V 3 S L V 2 S L V 1 S L VG 0C Read SMB0DAT Write to SMB0DAT 8 1
FILTER
SDA
N 0
SMB0ADR
SFR Bus
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Figure 19.2 shows a typical SMBus configuration. The SMBus0 interface will work at any voltage between 3.0 V and 5.0 V and different devices on the bus may operate at different voltage levels. The bi-directional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage through a pull-up resistor or similar circuit. Every device connected to the bus must have an open-drain or open-collector output for both the SCL and SDA lines, so that both are pulled high when the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise and fall times on the bus will not exceed 300 ns and 1000 ns, respectively.
Figure 19.2. Typical SMBus Configuration
VDD = 5V VDD = 3V VDD = 5V VDD = 3V
Master Device
Slave Device 1
Slave Device 2
SDA SCL
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19.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents: 1. 2. 3. The I2C-bus and how to use it (including specifications), Philips Semiconductor. The I2C-Bus Specification -- Version 2.0, Philips Semiconductor. System Management Bus Specification -- Version 1.1, SBS Implementers Forum.
19.2.
SMBus Protocol
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ). The master device initiates both types of data transfers and provides the serial clock pulses on SCL. Note: multiple master devices on the same bus are supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme is employed with a single master always winning the arbitration. Note that it is not necessary to specify one device as the master in a system; any device who transmits a START and a slave address becomes the master for that transfer. A typical SMBus transaction consists of a START condition followed by an address byte (Bits7-1: 7-bit slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see Figure 19.3). If the receiving device does not ACK, the transmitting device will read a "not acknowledge" (NACK), which is a high SDA during a high SCL. The direction bit (R/W) occupies the least-significant bit position of the address. The direction bit is set to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation. All transactions are initiated by a master, with one or more addressed slave devices as the target. The master generates the START condition and then transmits the slave address and direction bit. If the transaction is a WRITE operation from the master to the slave, the master transmits the data a byte at a time waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master generates a STOP condition to terminate the transaction and free the bus. Figure 19.3 illustrates a typical SMBus transaction.
Figure 19.3. SMBus Transaction
SCL
SDA SLA6 SLA5-0 R/W D7 D6-0
START
Slave Address + R/W
ACK
Data Byte
NACK
STOP
19.2.1. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL and SDA lines remain high for a specified time (see Section 19.2.4). In the event that two or more devices attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-
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drain, the bus will be pulled LOW. The master attempting the HIGH will detect a LOW SDA and give up the bus. The winning master continues its transmission without interruption; the losing master becomes a slave and receives the rest of the transfer. This arbitration scheme is non-destructive: one device always wins, and no data is lost.
19.2.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line LOW to extend the clock low period, effectively decreasing the serial clock frequency.
19.2.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore, the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than 25 ms as a "timeout" condition. Devices that have detected the timeout condition must reset the communication no later than 10 ms after detecting the timeout condition.
19.2.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 s, the bus is designated as free. If an SMBus device is waiting to generate a Master START, the START will be generated following the bus free timeout.
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19.3.
SMBus Transfer Modes
The SMBus0 interface may be configured to operate as a master and/or a slave. At any particular time, the interface will be operating in one of the following modes: Master Transmitter, Master Receiver, Slave Transmitter, or Slave Receiver. See Table 19.1 for transfer mode status decoding using the SMB0STA status register. The following mode descriptions illustrate an interrupt-driven SMBus0 application; SMBus0 may alternatively be operated in polled mode.
19.3.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. SMBus0 generates a START condition and then transmits the first byte containing the address of the target slave device and the data direction bit. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The SMBus0 interface transmits one or more bytes of serial data, waiting for an acknowledge (ACK) from the slave after each byte. To indicate the end of the serial transfer, SMBus0 generates a STOP condition.
Figure 19.4. Typical Master Transmitter Sequence
S SLA W A Data Byte A Data Byte A P
Interrupt
Interrupt
Interrupt
Interrupt
Received by SMBus Interface Transmitted by SMBus Interface
S = START P = STOP A = ACK W = WRITE SLA = Slave Address
19.3.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. The SMBus0 interface generates a START followed by the first data byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 to indicate a "READ" operation. The SMBus0 interface receives serial data from the slave and generates the clock on SCL. After each byte is received, SMBus0 generates an ACK or NACK depending on the state of the AA bit in register SMB0CN. SMBus0 generates a STOP condition to indicate the end of the serial transfer.
Figure 19.5. Typical Master Receiver Sequence
S SLA R A Data Byte A Data Byte N P
Interrupt
Interrupt
Interrupt
Interrupt
Received by SMBus Interface Transmitted by SMBus Interface
S = START P = STOP A = ACK N = NACK R = READ SLA = Slave Address
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19.3.3. Slave Transmitter Mode
Preliminary
Serial data is transmitted on SDA while the serial clock is received on SCL. The SMBus0 interface receives a START followed by data byte containing the slave address and direction bit. If the received slave address matches the address held in register SMB0ADR, the SMBus0 interface generates an ACK. SMBus0 will also ACK if the general call address (0x00) is received and the General Call Address Enable bit (SMB0ADR.0) is set to logic 1. In this case the data direction bit (R/W) will be logic 1 to indicate a "READ" operation. The SMBus0 interface receives the clock on SCL and transmits one or more bytes of serial data, waiting for an ACK from the master after each byte. SMBus0 exits slave mode after receiving a STOP condition from the master.
Figure 19.6. Typical Slave Transmitter Sequence
Interrupt
S
SLA
W
A
Data Byte
A
Data Byte
N
P
Interrupt Received by SMBus Interface Transmitted by SMBus Interface
Interrupt
Interrupt
S = START P = STOP N = NACK W = WRITE SLA = Slave Address
19.3.4. Slave Receiver Mode
Serial data is received on SDA while the serial clock is received on SCL. The SMBus0 interface receives a START followed by data byte containing the slave address and direction bit. If the received slave address matches the address held in register SMB0ADR, the interface generates an ACK. SMBus0 will also ACK if the general call address (0x00) is received and the General Call Address Enable bit (SMB0ADR.0) is set to logic 1. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The SMBus0 interface receives one or more bytes of serial data; after each byte is received, the interface transmits an ACK or NACK depending on the state of the AA bit in SMB0CN. SMBus0 exits Slave Receiver Mode after receiving a STOP condition from the master.
Figure 19.7. Typical Slave Receiver Sequence
Interrupt
S
SLA
R
A
Data Byte
A
Data Byte
A
P
Interrupt Received by SMBus Interface Transmitted by SMBus Interface
Interrupt
Interrupt
S = START P = STOP A = ACK R = READ SLA = Slave Address
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19.4.
SMBus Special Function Registers
The SMBus0 serial interface is accessed and controlled through five SFR's: SMB0CN Control Register, SMB0CR Clock Rate Register, SMB0ADR Address Register, SMB0DAT Data Register and SMB0STA Status Register. The five special function registers related to the operation of the SMBus0 interface are described in the following sections.
19.4.1. Control Register
The SMBus0 Control register SMB0CN is used to configure and control the SMBus0 interface. All of the bits in the register can be read or written by software. Two of the control bits are also affected by the SMBus0 hardware. The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by the hardware when a valid serial interrupt condition occurs. It can only be cleared by software. The Stop flag (STO, SMB0CN.4) is set to logic 1 by software. It is cleared to logic 0 by hardware when a STOP condition is detected on the bus. Setting the ENSMB flag to logic 1 enables the SMBus0 interface. Clearing the ENSMB flag to logic 0 disables the SMBus0 interface and removes it from the bus. Momentarily clearing the ENSMB flag and then resetting it to logic 1 will reset SMBus0 communication. However, ENSMB should not be used to temporarily remove a device from the bus since the bus state information will be lost. Instead, the Assert Acknowledge (AA) flag should be used to temporarily remove the device from the bus (see description of AA flag below). Setting the Start flag (STA, SMB0CN.5) to logic 1 will put SMBus0 in a master mode. If the bus is free, SMBus0 will generate a START condition. If the bus is not free, SMBus0 waits for a STOP condition to free the bus and then generates a START condition after a 5 s delay per the SMB0CR value (In accordance with the SMBus protocol, the SMBus0 interface also considers the bus free if the bus is idle for 50 s and no STOP condition was recognized). If STA is set to logic 1 while SMBus0 is in master mode and one or more bytes have been transferred, a repeated START condition will be generated. When the Stop flag (STO, SMB0CN.4) is set to logic 1 while the SMBus0 interface is in master mode, the interface generates a STOP condition. In a slave mode, the STO flag may be used to recover from an error condition. In this case, a STOP condition is not generated on the bus, but the SMBus hardware behaves as if a STOP condition has been received and enters the "not addressed" slave receiver mode. Note that this simulated STOP will not cause the bus to appear free to SMBus0. The bus will remain occupied until a STOP appears on the bus or a Bus Free Timeout occurs. Hardware automatically clears the STO flag to logic 0 when a STOP condition is detected on the bus. The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by hardware when the SMBus0 interface enters one of 27 possible states. If interrupts are enabled for the SMBus0 interface, an interrupt request is generated when the SI flag is set. The SI flag must be cleared by software. Important Note: If SI is set to logic 1 while the SCL line is low, the clock-low period of the serial clock will be stretched and the serial transfer is suspended until SI is cleared to logic 0. A high level on SCL is not affected by the setting of the SI flag. The Assert Acknowledge flag (AA, SMB0CN.2) is used to set the level of the SDA line during the acknowledge clock cycle on the SCL line. Setting the AA flag to logic 1 will cause an ACK (low level on SDA) to be sent during the acknowledge cycle if the device has been addressed. Setting the AA flag to logic 0 will cause a NACK (high level on SDA) to be sent during acknowledge cycle. After the transmission of a byte in slave mode, the slave can be temporarily removed from the bus by clearing the AA flag. The slave's own address and general call address will be ignored. To resume operation on the bus, the AA flag must be reset to logic 1 to allow the slave's address to be recognized. Setting the SMBus0 Free Timer Enable bit (FTE, SMB0CN.1) to logic 1 enables the timer in SMB0CR. When SCL goes high, the timer in SMB0CR counts up. A timer overflow indicates a free bus timeout: if SMBus0 is waiting to
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generate a START, it will do so after this timeout. The bus free period should be less than 50 s (see Figure 19.9, SMBus0 Clock Rate Register). When the TOE bit in SMB0CN is set to logic 1, Timer 4 is used to detect SCL low timeouts. If Timer 4 is enabled (see Section "23.2. Timer 2, Timer 3, and Timer 4" on page 283), Timer 4 is forced to reload when SCL is high, and forced to count when SCL is low. With Timer 4 enabled and configured to overflow after 25 ms (and TOE set), a Timer 4 overflow indicates a SCL low timeout; the Timer 4 interrupt service routine can then be used to reset SMBus0 communication in the event of an SCL low timeout.
Figure 19.8. SMB0CN: SMBus0 Control Register
R R/W R/W R/W R/W R/W R/W R/W Reset Value
BUSY
Bit7
ENSMB
Bit6
STA
Bit5
STO
Bit4
SI
Bit3
AA
Bit2
FTE
Bit1
TOE
Bit0
00000000
Bit Addressable
SFR Address: 0xC0 SFR Page: 0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
BUSY: Busy Status Flag. 0: SMBus0 is free 1: SMBus0 is busy ENSMB: SMBus Enable. This bit enables/disables the SMBus serial interface. 0: SMBus0 disabled. 1: SMBus0 enabled. STA: SMBus Start Flag. 0: No START condition is transmitted. 1: When operating as a master, a START condition is transmitted if the bus is free. (If the bus is not free, the START is transmitted after a STOP is received.) If STA is set after one or more bytes have been transmitted or received and before a STOP is received, a repeated START condition is transmitted. STO: SMBus Stop Flag. 0: No STOP condition is transmitted. 1: Setting STO to logic 1 causes a STOP condition to be transmitted. When a STOP condition is received, hardware clears STO to logic 0. If both STA and STO are set, a STOP condition is transmitted followed by a START condition. In slave mode, setting the STO flag causes SMBus to behave as if a STOP condition was received. SI: SMBus Serial Interrupt Flag. This bit is set by hardware when one of 27 possible SMBus0 states is entered. (Status code 0xF8 does not cause SI to be set.) When the SI interrupt is enabled, setting this bit causes the CPU to vector to the SMBus interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. AA: SMBus Assert Acknowledge Flag. This bit defines the type of acknowledge returned during the acknowledge cycle on the SCL line. 0: A "not acknowledge" (high level on SDA) is returned during the acknowledge cycle. 1: An "acknowledge" (low level on SDA) is returned during the acknowledge cycle. FTE: SMBus Free Timer Enable Bit 0: No timeout when SCL is high 1: Timeout when SCL high time exceeds limit specified by the SMB0CR value. TOE: SMBus Timeout Enable Bit 0: No timeout when SCL is low. 1: Timeout when SCL low time exceeds limit specified by Timer 4, if enabled.
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19.4.2. Clock Rate Register
Figure 19.9. SMB0CR: SMBus0 Clock Rate Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xCF SFR Page: 0 Reset Value
00000000
Bits7-0:
SMB0CR.[7:0]: SMBus0 Clock Rate Preset The SMB0CR Clock Rate register controls the frequency of the serial clock SCL in master mode. The 8-bit word stored in the SMB0CR Register preloads a dedicated 8-bit timer. The timer counts up, and when it rolls over to 0x00, the SCL logic state toggles. The SMB0CR setting should be bounded by the following equation , where SMB0CR is the unsigned 8-bit value in register SMB0CR, and SYSCLK is the system clock frequency in Hz:
SYSCLK SMB0CR < 288 - 0.85 --------------------- 1.125 - 4
The resulting SCL signal high and low times are given by the following equations:
T LOW = 4 x ( 256 - SMB0CR ) SYSCLK
T HIGH 4 x ( 258 - SMB0CR ) SYSCLK + 625ns
Using the same value of SMB0CR from above, the Bus Free Timeout period is given in the following equation:
4 x ( 256 - SMB0CR ) + 1 T BFT 10 x ------------------------------------------------------------SYSCLK
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19.4.3. Data Register
Preliminary
The SMBus0 Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received. Software can read or write to this register while the SI flag is set to logic 1; software should not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag reads logic 0 since the hardware may be in the process of shifting a byte of data in or out of the register. Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously being shifted in. Therefore, SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data in SMB0DAT.
Figure 19.10. SMB0DAT: SMBus0 Data Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xC2 SFR Page: 0 Reset Value
00000000
Bits7-0:
SMB0DAT: SMBus0 Data. The SMB0DAT register contains a byte of data to be transmitted on the SMBus0 serial interface or a byte that has just been received on the SMBus0 serial interface. The CPU can read from or write to this register whenever the SI serial interrupt flag (SMB0CN.3) is set to logic 1. When the SI flag is not set, the system may be in the process of shifting data and the CPU should not attempt to access this register.
19.4.4. Address Register
The SMB0ADR Address register holds the slave address for the SMBus0 interface. In slave mode, the seven mostsignificant bits hold the 7-bit slave address. The least significant bit (Bit0) is used to enable the recognition of the general call address (0x00). If Bit0 is set to logic 1, the general call address will be recognized. Otherwise, the general call address is ignored. The contents of this register are ignored when SMBus0 is operating in master mode.
Figure 19.11. SMB0ADR: SMBus0 Address Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SLV6
Bit7
SLV5
Bit6
SLV4
Bit5
SLV3
Bit4
SLV2
Bit3
SLV1
Bit2
SLV0
Bit1
GC
Bit0
00000000
SFR Address: 0xC3 SFR Page: 0
Bits7-1:
SLV6-SLV0: SMBus0 Slave Address. These bits are loaded with the 7-bit slave address to which SMBus0 will respond when operating as a slave transmitter or slave receiver. SLV6 is the most significant bit of the address and corresponds to the first bit of the address byte received. GC: General Call Address Enable. This bit is used to enable general call address (0x00) recognition. 0: General call address is ignored. 1: General call address is recognized.
Bit0:
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19.4.5. Status Register
The SMB0STA Status register holds an 8-bit status code indicating the current state of the SMBus0 interface. There are 28 possible SMBus0 states, each with a corresponding unique status code. The five most significant bits of the status code vary while the three least-significant bits of a valid status code are fixed at zero when SI = `1'. Therefore, all possible status codes are multiples of eight. This facilitates the use of status codes in software as an index used to branch to appropriate service routines (allowing 8 bytes of code to service the state or jump to a more extensive service routine). For the purposes of user software, the contents of the SMB0STA register is only defined when the SI flag is logic 1. Software should never write to the SMB0STA register; doing so will yield indeterminate results. The 28 SMBus0 states, along with their corresponding status codes, are given in Table 1.1.
Figure 19.12. SMB0STA: SMBus0 Status Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
STA7
Bit7
STA6
Bit6
STA5
Bit5
STA4
Bit4
STA3
Bit3
STA2
Bit2
STA1
Bit1
STA0
Bit0
00000000
SFR Address: 0xC1 SFR Page: 0
Bits7-3:
STA7-STA3: SMBus0 Status Code. These bits contain the SMBus0 Status Code. There are 28 possible status codes; each status code corresponds to a single SMBus state. A valid status code is present in SMB0STA when the SI flag (SMB0CN.3) is set to logic 1. The content of SMB0STA is not defined when the SI flag is logic 0. Writing to the SMB0STA register at any time will yield indeterminate results. STA2-STA0: The three least significant bits of SMB0STA are always read as logic 0 when the SI flag is logic 1.
Bits2-0:
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Table 19.1. SMB0STA Status Codes and States Mode Status Code
0x08
SMBus State
START condition transmitted. Repeated START condition transmitted. Slave Address + W transmitted. ACK received. Slave Address + W transmitted. NACK received. Data byte transmitted. ACK received.
Typical Action
Load SMB0DAT with Slave Address + R/W. Clear STA. Load SMB0DAT with Slave Address + R/W. Clear STA. Load SMB0DAT with data to be transmitted. Acknowledge poll to retry. Set STO + STA. 1) Load SMB0DAT with next byte, OR 2) Set STO, OR 3) Clear STO then set STA for repeated START. 1) Retry transfer OR 2) Set STO. Save current data. If only receiving one byte, clear AA (send NACK after received byte). Wait for received data. Acknowledge poll to retry. Set STO + STA. Read SMB0DAT. Wait for next byte. If next byte is last byte, clear AA. Set STO.
MT/ MR Master Transmitter
0x10 0x18 0x20
0x28
0x30 0x38 0x40
Data byte transmitted. NACK received. Arbitration Lost. Slave Address + R transmitted. ACK received.
Master Receiver
0x48 0x50 0x58
Slave Address + R transmitted. NACK received. Data byte received. ACK transmitted. Data byte received. NACK transmitted.
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Table 19.1. SMB0STA Status Codes and States Mode Status Code
0x60 0x68
SMBus State
Own slave address + W received. ACK transmitted. Arbitration lost in sending SLA + R/W as master. Own address + W received. ACK transmitted. General call address received. ACK transmitted. Arbitration lost in sending SLA + R/W as master. General call address received. ACK transmitted. Data byte received. ACK transmitted. Data byte received. NACK transmitted. Data byte received after general call address. ACK transmitted. Data byte received after general call address. NACK transmitted. STOP or repeated START received. Own address + R received. ACK transmitted. Arbitration lost in transmitting SLA + R/W as master. Own address + R received. ACK transmitted. Data byte transmitted. ACK received. Data byte transmitted. NACK received. Last data byte transmitted (AA=0). ACK received. SCL Clock High Timer per SMB0CR timed out
Typical Action
Wait for data. Save current data for retry when bus is free. Wait for data. Wait for data. Save current data for retry when bus is free. Read SMB0DAT. Wait for next byte or STOP. Set STO to reset SMBus. Read SMB0DAT. Wait for next byte or STOP. Set STO to reset SMBus. No action necessary. Load SMB0DAT with data to transmit. Save current data for retry when bus is free. Load SMB0DAT with data to transmit. Load SMB0DAT with data to transmit. Wait for STOP. Set STO to reset SMBus.
0x70
Slave Receiver Slave Transmitter Slave
0x78
0x80 0x88 0x90 0x98 0xA0 0xA8 0xB0
0xB8 0xC0 0xC8
0xD0
Set STO to reset SMBus.
All
0x00 0xF8
Bus Error (illegal START or STOP) Idle
Set STO to reset SMBus. State does not set SI.
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20.
ENHANCED SERIAL PERIPHERAL INTERFACE (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports multiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional general purpose port I/O pins can be used to select multiple slave devices in master mode.
Figure 20.1. SPI Block Diagram
SFR Bus
SPI0CKR
SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0
SPI0CFG
SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT
SPI0CN
SPIF WCOL MODF RXOVRN NSSMD1 NSSMD0 TXBMT SPIEN
SYSCLK
Clock Divide Logic
SPI CONTROL LOGIC
Data Path Control Pin Interface Control
SPI IRQ
Tx Data
MOSI
SPI0DAT Transmit Data Buffer Pin Control Logic
SCK
Shift Register
76543210
Rx Data
MISO
C R O S S B A R
Port I/O
Receive Data Buffer
NSS
Write SPI0DAT
Read SPI0DAT
SFR Bus
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20.1. Signal Descriptions
Preliminary
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
20.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operating as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire mode.
20.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device. It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operating as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is always driven by the MSB of the shift register.
20.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 generates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is not selected (NSS = 1) in 4-wire slave mode.
20.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0 bits in the SPI0CN register. There are three possible modes that can be selected with these bits: 1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode. Since no select signal is present, SPI0 can be the only slave on the bus in 3-wire mode. This is intended for point-to-point communication between a master and one slave. 2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When operating as a master, a 1-to-0 transition of the NSS signal disables the master function of SPI0 so that multiple master devices can be used on the same SPI bus. 3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This configuration should only be used when operating SPI0 as a master device.
See Figure 20.2, Figure 20.3, and Figure 20.4 for typical connection diagrams of the various operational modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or 3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will be mapped to a pin on the device. See Section "18.1. Ports 0 through 3 and the Priority Crossbar Decoder" on page 205 for general purpose port I O and crossbar information.
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20.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic 1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by reading SPI0DAT. When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire singlemaster mode, and 4-wire single-master mode. The default, multi-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate and interrupt if enabled. SPI0 must be manually re-enabled in software under these circumstances. In multi-master systems, devices will typically default to being slave devices while they are not acting as the system master device. In multi-master mode, slave devices can be addressed individually (if needed) using generalpurpose I/O pins. Figure 20.2 shows a connection diagram between two master devices in multiple-master mode. 3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this mode, NSS is not used, and does not get mapped to an external port pin through the crossbar. Any slave devices that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 20.3 shows a connection diagram between a master device in 3-wire master mode and a slave device. 4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be addressed using general-purpose I/O pins. Figure 20.4 shows a connection diagram for a master device in 4-wire master mode and two slave devices.
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Figure 20.2. Multiple-Master Mode Connection Diagram
NSS GPIO MISO MOSI SCK NSS
Master Device 1
MISO MOSI SCK GPIO
Master Device 2
Figure 20.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram
Master Device
MISO MOSI SCK
MISO MOSI SCK
Slave Device
Figure 20.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram
Master Device
GPIO
MISO MOSI SCK NSS
MISO MOSI SCK NSS
Slave Device
MISO MOSI SCK NSS
Slave Device
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20.3.
SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK signal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift register, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit buffer will immediately be transferred into the shift register. When the shift register already contains data, the SPI will wait until the byte is transferred before loading it with the transmit buffer's contents. When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0, and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS signal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer. Figure 20.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master device. 3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not used in this mode, and does not get mapped to an external port pin through the crossbar. Since there is no way of uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter that determines when a full byte has been received. The bit counter can only be reset by disabling and re-enabling SPI0 with the SPIEN bit. Figure 20.3 shows a connection diagram between a slave device in 3-wire slave mode and a master device.
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20.4. SPI0 Interrupt Sources
Preliminary
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to logic 1: Note all of the following bits are cleared in software. 1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This flag can occur in all SPI0 modes. 2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPI0 modes. 3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master, and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master device to access the bus. 4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave, and a transfer is completed and the receive buffer still holds an unread byte from a previous transfer. The new byte is not transferred to the receive buffer, allowing the previously received data byte to be read. The data byte which caused the overrun is lost.
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20.5.
Serial Clock Timing
As shown in Figure 20.5, four combinations of serial clock phase and polarity can be selected using the clock control bits in the SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases (edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low clock. Both master and slave devices must be configured to use the same clock phase and polarity. Note: SPI0 should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The SPI0 Clock Rate Register (SPI0CKR) as shown in Figure 20.8 controls the master mode serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4-wire slave mode), and the serial input data synchronously with the system clock. If the master issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec) must be less than 1/10 the system clock frequency. In the special case where the master only wants to transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency. This is provided that the master issues SCK, NSS, and the serial input data synchronously with the system clock.
Figure 20.5. Data/Clock Timing Diagram
SCK (CKPOL=0, CKPHA=0)
SCK (CKPOL=0, CKPHA=1)
SCK (CKPOL=1, CKPHA=0)
SCK (CKPOL=1, CKPHA=1)
MISO/MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS
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20.6.
Preliminary
SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate Register. The four special function registers related to the operation of the SPI0 Bus are described in the following figures.
Figure 20.6. SPI0CFG: SPI0 Configuration Register
R R/W R/W R/W R R R R Reset Value
SPIBSY
Bit7
MSTEN
Bit6
CKPHA
Bit5
CKPOL
Bit4
SLVSEL
Bit3
NSSIN
Bit2
SRMT
Bit1
RXBMT
Bit0
00000000
SFR Address: 0x9A SFR Page: 0
Bit 7: Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
SPIBSY: SPI Busy. This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode). MSTEN: Master Mode Enable. 0: Disable master mode. Operate in slave mode. 1: Enable master mode. Operate as a master. CKPHA: SPI0 Clock Phase. This bit controls the SPI0 clock phase. 0: Data sampled on first edge of SCK period. 1: Data sampled on second edge of SCK period. CKPOL: SPI0 Clock Polarity. This bit controls the SPI0 clock polarity. 0: SCK line low in idle state. 1: SCK line high in idle state. SLVSEL: Slave Selected Flag. This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the instantaneous value at the NSS pin, but rather a de-glitched version of the pin input. NSSIN: NSS Instantaneous Pin Input. This bit mimics the instantaneous value that is present on the NSS port pin at the time that the register is read. This input is not de-glitched. SRMT: Shift Register Empty (Valid in Slave Mode). This bit will be set to logic 1 when all data has been transferred in/out of the shift register, and there is no new information available to read from the transmit buffer or write to the receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from the transmit buffer or by a transition on SCK. NOTE: SRMT = 1 when in Master Mode. RXBMT: Receive Buffer Empty (Valid in Slave Mode). This bit will be set to logic 1 when the receive buffer has been read and contains no new information. If there is new information available in the receive buffer that has not been read, this bit will return to logic 0. NOTE: RXBMT = 1 when in Master Mode.
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Figure 20.7. SPI0CN: SPI0 Control Register
R/W R/W R/W R/W R/W R/W R R/W Reset Value
SPIF
Bit7
WCOL
Bit6
MODF
Bit5
RXOVRN NSSMD1
Bit4 Bit3
NSSMD0
Bit2
TXBMT
Bit1
SPIEN
Bit0
00000100
Bit Addressable
SFR Address: 0xF8 SFR Page: 0
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bits 3-2:
Bit 1:
Bit 0:
SPIF: SPI0 Interrupt Flag. This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled, setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not automatically cleared by hardware. It must be cleared by software. WCOL: Write Collision Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to the SPI0 data register was attempted while a data transfer was in progress. It must be cleared by software. MODF: Mode Fault Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not automatically cleared by hardware. It must be cleared by software. RXOVRN: Receive Overrun Flag (Slave Mode only). This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buffer still holds unread data from a previous transfer and the last bit of the current transfer is shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must be cleared by software. NSSMD1-NSSMD0: Slave Select Mode. Selects between the following NSS operation modes: (See Section "20.2. SPI0 Master Mode Operation" on page 241 and Section "20.3. SPI0 Slave Mode Operation" on page 243). 00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin. 01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device. 1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will assume the value of NSSMD0. TXBMT: Transmit Buffer Empty. This bit will be set to logic 0 when new data has been written to the transmit buffer. When data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1, indicating that it is safe to write a new byte to the transmit buffer. SPIEN: SPI0 Enable. This bit enables/disables the SPI. 0: SPI disabled. 1: SPI enabled.
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Figure 20.8. SPI0CKR: SPI0 Clock Rate Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SCR7
Bit7
SCR6
Bit6
SCR5
Bit5
SCR4
Bit4
SCR3
Bit3
SCR2
Bit2
SCR1
Bit1
SCR0
Bit0
00000000
SFR Address: 0x9D SFR Page: 0
Bits 7-0:
SCR7-SCR0: SPI0 Clock Rate These bits determine the frequency of the SCK output when the SPI0 module is configured for master mode operation. The SCK clock frequency is a divided version of the system clock, and is given in the following equation, where SYSCLK is the system clock frequency and SPI0CKR is the 8-bit value held in the SPI0CKR register.
SYSCLK f SCK = -----------------------------------------------2 x ( SPI0CKR + 1 )
for 0 <= SPI0CKR <= 255 Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
2000000 f SCK = ------------------------2 x (4 + 1)
f SCK = 200kHz
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Figure 20.9. SPI0DAT: SPI0 Data Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x9B SFR Page: 0 Reset Value
00000000
Bits 7-0:
SPI0DAT: SPI0 Transmit and Receive Data. The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT places the data into the transmit buffer and initiates a transfer when in Master Mode. A read of SPI0DAT returns the contents of the receive buffer.
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Figure 20.10. SPI Slave Timing (CKPHA = 0)
NSS T T T
SE
CKL
SD
SCK* T
CKH
T
SIS
T
SIH
MOSI
T
SOH
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.11. SPI Slave Timing (CKPHA = 1)
NSS T T T
SE
CKL
SD
SCK* T
CKH
T
SIS
T
SIH
MOSI
T
SOH
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
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Table 20.1. SPI Slave Timing Parameters
PARAMETER TSYSCLK TSYSCLK TSE TSD TCKH TCKL TSIS TSIH TSOH DESCRIPTION System Clock Period (C8051F120/1/2/3) System Clock Period (C8051F124/5/6/7) NSS Falling to First SCK Edge (Slave Enable) Last SCK Edge to NSS Rising (Slave Disable) SCK High Time SCK Low Time MOSI Valid to SCK Active Edge (MOSI Setup) SCK Active Edge to MOSI Change (MOSI Hold) SCK Inactive Edge to MISO Change (MISO Hold) MIN 10 20 2*TSYSCLK 2*TSYSCLK 5*TSYSCLK 5*TSYSCLK 2*TSYSCLK 2*TSYSCLK 4*TSYSCLK MAX UNITS ns ns ns ns ns ns ns ns ns
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Notes
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21.
UART0
UART0 is an enhanced serial port with frame error detection and address recognition hardware. UART0 may operate in full-duplex asynchronous or half-duplex synchronous modes, and mutiproccessor communication is fully supported. Receive data is buffered in a holding register, allowing UART0 to start reception of a second incoming data byte before software has finished reading the previous data byte. A Receive Overrun bit indicates when new received data is latched into the receive buffer before the previously received byte has been read. UART0 is accessed via its associated SFR's, Serial Control (SCON0) and Serial Data Buffer (SBUF0). The single SBUF0 location provides access to both transmit and receive registers. Reading SCON0 accesses the Receive register and writing SCON0 accesses the Transmit register. UART0 may be operated in polled or interrupt mode. UART0 has two sources of interrupts: a Transmit Interrupt flag, TI0 (SCON0.1) set when transmission of a data byte is complete, and a Receive Interrupt flag, RI0 (SCON0.0) set when reception of a data byte is complete. UART0 interrupt flags are not cleared by hardware when the CPU vectors to the interrupt service routine; they must be cleared manually by software. This allows software to determine the cause of the UART0 interrupt (transmit complete or receive complete).
Figure 21.1. UART0 Block Diagram
SFR Bus
Write to SBUF0 TB80
SET
D
Q
CLR
SBUF0
SSTA0
FRTS EXXM 0OCO VOD 0L0 0 S 0 T C L K 1 S 0 T C L K 1 S 0 R C L K 1 S 0 R C L K 1
TX0
Crossbar
Zero Detector
Stop Bit Gen. Start Tx Clock
Shift
Data
Tx Control
Tx IRQ Send
UART0 Baud Rate Generation Logic
SCON0
S M 0 0 S M 1 0 S M 2 0 R E N 0 T B 8 0 RTR BII 800 0
TI0 Serial Port (UART0) Interrupt RI0
Rx Clock
EN
Rx IRQ
Load SBUF Address Match
Rx Control
Start Shift 0x1FF
Port I/O
Frame Error Detection
Input Shift Register (9 bits)
Load SBUF0
RB80
SBUF0
Match Detect
Read SBUF0
SADDR0 SADEN0
SFR Bus
RX0
Crossbar
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Preliminary
UART0 provides four operating modes (one synchronous and three asynchronous) selected by setting configuration bits in the SCON0 register. These four modes offer different baud rates and communication protocols. The four modes are summarized in Table 21.1.
Table 21.1. UART0 Modes
Mode 0 1 2 3 Synchronization Synchronous Asynchronous Asynchronous Asynchronous Baud Clock SYSCLK / 12 Timer 1, 2, 3, or 4 Overflow SYSCLK / 32 or SYSCLK / 64 Timer 1, 2, 3, or 4 Overflow Data Bits 8 8 9 9 Start/Stop Bits None 1 Start, 1 Stop 1 Start, 1 Stop 1 Start, 1 Stop
21.1.1. Mode 0: Synchronous Mode
Mode 0 provides synchronous, half-duplex communication. Serial data is transmitted and received on the RX0 pin. The TX0 pin provides the shift clock for both transmit and receive. The MCU must be the master since it generates the shift clock for transmission in both directions (see the interconnect diagram in Figure 21.3). Data transmission begins when an instruction writes a data byte to the SBUF0 register. Eight data bits are transferred LSB first (see the timing diagram in Figure 21.2), and the TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the eighth bit time. Data reception begins when the REN0 Receive Enable bit (SCON0.4) is set to logic 1 and the RI0 Receive Interrupt Flag (SCON0.0) is cleared. One cycle after the eighth bit is shifted in, the RI0 flag is set and reception stops until software clears the RI0 bit. An interrupt will occur if enabled when either TI0 or RI0 are set. The Mode 0 baud rate is SYSCLK / 12. RX0 is forced to open-drain in Mode 0, and an external pull-up will typically be required.
Figure 21.2. UART0 Mode 0 Timing Diagram
MODE 0 TRANSMIT RX (data out) TX (clk out)
D0 D1 D2 D3 D4 D5 D6 D7
MODE 0 RECEIVE RX (data in) TX (clk out)
D0 D1 D2 D3 D4 D5 D6 D7
Figure 21.3. UART0 Mode 0 Interconnect
TX CLK DATA
C8051Fxxx
RX
Shift Reg.
8 Extra Outputs
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21.1.2. Mode 1: 8-Bit UART, Variable Baud Rate
Mode 1 provides standard asynchronous, full duplex communication using a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop bit. Data are transmitted from the TX0 pin and received at the RX0 pin. On receive, the eight data bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2). Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met: RI0 must be logic 0, and if SM20 is logic 1, the stop bit must be logic 1. If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set. An interrupt will occur if enabled when either TI0 or RI0 are set.
Figure 21.4. UART0 Mode 1 Timing Diagram
MARK SPACE BIT TIMES START BIT D0 D1 D2 D3 D4 D5 D6 D7 STOP BIT
BIT SAMPLING
The baud rate generated in Mode 1 is a function of timer overflow, shown in Equation 21.1 and Equation 21.2. UART0 can use Timer 1 operating in 8-Bit Auto-Reload Mode, or Timer 2, 3, or 4 operating in Auto-reload Mode to generate the baud rate (note that the TX and RX clocks are selected separately). On each timer overflow event (a rollover from all ones - (0xFF for Timer 1, 0xFFFF for Timer 2) - to zero) a clock is sent to the baud rate logic. Timers 2, 3, and 4 are selected as the baud rate source with bits in the SSTA0 register (see Figure 21.9). The transmit baud rate clock is selected using the S0TCLK1 and S0TCLK0 bits, and the receive baud rate clock is selected using the S0RCLK1 and S0RCLK0 bits. The Mode 1 baud rate equations are shown below, where T1M is bit4 of register CKCON, TH1 is the 8-bit reload register for Timer 1, and [RCAPnH , RCAPnL] is the 16-bit reload register for Timer 2, 3, or 4.
Equation 21.1. Mode 1 Baud Rate using Timer 1 2 SYSCLK x 12 - BaudRate = ------------------ x ------------------------------------------------------- 32 - ( 256 - TH1 ) Equation 21.2. Mode 1 Baud Rate using Timer 2, 3, or 4 SYSCLK BaudRate = -------------------------------------------------------------------------------------------16 x ( 65536 - [ RCAPnH, RCAPnL ] )
SMOD0 ( T1M - 1 ) )
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21.1.3. Mode 2: 9-Bit UART, Fixed Baud Rate
Mode 2 provides asynchronous, full-duplex communication using a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. Mode 2 supports multiprocessor communications and hardware address recognition (see Section 21.2). On transmit, the ninth data bit is determined by the value in TB80 (SCON0.3). It can be assigned the value of the parity flag P in the PSW or used in multiprocessor communications. On receive, the ninth data bit goes into RB80 (SCON0.2) and the stop bit is ignored. Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is received, the data byte will be loaded into the SBUF0 receive register if RI0 is logic 0 and one of the following requirements are met: 1. 2. SM20 is logic 0 SM20 is logic 1, the received 9th bit is logic 1, and the received address matches the UART0 address as described in Section 21.2.
If the above conditions are satisfied, the eight bits of data are stored in SBUF0, the ninth bit is stored in RB80 and the RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set. An interrupt will occur if enabled when either TI0 or RI0 are set. The baud rate in Mode 2 is either SYSCLK / 32 or SYSCLK / 64, according to the value of the SMOD0 bit in register SSTA0.
Equation 21.3. Mode 2 Baud Rate SMOD0 SYSCLK BaudRate = 2 x --------------------- 64 Figure 21.5. UART0 Modes 2 and 3 Timing Diagram
MARK SPACE BIT TIMES START BIT D0 D1 D2 D3 D4 D5 D6 D7 D8 STOP BIT
BIT SAMPLING
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Figure 21.6. UART0 Modes 1, 2, and 3 Interconnect Diagram
TX RX
RS-232
RS-232 LEVEL XLTR
C8051Fxxx
OR
TX TX
MCU
RX RX
C8051Fxxx
21.1.4. Mode 3: 9-Bit UART, Variable Baud Rate
Mode 3 uses the Mode 2 transmission protocol with the Mode 1 baud rate generation. Mode 3 operation transmits 11 bits: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The baud rate is derived from Timer 1 or Timer 2, 3, or 4 overflows, as defined by Equation 21.1 and Equation 21.2. Multiprocessor communications and hardware address recognition are supported, as described in Section 21.2.
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21.2.
Preliminary
Multiprocessor Communications
Modes 2 and 3 support multiprocessor communication between a master processor and one or more slave processors by special use of the ninth data bit and the built-in UART0 address recognition hardware. When a master processor wants to transmit to one or more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0. UART0 will recognize as "valid" (i.e., capable of causing an interrupt) two types of addresses: (1) a masked address and (2) a broadcast address at any given time. Both are described below.
21.2.1. Configuration of a Masked Address
The UART0 address is configured via two SFR's: SADDR0 (Serial Address) and SADEN0 (Serial Address Enable). SADEN0 sets the bit mask for the address held in SADDR0: bits set to logic 1 in SADEN0 correspond to bits in SADDR0 that are checked against the received address byte; bits set to logic 0 in SADEN0 correspond to "don't care" bits in SADDR0. Example 1, SLAVE #1 SADDR0 = 00110101 SADEN0 = 00001111 UART0 Address = xxxx0101 Example 2, SLAVE #2 SADDR0 = 00110101 SADEN0 = 11110011 UART0 Address = 0011xx01 Example 3, SLAVE #3 SADDR0 = 00110101 SADEN0 = 11000000 UART0 Address = 00xxxxxx
Setting the SM20 bit (SCON0.5) configures UART0 such that when a stop bit is received, UART0 will generate an interrupt only if the ninth bit is logic 1 (RB80 = `1') and the received data byte matches the UART0 slave address. Following the received address interrupt, the slave will clear its SM20 bit to enable interrupts on the reception of the following data byte(s). Once the entire message is received, the addressed slave resets its SM20 bit to ignore all transmissions until it receives the next address byte. While SM20 is logic 1, UART0 ignores all bytes that do not match the UART0 address and include a ninth bit that is logic 1.
21.2.2. Broadcast Addressing
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The broadcast address is the logical OR of registers SADDR0 and SADEN0, and `0's of the result are treated as "don't cares". Typically a broadcast address of 0xFF (hexadecimal) is acknowledged by all slaves, assuming "don't care" bits as `1's. The master processor can be configured to receive all transmissions or a protocol can be implemented such that the master/slave role is temporarily reversed to enable half-duplex transmission between the original master and slave(s).. Example 4, SLAVE #1 Example 5, SLAVE #2 Example 6, SLAVE #3 SADDR0 = 00110101 SADDR0 = 00110101 SADDR0 = 00110101 SADEN0 = 00001111 SADEN0 = 11110011 SADEN0 = 11000000 Broadcast Address = 00111111 Broadcast Address = 11110111 Broadcast Address = 11110101 Where all ZEROES in the Broadcast address are don't cares. Note in the above examples 4, 5, and 6, each slave would recognize as "valid" an address of 0xFF as a broadcast address. Also note that examples 4, 5, and 6 uses the same SADDR0 and SADEN0 register values as shown in the examples 1, 2, and 3 respectively (slaves #1, 2, and 3). Thus, a master could address each slave device individually using a masked address, and also broadcast to all three slave devices. For example, if a Master were to send an address "11110101", only slave #1 would recognize the address as valid. If a master were to then send an address of "11111111", all three slave devices would recognize the address as a valid broadcast address.
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Figure 21.7. UART Multi-Processor Mode Interconnect Diagram
Master Device
RX TX
Slave Device
RX TX
Slave Device
RX TX
Slave Device
+5V RX TX
21.3.
Frame and Transmission Error Detection
All Modes: The Transmit Collision bit (TXCOL0 bit in register SCON0) reads `1' if user software writes data to the SBUF0 register while a transmit is in progress. Note that the TXCOL0 bit is also used as the SM20 bit when written by user software. Modes 1, 2, and 3: The Receive Overrun bit (RXOVR0 in register SCON0) reads `1' if a new data byte is latched into the receive buffer before software has read the previous byte. Note that the RXOVR0 bit is also used as the SM10 bit when written by user software. The Frame Error bit (FE0 in register SCON0) reads `1' if an invalid (low) STOP bit is detected. Note that the FE0 bit is also used as the SM00 bit when written by user software.
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Table 21.2. Oscillator Frequencies for Standard Baud Rates
System Clock Frequency Divide Factor Timer 1 Reload Timer 2, 3, or 4 Resulting Baud Rate (Hz)** (MHz) Value* Reload Value 100.0 864 0xCA 0xFFCA 115200 (115741) 99.5328 864 0xCA 0xFFCA 115200 50.0 432 0xE5 0xFFE5 115200 (115741) 49.7664 432 0xE5 0xFFE5 115200 24.0 208 0xF3 0xFFF3 115200 (115384) 22.1184 192 0xF4 0xFFF4 115200 18.432 160 0xF6 0xFFF6 115200 11.0592 96 0xFA 0xFFFA 115200 3.6864 32 0xFE 0xFFFE 115200 1.8432 16 0xFF 0xFFFF 115200 100.0 3472 0x27 0xFF27 28800 (28802) 99.5328 3456 0x28 0xFF28 28800 50.0 1744 0x93 0xFF93 28800 (28670) 49.7664 1728 0x94 0xFF94 28800 24.0 832 0xCC 0xFFCC 28800 (28846) 22.1184 768 0xD0 0xFFD0 28800 18.432 640 0xD8 0xFFD8 28800 11.0592 348 0xE8 0xFFE8 28800 3.6864 128 0xF8 0xFFF8 28800 1.8432 64 0xFC 0xFFFC 28800 100.0 10416 0xFD75 9600 (9601) 99.5328 10368 0xFD78 9600 50.0 5216 0xFEBA 9600 (9586) 49.7664 5184 0xFEBC 9600 24.0 2496 0x64 0xFF64 9600 (9615) 22.1184 2304 0x70 0xFF70 9600 18.432 1920 0x88 0xFF88 9600 11.0592 1152 0xB8 0xFFB8 9600 3.6864 384 0xE8 0xFFE8 9600 1.8432 192 0xF4 0xFFF4 9600 * Assumes SMOD0=1 and T1M=1. ** Numbers in parenthesis show the actual baud rate.
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Figure 21.8. SCON0: UART0 Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SM00
Bit7
SM10
Bit6
SM20
Bit5
REN0
Bit4
TB80
Bit3
RB80
Bit2
TI0
Bit1
RI0
Bit0
00000000
SFR Address: 0x98 SFR Page: 0
Bits7-6:
SM00-SM10: Serial Port Operation Mode: Write: When written, these bits select the Serial Port Operation Mode as follows: SM00 0 0 1 1 SM10 0 1 0 1 Mode Mode 0: Synchronous Mode Mode 1: 8-Bit UART, Variable Baud Rate Mode 2: 9-Bit UART, Fixed Baud Rate Mode 3: 9-Bit UART, Variable Baud Rate
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
Reading these bits returns the current UART0 mode as defined above. SM20: Multiprocessor Communication Enable. The function of this bit is dependent on the Serial Port Operation Mode. Mode 0: No effect Mode 1: Checks for valid stop bit. 0: Logic level of stop bit is ignored. 1: RI0 will only be activated if stop bit is logic level 1. Mode 2 and 3: Multiprocessor Communications Enable. 0: Logic level of ninth bit is ignored. 1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1 and the received address matches the UART0 address or the broadcast address. REN0: Receive Enable. This bit enables/disables the UART0 receiver. 0: UART0 reception disabled. 1: UART0 reception enabled. TB80: Ninth Transmission Bit. The logic level of this bit will be assigned to the ninth transmission bit in Modes 2 and 3. It is not used in Modes 0 and 1. Set or cleared by software as required. RB80: Ninth Receive Bit. The bit is assigned the logic level of the ninth bit received in Modes 2 and 3. In Mode 1, if SM20 is logic 0, RB80 is assigned the logic level of the received stop bit. RB8 is not used in Mode 0. TI0: Transmit Interrupt Flag. Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in Mode 0, or at the beginning of the stop bit in other modes). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software RI0: Receive Interrupt Flag. Set by hardware when a byte of data has been received by UART0 (as selected by the SM20 bit). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software.
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Figure 21.9. SSTA0: UART0 Status and Clock Selection Register
R/W R/W R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x91 SFR Page; 0 Reset Value
FE0
Bit7
RXOV0
Bit6
TXCOL0 SMOD0 S0TCLK1 S0TCLK0 S0RCLK1 S0RCLK0
00000000
Bit7:
Bit6:
Bit5:
Bit4:
FE0: Frame Error Flag. This flag indicates if an invalid (low) STOP bit is detected. 0: Frame Error has not been detected 1: Frame Error has been detected. RXOV0: Receive Overrun Flag. This flag indicates new data has been latched into the receive buffer before software has read the previous byte. 0: Receive overrun has not been detected. 1: Receive Overrun has been detected. TXCOL0: Transmit Collision Flag. This flag indicates user software has written to the SBUF0 register while a transmission is in progress. 0: Transmission Collision has not been detected. 1: Transmission Collision has been detected. SMOD0: UART0 Baud Rate Doubler Enable. This bit enables/disables the divide-by-two function of the UART0 baud rate logic for configurations described in the UART0 section. 0: UART0 baud rate divide-by-two enabled. 1: UART0 baud rate divide-by-two disabled. UART0 Transmit Baud Rate Clock Selection Bits. S0TCLK1 0 0 1 1 S0TCLK0 0 1 0 1 Serial Transmit Baud Rate Clock Source Timer 1 generates UART0 TX Baud Rate Timer 2 Overflow generates UART0 TX baud rate Timer 3 Overflow generates UART0 TX baud rate Timer 4 Overflow generates UART0 TX baud rate
Bits3-2:
Bits1-0:
UART0 Receive Baud Rate Clock Selection Bits S0RCLK1 0 0 1 1 S0RCLK0 0 1 0 1 Serial Receive Baud Rate Clock Source Timer 1 generates UART0 RX Baud Rate Timer 2 Overflow generates UART0 RX baud rate Timer 3 Overflow generates UART0 RX baud rate Timer 4 Overflow generates UART0 RX baud rate
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Figure 21.10. SBUF0: UART0 Data Buffer Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x99 SFR Page: 0 Reset Value
00000000
Bits7-0:
SBUF0.[7:0]: UART0 Buffer Bits 7-0 (MSB-LSB) This is actually two registers; a transmit and a receive buffer register. When data is moved to SBUF0, it goes to the transmit buffer and is held for serial transmission. Moving a byte to SBUF0 is what initiates the transmission. When data is moved from SBUF0, it comes from the receive buffer.
Figure 21.11. SADDR0: UART0 Slave Address Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xA9 SFR Page: 0 Reset Value
00000000
Bits7-0:
SADDR0.[7:0]: UART0 Slave Address The contents of this register are used to define the UART0 slave address. Register SADEN0 is a bit mask to determine which bits of SADDR0 are checked against a received address: corresponding bits set to logic 1 in SADEN0 are checked; corresponding bits set to logic 0 are "don't cares".
Figure 21.12. SADEN0: UART0 Slave Address Enable Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xB9 SFR Page: 0 Reset Value
00000000
Bits7-0:
SADEN0.[7:0]: UART0 Slave Address Enable Bits in this register enable corresponding bits in register SADDR0 to determine the UART0 slave address. 0: Corresponding bit in SADDR0 is a "don't care". 1: Corresponding bit in SADDR0 is checked against a received address.
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22.
UART1
UART1 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART. Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details in Section "22.1. Enhanced Baud Rate Generation" on page 266). Received data buffering allows UART1 to start reception of a second incoming data byte before software has finished reading the previous data byte. UART1 has two associated SFRs: Serial Control Register 1 (SCON1) and Serial Data Buffer 1 (SBUF1). The single SBUF1 location provides access to both transmit and receive registers. Reading SBUF1 accesses the buffered Receive register; writing SBUF1 accesses the Transmit register. With UART1 interrupts enabled, an interrupt is generated each time a transmit is completed (TI1 is set in SCON1), or a data byte has been received (RI1 is set in SCON1). The UART1 interrupt flags are not cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually by software, allowing software to determine the cause of the UART1 interrupt (transmit complete or receive complete).
Figure 22.1. UART1 Block Diagram
SFR Bus
Write to SBUF1 TB81
SET D CLR Q
SBUF1 (TX Shift)
TX1
Crossbar
Zero Detector
Stop Bit Start Tx Clock
Shift
Data
Tx Control
Tx IRQ Send
SCON1 S1MODE MCE1 REN1 TB81 RB81 TI1 RI1 UART1 Baud Rate Generator
TI1 Serial Port Interrupt RI1
Port I/O
Rx IRQ Rx Clock
Rx Control
Start Shift 0x1FF RB81 Load SBUF1
Input Shift Register (9 bits)
Load SBUF1
SBUF1 (RX Latch)
Read SBUF1
SFR Bus
RX1
Crossbar
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22.1.
Preliminary
Enhanced Baud Rate Generation
The UART1 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 22.2), which is not user-accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates. The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to begin any time a START is detected, independent of the TX Timer state.
Figure 22.2. UART1 Baud Rate Logic
Timer 1 TL1
Overflow
UART1
2
TX Clock
TH1
Start Detected
RX Timer
Overflow
2
RX Clock
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section "23.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload" on page 277). The Timer 1 reload value should be set so that overflows will occur at two times the desired baud rate. Note that Timer 1 may be clocked by one of five sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, or the external oscillator clock / 8. For any given Timer 1 clock source, the UART1 baud rate is determined by Equation 22.1.
Equation 22.1. UART1 Baud Rate T1CLK 1 -UARTBaudRate = ------------------------------ x -( 256 - T1H ) 2
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload value). Timer 1 clock frequency is selected as described in Section "23.1. Timer 0 and Timer 1" on page 275. A quick reference for typical baud rates and system clock frequencies is given in Table 22.1 through Table 22.5. Note that the internal oscillator or PLL may still generate the system clock when the external oscillator is driving Timer 1 (see Section "23.1. Timer 0 and Timer 1" on page 275 for more details).
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22.2. Operational Modes
UART1 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is selected by the S1MODE bit (SCON1.7). Typical UART connection options are shown below.
Figure 22.3. UART Interconnect Diagram
RS-232 RS-232 LEVEL XLTR TX RX
C8051Fxxx
OR
TX TX
MCU
RX RX
C8051Fxxx
22.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop bit. Data are transmitted LSB first from the TX1 pin and received at the RX1 pin. On receive, the eight data bits are stored in SBUF1 and the stop bit goes into RB81 (SCON1.2). Data transmission begins when software writes a data byte to the SBUF1 register. The TI1 Transmit Interrupt Flag (SCON1.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN1 Receive Enable bit (SCON1.4) is set to logic 1. After the stop bit is received, the data byte will be loaded into the SBUF1 receive register if the following conditions are met: RI1 must be logic 0, and if MCE1 is logic 1, the stop bit must be logic 1. In the event of a receive data overrun, the first received 8 bits are latched into the SBUF1 receive register and the following overrun data bits are lost. If these conditions are met, the eight bits of data is stored in SBUF1, the stop bit is stored in RB81 and the RI1 flag is set. If these conditions are not met, SBUF1 and RB81 will not be loaded and the RI1 flag will not be set. An interrupt will occur if enabled when either TI1 or RI1 is set.
Figure 22.4. 8-Bit UART Timing Diagram
MARK SPACE
BIT TIMES START BIT D0 D1 D2 D3 D4 D5 D6 D7 STOP BIT
BIT SAMPLING
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22.2.2. 9-Bit UART
Preliminary
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB81 (SCON1.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit goes into RB81 (SCON1.2) and the stop bit is ignored. Data transmission begins when an instruction writes a data byte to the SBUF1 register. The TI1 Transmit Interrupt Flag (SCON1.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN1 Receive Enable bit (SCON1.4) is set to `1'. After the stop bit is received, the data byte will be loaded into the SBUF1 receive register if the following conditions are met: (1) RI1 must be logic 0, and (2) if MCE1 is logic 1, the 9th bit must be logic 1 (when MCE1 is logic 0, the state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in SBUF1, the ninth bit is stored in RB81, and the RI1 flag is set to `1'. If the above conditions are not met, SBUF1 and RB81 will not be loaded and the RI1 flag will not be set to `1'. A UART1 interrupt will occur if enabled when either TI1 or RI1 is set to `1'.
Figure 22.5. 9-Bit UART Timing Diagram
MARK SPACE
BIT TIMES START BIT D0 D1 D2 D3 D4 D5 D6 D7 D8 STOP BIT
BIT SAMPLING
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22.3.
Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0. Setting the MCE1 bit (SCON.5) of a slave processor configures its UART such that when a stop bit is received, the UART will generate an interrupt only if the ninth bit is logic one (RB81 = 1) signifying an address byte has been received. In the UART interrupt handler, software should compare the received address with the slave's own assigned 8-bit address. If the addresses match, the slave should clear its MCE1 bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE1 bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the data. Once the entire message is received, the addressed slave should reset its MCE1 bit to ignore all transmissions until it receives the next address byte. Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master processor can be configured to receive all transmissions or a protocol can be implemented such that the master/slave role is temporarily reversed to enable half-duplex transmission between the original master and slave(s).
Figure 22.6. UART Multi-Processor Mode Interconnect Diagram
Master Device
RX TX
Slave Device
RX TX
Slave Device
RX TX
Slave Device
+5V RX TX
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Figure 22.7. SCON1: Serial Port 1 Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
S1MODE
Bit7
Bit6
MCE1
Bit5
REN1
Bit4
TB81
Bit3
RB81
Bit2
TI1
Bit1
RI1
Bit0
00000000
Bit Addressable
SFR Address: 0x98 SFR Page: 1
Bit7:
Bit6: Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
S1MODE: Serial Port 1 Operation Mode. This bit selects the UART1 Operation Mode. 0: Mode 0: 8-bit UART with Variable Baud Rate 1: Mode 1: 9-bit UART with Variable Baud Rate UNUSED. Read = 1b. Write = don't care. MCE1: Multiprocessor Communication Enable. The function of this bit is dependent on the Serial Port 0 Operation Mode. Mode 0: Checks for valid stop bit. 0: Logic level of stop bit is ignored. 1: RI1 will only be activated if stop bit is logic level 1. Mode 1: Multiprocessor Communications Enable. 0: Logic level of ninth bit is ignored. 1: RI1 is set and an interrupt is generated only when the ninth bit is logic 1. REN1: Receive Enable. This bit enables/disables the UART receiver. 0: UART1 reception disabled. 1: UART1 reception enabled. TB81: Ninth Transmission Bit. The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It is not used in 8-bit UART Mode. Set or cleared by software as required. RB81: Ninth Receive Bit. RB81 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th data bit in Mode 1. TI1: Transmit Interrupt Flag. Set by hardware when a byte of data has been transmitted by UART1 (after the 8th bit in 8-bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART1 interrupt is enabled, setting this bit causes the CPU to vector to the UART1 interrupt service routine. This bit must be cleared manually by software RI1: Receive Interrupt Flag. Set to `1' by hardware when a byte of data has been received by UART1 (set at the STOP bit sampling time). When the UART1 interrupt is enabled, setting this bit to `1' causes the CPU to vector to the UART1 interrupt service routine. This bit must be cleared manually by software.
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Figure 22.8. SBUF1: Serial (UART1) Port Data Buffer Register
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x99 SFR Page: 1 Reset Value
00000000
Bits7-0:
SBUF1[7:0]: Serial Data Buffer Bits 7-0 (MSB-LSB) This SFR accesses two registers; a transmit shift register and a receive latch register. When data is written to SBUF1, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF1 is what initiates the transmission. A read of SBUF1 returns the contents of the receive latch.
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Table 22.1. Timer Settings for Standard Baud Rates Using The Internal Oscillator Frequency: 24.5 MHz
Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 Baud Rate % Error -0.32% -0.32% 0.15% -0.32% 0.15% -0.32% -0.32% 0.15% X = Don't care
SCA1-SCA0
Oscillator Divide Factor 106 212 426 848 1704 2544 10176 20448
Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK SYSCLK SYSCLK / 4 SYSCLK / 12 SYSCLK / 12 SYSCLK / 48 SYSCLK / 48 XX XX XX 01 00 00 10 10
T1M Timer 1 Reload Value (hex) 1 0xCB 1 0x96 1 0x2B 0 0x96 0 0xB9 0 0x96 0 0x96 0 0x2B
SYSCLK from Internal Osc.
and T1M bit definitions can be found in Section 23.1.
Table 22.2. Timer Settings for Standard Baud Rates Using an External Oscillator Frequency: 25.0 MHz
Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 57600 28800 14400 9600 Baud Rate % Error -0.47% 0.45% -0.01% 0.45% -0.01% 0.15% 0.45% -0.01% -0.47% -0.47% 0.45% 0.15% X = Don't care
SCA1-SCA0
SYSCLK from Internal Osc.
Oscillator Divide Factor 108 218 434 872 1736 2608 10464 20832 432 864 1744 2608
Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK SYSCLK SYSCLK / 4 SYSCLK / 4 EXTCLK / 8 SYSCLK / 48 SYSCLK / 48 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 XX XX XX 01 01 11 10 10 11 11 11 11
T1M Timer 1 Reload Value (hex) 1 0xCA 1 0x93 1 0x27 0 0x93 0 0x27 0 0x5D 0 0x93 0 0x27 0 0xE5 0 0xCA 0 0x93 0 0x5D
SYSCLK from External Osc.
and T1M bit definitions can be found in Section 23.1.
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Table 22.3. Timer Settings for Standard Baud Rates Using an External Oscillator Frequency: 22.1184 MHz
Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Baud Rate % Error 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% X = Don't care
Oscillator Divide Factor 96 192 384 768 1536 2304 9216 18432 96 192 384 768 1536 2304
Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK SYSCLK SYSCLK / 12 SYSCLK / 12 SYSCLK / 12 SYSCLK / 48 SYSCLK / 48 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 EXTCLK / 8 XX XX XX 00 00 00 10 10 11 11 11 11 11 11
T1M Timer 1 Reload Value (hex) 1 0xD0 1 0xA0 1 0x40 0 0xE0 0 0xC0 0 0xA0 0 0xA0 0 0x40 0 0xFA 0 0xF4 0 0xE8 0 0xD0 0 0xA0 0 0x70
SYSCLK from Internal Osc.
SYSCLK from External Osc.
SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Table 22.4. Timer Settings for Standard Baud Rates Using the PLL Frequency: 50.0 MHz
Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 Baud Rate % Error 0.45% -0.01% 0.45% -0.01% 0.22% -0.01% -0.01% X = Don't care
Oscillator Divide Factor 218 434 872 1736 3480 5208 20832
Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK SYSCLK / 4 SYSCLK / 4 SYSCLK / 12 SYSCLK / 12 SYSCLK / 48 XX XX 01 01 00 00 10
T1M Timer 1 Reload Value (hex) 1 0x93 1 0x27 0 0x93 0 0x27 0 0x6F 0 0x27 0 0x27
SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
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Table 22.5. Timer Settings for Standard Baud Rates Using the PLL Frequency: 100.0 MHz
Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 Baud Rate % Error -0.01% 0.45% -0.01% 0.22% -0.47% 0.45% X = Don't care
Oscillator Divide Factor 434 872 1736 3480 6912 10464
Timer Clock SCA1-SCA0 Source (pre-scale select) SYSCLK SYSCLK / 4 SYSCLK / 4 SYSCLK / 12 SYSCLK / 48 SYSCLK / 48 XX 01 01 00 10 10
T1M Timer 1 Reload Value (hex) 1 0x27 0 0x93 0 0x27 0 0x6F 0 0xB8 0 0x93
SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
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23.
TIMERS
Each MCU includes 5 counter/timers: Timer 0 and Timer 1 are 16-bit counter/timers compatible with those found in the standard 8051. Timer 2, Timer 3, and Timer 4 are 16-bit auto-reload and capture counter/timers for use with the ADC, DAC's, square-wave generation, or for general-purpose use. These timers can be used to measure time intervals, count external events and generate periodic interrupt requests. Timer 0 and Timer 1 are nearly identical and have four primary modes of operation. Timer 3 offers 16-bit auto-reload and capture. Timers 2 and 4 are identical, and offer not only 16-bit auto-reload and capture, but have the ability to produce a 50% duty-cycle square-wave (toggle output) at an external port pin. Timer 0 and Timer 1 Modes: Timer 2, 3 and 4 Modes: 13-bit counter/timer 16-bit counter/timer with auto-reload 16-bit counter/timer 16-bit counter/timer with capture 8-bit counter/timer with auto-reload Toggle Output (Timer 2 and 4 only) Two 8-bit counter/timers (Timer 0 only) Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M-T0M) and the Clock Scale bits (SCA1-SCA0). The Clock Scale bits define a pre-scaled clock by which Timer 0 and/or Timer 1 may be clocked (See Figure 23.6 for pre-scaled clock selection). Timer 0/1 may then be configured to use this pre-scaled clock signal or the system clock. Timer 2, 3, or 4 may be clocked by the system clock, the system clock divided by 12, or the external oscillator clock source divided by 8. Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer register is incremented on each high-to-low transition at the selected input pin. Events with a frequency of up to one-fourth the system clock's frequency can be counted. The input signal need not be periodic, but it should be held at a given logic level for at least two full system clock cycles to ensure the level is properly sampled.
23.1.
Timer 0 and Timer 1
Each timer is implemented as 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1) and a high byte (TH0 or TH1). The Counter/Timer Control register (TCON) is used to enable Timer 0 and Timer 1 as well as indicate their status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE register (Section "12.7.5. Interrupt Register Descriptions" on page 147); Timer 1 interrupts can be enabled by setting the ET1 bit in the IE register (Section 12.7.5). Both counter/timers operate in one of four primary modes selected by setting the Mode Select bits T1M1-T0M0 in the Counter/Timer Mode register (TMOD). Each timer can be configured independently.
23.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same manner as described for Timer 0. The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions TL0.4TL0.0. The three upper bits of TL0 (TL0.7-TL0.5) are indeterminate and should be masked out or ignored when reading. As the 13-bit timer register increments and overflows from 0x1FFF (all ones) to 0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if Timer 0 interrupts are enabled. The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section "18.1. Ports 0 through 3 and the Priority Crossbar Decoder" on page 205 for information on selecting and configuring external I/O pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When T0M is set, Timer 0 is clocked by the system
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clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock Scale bits in CKCON (see Figure 23.6). Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal /INT0 is logic-level 1. Setting GATE0 to `1' allows the timer to be controlled by the external input signal /INT0 (see Section "12.7.5. Interrupt Register Descriptions" on page 147), facilitating pulse width measurements. TR0 GATE0 0 X 1 0 1 1 1 1 X = Don't Care /INT0 X X 0 1 Counter/Timer Disabled Enabled Disabled Enabled
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial value before the timer is enabled. TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0. Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The input signal /INT1 is used with Timer 1.
Figure 23.1. T0 Mode 0 Block Diagram
CKCON
TT 10 MM SS CC AA 10
G A T E 1 C / T 1
TMOD
TTG 11A MM T 10E 0 CTT /00 T MM 010
Pre-scaled Clock
0 0
SYSCLK
1 1
T0 TR0 GATE0 Crossbar
TCLK
/INT0
23.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
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TCON
TL0 (5 bits)
TH0 (8 bits)
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Interrupt
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23.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 and Timer 1 to operate as 8-bit counter/timers with automatic reload of the start value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from 0xFF to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If Timer 0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is not changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be correct. When in Mode 2, Timer 1 operates identically to Timer 0. Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or when the input signal /INT0 is low.
Figure 23.2. T0 Mode 2 Block Diagram
CKCON
TT 10 MM SS CC AA 10
G A T E 1 C / T 1
TMOD
TTG 11A MM T 10E 0 C / T 0 TT 00 MM 10
Pre-scaled Clock
0 0
SYSCLK
1 1
T0
TCLK
TL0 (8 bits) TCON
TR0 Crossbar GATE0 TH0 (8 bits) /INT0
Reload
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Interrupt
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23.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The counter/timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0 and TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register is restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled using the Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls the Timer 1 interrupt. Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0, 1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However, the Timer 1 overflow can be used to generate baud rates for the SMBus and/or UART, and/or initiate ADC conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode settings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1, configure it for Mode 3.
Figure 23.3. T0 Mode 3 Block Diagram
CKCON
TT 10 MM S C A 1 S C A 0
G A T E 1 C / T 1
TMOD
TTG 11A MM T 10E 0 C / T 0 TT 00 MM 10
Pre-scaled Clock
0 TR1 TH0 (8 bits) TCON
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Interrupt Interrupt
SYSCLK
1 0
1 T0 TL0 (8 bits) TR0 Crossbar GATE0
/INT0
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Figure 23.4. TCON: Timer Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF1
Bit7
TR1
Bit6
TF0
Bit5
TR0
Bit4
IE1
Bit3
IT1
Bit2
IE0
Bit1
IT0
Bit0
00000000
Bit Addressable
SFR Address: 0x88 SFR Page: 0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
TF1: Timer 1 Overflow Flag. Set by hardware when Timer 1 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 1 interrupt service routine. 0: No Timer 1 overflow detected. 1: Timer 1 has overflowed. TR1: Timer 1 Run Control. 0: Timer 1 disabled. 1: Timer 1 enabled. TF0: Timer 0 Overflow Flag. Set by hardware when Timer 0 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 0 interrupt service routine. 0: No Timer 0 overflow detected. 1: Timer 0 has overflowed. TR0: Timer 0 Run Control. 0: Timer 0 disabled. 1: Timer 0 enabled. IE1: External Interrupt 1. This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 1 service routine if IT1 = 1. This flag is the inverse of the /INT1 signal. IT1: Interrupt 1 Type Select. This bit selects whether the configured /INT1 interrupt will be falling-edge sensitive or active-low. 0: /INT1 is level triggered, active-low. 1: /INT1 is edge triggered, falling-edge. IE0: External Interrupt 0. This flag is set by hardware when an edge/level of type defined by IT0 is detected. It can be cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 0 service routine if IT0 = 1. This flag is the inverse of the /INT0 signal. IT0: Interrupt 0 Type Select. This bit selects whether the configured /INT0 interrupt will be falling-edge sensitive or active-low. 0: /INT0 is level triggered, active logic-low. 1: /INT0 is edge triggered, falling-edge.
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Figure 23.5. TMOD: Timer Mode Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
GATE1
Bit7
C/T1
Bit6
T1M1
Bit5
T1M0
Bit4
GATE0
Bit3
C/T0
Bit2
T0M1
Bit1
T0M0
Bit0
00000000
SFR Address: 0x89 SFR Page: 0
Bit7:
Bit6:
Bits5-4:
GATE1: Timer 1 Gate Control. 0: Timer 1 enabled when TR1 = 1 irrespective of /INT1 logic level. 1: Timer 1 enabled only when TR1 = 1 AND /INT1 = logic 1. C/T1: Counter/Timer 1 Select. 0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4). 1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin (T1). T1M1-T1M0: Timer 1 Mode Select. These bits select the Timer 1 operation mode. T1M1 0 0 1 1 T1M0 0 1 0 1 Mode Mode 0: 13-bit counter/timer Mode 1: 16-bit counter/timer Mode 2: 8-bit counter/timer with auto-reload Mode 3: Timer 1 inactive
Bit3:
Bit2:
Bits1-0:
GATE0: Timer 0 Gate Control. 0: Timer 0 enabled when TR0 = 1 irrespective of /INT0 logic level. 1: Timer 0 enabled only when TR0 = 1 AND /INT0 = logic 1. C/T0: Counter/Timer Select. 0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3). 1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin (T0). T0M1-T0M0: Timer 0 Mode Select. These bits select the Timer 0 operation mode. T0M1 0 0 1 1 T0M0 0 1 0 1 Mode Mode 0: 13-bit counter/timer Mode 1: 16-bit counter/timer Mode 2: 8-bit counter/timer with auto-reload Mode 3: Two 8-bit counter/timers
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Figure 23.6. CKCON: Clock Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
T1M
Bit4
T0M
Bit3
Bit2
SCA1
Bit1
SCA0
Bit0
00000000
SFR Address: 0x8E SFR Page: 0
Bits7-5: Bit4:
Bit3:
Bit2: Bits1-0:
UNUSED. Read = 000b, Write = don't care. T1M: Timer 1 Clock Select. This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logic 1. 0: Timer 1 uses the clock defined by the prescale bits, SCA1-SCA0. 1: Timer 1 uses the system clock. T0M: Timer 0 Clock Select. This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to logic 1. 0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1-SCA0. 1: Counter/Timer 0 uses the system clock. UNUSED. Read = 0b, Write = don't care. SCA1-SCA0: Timer 0/1 Prescale Bits These bits control the division of the clock supplied to Timer 0 and/or Timer 1 if configured to use prescaled clock inputs. SCA1 0 0 1 1 SCA0 0 1 0 1 Prescaled Clock System clock divided by 12 System clock divided by 4 System clock divided by 48 External clock divided by 8
Note: External clock divided by 8 is synchronized with the system clock.
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Figure 23.7. TL0: Timer 0 Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x8A SFR Page: 0 Reset Value
00000000
Bits 7-0:
TL0: Timer 0 Low Byte. The TL0 register is the low byte of the 16-bit Timer 0.
Figure 23.8. TL1: Timer 1 Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x8B SFR Page: 0 Reset Value
00000000
Bits 7-0:
TL1: Timer 1 Low Byte. The TL1 register is the low byte of the 16-bit Timer 1.
Figure 23.9. TH0: Timer 0 High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x8C SFR Page: 0 Reset Value
00000000
Bits 7-0:
TH0: Timer 0 High Byte. The TH0 register is the high byte of the 16-bit Timer 0.
Figure 23.10. TH1: Timer 1 High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0x8D SFR Page: 0 Reset Value
00000000
Bits 7-0:
TH1: Timer 1 High Byte. The TH1 register is the high byte of the 16-bit Timer 1.
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23.2. Timer 2, Timer 3, and Timer 4
Timers 2, 3, and 4 are 16-bit counter/timers, each formed by two 8-bit SFR's: TMRnL (low byte) and TMRnH (high byte) where n = 2, 3, and 4 for timers 2, 3, and 4 respectively. Timers 2 and 4 feature auto-reload, capture, and toggle output modes with the ability to count up or down. Timer 3 features auto-reload and capture modes, with the ability to count up or down. Capture Mode and Auto-reload mode are selected using bits in the Timer 2, 3, and 4 Control registers (TMRnCN). Toggle output mode is selected using the Timer 2 or 4 Configuration registers (TMRnCF). These timers may also be used to generate a square-wave at an external pin. As with Timers 0 and 1, Timers 2, 3, and 4 can use either the system clock (divided by one, two, or twelve), external clock (divided by eight) or transitions on an external input pin as its clock source. The Counter/Timer Select bit C/Tn bit (TMRnCN.1) configures the peripheral as a counter or timer. Clearing C/Tn configures the Timer to be in a timer mode (i.e., the system clock or transitions on an external pin as the input for the timer). When C/Tn is set to 1, the timer is configured as a counter (i.e., high-tolow transitions at the Tn input pin increment (or decrement) the counter/timer register. Timer 3 and Timer 2 share the T2 input pin. Refer to Section "18.1. Ports 0 through 3 and the Priority Crossbar Decoder" on page 205 for information on selecting and configuring external I/O pins for digital peripherals, such as the Tn pin. Timer 2 and 3 can be used to start an ADC Data Conversion and Timers 2, 3, and 4 can schedule DAC outputs. Only Timer 1 can be used to generate baud rates for UART 1, and Timers 1, 2, 3, or 4 may be used to generate baud rates for UART 0. Timer 2, 3, and 4 can use either SYSCLK, SYSCLK divided by 2, SYSCLK divided by 12, an external clock divided by 8, or high-to-low transitions on the Tn input pin as its clock source when operating in Counter/Timer with Capture mode. Clearing the C/Tn bit (TnCON.1) selects the system clock/external clock as the input for the timer. The Timer Clock Select bits TnM0 and TnM1 in TMRnCF can be used to select the system clock undivided, system clock divided by two, system clock divided by 12, or an external clock provided at the XTAL1/XTAL2 pins divided by 8 (see Figure 23.14). When C/Tn is set to logic 1, a high-to-low transition at the Tn input pin increments the counter/ timer register (i.e., configured as a counter).
23.2.1. Configuring Timer 2, 3, and 4 to Count Down
Timers 2, 3, and 4 have the ability to count down. When the timer's Decrement Enable Bit (DCEN) in the Timer Configuration Register (See Figure 23.14) is set to `1', the timer can then count up or down. When DCEN = 1, the direction of the timer's count is controlled by the TnEX pin's logic level (Timer 3 shares the T2EX pin with Timer 2). When TnEX = 1, the counter/timer will count up; when TnEX = 0, the counter/timer will count down. To use this feature, TnEX must be enabled in the digital crossbar and configured as a digital input. Note: When DCEN = 1, other functions of the TnEX input (i.e., capture and auto-reload) are not available. TnEX will only control the direction of the timer when DCEN = 1.
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23.2.2. Capture Mode
Preliminary
In Capture Mode, Timer 2, 3, and 4 will operate as a 16-bit counter/timer with capture facility. When the Timer External Enable bit (found in the TMRnCN register) is set to `1', a high-to-low transition on the TnEX input pin (Timer 3 shares the T2EX pin with Timer 2) causes the 16-bit value in the associated timer (THn, TLn) to be loaded into the capture registers (RCAPnH, RCAPnL). If a capture is triggered in the counter/timer, the Timer External Flag (TMRnCN.6) will be set to `1' and an interrupt will occur if the interrupt is enabled. See Section "12.7. Interrupt Handler" on page 144 for further information concerning the configuration of interrupt sources. As the 16-bit timer register increments and overflows TMRnH:TMRnL, the TFn Timer Overflow/Underflow Flag (TMRnCN.7) is set to `1' and an interrupt will occur if the interrupt is enabled. The timer can be configured to count down by setting the Decrement Enable Bit (TMRnCF.0) to `1'. This will cause the timer to decrement with every timer clock/count event and underflow when the timer transitions from 0x0000 to 0xFFFF. Just as in overflows, the Overflow/Underflow Flag (TFn) will be set to `1', and an interrupt will occur if enabled. Counter/Timer with Capture mode is selected by setting the Capture/Reload Select bit CP/RLn (TMRnCN.0) and the Timer 2, 3, and 4 Run Control bit TRn (TnCON.2) to logic 1. The Timer 2, 3, and 4 respective External Enable EXENn (TnCON.3) must also be set to logic 1 to enable captures. If EXENn is cleared, transitions on TnEX will be ignored.
Figure 23.11. T2, 3, and 4 Capture Mode Block Diagram
TMRnCF TTTTD n nOnC MMG O E 1 0 n EN
Toggle Logic
2 SYSCLK 12 0xFF 0xFF
0 1 Tn (Port Pin)
External Clock
8
0 1
TCLK TMRnL TMRnH
OVF
CP/RLn C/Tn TRn EXENn EXFn TFn
Tn
Crossbar TRn EXENn
TnCON
Capture
Interrupt
RCAPnL
RCAPnH
TnEX
Crossbar
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23.2.3. Auto-Reload Mode
In Auto-Reload Mode, the counter/timer can be configured to count up or down and cause an interrupt/flag to occur upon an overflow/underflow event. When counting up, the counter/timer will set its overflow/underflow flag (TFn) and cause an interrupt (if enabled) upon overflow/underflow, and the values in the Reload/Capture Registers (RCAPnH and RCAPnL) are loaded into the timer and the timer is restarted. When the Timer External Enable Bit (EXENn) bit is set to `1' and the Decrement Enable Bit (DCEN) is `0', a `0'-to-`1' transition on the TnEX pin will cause a timer reload. Note that timer overflows will also cause auto-reloads. When DCEN is set to `1', the state of the TnEX pin controls whether the counter/timer counts up (increments) or down (decrements), and will not cause an auto-reload or interrupt event (Timer 3 shares the T2EX pin with Timer 2). See Section 23.2.1 for information concerning configuration of a timer to count down. When counting down, the counter/timer will set its overflow/underflow flag (TFn) and cause an interrupt (if enabled) when the value in the TMRnH and TMRnL registers matches the 16-bit value in the Reload/Capture Registers (RCAPnH and RCAPnL). This is considered an underflow event, and will cause the timer to load the value 0xFFFF. The timer is automatically restarted when an underflow occurs. Counter/Timer with Auto-Reload mode is selected by clearing the CP/RLn bit. Setting TRn to logic 1 enables and starts the timer. In Auto-Reload Mode, the External Flag (EXFn) toggles upon every overflow or underflow and does not cause an interrupt. The EXFn flag can be used as the most significant bit (MSB) of a 17-bit counter. .
Figure 23.12. T2, 3, and 4 Auto-reload Mode Block Diagram
TMRnCF TTTTD n nOnC MMG O E 1 0 n EN
Toggle Logic
2 SYSCLK 12 0xFF 0xFF
0 1
Tn (Port Pin)
External Clock
8
0 1
OVF TCLK TMRnL TMRnH
TnCON CP/RLn C/Tn TRn EXENn EXFn TFn
Tn
Crossbar TRn EXENn Reload TnEX Crossbar SMBus (Timer 4 Only) RCAPnL RCAPnH
Interrupt
23.2.4. Toggle Output Mode (Timer 2 and Timer 4 Only)
Timers 2 and 4 have the capability to toggle the state of their respective output port pins (T2 or T4) to produce a 50% duty cycle waveform output. The port pin state will change upon the overflow or underflow of the respective timer (depending on whether the timer is counting up or down). The toggle frequency is determined by the clock source of
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the timer and the values loaded into RCAPnH and RCAPnL. When counting DOWN, the auto-reload value for the timer is 0xFFFF, and underflow will occur when the value in the timer matches the value stored in RCAPnH:RCAPnL. When counting UP, the auto-reload value for the timer is RCAPnH:RCAPnL, and overflow will occur when the value in the timer transitions from 0xFFFF to the reload value. To output a square wave, the timer is placed in reload mode (the Capture/Reload Select Bit in TMRnCN and the Timer/Counter Select Bit in TMRnCN are cleared to `0'). The timer output is enabled by setting the Timer Output Enable Bit in TMRnCF to `1'. The timer should be configured via the timer clock source and reload/underflow values such that the timer overflow/underflows at 1/2 the desired output frequency. The port pin assigned by the crossbar as the timer's output pin should be configured as a digital output (see Section "18. PORT INPUT/OUTPUT" on page 203). Setting the timer's Run Bit (TRn) to `1' will start the toggle of the pin. A Read/Write of the Timer's Toggle Output State Bit (TMRnCF.2) is used to read the state of the toggle output, or to force a value of the output. This is useful when it is desired to start the toggle of a pin in a known state, or to force the pin into a desired state when the toggle mode is halted.
Equation 23.1. Square Wave Frequency (Timer 2 and Timer 4 Only)
If timer is configured to count up:
F TCLK F sq = -----------------------------------------------------2 x ( 65536 - RCAPn ) F TCLK F sq = -----------------------------------------2 x ( 1 + RCAPn )
If timer is configured to count down:
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Figure 23.13. TMRnCN: Timer 2, 3, and 4 Control Registers
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TFn
Bit7
EXFn
Bit6
Bit5
Bit4
EXENn
Bit3
TRn
Bit2
C/Tn
Bit1
CP/RLn
Bit0
00000000
Bit Addressable
SFR Address: TMR2CN:0xC8;TMR3CN:0xC8;TMR4CN:0xC8 SFR Page: TMR2CN: page 0;TMR3CN: page 1;TMR4CN: page 2
Bit7:
Bit6:
Bit5-4: Bit3:
Bit2:
Bit1:
Bit0:
TFn: Timer 2, 3, and 4 Overflow/Underflow Flag. Set by hardware when either the Timer overflows from 0xFFFF to 0x0000, underflows from the value placed in RCAPnH:RCAPnL to 0xFFFF (in Auto-reload Mode), or underflows from 0x0000 to 0xFFFF (in Capture Mode). When the Timer interrupt is enabled, setting this bit causes the CPU to vector to the Timer interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. EXFn: Timer 2, 3, or 4 External Flag. Set by hardware when either a capture or reload is caused by a high-to-low transition on the TnEX input pin and EXENn is logic 1. When the Timer interrupt is enabled, setting this bit causes the CPU to vector to the Timer Interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. Reserved. EXENn: Timer 2, 3, and 4 External Enable. Enables high-to-low transitions on TnEX to trigger captures, reloads, and control the direction of the timer/counter (up or down count). If DECEN = 1, TnEX will determine if the timer counts up or down when in Auto-reload Mode. If EXENn = 1, TnEX should be configured as a digital input. 0: Transitions on the TnEX pin are ignored. 1: Transitions on the TnEX pin cause capture, reload, or control the direction of timer count (up or down) as follows: Capture Mode: `1'-to-'0' Transition on TnEX pin causes RCAPnH:RCAPnL to capture timer value. Auto-Reload Mode: DCEN = 0: `1'-to-'0' transition causes reload of timer and sets the EXFn Flag. DCEN = 1: TnEX logic level controls direction of timer (up or down). TRn: Timer 2, 3, and 4 Run Control. This bit enables/disables the respective Timer. 0: Timer disabled. 1: Timer enabled and running/counting. C/Tn: Counter/Timer Select. 0: Timer Function: Timer incremented by clock defined by TnM1:TnM0 (TMRnCF.4:TMRnCF.3). 1: Counter Function: Timer incremented by high-to-low transitions on external input pin. CP/RLn: Capture/Reload Select. This bit selects whether the Timer functions in capture or auto-reload mode. 0: Timer is in Auto-Reload Mode. 1: Timer is in Capture Mode.
Note: Timer 3 and Timer 2 share the T2 and T2EX pins.
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Figure 23.14. TMRnCF: Timer 2, 3, and 4 Configuration Registers
R/W R/W R/W R/W R/W Reset Value
Bit7
Bit6
Bit5
TnM1
Bit4
TnM0
Bit3
TOGn
Bit2
TnOE
Bit1
DCEN
Bit0
00000000
Bit Addressable
SFR Address: TMR2CF:0xC9;TMR3CF:0xC9;TMR4CF:0xC9 SFR Page TMR2CF: page 0;TMR3CF: page 1;TMR4CF: Page 2
Bit7-5: Bit4-3:
Bit2:
Bit1:
Bit0:
Reserved. TnM1 and TnM0: Timer Clock Mode Select Bits. Bits used to select the Timer clock source. The sources can be the System Clock (SYSCLK), SYSCLK divided by 2 or 12, or the external clock divided by 8. Clock source is selected as follows: 00: SYSCLK/12 01: SYSCLK 10: EXTERNAL CLOCK/8 (Synchronized to the System Clock) 11: SYSCLK/2 TOGn: Toggle output state bit. When timer is used to toggle a port pin, this bit can be used to read the state of the output, or can be written to in order to force the state of the output (Timer 2 and Timer 4 Only). TnOE: Timer output enable bit. This bit enables the timer to output a 50% duty cycle output to the timer's assigned external port pin. NOTE: A timer is configured for Square Wave Output as follows: CP/RLn = 0 C/Tn =1 TnOE = 1 Load RCAPnH:RCAPnL (See "Square Wave Frequency (Timer 2 and Timer 4 Only)" on page 286.) Configure Port Pin to output squarewave (See Section "18. PORT INPUT/OUTPUT" on page 203) 0: Output of toggle mode not available at Timers's assigned port pin. 1: Output of toggle mode available at Timers's assigned port pin. DCEN: Decrement Enable Bit. This bit enables the timer to count up or down as determined by the state of TnEX. 0: Timer will count up, regardless of the state of TnEX. 1: Timer will count up or down depending on the state of TnEX as follows: if TnEX = 0, the timer counts DOWN. if TnEX = 1, the timer counts UP.
Note: Timer 3 and Timer 2 share the T2 and T2EX pins.
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Figure 23.15. RCAPnL: Timer 2, 3, and 4 Capture Register Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address: RCAP2L: 0xCA; RCAP3L: 0xCA; RCAP4L: 0xCA SFR Page: RCAP2L: page 0; RCAP3L: page 1; RCAP4L: page 2
Bits 7-0:
RCAP2, 3, and 4L: Timer 2, 3, and 4 Capture Register Low Byte. The RCAP2, 3, and 4L register captures the low byte of Timer 2, 3, and 4 when Timer 2, 3, and 4 is configured in capture mode. When Timer 2, 3, and 4 is configured in auto-reload mode, it holds the low byte of the reload value.
Figure 23.16. RCAPnH: Timer 2, 3, and 4 Capture Register High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address: RCAP2H: 0xCB; RCAP3H: 0xCB; RCAP4H: 0xCB SFR Page: RCAP2H: page 0; RCAP3H: page 1; RCAP4H: page 2
Bits 7-0:
RCAP2, 3, and 4H: Timer 2, 3, and 4 Capture Register High Byte. The RCAP2, 3, and 4H register captures the highballed of Timer 2, 3, and 4 when Timer 2, 3, and 4 is configured in capture mode. When Timer 2, 3, and 4 is configured in auto-reload mode, it holds the high byte of the reload value.
Figure 23.17. TMRnL: Timer 2, 3, and 4 Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address: TMR2L: 0xCC; TMR3L: 0xCC; TMR4L: 0xCC SFR Page: TMR2L: page 0; TMR3L: page 1; TMR4L: page 2
Bits 7-0:
TL2, 3, and 4: Timer 2, 3, and 4 Low Byte. The TL2, 3, and 4 register contains the low byte of the 16-bit Timer 2, 3, and 4
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Figure 23.18. TMRnH Timer 2, 3, and 4 High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address: TMR2H: 0xCD; TMR3H: 0xCD; TMR4H: 0xCD SFR Page: TMR2H: page 0; TMR3H: page 1; TMR4H: page 2
Bits 7-0:
TH2, 3, and 4: Timer 2, 3, and 4 High Byte. The TH2, 3, and 4 register contains the high byte of the 16-bit Timer 2, 3, and 4
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24.
PROGRAMMABLE COUNTER ARRAY
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU intervention than the standard 8051 counter/timers. PCA0 consists of a dedicated 16-bit counter/timer and six 16-bit capture/ compare modules. Each capture/compare module has its own associated I/O line (CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section "18.1. Ports 0 through 3 and the Priority Crossbar Decoder" on page 205). The counter/timer is driven by a programmable timebase that can select between six inputs as its source: system clock, system clock divided by four, system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or an external clock signal on the ECI line. Each capture/compare module may be configured to operate independently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Frequency Output, 8-Bit PWM, or 16-Bit PWM (each is described in Section 24.2). The PCA is configured and controlled through the system controller's Special Function Registers. The basic PCA block diagram is shown in Figure 24.1.
Figure 24.1. PCA Block Diagram
SYSCLK/12 SYSCLK/4 Timer 0 Overflow ECI SYSCLK External Clock/8 PCA CLOCK MUX 16-Bit Counter/Timer
Capture/Compare Module 0
Capture/Compare Module 1
Capture/Compare Module 2
Capture/Compare Module 3
Capture/Compare Module 4
Capture/Compare Module 5
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
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ECI
Crossbar
Port I/O
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24.1. PCA Counter/Timer
Preliminary
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte (MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches the value of PCA0H into a "snapshot" register; the following PCA0H read accesses this "snapshot" register. Reading the PCA0L Register first guarantees an accurate reading of the entire 16-bit PCA0 counter. Reading PCA0H or PCA0L does not disturb the counter operation. The CPS2-CPS0 bits in the PCA0MD register select the timebase for the counter/timer as shown in Table 24.1. When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing the CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle mode.
Table 24.1. PCA Timebase Input Options
CPS2 0 0 0 0 1 1 CPS1 0 0 1 1 0 0 CPS0 0 1 0 1 0 1 Timebase System clock divided by 12 System clock divided by 4 Timer 0 overflow High-to-low transitions on ECI (max rate = system clock divided by 4) System clock External oscillator source divided by 8
Note: External clock divided by 8 is synchronized with the system clock.
Figure 24.2. PCA Counter/Timer Block Diagram
IDLE
PCA0MD
CWW I DD DTL LEC K C P S 2 CCE PPC SSF 10
PCA0CN
CCC FRC F 5 CC CC FF 43 CC CC FF 21 C C F 0
PCA0L read
To SFR Bus
Snapshot Register
SYSCLK/12 SYSCLK/4 Timer 0 Overflow ECI SYSCLK External Clock/8 000 001 010 011 100 101 0 1
PCA0H
PCA0L
Overflow CF To PCA Modules
To PCA Interrupt System
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24.2.
Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP-51 system controller. These registers are used to exchange data with a module and configure the module's mode of operation. Table 24.2 summarizes the bit settings in the PCA0CPMn registers used to select the PCA0 capture/compare module's operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit (EIE1.3) to logic 1. See Figure 24.3 for details on the PCA interrupt configuration.
Table 24.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM X X X X X X 0 1 X X X CAPP CAPN 1 0 1 0 1 1 0 0 0 0 0 MAT 0 0 0 1 1 0 0 0 TOG 0 0 0 0 1 1 0 0 PWM ECCF Operation Mode Capture triggered by positive edge on 0 X CEXn Capture triggered by negative edge on 0 X CEXn Capture triggered by transition on 0 X CEXn 0 X Software Timer 0 X High Speed Output 1 X Frequency Output 1 0 8-Bit Pulse Width Modulator 1 0 16-Bit Pulse Width Modulator
1 0 1 0 1 0 1 0 1 0 X = Don't Care
Figure 24.3. PCA Interrupt Block Diagram
(for n = 0 to 5)
PCA0CPMn
PEC WCA MOP 1 MP 6nn n CMT P E A A OWC P TGMC Nnn nF n n
PCA0CN
CCC FRC F 5 C C F 4 C C F 3 C C F 2 C C F 1 C C F 0 C I D L
PCA0MD
C P S 2 C P S 1 CE PC SF 0
PCA Counter/ Timer Overflow
0 1
ECCF0
PCA Module 0 (CCF0)
ECCF1
0 1
EPCA0 (EIE.3)
0 1
EA (IE.7)
0 1
Interrupt Priority Decoder
PCA Module 1 (CCF1)
ECCF2
0 1
PCA Module 2 (CCF2)
ECCF3
0 1
PCA Module 3 (CCF3)
ECCF4
0 1
PCA Module 4 (CCF4)
ECCF5
0 1
PCA Module 5 (CCF5)
0 1
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24.2.1. Edge-triggered Capture Mode
Preliminary
In this mode, a valid transition on the CEXn pin causes PCA0 to capture the value of the PCA0 counter/timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn register are used to select the type of transition that triggers the capture: low-tohigh transition (positive edge), high-to-low transition (negative edge), or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software.
Figure 24.4. PCA Capture Mode Diagram
PCA Interrupt
PCA0CPMn
P ECCMT P E WC A A AOWC MOPP TGMC 1 MPN n n n F 6nnn n n
PCA0CN
CCCCCCCC FRCCCCCC FFFFFF 543210
(to CCFn)
PCA0CPLn
PCA0CPHn
0
Port I/O
Crossbar
CEXn
1 0 1 PCA Timebase
Capture
PCA0L
PCA0H
Note: The signal at CEXn must be high or low for at least 2 system clock cycles in order to be valid.
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24.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA0 counter/timer is compared to the module's 16-bit capture/compare register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software Timer mode.
Figure 24.5. PCA Software Timer Mode Diagram
Write to PCA0CPLn Reset Write to PCA0CPHn PCA Interrupt
ENB
0
ENB
1
PCA0CPMn
P ECCMT P E WC A A AOWC MOPP TGMC 1 MP N n n n F 6nnn n n
x 00 00x Enable Match
PCA0CN PCA0CPLn PCA0CPHn
CCCCCCCC FRCCCCCC FFFFFF 543210
0 1
16-bit Comparator
PCA Timebase
PCA0L
PCA0H
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24.2.3. High Speed Output Mode
Preliminary
In High Speed Output mode, a module's associated CEXn pin is toggled each time a match occurs between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and PCA0CPLn) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the High-Speed Output mode.
Figure 24.6. PCA High Speed Output Mode Diagram
Write to PCA0CPLn Reset Write to PCA0CPHn 0
ENB
PCA0CPMn
ENB
1
P ECCMT P E WC A A AOWC MOPP TGMC 1 MP N n n n F n 6nnn n
x 00 0x
PCA Interrupt
PCA0CN PCA0CPLn PCA0CPHn
CCCCCCCC FRCCCCCC FFFFFF 543210
Enable
16-bit Comparator
Match
0 1
TOGn
Toggle
0 CEXn 1
Crossbar
Port I/O
PCA Timebase
PCA0L
PCA0H
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24.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module's associated CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the output is toggled. The frequency of the square wave is then defined by Equation 24.1.
Equation 24.1. Square Wave Frequency Output F PCA Fsqr = ---------------------------------------2 x PCA0CPHn
Where FPCA is the frequency of the clock selected by the CPS2-0 bits in the PCA mode register, PCA0MD. The lower byte of the capture/compare module is compared to the PCA0 counter low byte; on a match, CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn. Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn register.
Figure 24.7. PCA Frequency Output Mode
PCA0CPMn
P ECCMT P E WC A A AOWC MOPP TGMC 1 MP N n n n F 6nnn n n
0 0001 0 Enable
PCA0CPLn
8-bit Adder
Adder Enable
PCA0CPHn
TOGn
Toggle 8-bit Comparator
match
0 CEXn 1
Crossbar
Port I/O
PCA Timebase
PCA0L
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24.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate pulse width modulated (PWM) outputs on its associated CEXn pin. The frequency of the output is dependent on the timebase for the PCA0 counter/timer. The duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register. When the value in the low byte of the PCA0 counter/timer (PCA0L) is equal to the value in PCA0CPLn, the output on the CEXn pin will be high. When the count value in PCA0L overflows, the CEXn output will be low (see Figure 24.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00, PCA0CPLn is reloaded automatically with the value stored in the counter/timer's high byte (PCA0H) without software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register enables 8-Bit Pulse Width Modulator mode. The duty cycle for 8-Bit PWM Mode is given by Equation 24.2.
Equation 24.2. 8-Bit PWM Duty Cycle ( 256 - PCA0CPHn ) DutyCycle = -------------------------------------------------256
Figure 24.8. PCA 8-Bit PWM Mode Diagram
PCA0CPHn
PCA0CPMn
P ECCMT P E WC A A AOWC MOPP TGMC 1 MPN n n n F 6nnn n n
0 0000 0 Enable
PCA0CPLn
8-bit Comparator
match
S
SET
Q
CEXn
Crossbar
Port I/O
R
PCA Timebase
CLR
Q
PCA0L
Overflow
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24.2.6. 16-Bit Pulse Width Modulator Mode
Each PCA0 module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare module defines the number of PCA0 clocks for the low time of the PWM signal. When the PCA0 counter matches the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is asserted low. To output a varying duty cycle, new value writes should be synchronized with PCA0 CCFn match interrupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn register. For a varying duty cycle, CCFn should also be set to logic 1 to enable match interrupts. The duty cycle for 16-Bit PWM Mode is given by
Equation 24.3. 16-Bit PWM Duty Cycle ( 65536 - PCA0CPn ) DutyCycle = ---------------------------------------------------65536
Figure 24.9. PCA 16-Bit PWM Mode
PCA0CPMn
P ECCMT P E WC A A A OWC MOP P TGMC 1 MP N n n n F 6nnn n n
1 0000 0 Enable
PCA0CPHn
PCA0CPLn
16-bit Comparator
match
S
SET
Q
CEXn
Crossbar
Port I/O
R
PCA Timebase
CLR
Q
PCA0H
PCA0L
Overflow
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24.3. Register Descriptions for PCA0
Following are detailed descriptions of the special function registers related to the operation of PCA0.
Figure 24.10. PCA0CN: PCA Control Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CF
Bit7
CR
Bit6
CCF5
Bit5
CCF4
Bit4
CCF3
Bit3
CCF2
Bit2
CCF1
Bit1
CCF0
Bit0
00000000
SFR Address: 0xD8 SFR Page: 0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
CF: PCA Counter/Timer Overflow Flag. Set by hardware when the PCA0 Counter/Timer overflows from 0xFFFF to 0x0000. When the Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vector to the CF interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CR: PCA0 Counter/Timer Run Control. This bit enables/disables the PCA0 Counter/Timer. 0: PCA0 Counter/Timer disabled. 1: PCA0 Counter/Timer enabled. CCF5: PCA0 Module 5 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF interrupt is enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF4: PCA0 Module 4 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF interrupt is enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF3: PCA0 Module 3 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF interrupt is enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF2: PCA0 Module 2 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF interrupt is enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF1: PCA0 Module 1 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF interrupt is enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. CCF0: PCA0 Module 0 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF interrupt is enabled, set-
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Figure 24.11. PCA0MD: PCA0 Mode Register
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CIDL
Bit7
WDTE
Bit6
WDLCK
Bit5
Bit4
CPS2
Bit3
CPS1
Bit2
CPS0
Bit1
ECF
Bit0
01000000
SFR Address: 0xD9 SFR Page: 0
Bit7:
Bits6-4: Bits3-1:
CIDL: PCA0 Counter/Timer Idle Control. Specifies PCA0 behavior when CPU is in Idle Mode. 0: PCA0 continues to function normally while the system controller is in Idle Mode. 1: PCA0 operation is suspended while the system controller is in Idle Mode. UNUSED. Read = 000b, Write = don't care. CPS2-CPS0: PCA0 Counter/Timer Pulse Select. These bits select the timebase source for the PCA0 counter CPS2 0 0 0 0 1 1 1 1 CPS1 0 0 1 1 0 0 1 1 CPS0 0 1 0 1 0 1 0 1 Timebase System clock divided by 12 System clock divided by 4 Timer 0 overflow High-to-low transitions on ECI (max rate = system clock divided by 4) System clock External clock divided by 8 (synchronized with system clock) Reserved Reserved
Bit0:
ECF: PCA Counter/Timer Overflow Interrupt Enable. This bit sets the masking of the PCA0 Counter/Timer Overflow (CF) interrupt. 0: Disable the CF interrupt. 1: Enable a PCA0 Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
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Figure 24.12. PCA0CPMn: PCA0 Capture/Compare Mode Registers
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PWM16n
Bit7
ECOMn
Bit6
CAPPn
Bit5
CAPNn
Bit4
MATn
Bit3
TOGn
Bit2
PWMn
Bit1
EECFn
Bit0
00000000
SFR Address: PCA0CPM0: 0xDA, PCA0CPM1: 0xDB, PCA0CPM2: 0xDC, PCA0CPM3: 0xDD, PCA0CPM4: 0xDE, PCA0CPM5: 0xDF SFR Page: PCA0CPM0: page 0, PCA0CPM1: page 0, PCA0CPM2: page 0, PCA0CPM3: 0, PCA0CPM4: page 0, PCA0CPM5: page 0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
PWM16n: 16-bit Pulse Width Modulation Enable This bit selects 16-bit mode when Pulse Width Modulation mode is enabled (PWMn = 1). 0: 8-bit PWM selected. 1: 16-bit PWM selected. ECOMn: Comparator Function Enable. This bit enables/disables the comparator function for PCA0 module n. 0: Disabled. 1: Enabled. CAPPn: Capture Positive Function Enable. This bit enables/disables the positive edge capture for PCA0 module n. 0: Disabled. 1: Enabled. CAPNn: Capture Negative Function Enable. This bit enables/disables the negative edge capture for PCA0 module n. 0: Disabled. 1: Enabled. MATn: Match Function Enable. This bit enables/disables the match function for PCA0 module n. When enabled, matches of the PCA0 counter with a module's capture/compare register cause the CCFn bit in PCA0MD register to be set to logic 1. 0: Disabled. 1: Enabled. TOGn: Toggle Function Enable. This bit enables/disables the toggle function for PCA0 module n. When enabled, matches of the PCA0 counter with a module's capture/compare register cause the logic level on the CEXn pin to toggle. If the PWMn bit is also set to logic 1, the module operates in Frequency Output Mode. 0: Disabled. 1: Enabled. PWMn: Pulse Width Modulation Mode Enable. This bit enables/disables the PWM function for PCA0 module n. When enabled, a pulse width modulated signal is output on the CEXn pin. 8-bit PWM is used if PWM16n is logic 0; 16-bit mode is used if PWM16n logic 1. If the TOGn bit is also set, the module operates in Frequency Output Mode. 0: Disabled. 1: Enabled. ECCFn: Capture/Compare Flag Interrupt Enable. This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt. 0: Disable CCFn interrupts. 1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
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Figure 24.13. PCA0L: PCA0 Counter/Timer Low Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xF9 SFR Page: 0 Reset Value
00000000
Bits 7-0:
PCA0L: PCA0 Counter/Timer Low Byte. The PCA0L register holds the low byte (LSB) of the 16-bit PCA0 Counter/Timer.
Figure 24.14. PCA0H: PCA0 Counter/Timer High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 SFR Address: 0xFA SFR Page: 0 Reset Value
00000000
Bits 7-0:
PCA0H: PCA0 Counter/Timer High Byte. The PCA0H register holds the high byte (MSB) of the 16-bit PCA0 Counter/Timer.
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Figure 24.15. PCA0CPLn: PCA0 Capture Module Low Byte
R/W Bit7 SFR Page: R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address: PCA0CPL0: 0xFB, PCA0CPL1: 0xFD, PCA0CPL2: 0xE9, PCA0CPL3: 0xEB, PCA0CPL4: 0xED, PCA0CPL5: 0xE1 PCA0CPL0: page 0, PCA0CPL1: page 0, PCA0CPL2: page 0, PCA0CPL3: page 0, PCA0CPL4: page 0, PCA0CPL5: page 0
\ Bits7-0: PCA0CPLn: PCA0 Capture Module Low Byte. The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
Figure 24.16. PCA0CPHn: PCA0 Capture Module High Byte
R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W Bit2 R/W Bit1 R/W Bit0 Reset Value
00000000
SFR Address: PCA0CPH0: 0xFC, PCA0CPH1: 0xFD, PCA0CPH2: 0xEA, PCA0CPH3: 0xEC, PCA0CPH4: 0xEE, PCA0CPH5: 0xE2 SFR Page: PCA0CPH0: page 0, PCA0CPH1: page 0, PCA0CPH2: page 0, PCA0CPH3: page 0, PCA0CPH4: page 0, PCA0CPH5: page 0
Bits7-0:
PCA0CPHn: PCA0 Capture Module High Byte. The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
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25.
JTAG (IEEE 1149.1)
Each MCU has an on-chip JTAG interface and logic to support boundary scan for production and in-system testing, Flash read/write operations, and non-intrusive in-circuit debug. The JTAG interface is fully compliant with the IEEE 1149.1 specification. Refer to this specification for detailed descriptions of the Test Interface and Boundary-Scan Architecture. Access of the JTAG Instruction Register (IR) and Data Registers (DR) are as described in the Test Access Port and Operation of the IEEE 1149.1 specification. The JTAG interface is accessed via four dedicated pins on the MCU: TCK, TMS, TDI, and TDO. Through the 16-bit JTAG Instruction Register (IR), any of the eight instructions shown in Figure 25.1 can be commanded. There are three DR's associated with JTAG Boundary-Scan, and four associated with Flash read/write operations on the MCU.
Figure 25.1. IR: JTAG Instruction Register
Reset Value
0x0000
Bit15 Bit0
IR Value 0x0000 0x0002 0x0004 0xFFFF 0x0082 0x0083 0x0084 0x0085
Instruction EXTEST SAMPLE/ PRELOAD IDCODE BYPASS Flash Control Flash Data Flash Address Flash Scale
Description Selects the Boundary Data Register for control and observability of all device pins Selects the Boundary Data Register for observability and presetting the scan-path latches Selects device ID Register Selects Bypass Data Register Selects FLASHCON Register to control how the interface logic responds to reads and writes to the FLASHDAT Register Selects FLASHDAT Register for reads and writes to the Flash memory Selects FLASHADR Register which holds the address of all Flash read, write, and erase operations Selects FLASHSCL Register which controls the Flash one-shot timer and readalways enable
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25.1. Boundary Scan
Preliminary
The DR in the Boundary Scan path is an 134-bit shift register. The Boundary DR provides control and observability of all the device pins as well as the SFR bus and Weak Pullup feature via the EXTEST and SAMPLE commands.
Table 25.1. Boundary Data Register Bit Definitions
EXTEST provides access to both capture and update actions, while Sample only performs a capture. Bit Action Target 0 Capture Reset Enable from MCU (C8051F121/3/5/7 devices) Update Reset Enable to /RST pin (C8051F121/3/5/7 devices) 1 Capture Reset input from /RST pin (C8051F121/3/5/7 devices) Update Reset output to /RST pin (C8051F121/3/5/7 devices) 2 Capture Reset Enable from MCU (C8051F120/2/4/6 devices) Update Reset Enable to /RST pin (C8051F120/2/4/6 devices) 3 Capture Reset input from /RST pin (C8051F120/2/4/6 devices) Update Reset output to /RST pin (C8051F120/2/4/6 devices) 4 Capture External Clock from XTAL1 pin Update Not used 5 Capture Weak pullup enable from MCU Update Weak pullup enable to Port Pins 6, 8, 10, 12, 14, 16, Capture P0.n output enable from MCU (e.g. Bit6=P0.0, Bit8=P0.1, etc.) 18, 20 Update P0.n output enable to pin (e.g. Bit6=P0.0oe, Bit8=P0.1oe, etc.) 7, 9, 11, 13, 15, 17, Capture P0.n input from pin (e.g. Bit7=P0.0, Bit9=P0.1, etc.) 19, 21 Update P0.n output to pin (e.g. Bit7=P0.0, Bit9=P0.1, etc.) 22, 24, 26, 28, 30, Capture P1.n output enable from MCU 32, 34, 36 Update P1.n output enable to pin 23, 25, 27, 29, 31, Capture P1.n input from pin 33, 35, 37 Update P1.n output to pin 38, 40, 42, 44, 46, Capture P2.n output enable from MCU 48, 50, 52 Update P2.n output enable to pin 39, 41, 43, 45, 47, Capture P2.n input from pin 49, 51, 53 Update P2.n output to pin 54, 56, 58, 60, 62, Capture P3.n output enable from MCU 64, 66, 68 Update P3.n output enable to pin 55, 57, 59, 61, 63, Capture P3.n input from pin 65, 67, 69 Update P3.n output to pin 70, 72, 74, 76, 78, Capture P4.n output enable from MCU 80, 82, 84 Update P4.n output enable to pin 71, 73, 75, 77, 79, Capture P4.n input from pin 81, 83, 85 Update P4.n output to pin 86, 88, 90, 92, 94, Capture P5.n output enable from MCU 96, 98, 100 Update P5.n output enable to pin 87, 89, 91, 93, 95, Capture P5.n input from pin 97, 99, 101 Update P5.n output to pin 102, 104, 106, 108, Capture P6.n output enable from MCU 110, 112, 114, 116 Update P6.n output enable to pin 103, 105, 107, 109, Capture P6.n input from pin 111, 113, 115, 117 Update P6.n output to pin
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Table 25.1. Boundary Data Register Bit Definitions
Bit 118, 120, 122, 124, 126, 128, 130, 132 119, 121, 123, 125, 127, 129, 131, 133 Action Capture Update Capture Update Target P7.n output enable from MCU P7.n output enable to pin P7.n input from pin P7.n output to pin
25.1.1. EXTEST Instruction
The EXTEST instruction is accessed via the IR. The Boundary DR provides control and observability of all the device pins as well as the Weak Pullup feature. All inputs to on-chip logic are set to logic 1.
25.1.2. SAMPLE Instruction
The SAMPLE instruction is accessed via the IR. The Boundary DR provides observability and presetting of the scanpath latches.
25.1.3. BYPASS Instruction
The BYPASS instruction is accessed via the IR. It provides access to the standard JTAG Bypass data register.
25.1.4. IDCODE Instruction
The IDCODE instruction is accessed via the IR. It provides access to the 32-bit Device ID register.
Figure 25.2. DEVICEID: JTAG Device ID Register
Reset Value
Version
Bit31 Bit28 Bit27
Part Number
Bit12 Bit11
Manufacturer ID
Bit1
1
Bit0
0xn0003243
Version = 0000b Part Number = 0000 0000 0000 0111b (C8051F120/1/2/3/4/5/6/7) Manufacturer ID = 0010 0100 001b (Cygnal Integrated Products)
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25.2.
Preliminary
Flash Programming Commands
The Flash memory can be programmed directly over the JTAG interface using the Flash Control, Flash Data, Flash Address, and Flash Scale registers. These Indirect Data Registers are accessed via the JTAG Instruction Register. Read and write operations on indirect data registers are performed by first setting the appropriate DR address in the IR register. Each read or write is then initiated by writing the appropriate Indirect Operation Code (IndOpCode) to the selected data register. Incoming commands to this register have the following format: 19:18 IndOpCode 17:0 WriteData
IndOpCode: These bit set the operation to perform according to the following table: IndOpCode 0x 10 11 Operation Poll Read Write
The Poll operation is used to check the Busy bit as described below. Although a Capture-DR is performed, no Update-DR is allowed for the Poll operation. Since updates are disabled, polling can be accomplished by shifting in/ out a single bit. The Read operation initiates a read from the register addressed by the DRAddress. Reads can be initiated by shifting only 2 bits into the indirect register. After the read operation is initiated, polling of the Busy bit must be performed to determine when the operation is complete. The write operation initiates a write of WriteData to the register addressed by DRAddress. Registers of any width up to 18 bits can be written. If the register to be written contains fewer than 18 bits, the data in WriteData should be leftjustified, i.e. its MSB should occupy bit 17 above. This allows shorter registers to be written in fewer JTAG clock cycles. For example, an 8-bit register could be written by shifting only 10 bits. After a Write is initiated, the Busy bit should be polled to determine when the next operation can be initiated. The contents of the Instruction Register should not be altered while either a read or write operation is busy. Outgoing data from the indirect Data Register has the following format: 19 0 18:1 ReadData 0 Busy
The Busy bit indicates that the current operation is not complete. It goes high when an operation is initiated and returns low when complete. Read and Write commands are ignored while Busy is high. In fact, if polling for Busy to be low will be followed by another read or write operation, JTAG writes of the next operation can be made while checking for Busy to be low. They will be ignored until Busy is read low, at which time the new operation will initiate. This bit is placed ate bit 0 to allow polling by single-bit shifts. When waiting for a Read to complete and Busy is 0, the following 18 bits can be shifted out to obtain the resulting data. ReadData is always right-justified. This allows registers shorter than 18 bits to be read using a reduced number of shifts. For example, the results from a byte-read requires 9 bit shifts (Busy + 8 bits).
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Figure 25.3. FLASHCON: JTAG Flash Control Register
Reset Value
WRMD3
Bit7
WRMD2
Bit6
WRMD1
Bit5
WRMD0
Bit4
RDMD3
Bit3
RDMD2
Bit2
RDMD1
Bit1
RDMD0
Bit0
00000000
This register determines how the Flash interface logic will respond to reads and writes to the FLASHDAT Register. Bits7-4: WRMD3-0: Write Mode Select Bits. The Write Mode Select Bits control how the interface logic responds to writes to the FLASHDAT Register per the following values: 0000: A FLASHDAT write replaces the data in the FLASHDAT register, but is otherwise ignored. 0001: A FLASHDAT write initiates a write of FLASHDAT into the memory address by the FLASHADR register. FLASHADR is incremented by one when complete. 0010: A FLASHDAT write initiates an erasure (sets all bytes to 0xFF) of the Flash page containing the address in FLASHADR. The data written must be 0xA5 for the erase to occur. FLASHADR is not affected. If FLASHADR = 0x1FBFE - 0x1FBFF, the entire user space will be erased (i.e. entire Flash memory except for Reserved area 0x1FC00 - 0x1FFFF). (All other values for WRMD3-0 are reserved.) RDMD3-0: Read Mode Select Bits. The Read Mode Select Bits control how the interface logic responds to reads to the FLASHDAT Register per the following values: 0000: A FLASHDAT read provides the data in the FLASHDAT register, but is otherwise ignored. 0001: A FLASHDAT read initiates a read of the byte addressed by the FLASHADR register if no operation is currently active. This mode is used for block reads. 0010: A FLASHDAT read initiates a read of the byte addressed by FLASHADR only if no operation is active and any data from a previous read has already been read from FLASHDAT. This mode allows single bytes to be read (or the last byte of a block) without initiating an extra read. (All other values for RDMD3-0 are reserved.)
Bits3-0:
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Figure 25.6. FLASHADR: JTAG Flash Address Register
Reset Value
0x00000
Bit16 Bit0
This register holds the address for all JTAG Flash read, write, and erase operations. This register autoincrements after each read or write, regardless of whether the operation succeeded or failed. Bits15-0: Flash Operation 17-bit Address.
Figure 25.4. FLASHDAT: JTAG Flash Data Register
Reset Value
0000000000
Bit9 Bit0
This register is used to read or write data to the Flash memory across the JTAG interface. Bits9-2: Bit1: DATA7-0: Flash Data Byte. FAIL: Flash Fail Bit. 0: Previous Flash memory operation was successful. 1: Previous Flash memory operation failed. Usually indicates the associated memory location was locked. BUSY: Flash Busy Bit. 0: Flash interface logic is not busy. 1: Flash interface logic is processing a request. Reads or writes while BUSY = 1 will not initiate another operation
Bit0:
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Figure 25.5. FLASHSCL: JTAG Flash Scale Register
Reset Value
Bit7
Bit6 Bit5
FLRT
Bit4
Reserved
Bit3
Reserved
Bit2
Reserved
Bit1
FLWE
Bit0
10000000
Bits 7-6: Bits 5-4:
Bits 3-1: Bit0:
Unused. FLRT: FLASH Read Time. These bits should be programmed to the smallest allowed value, according to the system clock speed. 00: SYSCLK <= 25 MHz. 01: SYSCLK <= 50 MHz. 10: SYSCLK <= 75 MHz. 11: SYSCLK <= 100 MHz. RESERVED. Read = 000b. Must Write 000b. FLWE: FLASH Write/Erase Enable This bit must be set to allow FLASH writes/erases from user software. 0: FLASH writes/erases disabled. 1: FLASH writes/erases enabled.
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25.3. Debug Support
Preliminary
Each MCU has on-chip JTAG and debug logic that provides non-intrusive, full speed, in-circuit debug support using the production part installed in the end application, via the four pin JTAG I/F. Cygnal's debug system supports inspection and modification of memory and registers, breakpoints, and single stepping. No additional target RAM, program memory, or communications channels are required. All the digital and analog peripherals are functional and work correctly (remain synchronized) while debugging. The Watchdog Timer (WDT) is disabled when the MCU is halted during single stepping or at a breakpoint. The C8051F120DK is a development kit with all the hardware and software necessary to develop application code and perform in-circuit debug with the C8051F12x family. Each kit includes an Integrated Development Environment (IDE) which has a debugger and integrated 8051 assembler. The kit also includes an RS-232 to JTAG interface module referred to as the Serial Adapter. There is also a target application board with a C8051F120 installed. RS-232 and JTAG cables and wall-mount power supply are also included.
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Disclaimers
Life support: These products are not designed for use in life support appliances or systems where malfunction of these products can reasonably be expected to result in personal injury. Cygnal Integrated Products customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Cygnal Integrated Products for any damages resulting from such applications. Right to make changes: Cygnal Integrated Products reserves the right to make changes, without notice, in the products, including circuits and/or software, described or contained herein in order to improve design and/or performance. Cygnal Integrated Products assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask work infringement, unless otherwise specified.
CYGNAL INTEGRATED PRODUCTS 4301 Westbank Drive Suite B-100 Austin, TX 78746 www.cygnal.com
CIP-51 is a trademark of Cygnal Integrated Products, Inc. MCS-51 and SMBus are trademarks of Intel Corporation. SPI is a trademark of Motorola, Inc. I2C is a trademark of Philips Semiconductor.
(c) 2002 Cygnal Integrated Products, Inc. DS008-0.8-AUG02
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Preliminary
Notes
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DS008-0.8-AUG02 (c) 2002 Cygnal Integrated Products, Inc.

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