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IRCC
Infrared Communications Controller
FEATURES
* * * * * Multi-Protocol Serial Communications Controller Full IrDA v1.1 Implementation: 2.4Kbps, 115.2Kbps, .576Mbps, 1.152Mbps and 4Mbps Consumer Infrared (TV Remote Control) Interface SHARP Amplitude Shift Keyed Infrared (ASK IR) Interface Direct Rx/Tx Infrared Diode Control (Raw) and General Purpose Data Pins * * Programmable High-Speed Synchronous Communications Engine (SCE) with a 128Byte FIFO and Programmable Threshold High-Speed NS16C550A-Compatible Universal Asynchronous Receiver/ Transmitter Interface (ACE UART2) with 16Byte Send and Receive FIFOs ISA Single-Byte and Burst-Mode DMA and Interrupt-Driven Programmed I/O with Zero Wait State and String Move Timing 16-bit CRC-CCITT and 32-bit IEEE 802 CRC32 Hardware CRC Generators
* *
GENERAL DESCRIPTION
This document describes the Infrared Communications Controller (IRCC) function which is common to a number of SMSC products including the FDC37C669FR, FDC37C93xFR, and FDC37C957FR devices. The IRCC consists of two main architectural blocks: the ACE 16550A UART and a Synchronous Communications Engine (SCE) (Figure 2). Each block is supported by its own unique register set. The IRCC UART-driven IrDA SIR and SHARP ASK modes are backward-compatible with early SMSC Super I/O and Ultra I/O infrared implementations. The IRCC SCE supports IrDA v1.1 .576Mbps, 1.152Mbps, 4Mbps, and Consumer IR modes. All of the SCE modes use DMA. The IRCC offers flexible signal routing and programmable output control through the Raw mode interface, General Purpose Data pins and Output Multiplexer. Chip-level address decoding is required to access the IRCC register sets.
TABLE OF CONTENTS
FEATURES............................................................................................................................................. 1 GENERAL DESCRIPTION ..................................................................................................................... 1 INTERFACE DESCRIPTION .................................................................................................................. 4 PORTS ............................................................................................................................................ 4 CHIP-LEVEL CONFIGURATION CONTROLS................................................................................ 6 RAW IR................................................................................................................................................... 8 CONSUMER IR (TV REMOTE) .............................................................................................................. 9 INTRODUCTION ............................................................................................................................. 9 DESCRIPTION .............................................................................................................................. 10 IrDA SIR AND SHARP ASK IR INTERFACE........................................................................................ 14 INFRARED DATA ASSOCIATION ................................................................................................ 19 REGISTERS ......................................................................................................................................... 24 ACE UART CONTROLS................................................................................................................ 24 SCE CONTROLS .......................................................................................................................... 25 MASTER BLOCK CONTROL REGISTER..................................................................................... 26 REGISTER BLOCK ZERO ............................................................................................................ 27 REGISTER BLOCK ONE .............................................................................................................. 32 REGISTER BLOCK TWO.............................................................................................................. 36 REGISTER BLOCK THREE .......................................................................................................... 37 REGISTER BLOCK FOUR ............................................................................................................ 38 ACE UART............................................................................................................................................ 40 REGISTER DESCRIPTION........................................................................................................... 40 SCE ...................................................................................................................................................... 55 DESCRIPTION .............................................................................................................................. 55 FRAMING ...................................................................................................................................... 55 ACTIVE FRAME INDICATOR ....................................................................................................... 55 IrDA ENCODER............................................................................................................................. 56 CONSUMER IR ENCODER .......................................................................................................... 61 LOOPBACK MODE ....................................................................................................................... 63 BUS INTERFACE I/O ........................................................................................................................... 65 FIFO MULTIPLEXER..................................................................................................................... 65 128-BYTE SCE FIFO..................................................................................................................... 65 DMA............................................................................................................................................... 67 PROGRAMMED I/O ...................................................................................................................... 71 IOCHRDY TIME-OUT.................................................................................................................... 73 ZERO WAIT STATE SUPPORT.................................................................................................... 75 OUTPUT MULTIPLEXER ..................................................................................................................... 76 CHIP-LEVEL IRCC ADDRESSING SUPPORT...................................................................................... 77 AC TIMING ........................................................................................................................................... 78
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Encoders REGISTERS ACE UART SCE Raw IR Consumer IR ASK IR Bus Interface I/O Clock Generator IrDA IR COM M Port Output M ux IR Transducer M odule
COM AUX
SM C Infrared Communications Controller
System
FIGURE 1 - SMSC IRCC FUNCTIONAL COMPONENTS
nACE Bus Interface ISA Controls Data (0-7) Address (0-2) FIFO, DMA, I/O, Interrupts Databus MUX
ACE Registers COM IrDA SIR ACE UART Sharp ASK IR Output MUX COM AUX SCE IrDA FIR Consumer SCE Registers GP/Raw/Fast G.P.
nSCE
FIGURE 2 - IRCC ARCHITECTURAL BLOCK DIAGRAM
3
INTERFACE DESCRIPTION
The Interface Description lists the signals that are required to place the IRCC in a larger chiplevel context. There are four groups of signals in this section: PORT signals, HOST BUS controls, SYSTEM controls, and CHIP-LEVEL CONFIGURATION controls. PORTS The four Ports (IR, COM, AUX, and General Purpose) provide external access for serial data and controls. The active IRCC encoder is routed through the Output Multiplexer to either the IR, COM, or AUX port. The General Purpose port provides external access for controls that are independent of the IRCC Block Control bits or the Output Multiplexer.
NAME IRRx IRTx
Table 1 - IR Port Signals SIZE (BITS) TYPE DESCRIPTION 1 1 Input Output Infrared Receive Data Infrared Transmit Data
NAME CRx CTx nRTS nDTR nCTS nDSR nDCD nRI
Table 2 - COM Port Signals SIZE (BITS) TYPE DESCRIPTION 1 1 1 1 1 1 1 1 Input Output Output Output Input Input Input Input COM Receive Data COM Transmit Data Request to Send Data Terminal Ready Clear To Send Data Set Ready Data Carrier Detect Ring Indicator
Table 3 - AUX Port Signals (e.g., can be used for high-current drivers for Consumer IR) NAME SIZE (BITS) TYPE DESCRIPTION ARx ATx 1 1 Input Output Aux. Receive Data Aux. Transmit Data
4
NAME Fast GP Data Fast
Table 4 - G. P. Port Signals SIZE (BITS) TYPE DESCRIPTION 1 1 Output Output GP Data The G.P. Data pin always reflects the state of General Purpose Data, bit 5 of SCE Line Control Register A. The state of G.P. Data is independent of the IRCC Block Controls or the Output Multiplexer. General Purpose Data General Purpose Data
The Fast pin always reflects the state of Fast, bit 6 of SCE Line Control Register A. The state of Fast is independent of the IRCC Block Controls or the Output Multiplexer. The Fast pin can be used at the chip level for IR Transceiver configuration.
NAME D0-D7 A0-A2 nIOR nIOW AEN DRQ nDACK TC IRQ IOCHRDY nSRDY
SIZE (BITS) 8 3 1 1 1 1 1 1 1 1 1
Table 5 - HOST Signals TYPE Bidirectional Input Input Input Input Output Input Input Output Output Output
DESCRIPTION Host Data Bus IRCC Register Address Bus ISA I/O Read ISA I/O Write ISA Address Enable DMA Request ISA DMA Acknowledge ISA DMA Terminal Count Interrupt Request ISA I/O Channel Ready
ISA Synchronous Ready (Zero Wait State)
5
NAME CLK RESET Power Down DMAEN IRQEN nACE nSCE VCC GND DMAEN
SIZE (BITS) 1 1 1 1 1 1 1
Table 6 - SYSTEM Signals TYPE Input Input Input Output Output Input Input Power Power
DESCRIPTION System Clock IRCC System Reset Low Power Control DRQ Tristate Control IRQ Tristate Control
ACE 550 Register Bank Select SCE Register Bank Select System Supply System Ground CHIP-LEVEL CONFIGURATION CONTROLS The following signals come from chip-level configuration registers. There are two types of Chip-Level Configuration Controls: IRCC-Specific controls, and Legacy Controls. Both types have equivalent controls in either the IRCC ACE or SCE Registers. The IRCC-Specific controls have been newly added primarily to support the IRCC block. Provisions have been made in new chip-level configuraton contexts to accommodate these signals. The Legacy controls already exist in other contexts. Provisions have been made in legacy devices to accommodate these controls from either the Chip-Level Configuration Registers or the IRCC Registers; i.e., the last updated value from either source determines the current control state and is visible in both registers.
DMAEN is used by the chip-level interface to tristate the IRCC DRQ output when the DMA Enable bit is inactive. The DMA Enable bit is located in SCE Configuration Register B, bit 0. IRQEN IRQEN is used by the chip-level interface to tristate the IRCC IRQ output when the OUT2 bit is inactive. The OUT2 bit is located in 16550A MODEM Control Register. Power Down The Power Down pin is used by the chip-level interface to put the SCE into low power mode. NOTE: Power Down does not force the ACE550 into low power mode.
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NAME DMA Channel IRQ Level DMA Channel
Table 7 - IRCC-Specific Chip-Level Controls SIZE (BITS) TYPE DESCRIPTION 4 4 Input Input IRQ Level 4-bit bus from a chip-level configuration register, used to identify the current IRCC IRQ level. The value appears in the lower nibble of IRCC Register Block Three, Address Four. ISA DMA Channel Number ISA Interrupt Level
4-bit bus from a chip-level configuration register, used to identify the current IRCC DMA channel number. The value appears in the upper nibble of IRCC Register Block Three, Address Four.
NAME Tx Polarity Rx Polarity Half Duplex IR Mode IR Location Tx Polarity
Table 8 - Legacy Chip-Level Controls SIZE (BITS) TYPE DESCRIPTION 1 1 1 3 2 Input Input Input Input Input Output Mux. Transmit Polarity Output Mux. Receive Polarity 16550A UART Half Duplex Control IR Mode Register Bits IR Option Register Location Bits IR Mode Typically part of a 16550A Serial Port Option Register. These values are also part of the IRCC Block Control bits 3-5, Register Block One, Address Zero. IR Location
Typically part of a 16550A Serial Port Option Register. The value also appears in IRCC Register Block One, Address Zero. Rx Polarity Typically part of a 16550A Serial Port Option Register. The value also appears in IRCC Register Block One, Address Zero. Half Duplex Typically part of a 16550A Serial Port Option Register. The value also appears in IRCC Register Block One, Address Zero.
Typically part of a 16550A Serial Port IR Option Register. These values are the IRCC Output Mux bits, Register Block One, Address One. NOTE: These legacy controls are uniformly updated in the IRCC and the Top-level Device Configuration Registers only when either set of registers are explicitly written using IOW or following a device-level POR. IRCC software resets will not affect the legacy bits.
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OPERATION MODES
RAW IR In Raw mode the state of the IR emitter and detector can be directly accessed through the host interface (Figure 3). The IR emitter tracks the Raw Tx Control bit. For example, depending on the state of the Tx Polarity control a logic '1' may turn the LED on and a logic '0' may turn the LED off. Care must be taken in software to ensure that the LED is not on continuously. The Raw Rx Control bit represents the state of the PIN diode. For example, depending on the state of the Rx Polarity control a logic '1' may mean no IR is detected, a logic '0' may mean IR is being detected. If an IR carrier is being received, the Raw Rx Control bit will oscillate at the carrier frequency. If enabled, a Raw Mode Interrupt will be generated when the Raw Rx Control bit transitions to the active state, depending on the state of the Rx Polarity control.
Encoder/Decoder RAW Tx Registers Transition Detect Interrupt RAW Rx Enable
FIGURE 3 - RAW IR BLOCK DIAGRAM
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CONSUMER IR (TV REMOTE)
INTRODUCTION The IRCC Consumer IR (TV Remote) block is a general-purpose programmable Amplitude Shift Keyed serial communications interface that includes a Carrier Frequency Divider, a Programmable Receive Carrier Range Sensitivity Register, and Receive and Transmit Modulators (Figure 4). The Consumer IR block transfers data between the SCE and Output Multiplexer without framing as a fixed bit-cell serial NRZ data stream. The components of this block can also modulate and demodulate serial data at programmable bit rates and carrier frequencies. Variable length encoding and all packet framing is handled by system software. Consequently, many encoding methods, modulation frequencies and bit rates can be supported, including 38KHz PPM, PWM and RC-5 TV Remote formats. Register controls for this block can be found in Register Block Two. They are the Consumer IR Control Register, the Consumer IR Carrier Rate Register, and the Consumer IR Bit Rate Register.
Encoder/Decoder
Tx Enable Transmit Bit-Rate Divider TV Tx
SCE
Clock Carrier Off Receive Bit-Rate Divider Rx Enable Sync
Carrier Frequency Divider Programmable Receive Carrier Sense Range
TV Rx
FIGURE 4 - IRCC CONSUMER IR (TV REMOTE) BLOCK
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DESCRIPTION Carrier Frequency Divider The Carrier Frequency Divider register is used to program the ASK carrier frequency for the transmit modulator and receive detector (Figure 5). The divider is eight bits wide. The input clock to the Carrier Frequency Divider is 1.6MHz (48MHz / 30). The relationship between the divider value (CFD) and the carrier frequency (Fc) is as follows: CFD = (1.6MHz/Fc) - 1
For example, program the Carrier Frequency Divider register with 41 ('29'Hex) for a 38KHz TV Remote: Fc = 38.095KHz. This is ~.25% accuracy. Table 9 contains representative CFD vs. Carrier Frequency relationships. The Carrier Frequency range is 1.6MHz to 6.25KHz. The carrier frequency encoder/decoder can be defeated using the Carrier Off bit. When Carrier Off is one, the transmitter outputs a nonmodulated SCE serial NRZ data stream at the programmed bit rate; the receiver does not attempt to demodulate a carrier from the incoming serial data stream.
Table 9 - Representative Carrier Frequencies
CFD 001 005 009 013 017 021 025 029 033 037 041 045 049 053 057 061 Fc (KHz) 800.000 266.667 160.000 114.286 88.889 72.727 61.538 53.333 47.059 42.105 38.095 34.783 32.000 29.630 27.586 25.806 CFD 065 069 073 077 081 085 089 093 097 101 105 109 113 117 121 125 Fc (KHz) 24.242 22.857 21.622 20.513 19.512 18.605 17.778 17.021 16.327 15.686 15.094 14.545 14.035 13.559 13.115 12.698 CFD 129 133 137 141 145 149 153 157 161 165 169 173 177 181 185 189 Fc (KHz) 12.308 11.940 11.594 11.268 10.959 10.667 10.390 10.127 9.877 9.639 9.412 9.195 8.989 8.791 8.602 8.421 CFD 193 197 201 205 209 213 217 221 225 229 233 237 241 245 249 253 Fc (KHz) 8.247 8.081 7.921 7.767 7.619 7.477 7.339 7.207 7.080 6.957 6.838 6.723 6.612 6.504 6.400 6.299
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Bit Rate Divider The Transmit and Receive Bit Rate Divider register is used to extract a serial NRZ data stream for the IRCC SCE. The divider is eight bits wide. The input clock to the Bit Rate Divider is 100KHz (Carrier Frequency Divider input clock / 16). The relationship between the Bit Rate
Divider (BRD) and the Bit Rate (Fb) is as follows: BRD = (.1MHz/Fb) - 1 For example, program the Bit Rate Divider with 55 ('37'Hex) for a .562ms TV Remote bit cell: Fb = 1.786KHz. This is ~.5% accuracy. Table 10 contains representative BRD vs. Bit Rate relationships. The Bit Rate range is 100KHz to 390.625Hz.
Table 10 - Representative Bit Rates
BRD 003 007 011 015 019 023 027 031 035 039 043 047 051 055 059 063 Fb (KHz) 25.000 12.500 8.333 6.250 5.000 4.167 3.571 3.125 2.778 2.500 2.273 2.083 1.923 1.786 1.667 1.563 BRD 067 071 075 079 083 087 091 095 099 103 107 111 115 119 123 127 Fb (KHz) 1.471 1.389 1.316 1.250 1.190 1.136 1.087 1.042 1.000 0.962 0.926 0.893 0.862 0.833 0.806 0.781 BRD 131 135 139 143 147 151 155 159 163 167 171 175 179 183 187 191 Fb (KHz) 0.758 0.735 0.714 0.694 0.676 0.658 0.641 0.625 0.610 0.595 0.581 0.568 0.556 0.543 0.532 0.521 BRD 195 199 203 207 211 215 219 223 227 231 235 239 243 247 251 255 Fb (KHz) 0.510 0.500 0.490 0.481 0.472 0.463 0.455 0.446 0.439 0.431 0.424 0.417 0.410 0.403 0.397 0.391
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Receive Carrier Sense The Programmable Receive Carrier Sense register is used to program the Consumer IR decoder to detect the presence of IR energy in a wide-to-narrow range of carrier frequencies. The register is two bits wide.
The range values are shown in Table 11. Carriers that fall outside of the Receive Carrier range sensitivity "abort" the message; i.e., the Abort bit is set, an EOM Interrupt is generated, and the receiver is disabled. If the "Carrier Off" bit is active, the Receive Carrier range sensitivity is disabled.
Table 11 - Receive Carrier Sense Range D1 D0 RANGE 0 0 1 1 0 1 0 1 10% 20% 40% reserved
1 SC E T x Data T ransm itter T V T x Output Tx Polarity bit = 1
0
1
Light N o Light 1/C arrier N o Light Light SC E R x Data
T V R x Input R eceiv er
R x Polarity bit = 0
1/Bit R ate
FIGURE 5 - TV REMOTE ASK ENCODE/DECODE
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Receiver Bit Cell Synchronization The Consumer IR Receiver demodulates incoming ASK waveforms into NRZ data for the SCE. The IRCC uses the edges of the demodulated incoming infrared data to indicate changes in bit state. For continuous periods of high or low data without transitions, the IRCC samples the signal level in the center of each incoming bit period. Using the Receiver Bit Cell Synchronization mechanism, any transition resets the timer that is used in the sampling process to eliminate errors due to timing differences between the receive decoder and the incoming bit period (Figure 6).
Clock 1 2 Sync 3 4
Receiver synchronization can be disabled to allow direct sampling of the demodulated incoming infrared data stream at some preset receive bit rate. This is useful in situations where the speed of the receive data is not strictly known. In such cases, the receive bit rate is set as high as possible, the Receiver Bit Cell Synchronization is disabled, and the system software is used to measure the bit-cell period from the oversampled data. The learned parameters can then be used to switch to the synchronized, fixed bit-cell mode to reduce processing overhead in the host CPU for all future transactions.
5
6
7
8 Sync
9
10
IR Rx Data NRZ Rx Data (SYNC) Clock IR Rx Data NRZ Rx Data (No SYNC) 1 1 0 0 0 1 1 1 1 0 1 1 1 0 0 0 1 1 1 0
2
3
4
5
6
7
8
9
10
11
FIGURE 6 - TV REMOTE RECEIVER: SYNC VS. NO SYNC
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IrDA SIR AND SHARP ASK IR INTERFACE
This infrared interface provides a two-way wireless communications port using infrared as a transmission medium. Two infrared implementations have been provided in this block of the IRCC, IrDA SIR and Sharp ASK IR. IrDA SIR allows serial communication at baud rates up to 115K Baud. Each word is sent serially beginning with a zero value start bit. A zero is signaled by sending a single infrared pulse at the beginning of the serial bit time. A one is signaled by sending no infrared pulse during the bit time. Please refer to Figure 7Figure 10 for the parameters of these pulses and the IrDA waveform. The ASK infrared allows serial communication at baud rates up to 19.2K Baud. Each word is sent serially beginning with a zero value start bit. A zero is signaled by sending a 500KHz waveform for the duration of the serial bit time. A one is signaled by sending no transmission during the bit time. Please refer to the AC timing for the parameters of the ASKIR waveform. If the Half Duplex option is chosen, there is a time-out when the direction of the transmission is changed. This time-out starts at the last bit transferred during a transmission and blocks the receiver input until the time-out expires. If the transmit buffer is loaded with more data before the time-out expires, the timer is restarted after the new byte is transmitted. If data is loaded into the transmit buffer while a character is being received, the transmission will not start until the time-out expires after the last receive bit has been received. If the start bit of another character is received during this time-out, the timer is restarted after the new character is received. The time-out is programmable up to a maximum of 10ms through the IR Half-Duplex Time-Out Configuration Register.
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DATA
0 t2 t1
1
0
1
0
0
1
1
0
1
1
t2
t1
IRRX nIRRX
FIGURE 7 - IrDA RECEIVE TIMING
PARAMETER t1 t1 t1 t1 t1 t1 t1 t2 t2 t2 t2 t2 t2 t2 Pulse Width at 115kbaud Pulse Width at 57.6kbaud Pulse Width at 38.4kbaud Pulse Width at 19.2kbaud Pulse Width at 9.6kbaud Pulse Width at 4.8kbaud Pulse Width at 2.4kbaud Bit Time at 115kbaud Bit Time at 57.6kbaud Bit Time at 38.4kbaud Bit Time at 19.2kbaud Bit Time at 9.6kbaud Bit Time at 4.8kbaud Bit Time at 2.4kbaud
MIN 1.4 1.4 1.4 1.4 1.4 1.4 1.4
TYP 1.6 3.22 4.8 9.7 19.5 39 78 8.68 17.4 26 52 104 208 416
MAX 2.71 3.69 5.53 11.07 22.13 44.27 88.5
UNITS s s s s s s s s s s s s s s
NOTES: 1. IrDA @ 115k is HPSIR compatible. IrDA @ 2400 will allow compatibility with HP95LX and 48SX. 2. IRRX: CRC Bit 1: 1 = XMIT active low nIRRX: CRC Bit 1: 0 = XMIT active high (default)
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DATA
0 t2 t1
1
0
1
0
0
1
1
0
1
1
t2
t1
IRTX nIRTX
FIGURE 8 - IrDA TRANSMIT TIMING
PARAMETER t1 t1 t1 t1 t1 t1 t1 t2 t2 t2 t2 t2 t2 t2 Pulse Width at 115kbaud Pulse Width at 57.6kbaud Pulse Width at 38.4kbaud Pulse Width at 19.2kbaud Pulse Width at 9.6kbaud Pulse Width at 4.8kbaud Pulse Width at 2.4kbaud Bit Time at 115kbaud Bit Time at 57.6kbaud Bit Time at 38.4kbaud Bit Time at 19.2kbaud Bit Time at 9.6kbaud Bit Time at 4.8kbaud Bit Time at 2.4kbaud
MIN 1.41 1.41 1.41 1.41 1.41 1.41 1.41
TYP 1.6 3.22 4.8 9.7 19.5 39 78 8.68 17.4 26 52 104 208 416
MAX 2.71 3.69 5.53 11.07 22.13 44.27 88.55
UNITS s s s s s s s s s s s s s s
NOTES: 1. Receive Pulse Detection Criteria: A received pulse is conidered detected if the received pulse is a minimum of 1.41 s 2. IRTX: CRC Bit 0: 1 = RCV active low nIRTX: CRC Bit 0: 0 = RCV active high (default)
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DATA
0 t1
1 t2
0
1
0
0
1
1
0
1
1
IRTX nIRTX t3 MIRTX t5 nMIRTX
FIGURE 9 - AMPLITUDE SHIFT KEYED IR TRANSMIT TIMING
t4
t6
PARAMETER t1 t2 t3 t4 t5 t6 Modulated Output Bit Time Off Bit Time Modulated Output "On" Modulated Output "Off" Modulated Output "On" Modulated Output "Off"
MIN
TYP
MAX
UNITS s s
0.8 0.8 0.8 0.8
1 1 1 1
1.2 1.2 1.2 1.2
s s s s
NOTES: 1. IRTX: CRC Bit 1: 1 = XMIT active low nIRTX: CRC Bit 1: 0 = XMIT active high (default) MIRTX, nMIRTX are the modulated outputs.
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DATA
0 t1
1 t2
0
1
0
0
1
1
0
1
1
IRTX nIRTX t3 MIRTX t5 nMIRTX
FIGURE 10 - AMPLITUDE SHIFT KEYED IR RECEIVE TIMING
t4
t6
PARAMETER t1 t2 t3 t4 t5 t6 Modulated Output Bit Time Off Bit Time Modulated Output "On" Modulated Output "Off" Modulated Output "On" Modulated Output "Off"
MIN
TYP
MAX
UNITS s s
0.8 0.8 0.8 0.8
1 1 1 1
1.2 1.2 1.2 1.2
s s s s
NOTES: 1. IRRX: CRC Bit 1: 1 = RCV active low nIRRX: CRC Bit 1: 0 = RCV active high (default) MIRRX, nMIRRX are the modulated outputs.
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INFRARED DATA ASSOCIATION Description The Infrared Data Association (IrDA) was created to develop an interoperable, low-cost, low-power, half-duplex serial data interconnection standard that supports a walk-up, point-to-point user model that is adaptable to a wide range of appliances and devices. The IrDA Serial Infrared Data Link Standard, Version 1.1 is the standard to which the SMSC IRCC conforms. Relevant IrDA documents in this specification include the SIR-Physical Layer Specification, Version 1.1, October 17, 1995, the SIR-Link Access Protocol (IrLAP), Version 1.0,
June 23, 1994, and the Link Management Protocol (IrLMP), Version 1.1, January 23, 1996. The high-speed extensions (FIR) to the IrDA physical layer as described in the SIR-Physical Layer Specification appear as alternate modulation and demodulation paths for data from IrLAP bound for the IR medium and are transparent to IrLAP as it is defined for SIR. IR hardware and software must comply as a system with the entire family of IrDA specifications, including the SIR/FIR-Physical Layer Specifications, IrLAP, and IrLMP. A block diagram of one end of an IrDA link that includes the SIR and FIR physical implementations is shown in Figure 11.
UART SCE
SIR Encoder 1.152Mb/s 4Mb/s SIP FIR Encoders
FIGURE 11 - IRCC IRDA BLOCK DIAGRAM
IR Transceiver Module IR In
IR Out
SIR Interaction Pulse The SIR Interaction Pulse (SIP) is intended to guarantee non-disruptive coexistence with SIRonly systems which might otherwise interfere with Fast IR links. A SIP is defined as a 1.6 microsecond transmitter on pulse followed by 7.1 microseconds of off time (Figure 12). Once a Fast connection has been established the station must generate one SIP every 500ms.
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8.7us 1.6us SIP Active SIP Time
FIGURE 12 - SIR INTERACTION PULSE The SIR Interaction Pulse is controlled by the IRCC configuration register SIP ENABLE bit and a timer. The IRCC transmits an SIR Interaction Pulse every 500ms when the SIP enable is active, an IrDA FIR mode has been selected, and the transmitter or receiver is not otherwise engaged. The timer that controls the SIP pulse is reset whenever 1) the SIP enable is inactive, 2) an active FIR frame is being transmitted or received or, 3) during an active SIP pulse. The timer is decrementing whenever the SIP enable bit is active and the SIP pulse generator, the transmitter, and the receiver are inactive. When the timer reaches zero, the SIP pulse generator is activated (Figure 13).
SIP Timer Countdown Active Frame SIP Enable Active SIP Time Reset SIP Timer
FIGURE 13 - SIP CONTROL TIMING
SIP Timer Zero
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HDLC BOF Counting The IRCC can account for system-dependent limitations such as long interrupt latencies and transceiver stabilization times by increasing the number of STA flags at the beginning of every HDLC frame (Figure 14).
The BOF COUNT register contains the number additional start flags that are to be appended to the standard BOF characters. NOTE: the BOF COUNT extensions only apply to messages that start from an idle line state; i.e., BOF counting does not apply to brick walled messages.
BOF COUNT register Appends 0 - 4095 Flags to Beginning of Frame
STA '01111110' binary
STA ADDR '01111110' 8-bit Address binary Field
DATA 8-bit Control field plus up to 2K - 3 bytes Information Field
FIGURE 14 - EXTENDED BEGINNING-OF-FRAME
HDLC Back-to-Back Frame Transmission HDLC back-to-back, or brick walled frames are allowed with two or more flags, '7E'hex, in between. If two consecutive frames are not back-to-back, the gap between the last STO flag of the first frame and the first STA field of the second frame are separated by at least seven bit times (abort sequence).
The IrDA FIR 1.152Mbps and .576Mbps physical layer specification allows back-to-back message packets with three flag characters which act as the closing flag of the first frame and the opening flags of the brick walled packet. Additional flags can be added by programming the Brick Wall Count register (Figure 15). NOTE: The BOF COUNT extensions do not apply to brick walled messages.
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BW COUNT register Inserts 0 - 4095 Flags between Brick Walled Frames Previous Frame FCS CCITT 16-bit CRC STO '01111110' binary STA STA ADDR '01111110' '01111110' 8-bit Address binary binary Field Brick Walled Frame DATA 8-bit Control field plus up to 2K - 3 bytes Information Field
FIGURE 15 - BRICK WALLED HDLC FRAMES
4PPM BOF Counting The IRCC can account for system-dependent limitations such as long interrupt latencies and transceiver stabilization times by increasing the number of PA flags at the beginning of every 4PPM frame (Figure 16). The BOF COUNT register contains the number
BOF COUNT register Appends 0 - 4095 PA Bytes to Beginning of Frame
of additional PA bytes that are to be appended to the standard 4PPM BOF characters. NOTE: the BOF COUNT extensions only apply to messages that start from an idle line state; i.e., BOF counting does not apply to brick walled messages.
PA (#1)
...
PA (#16)
STA 8-bit Start Field
ADDR 8-bit Address Field
DATA 8-bit Control field plus up to 2K - 3 bytes Information Field
FIGURE 16 - 4PPM EXTENDED BOF
22
4PPM Back-to-Back Frame Transmission Back-to-back, or brick walled frames are allowed with 32 or more PA flag bytes between the STO field of the first frame and the STA field of the second frame.
Additional flags can be added by programming the Brick Wall Count register. NOTE: the BOF COUNT extensions do not apply to brick walled messages.
BW COUNT register Inserts 0 - 4095 PA Bytes between Brick Walled Frames Previous Frame 16-byte 16-byte PA PA Sequence Sequence Brick Walled Frame ADDR 8-bit Address Field DATA 8-bit Control field plus up to 2K - 3 bytes Information Field
STO
STA
FIGURE 17 - BRICK WALLED 4MBPS FRAMES
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REGISTERS
The IRCC is partially enabled through binary controls found in two 8-byte register banks. The banks, the ACE550 UART Controls and the SCE Controls, are selected with the nACE and nSCE register-bank selector inputs found in the Interface Description. If nACE is zero, the three least significant bits of the Host Address Bus decode the 16550A UART control registers. If nSCE is zero, the SCE control bank is addressed. All of the IRCC registers are 8 bits wide. ACE UART CONTROLS The table below (Table 12) lists the ACE UART Control Registers (see the ACE UART section).
DLAB 0 0 0 X X X X X X X 1 1
A2 0 0 0 0 0 0 1 1 1 1 0 0
Table 12 - 16550A UART Addressing A1 A0 DIRECTION REGISTER NAME 0 0 0 1 1 1 0 0 1 1 0 0 0 0 1 0 0 1 0 1 0 1 0 1 Read Write Read/Write Read Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Receive Buffer Transmit Buffer Interrupt Enable Interrupt Identification FIFO Control Line Control Modem Control Line Status Modem Status Scratchpad Divisor (LSB) Divisor (MSB)
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SCE CONTROLS The IRCC SCE Registers are arranged in 7-byte blocks. Of the eight possible register blocks, five are used in this implementation.
The Master Block Control Register controls access to the register blocks. Table 13 lists all of the SCE registers in all blocks.
BLOCK X 0 0 0 0 0 0 0 0 1 1 1 2 2 2 3 3 3 3 3 4 4 4 4 4 4 4
Table 13 - SCE Register Addressing ADDRESS DIRECTION REGISTER NAME 7 0 1 2 3 3 4 5 6 0 1 2 0 1 2 0 1 2 3 4 0 1 2 3 4 5 6 R/W R/W RO R/W RO WO R/W R/W R/W R/W R/W R/W R/W R/W R/W RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W IRQ Level IrDA Control Master Control Data Register Interrupt Identification Interrupt Enable Line Status (read) Line Status Address (write) Line Control A Line Control B Bus Status SCE Configuration A SCE Configuration B FIFO Threshold Consumer IR Control Consumer IR Carrier Rate Consumer IR Bit Rate SMSC ID (high) SMSC ID (low) CHIP ID VERSION Number DMA Channel BOF Count (high)
BOF Count (low) Brick Wall Count (low) BW Count (high) Tx Data Size (high) Tx Data Size (low) Rx Data Size (high) Rx Data Size (low)
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MASTER BLOCK CONTROL REGISTER The Master Block Control Register contains the IRCC Power Down bit, two reset bits, the Master Interrupt Enable bit, and the Register Block Select lines (Table 14).
Address A2 A1 A0 1 1 1 Direction D7 R/W power down master reset D6 D5 master int en.
Address seven is solely reserved for the Master Block Control register. If the nSCE input is zero, the MBC is always visible, regardless of the state of the Register Block Select lines.
Table 14 - SCE Master Block Control Register
Description D4 D3 error reset Default D2 D1 D0 '00'hex register block select
Master Block Control Register
Register Block Select, bits 0-2 The Register Block Select bits enable access to each of the eight possible register blocks. To access a register block other than the default (0), write a 3-bit register block number to the least significant bits of the Master Block Control Register. All subsequent reads and writes to addresses 0 through 6 will access the registers in the new block. To return to register block 0, rewrite zeros to the register block select bits. Error Reset, bit 4 Writing a one to the Error Reset bit will return all of the SCE Line Status Register bits (Register Block Zero) to their inactive states and reset the Message Count bits to zero. Master Interrupt Enable, bit 5 Setting the Master Interrupt Enable to a one enables all of the SCE interrupts only if their individual controls are enabled. Setting this bit to
a zero disables all SCE interrupts regardless of the state of their individual enables. Master Reset, bit 6 Setting the Master Reset bit to a one forces data in the SCE registers and SCE logical blocks into the Power-On-Reset state. The Master Reset bit is reset to zero following the reset operation. NOTE: The Legacy bits (Register Block One, Address Zero, Bits D0-D6) are unaffected by Master Reset. Power Down, bit 7 Setting this bit to a one causes only the SCE to enter the low-power state. Power down mode does not preclude access to the Master Block Control register so that this mode can be maintained entirely under software control.
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REGISTER BLOCK ZERO
Register Block Zero contains the SCE Data Register, the Interrupt Control/Status registers, the Line Control/Status registers, and the Bus Status register (Table 15). Table 15 - Register Block Zero
A2 0 0 Address A1 A0 0 0 0 1 Directio D7 R/W RO active frame 0 1 0 R/W active frame 0 1 1 RO underrun 0 1 1 WO over run eom eom raw mode raw mode frame error D6 D5 Description D4 D3 Data Register
Typically, the controls in Register Block Zero are used during IrDA FIR and Consumer IR message transactions.
Default D2 D1 D0 '00'hex
Interrupt Identification Register fifo
Interrupt Enable Register fifo
'00'hex
Line Status Register (read) size error crc error frame abort status register address
'00'hex
Line Status Address Register (write)
1
0
0
R/W fifo reset fast
Line Control Register A g. p. data sip enable timeout raw tx brick wall raw rx abort data done
'00'hex
1
0
1
R/W sce modes bits
Line Control Register B message count
'00'hex
1
1
0
RO not empty fifo full
Bus Status Register
'00'hex
Data Register (Address 0) The Data Register is the FIFO access port. Typically, the user will only write to the FIFO when transmitting and read from the FIFO when receiving. The Host always has read access to the FIFO regardless of the state of the SCE Modes bits or the Loopback bit. Host read access to the FIFO is blocked when the FIFO is empty. The Host has write access to the FIFO only when the Loopback bit is inactive and the SCE Modes bits are zero or Transmit mode is
enabled. Host write access to the FIFO is blocked when the FIFO is full. Interrupt Identification Register (Address 1) Active Frame, bit 7 When this bit is one, an Active Frame has occurred (see the Active Frame Indicator section). The Active Frame typically indicates that the SCE receiver has detected a valid incoming IrDA FIR or TV Remote start-of-frame sequence. Reading the Interrupt Identification register resets the Active Frame bit. 27
EOM, bit 6 When this bit is one, an End of Message has occurred. The EOM indicates the end of an IrDA FIR EOF or Abort. During Consumer IR messages EOM also indicates FIFO underruns/ overruns and DMA Terminal Counts. Reading the Interrupt Identification register resets the EOM bit. Raw Mode Interrupt, bit 5 When this bit is one, a Raw Mode interrupt has occurred. The Raw Mode Interrupt indicates that the Raw Rx Control bit has gone active. Reading the Interrupt Identification register resets the Raw Mode Interrupt bit. FIFO Interrupt, bit 4 When this bit is one, a FIFO Interrupt has occurred. The FIFO Interrupt indicates that the FIFO Interrupt Enable is active and either a TxServReq or an RxServReq has occurred. The FIFO Interrupt bit is cleared when the interrupt is disabled; i.e., reading the Interrupt Identification register does not reset the FIFO Interrupt bit. Interrupt Enable Register (Address 2) Setting any of the bits in this register to one enables the associated interrupt (see the Interrupt Identification Register) onto the Interrupt Request (IRQ) line defined in the Interface Description. Interrupts will only occur if both the interrupt enable bit and the Master Interrupt Enable bit (see the Master Block Control Register) are active. The interrupt enables do not affect the bits in the Interrupt ID (IID) register, except for the FIFO Interrupt. For example, a Raw Mode interrupt that occurs while the Raw Mode Interrupt Enable is inactive will alter the Raw Mode Interrupt indicator in the IID register but will not activate the IRQ line. Toggling the FIFO Interrupt Enable will affect the FIFO Interrupt indicator in the IID register.
Line Status Register(s) (Address 3) Error Indicators (read-only) There are eight Line Status Registers at address 3. Each register is read-only and is accessed using the three Status Register Address bits, also located at this address. The FIFO Underrun, FIFO Overrun, Frame Error, Size Error, Frame Abort, and CRC Error flags indicate the status of any one of eight IrDA FIR message frames. The Error Indicators, in all registers, are reset following a Master Reset, Power-On-Reset, and Error Reset (see the Master Block Control Register). The error indicators for the current status register only (see the Message Count bits) are reset following a valid IrDA BOF sequence. FIFO Underrun, bit 7 The FIFO Underrun bit gets set to one when the IrDA FIR transmitter runs out of FIFO data and the Data Done bit is not active. FIFO Overrun, bit 6 The FIFO Overrun bit gets set to one when the IrDA FIR receiver tries to write data to the FIFO when the FIFO Full flag is active. Frame Error, bit 5 The Frame Error bit gets set to one when IrDA framing errors are detected; for example, HDLC pulse-widths greater than one bit-cell, and invalid framing fields (see the section Framing Errors). Size Error, bit 4 The Size Error bit is set to one whenever the IrDA FIR receiver decrements the Rx Data Size count to zero before the End-Of-Frame, or whenever the the Brick Wall bit is inactive and the IrDA FIR transmitter decrements the Tx Data Size count to zero before FIFO Empty goes active.
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CRC Error, bit 3 The CRC Error bit is set to one following FrameCheck-Sequence errors in IrDA FIR receive message frames. Frame Abort, bit 2 The Frame Abort bit is set to one following; 1) a forced abort, i.e. after setting the Abort bit to one in Line Control Register A; 2) an IrDA FIR FIFO underrun with the Data Done bit inactive during transmit; 3) an IrDA FIR FIFO Overrun during receive; 4) framing errors in IrDA FIR payload data during receive. NOTE: The Frame Abort bit will not go active during transmit if the Tx Data Size register decrements to zero when the last byte is read from the FIFO with the Data Done bit not set. Status Register Address, bits 0 - 2 (writeonly) Three Status Register Address bits control software access to, and reside at the same address as, the Line Status Registers. The Status Register Address bits are write-only and occupy bits D0 to D2. To access any one of the eight Line Status Registers, first write the address of the appropriate register (0 - 7), then read the register's contents. Line Control Register A (Address 4) FIFO Reset, bit 7 When set to one, the FIFO Reset bit clears the FIFO Full and Not Empty flags in the 128-byte SCE FIFO. The FIFO Reset bit is automatically set to zero following the re-initialization. Fast, bit 6 The Fast bit controls the state of an uncommitted IRCC output, Fast. The bit is read/write. General Purpose Data, bit 5 The General Purpose Data bit controls the state
of an uncommitted IRCC output, GP Data. The bit is read/write. Raw Tx, bit 4 The Raw Tx bit controls the state of the infrared emitter in Raw IR mode. The bit is read/write. Raw Rx, bit 3 The Raw Rx bit represents the state of the infrared detector in Raw IR mode. The bit is read-only. Abort, bit 2 The Abort bit is used to terminate transmit messages in progress; i.e., once the transmitter has been enabled and the line is active. When the Abort bit is one, the current transmit message is terminated, the EOM flag is activated and the SCE FIFO is cleared. The Abort bit is reset to zero by the End-Of-Frame. Abort is used for IrDA FIR transmit mode, only. Data Done, bit 1 When set to one, the Data Done bit is used during transmit to distinguish an end-of-validmessage-data condition from a FIFO Underrun that indicates incomplete message data. Terminal Count automatically activates the Data Done bit during DMA operations. Note: the Data Done bit is not activated by TC during receive operations. Data Done is automatically reset to zero following the end of a message only if the FIFO is empty. Line Control Register B (Address 5) SCE Modes, bits 6 - 7 The SCE Modes bits enable the SCE transmitter and receiver (Table 16). These bits are R/W and must be manually reset by the host following IrDA message transactions. The SCE Modes bits are automatically reset by the hardware following Consumer IR messages. NOTE: the SCE Modes bits must be zero for loopback tests.
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D7 0 0 1 1
D6 0 1 0 1
Table 16 - SCE Modes MODE DESCRIPTION Receive/Transmit Disabled (default) Transmit Mode Receive Mode Undefined SIP Enable, bit 5 If the SIP Enable is one, an SIR Interaction Pulse occurs every 500ms if an IrDA FIR mode has been selected and the transmitter or receiver is not otherwise engaged. Brick Wall, bit 4 When the Brick Wall bit is active the IRCC sends back-to-back IrDA FIR frames separated by the number of additional flags specified in the brick wall count register. NOTE: BOF counts do not apply during brick walled messages. The Data Size register can also be used when the Brick Wall bit is active to send back-to-back IrDA FIR frames when the DMA data block is larger than the IrDA message length. In this case, if the maximum number of data bytes according to the data size register have been transferred and the DMA terminal count or the FIFO Empty flags have not been activated the next message is brick walled to the previous message (Table 17). The Brick Wall bit is software controlled only.
Transmit Mode Transmit mode enables the SCE IrDA FIR and Consumer IR transmitters whenever TC goes active, or the FIFO THRESHOLD has been exceeded. In Transmit mode, the SCE FIFO input is connected to the Host System Data Bus and the FIFO output is connected to the SCE transmitter input. Transmit mode is strictly software controlled when the IrDA FIR encoders are active. The Consumer IR encoder will reset Transmit mode in hardware following the rising edge of nActive Frame following a FIFO underrun. Receive Mode Receive mode enables the SCE IrDA FIR and Consumer IR receivers. In Receive mode, the SCE FIFO output is connected to the Host System Data Bus, the FIFO input is connected to the SCE receiver output. Receive mode is strictly software controlled when the IrDA FIR encoders are active. The Consumer IR encoder will reset Receive mode in hardware following the rising edge of nActive Frame following a FIFO underrun or TC.
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BRICK WALL ENABLE 1 1 1 1 0 0 0 0
DATA DONE BIT 1 1 0 0 1 1 0 0
Table 17 - Message Flow Control STATE AFTER FIFO EOF EMPTY DESCRIPTION 0 BOF Brick Wall Next Message 1 0 1 0 1 0 1 Idle BOF BOF Idle Idle Idle Idle Multi-Frame Window Complete, Reset Data Done bit Brick Wall Next Message Brick Wall Next Message (possible underrun) Re-enable Transmitter for Next Message Single Message Complete, Reset Data Done bit Single Message Complete, Datasize Counter = 0 Single Message Complete, Datasize Counter = 0 in Figure 18, for example, the rising edge of nActive Frame increments Message Count by one indicating that the first message has been received; i.e., Line Status Register #1 (status register address 0) is valid, and Line Status Register #2 is currently active, although undefined. Hardware prevents the Message Count register from exceeding eight ('1000'Binary). NOTE: IrDA messages beyond eight frames are ignored.
Message Count, bits 0 - 3 The four Message Count bits control hardware access to the Line Status Registers and are unaffected by the Status Register Address bits. The Message Count bits also indicate the system message-state. For example, if the Message Count bits are zero, i.e. the power-up default, Line Status Register zero is active, although undefined because no messages have been sent or received. The Message Count bits are incremented after every active frame. At point A
A nActive Frame Message Count (0000) 0001 0010 0011
FIGURE 18 - MESSAGE COUNT EXAMPLE
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Bus Status Register (Address 6) FIFO Indicators (read-only) The FIFO Indicators reflect the current status of the SCE FIFO. FIFO Not Empty, bit 7 The FIFO Not Empty bit when set to one indicates that there is data in the SCE FIFO. FIFO Full, bit 6 The FIFO Full bit when set to one indicates that there is no room for data in the SCE FIFO.
Time-Out, bit 5 The Time-Out bit is the IOCHRDY time-out error bit. The Time-Out bit when set to one indicates that an IOCHRDY time-out error has occurred. Time-Out is reset by the IRCC System Reset (see Interface Description) following a read of the Bus Status register, and following a Master Reset (see Master Block Control Register). REGISTER BLOCK ONE Register Block One contains the SCE control registers (Table 18). Typically, the controls in Register Block One are needed to configure the SCE before message transactions can occur.
Description D4 D3 Default D2 half duplx no wait string move D1 tx polarity dma burst D0 '02'hex rx polarity '00'hex dma enable '00'hex
Table 18 - Register Block One
Address A2 A1 A0 0 0 0 Direction D7 R/W aux ir 0 0 1 R/W output mux bits 0 0 1 1 1 1 1 0 0 1 0 1 0 1 0 R/W D6 D5
SCE Configuration Register A block control bits loopback lpbck tx crc
SCE Configuration Register B
FIFO Threshold Register
SCE Configuration Register A (Address 0) Auxiliary IR, bit 7 When the Auxiliary IR bit is one and the active device is routed through the Output Multiplexer to the IR Port or the COM Port, the transmit signal also appears at the Auxiliary Port. Block Control, bits 3 - 6 The Block Control bits select one of the eight IRCC operational modes (Table 19). The three
low-order Block Control bits are equivalent to the IR Mode bits in the chip-level configuration space of earlier devices; e.g., the FDC37C93X IR Option Register, Serial Port 2, Logical Device 5, Register 0xF1. Provisions have been made in legacy devices to accommodate IR Mode selection through either the chip-level configuration registers or the IRCC Block Control bits; i.e., the last write from either source determines the current mode selection and is visible in both registers.
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D6 0 0 0 0 0 0 0 0 1
D5 0 0 0 0 1 1 1 1 X
D4 0 0 1 1 0 0 1 1 X
Table 19 - IRCC Logical Block Controls D3 MODE DESCRIPTION 0 1 0 1 0 1 0 1 X COM IrDA SIR - A ASK IR IrDA SIR - B IrDA HDLC IrDA4PPM CONSUMER RAW IR OTHER 16550 UART COM Port (default) Up to 115.2Kbps, Variable 3/16 Pulse Amplitude Shift Keyed Ir Interface Up to 115.2Kbps, Fixed 1.6us Pulse Includes.576Mbps & 1.152Mbps Includes 4Mbps TV Remote Direct IR Diode Control Reserved For backward compatibility, the Tx and Rx Polarity bits do not apply to COM mode; i.e., when the Block Control bits are zero. The relationship between the Output Multiplexer port signals and the Polarity bits is an exclusive-or (Table 20). For example, if the IRRx pin in the Output Multiplexer is one and the Rx Polarity bit is zero, the signal is inactive and therefore decoded as a one. The IRCC Tx Polarity bit (bit 1) is equivalent to the Transmit Polarity bit in the chip-level configuration space of earlier devices; e.g., the FDC37C93X IR Option Register, Serial Port 2, Logical Device 5, Register 0xF1. The Rx Polarity bit (bit 0) is equivalent to the Receive Polarity bit in the same register. Provisions have been made in legacy devices to accommodate Polarity bit selection through either the chip-level configuration registers or the SCE registers; i.e., the last write from either source determines the current Polarity bit value and is visible in both registers.
Half Duplex, bit 2 When Half Duplex is zero (default), the 16550A is in full duplex mode. The Half Duplex bit only supports the 16550A UART; i.e., this bit has no effect on the IRCC SCE. The Half Duplex bit is analogous to the chip-level configuration register Half Duplex bit and has the same affect on the UART. Provisions must be made in legacy devices to accommodate Half Duplex selection through either the chip-level configuration registers or the IRCC Half Duplex bit; i.e., the last write from either source determines the current mode selection and is visible in both registers. Tx/Rx Polarity Bits, 0 - 1 The Tx and Rx Polarity bits define the active states for signals entering and exiting the Output Multiplexer ports. IRCC Active states are typically decoded as zero. The Tx Polarity bit default is one; the Rx Polarity bit default is zero.
Table 20 - Tx/Rx Polarity Bit Effects SIGNAL POLARITY BIT DECODED SIGNAL 0 0 1 1 0 1 0 1 0 1 1 0
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SCE Configuration Register B (Address 1) Output Mux, bits 7 - 6 The Output Mux bits select the Output Multiplexer port for the active encoder/decoder (Table 21). Inactive outputs depend on the state of the Tx Polarity bit when the Output Mux bits are both high, otherwise inactive outputs are always low. The Output Mux bits are equivalent to the 93X IR Option Register bits 6-7. The IR
Location Mux, bit 6, in the 93X IR Option Register is equivalent to Output Mux bit, D6; Bit 7 (Reserved) in the 93X IR Option Register is equivalent to Output Mux bit, D7. Provisions have been made in legacy devices to accommodate Output Multiplexer port selection through either the chip-level configuration registers or the Output Mux bits; i.e., the last write from either source determines the current port selection and is visible in both registers.
D7 0 0 1 1
Table 21 - IRCC Output Multiplexer D6 MUX. MODE 0 1 0 1 Active Device to COM Port (default) Active Device to IR Port Active Device to AUX Port Outputs Inactive reset the Loopback bit automatically when the Rx Data Size register reaches zero. Provisions must be made following loopback tests in all modes to verify the Rx message data in the FIFO. Loopback Transmit CRC, bit 4 When the Loopback Transmit CRC bit is set to one, the CRC generator is used by the transmitter during loopback testing regardless of the state of the CRC Select bit. Otherwise, the CRC generator is connected to the receiver (Table 22).
Loopback, bit 5 The Loopback bit configures the FIFO and enables the transmitter/receiver for loopback testing. The SCE MODES bits must be set to zero before activating the Loopback bit. When the Loopback bit is one, the SCE enters a fullduplex mode with internal loopback capability for testing. The CRC generator can be selectively reconfigured for either transmit or receive. The 128-byte FIFO input is connected to the SCE receiver output, the FIFO output is connected to the SCE transmit input. For IrDA FIR loopback tests the Loopback bit must be set to zero to exit loopback mode. Consumer IR loopback tests
LOOPBACK BIT 0 0 1 1 1 1
Table 22 - Hardware CRC Programming CRC LOOPBACK TX SELECT CRC BIT HARDWARE DESCRIPTION 0 X No CRC Generation, No CRC Checking 1 0 0 1 1 X 0 1 0 1 CRC Generation., CRC Checking No CRC Generation, No CRC Checking CRC Generation, No CRC Checking CRC Checking, No CRC Generation CRC Generation, No CRC Checking
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No Wait, bit 3 When the No Wait bit is one, the ISA Bus nSRDY signal goes active following the trailing edge of the ISA I/O command and inactive following the rising edge (see Zero Wait State Support). String Move, Bit 2 When the String Move bit is one, the programmed I/O host interface is qualified by IOCHRDY (Table 23). See IOCHRDY Time-Out. DMA Burst Mode, bit 1 When the DMA Burst Mode bit is one, DMA Burst (Demand) mode is enabled. When the
DMA Burst Mode bit is zero, Single Byte DMA mode is enabled (Table 23). DMA Enable, bit 0 DMA Enable is connected to a signal in the Interface Description called DMAEN that is used by the chip-level interface to tristate the IRCC DMA controls when the DMA interface is inactive. When the DMA Enable bit is one, the DMA host interface is active (Table 23). When the DMA Enable bit is zero (default), the nDACK and TC inputs are disabled and DRQ output is gated off.
STRING MOVE 0 1 X X
DMA BURST X X 0 1
Table 23 - I/O Interface Modes DMA ENABLE FUNCTION 0 Programmed I/O, no IOCHRDY 0 1 1 Programmed I/O, uses IOCHRDY Single Byte DMA Mode Demand Mode DMA typically reflect the overall I/O performance characteristics of the host; the lower the value, the longer the interval between service requests and the faster the host must be to successfully service them. The same threshold value can be used for both I/O read and I/O write cases.
FIFO Threshold Register (Address 2) The FIFO Threshold Register contains the programmable FIFO threshold count. The FIFO Threshold is programmable from 0 to 127. Bit 7 in the FIFO Threshold register is read-only and will always return zero. FIFO Threshold values
35
REGISTER BLOCK TWO Register Block Two contains the Consumer IR
(TV Remote) encoder/decoder registers (Table 24). Table 24 - Register Block Two
configuration
Address A2 A1 A0 0 0 0
Direction D7 R/W sync bit D6 D5
Description D4 D3
Default D2 carrier off D1 D0 '00'hex
Consumer IR (TV Remote) Control Register carrier range bits
0 0 0 1 1 1
0 1 1 0 0 1
1 0 1 0 1 0
R/W R/W
Consumer IR Carrier Rate Register Consumer IR Bit Rate Register
'29'hex '37'hex
Consumer IR Control Register (Address 0) Sync Bit, bit 7 The Sync Bit enables the receiver bit-rate clock synchronization mechanisim. When the Sync bit is one, receiver edge synchronization is enabled. Carrier Off, bit 2 The Carrier Off bit bypasses the Consumer IR Carrier generator/receiver. When the Carrier Off bit is one, the transmitter outputs a nonmodulated SCE NRZ serial data stream at the programmed bit rate. Also, when the Carrier Off bit is one, the receiver does not attempt to demodulate a carrier from the incoming data stream and samples the state of the PIN diode at the programmed bit rate.
Carrier Range, bits 0 - 1 The Consumer IR Carrier Range Bits set the carrier detect sensitivity of the receiver. The effects of this register are shown in Table 11 Receive Carrier Sense Range. Consumer IR Carrier Rate Register (Address 1) The Consumer IR Carrier Rate Register programs the ASK carrier frequency divider. The effects of this register are shown in Table 9Representative Carrier Frequencies. Consumer IR Bit Rate Register (Address2) The Consumer IR Bit Rate Register programs the transmit and receive bit-rate divider. The effects of this register are shown in Table 10 Representative Bit Rates.
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REGISTER BLOCK THREE Register Block Three contains the IRCC Block Identifier Registers. These read-only registers
Address A2 A1 A0 0 0 0 0 1 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 Direction D7 RO RO RO RO RO IRQ Level D6 D5
classify the hardware Manufacturer, the Device ID, the Version number, and Host interface parameters.
Table 25 - Register Block Three
Description D4 D3 SMSC ID (high-byte) SMSC ID (low-byte) CHIP ID VERSION Number DMA Channel Default D2 D1 D0 '10'hex 'B8'hex 'F1'hex '01'hex
SMSC ID (Addresses 0 - 1) The SMSC ID registers contain a 16-bit manufacturer identification code. Address zero contains the high byte of this code, address one contains the low byte. Chip ID (Address 2)
IRQ Level/ DMA Channel (Address 4) IRQ Level, bits 4 - 7 The IRQ Level bits identify the current active IRQ number for this device. The value comes from the 4-bit IRQ Level Bus found in the Interface description. DMA Channel, bits 0 - 3
The Chip ID register specifically identifies this SMSC product. Version Number (Address 3) The Version Number register identifies the revision-level of the product referenced by the Chip ID register.
The DMA Channel bits identify the current active DMA Channel number for this device. The value comes from the 4-bit DMA Channel Bus found in the Interface description.
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REGISTER BLOCK FOUR Register Block Four contains the IrDA control registers. These registers control the IrDA
Address A2 A1 A0 0 0 0 Direction D7 R/W 1.152 selec t crc selec t D6 D5
message framing parameters, HDLC speed, and hardware CRC selection. registers are read/write.
clock The
Table 26 - SCE Register Block Four
Description D4 D3 IrDA Control Register bof count (high nibble) bof count (low byte) brick wall count (low byte) brick wall count (high nibble) tx data size (high nibble) rx data size (high nibble) rx data size (low byte) tx data size (low byte) '00'hex '00'hex '00'hex '00'hex '00'hex '00'hex Default D2 D1 D0 'C0'hex
0 0 0 1 1 1
0 1 1 0 0 1
1 0 1 0 1 0
R/W R/W R/W R/W R/W R/W
IrDA Control (Address 0)
Register/BOF
Count
High
BOF Count Low (Address 1) The BOF Count Low register is the lower byte of the BOF Count. Brick Wall Count Low (Address 2) The Brick Wall Count register specifies the number of additional interframe padding flags used for brick walled messages. The Brick Wall Count is a 12-bit value. The Brick Wall Count Low register is the Brick Wall Count lower byte. BW Count High/Tx Data Size High (Address 3) Brick Wall Count High, bits 4 - 7 The BW Count High register is the upper nibble of the Brick Wall Count. Tx Data Size High, bits 0 - 3 The Tx Data Size register specifies the IrLAPnegotiated maximum number of payload data bytes per IrDA transmit message frame if software CRC is selected, or the IrLAPnegotiated maximum number of payload data bytes minus the number of CRC bytes if hardware CRC is selected. This register is used
1.152 Select, bit 7 When the 1.152 Select bit is one, the IrDA 1.152Mbps HDLC-type FIR data rate is selected. Otherwise the .576Mbps rate is chosen. This bit only applies to the SCE clock when the Block Control bits select Mode 2, IrDA HDLC. CRC Select, bit 6 When the CRC Select bit is one, a hardwaregenerated CRC is appended to the frame payload data during IrDA FIR message transactions (Table 22). BOF Count High, bits 0 - 3 The BOF Count specifies the number of additional flags that are used in a BOF sequence. For example, at 1.152Mbps, insert the BOF Count number of additional flag characters ('7E'hex) at the start of every frame, excluding brick walled frames. At 4Mbps insert the BOF Count number of additional PA bytes at the start of every frame, excluding brick walled frames. The BOF Count is a 12-bit value. This register, BOF Count High, is the BOF Count upper nibble.
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to 1) constrain the transmitter to a valid IrDA frame size, 2) simplify multi-frame windowing for transmit data blocks that are larger than the maximum packet size and, 3) constrain the SCE transmitter during loopback testing. NOTE: only the Tx Data Size register is used for IrDA FIR loopback testing; only the Rx Data Size register is required for Consumer IR loopback tests. If the Tx Data Size register is zero, the IrDA transmit message size is unlimited; i.e., the transmitter will operate until the FIFO is empty. The Tx Data Size High register is the Tx Data Size high nibble. Tx Data Size Low (Address 4) The Tx Data Size Low register is the Tx Data Size low byte. Rx Data Size High (Address 5) Rx Data Size High, bits 0 - 3 The Rx Data Size register specifies the IrLAP-
negotiated maximum number of payload data bytes per IrDA receive message frame. This register is used to check each IrDA FIR receive frame for valid data size and to constrain the SCE receiver during Consumer IR loopback testing. NOTE: only the Rx Data Size register is required for Consumer IR loopback tests; only the Tx Data Size register is required for IrDA FIR loopback tests. For Consumer IR loopback tests, program the Rx Data Size register with Test_byte_count_1. If the Rx Data Size register is zero the IrDA receive message size is unlimited; i.e., a size error cannot occur because frame size checking is disabled. The Rx Data Size High register is the Rx Data Size high nibble. Rx Data Size Low (Address 6) The Rx Data Size Low register is the RxData Size low byte.
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ACE UART
The SMSC IRCC incorporates one full function UART compatible with the NS16450, the 16450 ACE registers and the NS16550A. The UART performs serial-to-parallel conversion on received characters and parallel-to-serial conversion on transmit characters. The data rates are independently programmable from 115.2K baud down to 50 baud. The character options are programmable for 1 start; 1, 1.5 or 2 stop bits; even, odd, sticky or no parity; and prioritized interrupts. The UART contains a programmable baud rate generator that is capable of dividing the input clock or crystal by a number from 1 to 65535. The UART is also capable of supporting the MIDI data rate. Refer to the Configuration Register section of the SMSC FDC37C669FR, FDC37C93XFR, or FDC37C957FR data sheet for information on disabling, power down and changing the base address of the UART. The interrupt from the UART is enabled by programming OUT2 of the UART to a logic "1". OUT2 being a logic "0" disables the UART's interrupt. REGISTER DESCRIPTION Addressing of the accessible registers of the Serial Port is shown below. The base addresses of the serial ports are defined by the configuration registers. The Serial Port registers are located at sequentially increasing addresses above these base addresses. The SMSC IRCC UART register set is described below.
DLAB* 0 0 0 X X X X X X X 1 1
A2 0 0 0 0 0 0 1 1 1 1 0 0
Table 27 - Addressing The Serial Port A1 A0 REGISTER NAME 0 0 0 1 1 1 0 0 1 1 0 0 0 0 1 0 0 1 0 1 0 1 0 1 Receive Buffer (read) Transmit Buffer (write) Interrupt Enable (read/write) Interrupt Identification (read) FIFO Control (write) Line Control (read/write) Modem Control (read/write) Line Status (read/write) Modem Status (read/write) Scratchpad (read/write) Divisor LSB (read/write) Divisor MSB (read/write
*NOTE: DLAB is Bit 7 of the Line Control Register
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The following section describes the operation of the registers. RECEIVE BUFFER REGISTER (RB) Address Offset = 0H, DLAB = 0, READ ONLY This register holds the received incoming data byte. Bit 0 is the least significant bit, which is transmitted and received first. Received data is double buffered; this uses an additional shift register to receive the serial data stream and convert it to a parallel 8 bit word which is transferred to the Receive Buffer register. The shift register is not accessible. TRANSMIT BUFFER REGISTER (TB) Address Offset = 0H, DLAB = 0, WRITE ONLY This register contains the data byte to be transmitted. The transmit buffer is double buffered, utilizing an additional shift register (not accessible) to convert the 8 bit data word to a serial format. This shift register is loaded from the Transmit Buffer when the transmission of the previous byte is complete. INTERRUPT ENABLE REGISTER (IER) Address Offset = 1H, DLAB = 0, READ/WRITE The lower four bits of this register control the enables of the five interrupt sources of the Serial Port interrupt. It is possible to totally disable the interrupt system by resetting bits 0 through 3 of this register. Similarly, setting the appropriate bits of this register to a high, selected interrupts can be enabled. Disabling the interrupt system inhibits the Interrupt Identification Register and disables any Serial Port interrupt out of the SMSC IRCC. All other system functions operate in their normal manner, including the Line Status and MODEM Status Registers. The contents of the Interrupt Enable Register are described below. Bit 0 This bit enables the Received Data Available Interrupt (and timeout interrupts in the FIFO mode) when set to logic "1".
Bit 1 This bit enables the Transmitter Holding Register Empty Interrupt when set to logic "1". Bit 2 This bit enables the Received Line Status Interrupt when set to logic "1". The error sources causing the interrupt are Overrun, Parity, Framing and Break. The Line Status Register must be read to determine the source. Bit 3 This bit enables the MODEM Status Interrupt when set to logic "1". This is caused when one of the Modem Status Register bits changes state. Bits 4 through 7 These bits are always logic "0". FIFO CONTROL REGISTER (FCR) Address Offset = 2H, DLAB = X, WRITE This is a write only register at the same location as the IIR. This register is used to enable and clear the FIFOs, set the RCVR FIFO trigger level. Note: DMA is not supported. Bit 0 Setting this bit to a logic "1" enables both the XMIT and RCVR FIFOs. Clearing this bit to a logic "0" disables both the XMIT and RCVR FIFOs and clears all bytes from both FIFOs. When changing from FIFO Mode to non-FIFO (16450) mode, data is automatically cleared from the FIFOs. This bit must be a 1 when other bits in this register are written to or they will not be properly programmed. Bit 1 Setting this bit to a logic "1" clears all bytes in the RCVR FIFO and resets its counter logic to 0. The shift register is not cleared. This bit is selfclearing.
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Bit 2 Setting this bit to a logic "1" clears all bytes in the XMIT FIFO and resets its counter logic to 0. The shift register is not cleared. This bit is selfclearing. Bit 3 Writting to this bit has no effect on the operation of the UART. The RXRDY and TXRDY pins are not available on this chip. Bit 4,5 Reserved RCVR FIFO TRIGGER LEVEL 1 4 8 14
3. 4.
Transmitter Holding Register Empty MODEM Status (lowest priority)
Information indicating that a prioritized interrupt is pending and the source of that interrupt is stored in the Interrupt Identification Register (refer to Interrupt Control Table). When the CPU accesses the IIR, the Serial Port freezes all interrupts and indicates the highest priority pending interrupt to the CPU. During this CPU access, even if the Serial Port records new interrupts, the current indication does not change until access is completed. The contents of the IIR are described below. Bit 0 This bit can be used in either a hardwired prioritized or polled environment to indicate whether an interrupt is pending. When bit 0 is a logic "0", an interrupt is pending and the contents of the IIR may be used as a pointer to the appropriate internal service routine. When bit 0 is a logic "1", no interrupt is pending. Bits 1 and 2 These two bits of the IIR are used to identify the highest priority interrupt pending as indicated by the Interrupt Control Table. Bit 3 In non-FIFO mode, this bit is a logic "0". In FIFO mode this bit is set along with bit 2 when a timeout interrupt is pending. Bits 4 and 5 These bits of the IIR are always logic "0". Bits 6 and 7 These two bits are set when the FIFO CONTROL Register bit 0 equals 1.
BIT 7 0 0 1 1
BIT 6 0 1 0 1
Bit 6,7 These bits are used to set the trigger level for the RCVR FIFO interrupt. INTERRUPT IDENTIFICATION REGISTER (IIR) Address Offset = 2H, DLAB = X, READ By accessing this register, the host CPU can determine the highest priority interrupt and its source. Four levels of priority interrupt exist. They are in descending order of priority: 1. 2. Receiver Line Status (highest priority) Received Data Ready
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Table 28 - Interrupt Control Table FIFO MODE ONLY BIT 3 0 0 INTERRUPT IDENTIFICATION REGISTER BIT 2 0 1 BIT 1 0 1 BIT 0 1 0
INTERRUPT SET AND RESET FUNCTIONS PRIORITY LEVEL Highest INTERRUPT TYPE None Receiver Line Status INTERRUPT SOURCE None Overrun Error, Parity Error, Framing Error or Break Interrupt Receiver Data Available INTERRUPT RESET CONTROL Reading the Line Status Register
0
1
0
0
Second
Received Data Available
Read Receiver Buffer or the FIFO drops below the trigger level. Reading the Receiver Buffer Register
1
1
0
0
Second
Character Timeout Indication
No Characters Have Been Removed From or Input to the RCVR FIFO during the last 4 Char times and there is at least 1 char in it during this time Transmitter Holding Register Empty
0
0
1
0
Third
Transmitter Holding Register Empty
Reading the IIR Register (if Source of Interrupt) or Writing the Transmitter Holding Register Reading the MODEM Status Register
0
0
0
0
Fourth
MODEM Status
Clear to Send or Data Set Ready or Ring Indicator or Data Carrier Detect
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LINE CONTROL REGISTER (LCR) Address Offset = 3H, DLAB = 0, READ/WRITE This register contains the format information of the serial line. The bit definitions are: Bits 0 and 1 These two bits specify the number of bits in each transmitted or received serial character. The encoding of bits 0 and 1 is as follows: BIT 1 0 0 1 1 BIT 0 0 1 0 1 WORD LENGTH 5 Bits 6 Bits 7 Bits 8 Bits
word bit and the first stop bit of the serial data. (The parity bit is used to generate an even or odd number of 1s when the data word bits and the parity bit are summed). Bit 4 Even Parity Select bit. When bit 3 is a logic "1" and bit 4 is a logic "0", an odd number of logic "1"'s is transmitted or checked in the data word bits and the parity bit. When bit 3 is a logic "1" and bit 4 is a logic "1" an even number of bits is transmitted and checked. Bit 5 Stick Parity bit. When bit 3 is a logic "1" and bit 5 is a logic "1", the parity bit is transmitted and then detected by the receiver in the opposite state indicated by bit 4. Bit 6 Set Break Control bit. When bit 6 is a logic "1", the transmit data output (TXD) is forced to the Spacing or logic "0" state and remains there (until reset by a low level bit 6) regardless of other transmitter activity. This feature enables the Serial Port to alert a terminal in a communications system. Bit 7 Divisor Latch Access bit (DLAB). It must be set high (logic "1") to access the Divisor Latches of the Baud Rate Generator during read or write operations. It must be set low (logic "0") to access the Receiver Buffer Register, the Transmitter Holding Register, or the Interrupt Enable Register. MODEM CONTROL REGISTER (MCR) Address Offset = 4H, DLAB = X, READ/WRITE This 8 bit register controls the interface with the MODEM or data set (or device emulating a MODEM). The contents of the MODEM control register are described below.
The Start, Stop and Parity bits are not included in the word length. Bit 2 This bit specifies the number of stop bits in each transmitted or received serial character. The following table summarizes the information. NUMBER OF STOP BITS 1 1.5 2 2 2
BIT 2 0 1 1 1 1
WORD LENGTH -5 bits 6 bits 7 bits 8 bits
Note: The receiver will ignore all stop bits beyond the first, regardless of the number used in transmitting. Bit 3 Parity Enable bit. When bit 3 is a logic "1", a parity bit is generated (transmit data) or checked (receive data) between the last data
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Bit 0 This bit controls the Data Terminal Ready (nDTR) output. When bit 0 is set to a logic "1", the nDTR output is forced to a logic "0". When bit 0 is a logic "0", the nDTR output is forced to a logic "1". Bit 1 This bit controls the Request To Send (nRTS) output. Bit 1 affects the nRTS output in a manner identical to that described above for bit 0. Bit 2 This bit controls the Output 1 (OUT1) bit. This bit does not have an output pin and can only be read or written by the CPU. Bit 3 Output 2 (OUT2). This bit is used to enable an UART interrupt. When OUT2 is a logic "0", the serial port interrupt output is forced to a high impedance state - disabled. When OUT2 is a logic "1", the serial port interrupt outputs are enabled. Bit 4 This bit provides the loopback feature for diagnostic testing of the Serial Port. When bit 4 is set to logic "1", the following occur: 1. The TXD is set to the Marking State(logic "1"). 2. The receiver Serial Input (RXD) is disconnected. 3. The output of the Transmitter Shift Register is "looped back" into the Receiver Shift Register input. 4. All MODEM Control inputs (nCTS, nDSR, nRI and nDCD) are disconnected. 5. The four MODEM Control outputs (nDTR, nRTS, and OUT2) are internally connected to the four MODEM Control inputs. 6. The Modem Control output pins are forced inactive high. 7. Data that is transmitted is immediately received.
This feature allows the processor to verify the transmit and receive data paths of the Serial Port. In the diagnostic mode, the receiver and the transmitter interrupts are fully operational. The MODEM Control Interrupts are also operational but the interrupts' sources are now the lower four bits of the MODEM Control Register instead of the MODEM Control inputs. The interrupts are still controlled by the Interrupt Enable Register. Bits 5 through 7 These bits are permanently set to logic zero. LINE STATUS REGISTER (LSR) Address Offset = 5H, DLAB = X, READ/ WRITE Bit 0 Data Ready (DR). It is set to a logic "1" whenever a complete incoming character has been received and transferred into the Receiver Buffer Register or the FIFO. Bit 0 is reset to a logic "0" by reading all of the data in the Receive Buffer Register or the FIFO. Bit 1 Overrun Error (OE). Bit 1 indicates that data in the Receiver Buffer Register was not read before the next character was transferred into the register, thereby destroying the previous character. In FIFO mode, an overrunn error will occur only when the FIFO is full and the next character has been completely received in the shift register, the character in the shift register is overwritten but not transferred to the FIFO. The OE indicator is set to a logic "1" immediately upon detection of an overrun condition, and reset whenever the Line Status Register is read. Bit 2 Parity Error (PE). Bit 2 indicates that the received data character does not have the correct even or odd parity, as selected by the even parity select bit. The PE is set to a logic "1" upon detection of a parity error and is reset to a logic "0" whenever the Line Status Register
45
is read. In the FIFO mode this error is associated with the particular character in the FIFO it applies to. This error is indicated when the associated character is at the top of the FIFO. Bit 3 Framing Error (FE). Bit 3 indicates that the received character did not have a valid stop bit. Bit 3 is set to a logic "1" whenever the stop bit following the last data bit or parity bit is detected as a zero bit (Spacing level). The FE is reset to a logic "0" whenever the Line Status Register is read. In the FIFO mode this error is associated with the particular character in the FIFO it applies to. This error is indicated when the associated character is at the top of the FIFO. The Serial Port will try to resynchronize after a framing error. To do this, it assumes that the framing error was due to the next start bit, so it samples this 'start' bit twice and then takes in the 'data'. Bit 4 Break Interrupt (BI). Bit 4 is set to a logic "1" whenever the received data input is held in the Spacing state (logic "0") for longer than a full word transmission time (that is, the total time of the start bit + data bits + parity bits + stop bits). The BI is reset after the CPU reads the contents of the Line Status Register. In the FIFO mode this error is associated with the particular character in the FIFO it applies to. This error is indicated when the associated character is at the top of the FIFO. When break occurs only one zero character is loaded into the FIFO. Restarting after a break is received, requires the serial data (RXD) to be logic "1" for at least 1/2 bit time. Note: Bits 1 through 4 are the error conditions that produce a Receiver Line Status Interrupt whenever any of the corresponding conditions are detected and the interrupt is enabled.
Bit 5 Transmitter Holding Register Empty (THRE). Bit 5 indicates that the Serial Port is ready to accept a new character for transmission. In addition, this bit causes the Serial Port to issue an interrupt when the Transmitter Holding Register interrupt enable is set high. The THRE bit is set to a logic "1" when a character is transferred from the Transmitter Holding Register into the Transmitter Shift Register. The bit is reset to logic "0" whenever the CPU loads the Transmitter Holding Register. In the FIFO mode this bit is set when the XMIT FIFO is empty, it is cleared when at least 1 byte is written to the XMIT FIFO. Bit 5 is a read only bit. Bit 6 Transmitter Empty (TEMT). Bit 6 is set to a logic "1" whenever the Transmitter Holding Register (THR) and Transmitter Shift Register (TSR) are both empty. It is reset to logic "0" whenever either the THR or TSR contains a data character. Bit 6 is a read only bit. In the FIFO mode this bit is set whenever the THR and TSR are both empty, Bit 7 This bit is permanently set to logic "0" in the 450 mode. In the FIFO mode, this bit is set to a logic "1" when there is at least one parity error, framing error or break indication in the FIFO. This bit is cleared when the LSR is read if there are no subsequent errors in the FIFO. MODEM STATUS REGISTER (MSR) Address Offset = 6H, DLAB = X, READ/ WRITE This 8 bit register provides the current state of the control lines from the MODEM (or peripheral device). In addition to this current state information, four bits of the MODEM Status Register (MSR) provide change information.
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These bits are set to logic "1" whenever a control input from the MODEM changes state. They are reset to logic "0" whenever the MODEM Status Register is read. Bit 0 Delta Clear To Send (DCTS). Bit 0 indicates that the nCTS input to the chip has changed state since the last time the MSR was read. Bit 1 Delta Data Set Ready (DDSR). Bit 1 indicates that the nDSR input has changed state since the last time the MSR was read. Bit 2 Trailing Edge of Ring Indicator (TERI). Bit 2 indicates that the nRI input has changed from logic "0" to logic "1". Bit 3 Delta Data Carrier Detect (DDCD). Bit 3 indicates that the nDCD input to the chip has changed state. Note: Whenever bit 0, 1, 2, or 3 is set to a logic "1", a MODEM Status Interrupt is generated. Bit 4 This bit is the complement of the Clear To Send (nCTS) input. If bit 4 of the MCR is set to logic "1", this bit is equivalent to nRTS in the MCR. Bit 5 This bit is the complement of the Data Set Ready (nDSR) input. If bit 4 of the MCR is set to logic "1", this bit is equivalent to DTR in the MCR. Bit 6 This bit is the complement of the Ring Indicator (nRI) input. If bit 4 of the MCR is set to logic "1", this bit is equivalent to OUT1 in the MCR.
Bit 7 This bit is the complement of the Data Carrier Detect (nDCD) input. If bit 4 of the MCR is set to logic "1", this bit is equivalent to OUT2 in the MCR. SCRATCHPAD REGISTER (SCR) Address Offset =7H, DLAB =X, READ/WRITE This 8 bit read/write register has no effect on the operation of the Serial Port. It is intended as a scratchpad register to be used by the programmer to hold data temporarily. PROGRAMMABLE BAUD RATE GENERATOR (AND DIVISOR LATCHES DLH, DLL) The Serial Port contains a programmable Baud Rate Generator that is capable of taking any clock input (DC to 3 MHz) and dividing it by any divisor from 1 to 65535. This output frequency of the Baud Rate Generator is 16x the Baud rate. Two 8 bit latches store the divisor in 16 bit binary format. These Divisor Latches must be loaded during initialization in order to insure desired operation of the Baud Rate Generator. Upon loading either of the Divisor Latches, a 16 bit Baud counter is immediately loaded. This prevents long counts on initial load. If a 0 is loaded into the BRG registers the output divides the clock by the number 3. If a 1 is loaded the output is the inverse of the input oscillator. If a two is loaded the output is a divide by 2 signal with a 50% duty cycle. If a 3 or greater is loaded the output is low for 2 bits and high for the remainder of the count. The input clock to the BRG is the 24 MHz crystal divided by 13, giving a 1.8462 MHz clock. Table 29 shows the baud rates possible with a 1.8462 MHz crystal.
47
Effect Of The Reset on Register File The Reset Function Table (Table 30) details the effect of the Reset input on each of the registers of the Serial Port. FIFO INTERRUPT MODE OPERATION When the RCVR FIFO and receiver interrupts are enabled (FCR bit 0 = "1", IER bit 0 = "1"), RCVR interrupts occur as follows: A. The receive data available interrupt will issued when the FIFO has reached programmed trigger level; it is cleared soon as the FIFO drops below programmed trigger level. be its as its B.
msec at 300 BAUD with a 12 bit character. Character times are calculated by using the RCLK input for a clock signal (this makes the delay proportional to the baudrate). When a timeout interrupt has occurred it is cleared and the timer reset when the CPU reads one character from the RCVR FIFO. When a timeout interrupt has not occurred the timeout timer is reset after a new character is received or after the CPU reads the RCVR FIFO.
C.
D.
B.
The IIR receive data available indication also occurs when the FIFO trigger level is reached. It is cleared when the FIFO drops below the trigger level. The receiver line status interrupt (IIR=06H), has higher priority than the received data available (IIR=04H) interrupt. The data ready bit (LSR bit 0)is set as soon as a character is transferred from the shift register to the RCVR FIFO. It is reset when the FIFO is empty.
When the XMIT FIFO and transmitter interrupts are enabled (FCR bit 0 = "1", IER bit 1 = "1"), XMIT interrupts occur as follows: A. The transmitter holding register interrupt (02H) occurs when the XMIT FIFO is empty; it is cleared as soon as the transmitter holding register is written to (1 of 16 characters may be written to the XMIT FIFO while servicing this interrupt) or the IIR is read. B. The transmitter FIFO empty indications will be delayed 1 character time minus the last stop bit time whenever the following occurs: THRE=1 and there have not been at least two bytes at the same time in the transmitte FIFO since the last THRE=1. The transmitter interrupt after changing FCR0 will be immediate, if it is enabled. Character timeout and RCVR FIFO trigger level interrupts have the sme priority as the current received data available interrupt; XMIT FIFO empty has the same priority as the current transmitter holding register empty interrupt. FIFO POLLED MODE OPERATION With FCR bit 0 = "1" resetting IER bits 0, 1, 2 or 3 or all to zero puts the UART in the FIFO Polled Mode of operation. Since the RCVR and are controlled separately, either one or both can be in the polled mode of operation. 48
C.
D.
When RCVR FIFO and receiver interrupts are enabled, RCVR FIFO timeout interrupts occur as follows: A. A FIFO timeout interrupt occurs if all the following conditions exist: - at least one character is in the FIFO - The most recent serial character received was longer than 4 continuous character times ago. (If 2 stop bits are programmed, the second one is included in this time delay.) - The most recent CPU read of the FIFO was longer than 4 continuous character times ago. - This will cause a maximum character received to interrupt issued delay of 160
In this mode, the user's program will check RCVR and XMITTER status via the LSR. LSR definitions for the FIFO Polled Mode are as follows: Bit 0=1 as long as there is one byte in the RCVR FIFO. Bits 1 to 4 specify which error(s) have occurred. Character error status is handled the same way as when in the interruptmode, the IIR is not affected since EIR bit 2=0. DESIRED BAUD RATE 50 75 110 134.5 150 300 600 1200 1800 2000 2400 3600 4800 7200 9600 19200 38400 57600 115200 230400 460800
-
Bit 5 indicates when the XMIT FIFO is empty. Bit 6 indicates that both the XMIT FIFO and shift register are empty. Bit 7 indicates whether there are any errors in the RCVR FIFO.
There is no trigger level reached or timeout condition indicated in the FIFO Polled Mode, however, the RCVR and XMIT FIFOs are still fully capable of holding characters.
Table 29 - Baud Rates Using 1.8462 MHz Clock (24 MHz/13) DIVISOR USED TO PERCENT ERROR DIFFERENCE GENERATE 16X CLOCK BETWEEN DESIRED AND ACTUAL* 2304 0.001 1536 1047 857 0.004 768 384 192 96 64 58 0.005 48 32 24 16 12 6 3 0.030 2 0.16 1 0.16 32770 0.16 32769 0.16
CRC: BIT 7 OR 6 X X X X X X X X X X X X X X X X X X X 1 1
*NOTE: The percentage error for all baud rates, except where indicated otherwise, is 0.2%.
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REGISTER/SIGNAL Interrupt Enable Register Interrupt Identification Reg. FIFO Control Line Control Reg. MODEM Control Reg. Line Status Reg. MODEM Status Reg. TXD1, TXD2 INTRPT (RCVR errs) INTRPT (RCVR Data Ready) INTRPT (THRE) OUT2B RTSB DTRB OUT1B RCVR FIFO XMIT FIFO
Table 30 - Reset Function Table RESET CONTROL RESET RESET RESET RESET RESET RESET RESET RESET RESET/Read LSR RESET/Read RBR RESET/ReadIIR/Write THR RESET RESET RESET RESET RESET/FCR1*FCR0/_FCR0 RESET/FCR1*FCR0/_FCR0
RESET STATE
All bits low Bit 0 is high; Bits 1 thru 7 low All bits low All bits low All bits low All bits low except 5, 6 high Bits 0 - 3 low; Bits 4 - 7 input High Low Low Low High High High High All Bits Low All Bits Low
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Table 31 - Register Summary For An Individual UART Channel
REGISTER ADDRESS* ADDR = 0 DLAB = 0 ADDR = 0 DLAB = 0 ADDR = 1 DLAB = 0 REGISTER NAME Receive Buffer Register (Read Only) Transmitter Holding Register (Write Only) Interrupt Enable Register REGISTER SYMBOL RBR THR IER BIT 0 Data Bit (Note 1) Data Bit 0 Enable Received Data Available Interrupt (ERDAI) BIT 1 0 Data Bit 1 Data Bit 1 Enable Transmitter Holding Register Empty Interrupt (ETHREI) ID
ADDR = 2 ADDR = 2 ADDR = 3
Interrupt Ident. Register (Read Only) FIFO Control Register (Write Only) Line Control Register
IIR FCR LCR
"0" if Interrupt Interrupt Pending Bit FIFO Enable Word Length Select Bit 0 (WLS0) Data Terminal Ready (DTR) Data Ready (DR)
RCVR FIFO Reset Word Length Select Bit 1 (WLS1) Request to Send (RTS) Overrun Error (OE)
ADDR = 4
MODEM Control Register
MCR
ADDR = 5 ADDR = 6
Line Status Register MODEM Status Register
LSR MSR
Delta Clear to Delta Data Send (DCTS) Set Ready (DDSR) Bit 0 Bit 0 Bit 8 Bit 1 Bit 1 Bit 9
ADDR = 7 ADDR = 0 DLAB = 1 ADDR = 1 DLAB = 1
Scratch Register (Note 4) Divisor Latch (LS) Divisor Latch (MS)
SCR DDL DLM
*DLAB is Bit 7 of the Line Control Register (ADDR = 3). Note 1: Bit 0 is the least significant bit. It is the first bit serially transmitted or received. Note 2: When operating in the XT mode, this bit will be set any time that the transmitter shift register is empty.
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Table 31 - Register Summary For An Individual UART Channel (continued) BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 Data Bit 2 Data Bit 2 Enable Receiver Line Status Interrupt (ELSI) Data Bit 3 Data Bit 3 Enable MODEM Status Interrupt (EMSI) Data Bit 4 Data Bit 4 0 Data Bit 5 Data Bit 5 0 Data Bit 6 Data Bit 6 0 Data Bit 7 Data Bit 7 0
Interrupt ID Bit Interrupt ID Bit 0 (Note 5) XMIT FIFO Reset Number of Stop Bits (STB) OUT1 (Note 3) Parity Error (PE) DMA Mode Select (Note 6) Parity Enable (PEN) OUT2 (Note 3) Framing Error (FE) Reserved
0
FIFOs FIFOs Enabled (Note Enabled (Note 5) 5) RCVR Trigger LSB Set Break RCVR Trigger MSB Divisor Latch Access Bit (DLAB) 0
Reserved
Even Parity Select (EPS) Loop Break Interrupt (BI)
Stick Parity
0 Transmitter Holding Register (THRE) Data Set Ready (DSR) Bit 5 Bit 5 Bit 13
0
Error in RCVR Transmitter Empty (TEMT) FIFO (Note 5) (Note 2) Ring Indicator (RI) Bit 6 Bit 6 Bit 14 Data Carrier Detect (DCD) Bit 7 Bit 7 Bit 15
Trailing Edge Ring Indicator (TERI) Bit 2 Bit 2 Bit 10 Note 3: Note 4: Note 5: Note 6:
Delta Data Carrier Detect (DDCD) Bit 3 Bit 3 Bit 11
Clear to Send (CTS) Bit 4 Bit 4 Bit 12
This bit no longer has a pin associated with it. When operating in the XT mode, this register is not available. These bits are always zero in the non-FIFO mode. Writing a one to this bit has no effect. DMA modes are not supported in this chip.
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NOTES ON SERIAL PORT OPERATION FIFO MODE OPERATION: GENERAL The RCVR FIFO will hold up to 16 bytes regardless of which trigger level is selected. TX AND RX FIFO OPERATION The Tx portion of the UART transmits data through TXD as soon as the CPU loads a byte into the Tx FIFO. The UART will prevent loads to the Tx FIFO if it currently holds 16 characters. Loading to the Tx FIFO will again be enabled as soon as the next character is transferred to the Tx shift register. These capabilities account for the largely autonomous operation of the Tx. The UART starts the above operations typically with a Tx interrupt. The chip issues a Tx interrupt whenever the Tx FIFO is empty and the Tx interrupt is enabled, except in the following instance. Assume that the Tx FIFO is empty and the CPU starts to load it. When the first byte enters the FIFO the Tx FIFO empty interrupt will transition from active to inactive. Depending on the execution speed of the service routine software, the UART may be able to transfer this byte from the FIFO to the shift register before the CPU loads another byte. If this happens, the Tx FIFO will be empty again and typically the UART's interrupt line would transition to the active state. This could cause a system with an interrupt control unit to record a Tx FIFO empty condition, even though the CPU is currently servicing that interrupt. Therefore, after the first byte has been loaded into the FIFO the UART will wait one serial character transmission time before issuing a new Tx FIFO empty interrupt.
This one character Tx interrupt delay will remain active until at least two bytes have been loaded into the FIFO, concurrently. When the Tx FIFO empties after this condition, the Tx interrupt will be activated without a one character delay. Rx support functions and operation are quite different from those described for the transmitter. The Rx FIFO receives data until the number of bytes in the FIFO equals the selected interrupt trigger level. At that time if Rx interrupts are enabled, the UART will issue an interrupt to the CPU. The Rx FIFO will continue to store bytes until it holds 16 of them. It will not accept any more data when it is full. Any more data entering the Rx shift register will set the Overrun Error flag. Normally, the FIFO depth and the programmable trigger levels will give the CPU ample time to empty the Rx FIFO before an overrun occurs. One side-effect of having a Rx FIFO is that the selected interrupt trigger level may be above the data level in the FIFO. This could occur when data at the end of the block contains fewer bytes than the trigger level. No interrupt would be issued to the CPU and the data would remain in the UART. To prevent the software from having to check for this situation the chip incorporates a timeout interrupt. The timeout interrupt is activated when there is a least one byte in the Rx FIFO, and neither the CPU nor the Rx shift register has accessed the Rx FIFO within 4 character times of the last byte. The timeout interrupt is cleared or reset when the CPU reads the Rx FIFO or another character enters it. These FIFO related features allow optimization of CPU/UART transactions and are especially useful given the higer baud rate capability (256 kbaud).
53
nIOW t1
nRTSx, nDTRx
t5 IRQx nCTSx, nDSRx, nDCDx t2 IRQx nIOW t3 IRQx nIOR nRIx t4
t6
FIGURE 19 - SERIAL PORT TIMING
54
SCE
DESCRIPTION The SCE is a half-duplex synchronous serial communications controller that controls data flow between the Bus Interface I/O block and the IrDA FIR and Consumer IR (TV Remote) Encoders (Figure 20). The SCE also includes partial full-duplex loopback functionality for diagnostic testing. Bit rates from .4Kbps to 4Mbps are supported. All of the SCE register controls are located in the nSCE-addressable 8bit Register Blocks.
Transmit
8
Parallel-to-Serial Converter 16/32-bit CRC Generator 16/32-bit CRC Checker
1
FIR/TV Encoder
Controls
Timing & Control
Receive
8
Serial-to-Parallel Converter
1
FIR/TV Decoder
FIGURE 20 - SCE BLOCK DIAGRAM FRAMING The SCE operates with and without framing. With framing implies that the SCE works with the IrDA FIR encoder/decoder so the required symbols for the non-payload data portions of the .576Mbps, 1.152Mbps and 4Mbps packets can be generated. Without framing implies that the SCE acts simply as serial-to-parallel converter for the Consumer IR (TV Remote) encoder/ decoder. ACTIVE FRAME INDICATOR The SCE signal nActiveFrame is a PLA state variable that is synchronized to both IrDA FIR and Consumer IR message frames. nActiveFrame cycles high and low for each message frame, regardless of the state of the Brick Wall bit. nActiveFrame is primarily used to trigger active frame interrupts and to advance the Message Count bits that control hardware access to the Line Status Registers. 55 IrDA Modes Transmit nActiveFrame goes active as soon as the IrDA transmitter initiates a BOF sequence. nActiveFrame becomes inactive as soon as the IrDA transmitter completes an EOF sequence. In the case of a transmit abort, nActiveFrame becomes inactive as soon as the IrDA transmitter completes the abort sequence. Receive nActiveFrame goes active as soon as the IrDA receiver detects valid payload data; i.e., after a valid BOF sequence. nActiveFrame becomes inactive as soon as the IrDA receiver detects an EOF sequence. In the case of a FIFO Overrun or abort, nActiveFrame becomes inactive as soon as the IrDA receiver updates the status register and signals the End of Message.
Consumer IR Mode Transmit nActiveFrame goes active as soon as the Consumer IR transmitter starts modulating the SCE data stream. nActiveFrame becomes inactive as soon as the transmit register is empty. Receive nActiveFrame goes active as soon as the Consumer IR receiver detects the first active bittime of infrared energy. nActiveFrame becomes inactive whenever the Consumer IR receiver is manually disabled, a DMA Terminal Count has occurred, or following a FIFO Overrun.
IRDA ENCODER Description The IrDA FIR Encoder supports the synchronous bit-oriented HDLC protocol at .576Mbps and 1.152Mbps, and 4PPM Encoding at 4Mbps including all message framing, bit stuffing, and CRC generation (Figure 21). The IrDA FIR Encoder exchanges only payload data with the host and supports Multi-Frame Windows for brick walled messages as well as BOF and BW framing extensions. The IrDA FIR Encoder also includes an SIR Interaction Pulse generator in hardware.
SIP Generator Framing 4PPM Encoder HDLC Encoder Tx
SCE
4PPM Decoder HDLC Decoder
Rx
Control & Status
FIGURE 21 - IrDA FIR ENCODER
56
Transmit Timing The SCE IrDA-mode transmitter is enabled by setting the appropriate SCE MODES bits in SCE Line Control Register B. If the FIFO Threshold is zero, message transmission begins as soon as transmit mode has been enabled and there is data in the FIFO (Figure 22). If the FIFO Threshold is greater than zero, message transmission begins only after transmit mode has been enabled and the FIFO Threshold has been exceeded or TC is active (Figure 23). NOTE: the IrDA-mode SCE transmitter will only be enabled when the SIR Interaction Pulse generator is inactive.
A c tiv e S IP T im e T r a n s m it F IF O E m p ty T x E n a b le
FIGURE 22 - IrDA FIR TRANSMIT ENABLE TIMING: FIFO THRESHOLD = 0
A c t iv e S IP T im e T r a n s m it F IF O T h r e s h o ld TC T x E n a b le
FIGURE 23 - IrDA FIR TRANSMIT TIMING: FIFO THRESHOLD > 0 Once an IrDA transmission has begun, the End of Message (EOM) and other state indicators are cleared and the nActive Frame signal is enabled. Following the frame check sequence, EOM is reactivated and an EOM interrupt is generated. Following the end of the frame, nActive Frame is disabled (Figure 24).
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BOF Active Frame EOM EOM Interrupt Tx Enable Data Done FIFO Empty
A
C
I
FCS
EOF
FIGURE 24 - IrDA FIR TX MESSAGE TIMING (SOFTWARE CRC) When active, the DATA DONE flag in Register Block Zero, Line Control Register A alerts the transmitter that the next FIFO underrun condition signifies the end of the valid payload data and that an EOF should begin (Figure 24). During DMA operations TC automatically sets the DATA DONE flag. A message byte counter that is initialized with the value in the data size register when the message begins can also signal the end of the valid payload data. If the message byte counter goes
BOF Active Frame EOM EOM Interrupt Tx Enable Data Done/TC FIFO Empty Underrun Error Abort Error A
to zero before the FIFO is empty and the Brick Wall bit is one, a FIFO underrun with an active DATA DONE flag is simulated, a hardware CRC is appended (if required), and the next message is brick walled (not shown). If the FIFO is empty, the DATA DONE flag is always cleared following the EOM, regardless of how the bit was set. If the DATA DONE flag is inactive when an underrun occurs, the transmitter aborts the message and set the Abort and Underrun errors appropriately (Figure 25).
C I Abort
FIGURE 25 - TX ABORT ON UNDERRUN TIMING
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Receive Timing Once enabled using the SCE Modes bits in Line Control Register B, the IrDA-mode receiver begins searching for valid FIR frames. The affects of non-valid IrDA infrared activity such as out of spec pulse widths and invalid BOF
BOF Active Frame EOM FIFO Empty EOM Interrupt Active Frame Int. Rx Enable A C
sequences are always reflected in the status indicators in the IRCC registers. When a valid BOF is detected, the EOM from the previous message is disabled, errors are reset, and an nActive Frame Interrupt is sent (Figure 26). EOM and the EOM Interrupt are enabled following an active FCS.
I FCS EOF
FIGURE 26 - IrDA RX MESSAGE TIMING Framing errors or a FIFO overrun that occurs before the Frame Check Sequence is complete is indicated in the appropriate status register bits and the message is aborted (Figure 27).
BOF Active Frame EOM FIFO Full EOM Interrupt Active Frame Int. Rx Enable
A
C
I
Overrun Error Abort Error
FIGURE 27 - IrDA FIR RX ABORT ON OVERRUN TIMING
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CRC Select Timing During transmit if the CRC Select control is low the FCS is assumed to be part of the message payload data sent from the Host and the hardware CRC generator is not engaged (Figure
BOF FIFO Empty EOM CRC Select Data Done TC A
28). During receive if the CRC Select control is low the hardware CRC generator is not engaged, no comparison with the received FCS is made, and the state of the configuration register CRC Error flag is undefined.
C
I
FCS
EOF
FIGURE 28 - IrDA FIR FRAME WITH SOFTWARE CRC
During transmit if the CRC Select control is high the FCS is assumed not to be part of the message data sent from the Host, the hardware CRC generator is engaged, and the FCS result is appended to the Host payload data (Figure 29). During receive, if the CRC Select control is high, the output from the hardware CRC generator is
compared to the CRC from the received message and the result recorded in the configuration register CRC Error flag. Note: for all IrDA FIR received messages, the FCS is sent to the Host through the FIFO regardless of the state of the CRC Select control.
BOF FIFO Empty EOM CRC SELECT Data Done TC
A
C
I
FCS
EOF
CRC (HW )
FIGURE 29 - IrDA FIR FRAME WITH HARDWARE CRC
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Framing Errors The IrDA FIR pulse and signaling violations listed in this section are considered framing errors. When the Frame Error bit in the IRCC Line Status register is one, a framing error has occurred. The IrDA receiver response to framing errors depends upon when the errors occur. Framing errors that occur before a valid BOF has been detected will always set the Frame Error bit but will not alter the system state in any other way; i.e., the abort bit is not activated. If framing errors occur following a valid BOF, i.e. while nActive Frame is zero, the message is aborted. For both the HDLC and 4PPM encoding schemes, messages with data fields larger than the value contained in the data size register violate IrDA framing rules but are not aborted. NOTE: the Size Error and the Frame Error bits are set. Pulses less than 60ns should be ignored, in all modes. The events listed in the following two sections are framing errors. 1.152Mbps Pulse Widths greater than one bit-cell. Invalid BOF: includes data fields before BOF, pulsewidth violations during BOF, and subsequent invalid BOFs (including Aborts) following a valid BOF before the Address field. Invalid data fields: includes frames with invalid data field characters (including aborts), and pulse-width violations during a data field (including during CRC). Invalid EOF fields: includes invalid EOF flags (including Aborts), pulse-width violations, and subsequent invalid EOFs following a valid EOF. 4Mbps Pulse Widths greater than two chip times. Invalid PA field: includes invalid PA symbols, pulsewidth violations, and subsequent invalid PA
symbols following at least one valid PA symbol (including Aborts) before the STA field. Invalid STA field: includes invalid STA symbols, pulsewidth violations, and subsequent invalid STA symbols following at least one valid symbol (including Aborts) before the payload data. Invalid Data field: includes frames with invalid data symbols (including Aborts), and pulse-width violations during a data field (including during CRC). Invalid EOF field: includes invalid EOF flag (including Aborts), pulse-width violations, and subsequent invalid EOFs following a valid EOF. CONSUMER IR ENCODER TIMING The Consumer IR-mode SCE does not require the framing signals that are specified in the IrDAmode timing, although both modes utilize the nActive Frame and EOM Interrupt. There is also no need to differentiate the IrDA-mode EOM signal from an inactive nActive Frame. The Consumer IR-mode SCE operates at the bit rates set in the Consumer IR Bit Rate Register. The Consumer IR-mode SCE can operate in Programmed I/O or DMA mode. The CRC Generator is not used. Transmit Timing The SCE TV Remote transmitter uses the same enabling mechanisms as the IrDA-mode transmitter (see page 57). Note: the IrDA-mode Active SIP Pulse Tx Enable timing restriction does not apply. Once enabled, the TV Remote transmitter operates until the FIFO underruns (Figure 30). The nActive Frame and EOM Interrupt signals behave as shown. The SCE Modes bits are reset to zero, disabling the transmitter, following nActive Frame.
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Active Frame FIFO Empty EOM Interrupt Tx Enable Tx Reg. Empty
FIGURE 30 - TV REMOTE TRANSMIT TIMING Receive Timing The SCE TV Remote receiver can be enabled with the configuration register SCE Modes bits, polled using programmed I/O, and manually disabled when sufficient data has been collected (Figure 31). Once enabled, the SCE receiver will only begin to interpret line data following the first valid zero detection.
Zero Detect
Active Frame Active Frame Int. Rx Enable
FIGURE 31 - TV REMOTE MANUAL RX TIMING Figure 32 illustrates how the TV Remote receiver operates using DMA. TC disables the receiver, sends an EOM Interrupt, and resets the SCE Modes bits to zero.
Zero Detect
Active Frame Active Frame Int. TC EOM Interrupt Rx Enable Clear FIFO
FIGURE 32 - TV REMOTE DMA RX TIMING
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The SCE TV Remote receiver will abort on a FIFO Overrun condition. When the overrun
Zero D etect
occurs the receiver is disabled, an EOM Interrupt is sent, and the FIFO is flushed.
Activ e Fram e Activ e Fram e Int. FIFO Full E OM Interrupt R x Enable Ov errun
FIGURE 33 - TV REMOTE RX ABORT ON OVERRUN IRDA MULTI-FRAME WINDOW SUPPORT The Tx Data Size register can be used with DMA blocks that are larger than the size of an IrDA message frame to support Multi-Frame Windows, i.e. multiple unacknowledged message frames. MFWs with a single DMA block can occur in both Brick Walled and non-Brick Walled modes. Non-Brickwalled MFWs To support non-Brick Walled multi-frame windows set the SCE Modes bits to zero and setup the DMA controller with a block-size larger than a single frame but smaller-than or equal-to the Tx Data Size x 8. Choose the appropriate encoder, start the transmitter, and wait for an EOM interrupt. Repeat this procedure by reseting and then re-enabling the transmitter DMA block-size / Tx Data Size times, until the DMA block has been transferred. Reset the FIFO Threshold for the last frame, if necessary. Brickwalled MFWs To support Brick Walled Multi-Frame Windows set the SCE Modes bits to zero and setup the DMA controller with a block-size larger than a single frame but smaller-than or equal-to the Tx Data Size x 8. Choose the appropriate encoder, initialize the Brick Wall Count, and set the Brick Wall bit. Start the transmitter and wait for DMA block-size / Tx Data Size EOF interrupts or poll the message count bits; i.e., until the DMA block has been transferred. LOOPBACK MODE Loopback mode allows diagnostic testing of the IrDA FIR and Consumer IR encoders. Loopback tests require that the SCE FIFO be used for both transmit and receive modes, simultaneously. The Data Size registers are used to constrain the Loopback test. Brick Walled messages are not supported in Loopback mode.
63
Initialization The FIFO must be loaded with the appropriate transmit data while the Block Control bits in SCE Configuration Register A are set to the required transfer mode with the SCE MODES bits set to Transmit/Receive Disabled. Enough room must remain in the FIFO for receive data. The Loopback Transmit CRC bit (D6) in SCE Configuration Register B must be initialized for the appropriate CRC response during loopback testing. The Data Size registers must be properly initialized to constrain the loopback function so that received data is not retransmitted. The Rx Data Size register is required for Consumer IR Loopback tests and the Tx Data Size register is required for IrDA FIR Loopback tests. The RX Data Size register must
be programmed with one less than the total number of bytes in the CIR loopback test; i.e., Test_byte_count_1. Proper programming of the Tx Data Size register depends upon the state of the CRC Select and Loopback Tx CRC bits. The FIFO Threshold is not used for loopback tests. The Tx Polarity and Rx Polarity bits must be the same state for loopback tests. Set the Loopback bit in SCE Configuration Register B to begin the loopback test. Retrieving Results The loopback test data can be read from the FIFO immediately following the End-of-Message; i.e., the Loopback bit does not need to be reset, nor does the FIFO need to be explicitly reconfigured for ISA bus access.
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BUS INTERFACE I/O
The Bus Interface I/O block contains a 128-byte FIFO, DMA/Interrupt logic, and multiplexers to control access to the FIFO and the ISA Bus (Figure 34). The Databus Multiplexer provides exclusive ISA Bus access to either the 16550A UART or the IRCC SCE depending on the state of Block Mode Controls in the configuration registers. Disabled blocks are tristated from the ISA Bus.
SCE
Transmit Loopback 16550A UART
FIFO Multiplexer
128-byte FIFO Loopback 0 0 1 Transmit 0 1 X Function FIFO In to SCE Rx FIFO Out to Host Bus FIFO In to Host Bus FIFO Out to SCE Tx FIFO In to SCE Rx FIFO Out to SCE Tx
I/O & Interrupt Control
Databus Multiplexer ISA Bus
FIGURE 34 - BUS INTERFACE I/O BLOCK
FIFO MULTIPLEXER SCE FIFO Access The FIFO Multiplexer controls the configuration of the SCE FIFO in the Bus Interface I/O Block. This configuration can be inferred from the state of the SCE Modes bits in Line Control Register B: when the transmit/receive modes are disabled, or the transmit mode is enabled, the FIFO is configured for transmit; otherwise, the FIFO is configured for receive. The signal Transmit in Figure 34, above, can be satisfied by the inverse of the SCE Modes msb; e.g., nD7.
HOST FIFO Access The Host always has read access to the FIFO, regardless of the state of the SCE Modes bits, or the Loopback bit. The Host has write access to the FIFO when the Loopback bit is inactive and the transmit/receive modes are disabled or the Transmit mode is enabled. 128-BYTE SCE FIFO FIFO Timing & Controls The FIFO uses interleaved access timing to allow simultaneous FIFO data reads and data
65
writes. This is required both for normal operation with asynchronous Host/ SCE access timing, and during loopback tests with synchronous SCEonly access timing where the FIFO is simultaneouly used for transmit and receive. FIFO controls include, separate read/ write lines, FIFO Full and FIFO Not Empty flags, Reset, FIFO Threshold, and Interrupt. FIFO Threshold Description The SCE FIFO Threshold generates programmed I/O service requests to accommodate systems with widely varying I/O response times. FIFO Threshold values typically reflect the overall I/O response characteristics of a system. The same threshold value can be used for both I/O read and I/O write cases. During DMA operatons, the FIFO Threshold is only used to trigger the SCE transmitter. The FIFO Threshold value is programmable from 0 to 127. The FIFO Threshold Register, located in Register Block One, Address Two, contains the FIFO Threshold value. Low threshold values result in longer periods of time between service requests because more of the FIFO is utilized before the request is issued. Systems that program low threshold values must typically provide fast response times to these requests; i.e., high performance systems that move I/O data quickly. High threshold values are used in "sluggish" systems with long service request latencies. Low performance systems typically take longer to move I/O data and require more frequent I/O service. For systems that program high FIFO threshold values, much less of the FIFO is utilized before service requests are issued. Receive Threshold Once the FIFO Interrupt is enabled, Receive Service Requests (RxServReq), i.e. data transfers from the FIFO to the host, are
generated whenever there are 128 minus the FIFO Threshold value or more data bytes in the FIFO, given by: RxServReq 128 - FIFO Threshold For example, if the FIFO Threshold value is 12, RxServReq will be active whenever there 116 to 128 data bytes in the FIFO. If the FIFO Threshold is 0, RxServReq will be active whenever the FIFO is full. If the FIFO Threshold is 127, RxServReq will be active whenever the FIFO is not empty. Transmit Threshold Once the FIFO Interrupt is enabled, Transmit Service Requests (TxServReq), i.e. data transfers from the host to the FIFO, are generated whenever there are FIFO Threshold value or fewer data bytes in the FIFO, given by: TxServReq FIFO Threshold For example, if the FIFO Threshold value is 12, TxServReq will be active whenever there are 12 or less data bytes in the FIFO. If the FIFO Threshold is 0, TxServReq will be active whenever the FIFO is empty. If the FIFO Threshold value is 127, TxServReq will be active whenever the FIFO is not full. FIFO Interrupt The FIFO Interrupt becomes active whenever the FIFO Interrupt Enable is active and either TxServReq or RxServReq is active. When FIFO Interrupt Enable becomes inactive, the FIFO Interrupt goes inactive. For example, the FIFO Interrupt will become active during a transmit operation if the FIFO Threshold is fifty, the FIFO Interrupt Enable is active, and there are from one to fifty data bytes in the FIFO (Figure 35). In Figure 35, notice that five bytes are written to the FIFO every time a service request is answered. The third request occurs as soon as the FIFO Interrupt Enable is activated because 66
the five bytes written to the FIFO following the second service request was not enough data to
Service Req. Satisfied
exceed the FIFO Threshold given the long interrupt latency.
Serv. Req. Satisfied (long int. latency)
Data Bytes in FIFO 51 TxServReq FIFO Int. Enable FIFO Interrupt
50 49
54
...
51
50 49
48
47 46
45 44
49
48
...
1st Service Request
2nd Service Request
3rd Service Request
FIGURE 35 - FIFO INTERRUPT EXAMPLE
DMA The DMA channel works in Single-Byte and Burst (Demand) Mode. AEN is high during DMA transfers. The DMA controls are located in SCE Configuration Register B. When the DMA Enable bit (D0) is one, DMA is enabled. The DMA Burst Mode bit (D1) controls the DMA mode. DRQ is further gated by the SCE Modes bits; e.g., DRQ can only be enabled if either Transmit or Receive mode has been enabled. During transmit DRQ remains active as long as
AEN DM A Burst DMA Enable DRQ nDACK I/Ox TC
the FIFO is not full until TC. During receive DRQ remains active as long as the FIFO is not empty until TC. Single-Byte Mode Single-Byte mode is enabled by resetting the DMA Burst bit in SCE Configuration Register B. Single-Byte DMA transfers one data byte for each DRQ (Figure 36). Terminal Count occurs only once, during the last byte of data block.
FIGURE 36 - DMA SINGLE-BYTE MODE TIMING
67
Burst (Demand) Mode DMA Burst mode is enabled by setting the DMA Burst bit in SCE Configuration Register B. Demand Mode DMA transfers up to 32 data
AEN D M A B u rst D M A E n a b le DRQ nDACK I/O x TC
bytes for each DRQ (Figure 37). The IRCC guarantees that DRQ relinquishes the ISA bus after thirty-two DMA I/O read or write cycles to allow for memory refresh.
FIGURE 37 - DMA BURST MODE TIMING
32 I/Ox Clock DMA Refresh Counter The 32 I/Ox Clock DMA Refresh Counter is used to prevent DRQ from staying active for more than 32 I/O read/write cycles at a time. The counter is stopped and preloaded whenever DRQ is not active. Once DRQ becomes active, the counter decrements until zero-count or DRQ is deactived.
In Demand Mode, the count-zero condition always clears DRQ and triggers a Refresh Interval. The Refresh Interval remains active for 350ns following an inactive nDACK (Figure 38). If there is more data to transfer, DRQ goes active again and the cycle repeats. Single Byte Mode DMA does not use the 32 I/Ox Clock Refresh Counter.
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Disable 32-Clk Countdown & Reset 32-Clk Counter DMA Burst DMA Enable DRQ nDACK I/Ox Refresh Interval
Enable 32-Clk Countdown
32 clocks max.
350ns min.
FIGURE 38 - 32 I/OX CLOCK DMA REFRESH COUNT TIMING
Burst Mode Transmit Uses FIFO Threshold for Triggered Transmit. The IrDA 4PPM transmit encoder can deplete the SCE FIFO faster than an ISA Host can fill it. The FIFO Threshold can be used to allow the DMA controller to load enough data into the FIFO before transmission begins to accommodate system latencies for subsequent DMA transfer cycles. The FIFO Threshold is otherwise not used for DMA transfers. DRQ Control In DMA Burst Mode, DRQ remains active until the entire DMA data block has been transferred, as indicated by DMA Terminal Count (TC). The internal FIFO Full signal can temporarily deactivate DRQ if the DMA block has not been completely transferred but there is no room left in the FIFO for more data. As soon as the FIFO Full becomes inactive, DRQ is reasserted. The
internal Refresh Interval signal can also temporarily deactivate DRQ (see the 32 I/Ox Clock DMA Refresh Counter). Example: Transmit a 256-Byte IrDA Message 1. 2. Setup and enable the DMA controller for the 256-byte message. Set the appropriate FIFO Threshold, typically this number can be high, e.g. 127, and set the SCE Modes bits in Register Block Zero, Address 6 to enable the transmitter. The DMA controller proceeds to load the FIFO until TxServReq activates the transmitter. DMA transfer cycles continue until TC. DRQ is only de-asserted when FIFO Full or Refresh Interval are active (Figure 39).
3.
69
D M A B u rst D M A E n a b le DRQ R e fr e s h In te r v a l F IF O F U L L T x E n a b le T xS erv R eq TC
FIGURE 39 - DMA BURST MODE TRANSMIT TIMING Burst Mode Receive DRQ Control In DMA Burst Mode, DRQ remains active until the entire DMA data block has been transferred, as indicated by DMA Terminal Count (TC). Since the FIFO Threshold is not used for DMA transfer cycles, DRQ is asserted as soon as FIFO Not Empty is true. FIFO Not Empty can temporarily deactivate DRQ if the DMA block has not been completely transferred but there is no data left in the FIFO to transfer. As soon as FIFO Not Empty becomes true, DRQ is reasserted. The internal Refresh Interval signal can also temporarily deactivate DRQ (see the 32 I/Ox Clock DMA Refresh Counter). Example: Receive a 256-Byte IrDA Message 1. 2. 3. 4. Setup and enable the DMA controller for the 256-byte message. Enable the IrDA Receiver. DRQ is asserted as soon as FIFO Not Empty is true. The DMA controller proceeds to empty the FIFO until TC. DRQ is otherwise only deasserted when FIFO Not Empty is false or Refresh Interval is active (Figure 40).
D M A B u rst D M A E n ab le R x E n ab le DRQ R e fre sh In te rv a l F IF O N O T E M PT Y TC
FIGURE 40 - DMA BURST MODE RECEIVE TIMING
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PROGRAMMED I/O Programmed I/O mode is selected when the DMA Enable bit in SCE Configuration Register B is zero.
The IRCC also supports String Move timing which is a block-mode programmed I/O operation that utilizes IOCHRDY to control the transfer (Figure 41). String Move mode is selected when the String Move bit in SCE Configuration Register B is one.
AE N S trin g M ov e F IF O N ot E m pty IO C HR DY IO R
FIGURE 41 - STRING MOVE TIMING
Polling Interface Programmed I/O without IOCHRDY requires polling the FIFO status flags before reading or writing FIFO data. The Receiver interface depends upon the FIFO Not Empty flag. If FIFO
Not Empty is true, there is read data available in the FIFO (Figure 42). The Transmitter interface depends upon the FIFO Full flag. If FIFO Full is false, there is room for write data in the FIFO ( Figure 43).
String M ove DM A Enable FIFO NOT EM PT Y IOR
FIFO Data READ
Status READ
FIGURE 42 - PROGRAMMED I/O READ TIMING
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String Move DMA Enable FIFO FULL IOW
FIFO Data WRITE
Status READ
FIGURE 43 - PROGRAMMED I/O WRITE TIMING
FIFO Interrupt Interface Transmit
transmitter is activated if the FIFO Threshold is greater than zero. Example: Transmit a 256-byte IrDA Message
Description 1. Transmitting messages with Programmed I/O using FIFO Interrupt requires writing a fixed number of data bytes, usually related to the threshold, whenever the FIFO Interrupt becomes active. An appropriate FIFO Threshold value allows the host to efficiently satsify the FIFO service requests until the message transmission is complete. For slow systems, the FIFO can be manually filled with transmit data before the transmitter is enabled. Note: the FIFO will automatically request service before the Set an appropriate FIFO Threshold for the system type. For the greatest performance advantage, pre-load the FIFO with transmit data. Set the FIFO Interrupt Enable active and activate the transmitter. Service the FIFO Interrupts as required. Set the Data Done flag when all of the transmit message data has been loaded (Figure 44).
2. 3.
String Move DMA Enable Tx Enable IOW TxServReq FIFO Int. Enable FIFO Interrupt Data Done EOM Interrupt
FIGURE 44 - INTERRUPT DRIVEN PROGRAMMED I/O TRANSMIT TIMING
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Receive Description Receiving messages with Programmed I/O using FIFO Interrupt requires reading a fixed number of data bytes, usually related to the threshold, whenever the FIFO Interrupt becomes active. An appropriate FIFO Threshold value allows the host to efficiently satisfy the FIFO service requests until the message reception is complete.
Example: Receive a 256-byte IrDA Message 1. 2. 3. Set an appropriate FIFO Threshold for the system type. Set the FIFO Interrupt Enable active and enable the receiver. Service the FIFO Interrupts as required (Figure 45). Note: the amount of data remaining in the FIFO following the last service request (RxServReq) in Figure 45 is probably less than the typical read block size. This will occur when an IrDA EOF has been detected, the FIFO Receive Threshold has not been reached and the FIFO Not Empty flag is true.
String M ove DM A Enable Rx Enable IOR RxServReq FIFO Int. Enable FIFO Interrupt EOM Interrupt
FIGURE 45 - INTERRUPT DRIVEN PROGRAMMED I/O RECEIVE TIMING IOCHRDY Time-out Description In programmed I/O mode when AEN = low and String Move = active, IOCHRDY can be used to slightly extend the access cycle if the FIFO is temporarily unable to fulfill the transfer request (Figure 46). If IOCHRDY remains inactive for more than 10us, a time-out error occurs and subsequent IOCHRDY cycles are prevented until the string move bit is specifically reactivated. Because of the 10us IOCHRDY time-out, it is recommended that string move timing only be used for 1.152Mbps transfers and above.
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AEN String M ove FIFO Not Empty IOCHRDY IOR 24ns (max) 10us (max)
FIGURE 46 - VALID I/O READ READY CYCLE
IOCHRDY Timer The 10us IOCHRDY Timer is initialized when IOCHRDY is active. The timer count sequence is activated when IOCHRDY goes inactive. If IOCHRDY becomes active before the 10us time-
out has elapsed, the timer is stopped and the count is re-initialized. If IOCHRDY is still inactive when the 10us time-out occurs, the timer stops, the time-out error bit is set, IOCHRDY is reasserted, and the string move bit is reset (Figure 47).
AEN String Move FIFO Not Empty IOCHRDY IOR IOCHRDY Time-out 10us Start Timer IOCHRDY Error
FIGURE 47 - IOCHRDY 10uS TIME-OUT
74
Zero Wait State Support nSRDY nSRDY can be driven by the IRCC to indicate that an access cycle shorter than the standard I/O cycle can be executed. NOTE: the names nSRDY & nNOWS can be used interchangeably. nSRDY is enabled by the No Wait bit in SCE
AEN No Wait I/Ox nSRDY
Configuration Register B. When No Wait is one, nSRDY goes active following the trailing edge of the ISA I/O command and inactive following the rising edge (Figure 48). nSRDY is suppressed during DMA & refresh cycles, i.e. when AEN is active, or when IOCHRDY is inactive. Zero Wait State support is only available when the SCE is enabled.
FIGURE 48 - nSRDY TIMING
The Interaction of nSRDY and IOCHRDY nSRDY and IOCHRDY determine the three types of ISA access cycles: no-wait-state cycle,
standard cycle, ready cycle (Table 32). NOTE: An inactive IOCHRDY suppresses nSRDY.
nSRDY active inactive x
Table 32 - nSRDY and IOCHRDY Interaction IOCHRDY DESCRIPTION active active inactive No-wait-state Cycle (shortest length) Standard Cycle (mean length) Ready Cycle (longest length)
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OUTPUT MULTIPLEXER
The Output Multiplexer routes the active encoder/decoder to one of three IRCC serial communications ports. There are no restrictions on any of these connections other than Rx/Tx source pairs go to the same destination (Figure 49). Descriptions of the Block Control, Output Mux. and Aux IR signals can be found in the SCE Configuration Registers in Register Block One. There are Rx and Tx Polarity controls that determine the active states for the IR port signals, see SCE Configuration Register A. The state of inactive IR outputs depends upon the Tx Polarity bit; e.g., if Tx Polarity is zero (default), inactive outputs will be one. Routing for the COM Port flow-control signals is fixed. When the COM Port is inactive, the flow-control signals behave according to the current SMSC 16550A serial port specification. The Tx/Rx Polarity bits do not apply when COM mode is selected. There is a provision for added transmit current capacity by selectively duplicating the transmit output of the IR Port or the COM Port at the AUX Port. This can be used, for example, to accommodate the high-power optics found in Consumer IR TV remote controls. There are GP Data pins that always reflects the state of General Purpose Data & Fast bits (5-6) of Line Control Register A, in Register Block Zero, Address Four. The state of the G.P. Data pins is independent of the IRCC Block Controls or the Output Multiplexer.
Block Tx Output Rx Aux. Control Polarity Mux. Polarity IR 4 1 2 1 1 6 to 1 Mux. 1 to 3 Demux. IRRx IRTx ARx ATx IR Port AUX Port
Raw Rx Raw Tx TV Rx TV Tx ASK Rx ASK Tx IrDA SIR Rx IrDA SIR Tx IrDA FIR Rx IrDA FIR Tx COM Rx COM Tx
2 to 1 Mux.
CRx CTx 1 to 6 Demux. 3 to 1 Mux. nRTS nDTR nCTS nDSR nDCD nRI COM Port
G.P. Data Fast
GP Data G.P. Port Fast
FIGURE 49 - OUTPUT MULTIPLEXER BLOCK
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CHIP-LEVEL IRCC ADDRESSING SUPPORT
IRCC Register addressing is controlled at the chip level. Both the ACE bank select, nACE, and the SCE bank select, nSCE, are decoded at the chip level from the Host Address Bus to access data in the IRCC register banks (Figure 50). Table 33 illustrates a chip-level IRCC address decoder using a base address of 2F8 for the ACE UART and 2F8+400 or 6F8 for the SCE registers.
Address Bus AEN I/O Select
Chip-Level Address Decoder
ACE Select SCE Select
nACE
IRCC
nSCE
FIGURE 50 - CHIP-LEVEL IRCC ADDRESS DECODE
Table 33 - IRCC Address Decode at '400'hex HEX ADDRESS NACE NSCE DESCRIPTION 2F8 - 2FF 6F8 - 6FF All other registers 0 1 1 1 0 1 ACE UART registers enabled SCE registers enabled IRCC registers not accessible
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AC TIMING
IR RX PULSE REJECTION ENCODER 4PPM HDLC 1.152Mbps HDLC .576Mbps IrDA SIR Consumer IR IRDA 4PPM Bit Rate Tolerance TBD of Bit Rate Rx Pulse Width MIN. Single Pulse Double Pulse 85ns 210ns NOM. 125ns 250ns MAX. TBD 290ns PULSE REJECTION 72.8ns 72.8ns 145.6ns 60.0ns 166ns
IRDA HDLC Bit Rate Tolerance TBD of Bit Rate Max Rx Pulse Width MIN. .576Mbps 1.152Mbps TBD TBD NOM. 434ns 217ns MAX. TBD TBD
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IRCC Rev. 5/10/96

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