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| CML Microcircuits COMMUNICATION SEMICONDUCTORS CMX866 V.22 bis Modem with AT Commands Provisional Issue D/866/4 January 2004 Features * V.22 bis, V.22 and Bell 212A QAM/DPSK * V.23, Bell 202, V.21 and Bell 103 FSK * Integral AT Command Set with 'Fast Connect' * V.23 and Bell 202 'Fast Turnaround' * Support for Type 1 Caller Line Identification * DTMF/Programmable Tones: Transmit and Receive * 'Zero-Power' and Powersave Standby Modes * Low Power Operation Applications * Telephone Telemetry Systems * Remote Utility Meter Reading * Security Systems * Industrial Control Systems * Electronic Cash Terminals / ATMs * Pay-Phones * Cable TV Set-Top Boxes * EPOS Terminals 1.1 Brief Description The CMX866 is a multi-standard modem for use in telephone based information and telemetry systems. Control of the device is via AT commands over a simple 9600b/s serial interface, compatible with most types of host Controller. An RS232 compatible interface can be created by the addition of a Level Converter. The data transmitted and received by the modem is also transferred over the same serial interface. The on-chip Controller interprets these AT commands and controls an internal DSP, which provides the modem and anciliary functions such as Ring Detection, Call Progress Detection, Hook Switch control and DTMF autodialling. User-specific DSP functions are also available via the AT command set. Hardware support is provided for V.23 and Bell 202 Fast Turnaround and for rapid return to AT Command mode. A Fast Connect mode has been implemented to reduce modem connection time. Flexible line driver and receive hybrid circuits are integrated on chip, requiring only passive external components to build a 2 or 4-wire line interface. Complete examples of 2-wire line interfaces to an external host C and to an RS232 interface, including the additional components required for Type 1 CLI, are provided. The device features a Hook Switch relay drive output and a Ring Detector circuit that remain operational when the CMX866 is in 'Zero-Power' or Powersave mode, providing an interrupt which can be used to wake up an external host C, as well as the CMX866, when line voltage reversal or ringing is detected. The device is also able to detect off-hook parallel phones by monitoring voice activity on the line. The CMX866 takes 5mA (typ.) from a single 2.7-5.5V supply and comes in 28-pin SSOP/SOIC packages. (c) 2004 CML Microsystems Plc V.22 bis Modem with AT Commands CMX866 CONTENTS Section 1.1 1.2 1.3 1.4 Page Brief Description..................................................................................1 Block Diagram .....................................................................................3 Signal List ............................................................................................4 External Components..........................................................................6 1.4.1 Ring Detector Interface ...........................................................8 1.4.2 Line Interface...........................................................................9 1.4.3 Serial Interface ...................................................................... 11 1.4.4 RESETN pin........................................................................... 12 General Description........................................................................... 13 1.5.1 Internal Structure .................................................................. 13 1.5.2 Operating States and Data Flow........................................... 14 1.5.3 Functional Description ......................................................... 16 1.5.4 AT Command and Register Set ............................................ 17 1.5.4.1 AT Command and S-Register Summary.................. 17 1.5.4.2 General Description of AT Commands.................... 19 1.5.4.3 AT Commands in Detail............................................ 20 1.5.4.4 Extended AT Commands ......................................... 23 1.5.4.5 S-Registers................................................................ 25 1.5.4.6 Result Codes............................................................. 29 1.5.5 Tx USART .............................................................................. 30 1.5.6 FSK and QAM/DPSK Modulators ......................................... 31 1.5.7 Tx Filter and Equaliser.......................................................... 32 1.5.8 DTMF/Tone Generator .......................................................... 32 1.5.9 Tx Level Control and Output Buffer..................................... 32 1.5.10 Rx DTMF/Tones Detectors.................................................... 33 1.5.11 Rx Modem Filterering and Demodulation............................ 34 1.5.12 Rx Modem Pattern Detectors and Descrambler .................. 35 1.5.13 Rx Data Register and USART ............................................... 35 Application Notes .............................................................................. 37 1.6.1 Hardware Interface ................................................................ 37 1.6.2 Calling Modem AT Commands............................................. 42 1.6.3 Answering Modem AT Commands....................................... 42 1.6.4 RS232 Transaction Sequence .............................................. 43 Performance Specification................................................................ 44 1.7.1 Electrical Performance.......................................................... 44 1.7.1.1 Absolute Maximum Ratings ..................................... 44 1.7.1.2 Operating Limits ....................................................... 44 1.7.1.3 Operating Characteristics ........................................ 45 1.7.2 Packaging.............................................................................. 51 1.5 1.6 1.7 (c) 2004 CML Microsystems Plc 2 D/866/4 V.22 bis Modem with AT Commands CMX866 1.2 Block Diagram Figure 1 Block Diagram (c) 2004 CML Microsystems Plc 3 D/866/4 V.22 bis Modem with AT Commands CMX866 1.3 Signal List CMX866 D1/D6 Pin No. 1 2 3 4 5 Signal Name XTALN XTAL/CLOCK N/C N/C RDRVN Type O/P I/P ~ ~ O/P The output of the on-chip Xtal oscillator inverter. The input to the oscillator inverter from the Xtal circuit or external clock source. Reserved for future use. Connect this pin to DVSS. Reserved for future use. Connect this pin to DVSS. Relay drive output, low resistance pull down to DVSS when active and medium resistance pull up to DVDD when inactive. The negative supply rail for the digital on-chip blocks. Schmitt trigger input to the Ring signal detector. Connect to DVSS if Ring Detector not used. Open drain output and Schmitt trigger input forming part of the Ring signal detector. Connect to DVDD if Ring Detector not used. Schmitt trigger input to an active-low reset pin. Connect to DVDD if no external reset signal used The output of the Rx Input Amplifier. An alternative, switched inverting input to the Rx Input Amplifier, used to increase the amplifier gain for the detection of on-hook signals. If this input is not required, leave the pin disconnected. The inverting input to the Rx Input Amplifier The non-inverting input to the Rx Input Amplifier. If this pin is to be connected to VBIAS then it should also be decoupled to AVSS locally. The negative supply rail for the analogue onchip blocks. Internally generated bias voltage of approximately AVDD /2, except when the device is in Powersave or 'Zero-Power' modes, when VBIAS will discharge to AVSS. This pin should be decoupled to AVSS by a capacitor mounted close to the device pins. The inverted output of the Tx Output Buffer. The non-inverted output of the Tx Output Buffer. Description 6 7 8 DVSS RD RT Power I/P BI 9 RESETN I/P 10 11 RXAFB RXBN O/P I/P 12 13 RXAN RXA I/P I/P 14 15 AVSS VBIAS Power O/P 16 17 TXAN TXA O/P O/P (c) 2004 CML Microsystems Plc 4 D/866/4 V.22 bis Modem with AT Commands CMX866 CMX866 D1/D6 18 Signal AVDD Power Description The positive supply rail for the analogue on-chip blocks. Levels and thresholds within the device are proportional to this voltage. The inverted DCD signal used for an RS232 interface with a Level Converter. The inverted DSR signal used for an RS232 interface with a Level Converter. The inverted CTS signal used for an RS232 interface with a Level Converter. The inverted DTR signal used for an RS232 interface with a Level Converter. The inverted RTS signal used for an RS232 interface with a Level Converter. The non-inverted TD signal used for an RS232 interface with a Level Converter. This pin accepts data from the external host C for transmission over the phone line. The non-inverted RD signal used for an RS232 interface with a Level Converter. This pin sends data to the external host C which was received over the phone line. An auxiliary pin to force the CMX866 into Command Mode from Data Mode and remain off-hook. The ATO command will return the CMX866 to Data Mode. This pin should be connected to DVSS if not required. The inverted RI signal used for an RS232 interface with a Level Converter. This is a 'wireORable' output for connection to an external host C Interrupt Request input. This output is pulled down to DVSS when active and is high impedance when inactive. An external pullup resistor is required (eg. R1 in Figure 2a). The positive supply rail for the digital on-chip blocks. Levels and thresholds within the device are proportional to this voltage. 19 20 21 22 23 24 DCDN DSRN CTSN DTRN RTSN TXD O/P O/P O/P I/P I/P I/P 25 RXD O/P 26 ESC I/P 27 RIN O/P 28 DVDD Power Notes: I/P O/P BI T/S NC = = = = = Input Output Bidirectional 3-state Output No Connection (c) 2004 CML Microsystems Plc 5 D/866/4 V.22 bis Modem with AT Commands CMX866 1.4 External Components C1, C2 R1 X1 22pF 100k 11.0592MHz C3, C4, C6 C5, C7 L1, L2 100nF 10uF 100nH (optional) Resistors 5%, capacitors 20% unless otherwise stated. Figure 2a Recommended External Components for Typical Application This device is capable of detecting and decoding small amplitude signals. To achieve this DVDD, AVDD and VBIAS should be decoupled and the receive path protected from extraneous in-band signals. It is recommended that the printed circuit board is laid out with both AVSS and DVSS ground planes in the CMX866 area, as shown in Figure 2b, with provision to make a link between them close to the CMX866. To provide a low impedance connection to ground, the decoupling capacitors (C3 - C7) must be mounted as close to the CMX866 as possible and connected directly to their respective ground plane. This will be achieved more easily by using surface mounted capacitors. VBIAS is used as an internal reference for detecting and generating the various analogue signals. It must be carefully decoupled, to ensure its integrity. Apart from the decoupling capacitor shown (C3), no other loads are allowed. If VBIAS needs to be used to set external analogue levels, it must be buffered with a high input impedance buffer. The DVSS connections to the Xtal oscillator capacitors C1 and C2 should also be of low impedance and preferably be part of the DVSS ground plane to ensure reliable start up of the oscillator. (c) 2004 CML Microsystems Plc 6 D/866/4 V.22 bis Modem with AT Commands CMX866 Figure 2b Recommended Power Supply Connections and De-coupling ANALOGUE C3, C6 C7 L2 100nF 10uF 100nH (optional, see note) DIGITAL C4 C5 L1 100nF 10uF 100nH (optional, see note) Note: The inductors L1 and L2 and the electrolytic capacitor C7 can be omitted without significantly degrading the system performance. (c) 2004 CML Microsystems Plc 7 D/866/4 V.22 bis Modem with AT Commands CMX866 1.4.1 Ring Detector Interface Figure 3 shows how the CMX866 may be used to detect the large amplitude Ringing signal voltage present on the 2-wire line at the start of an incoming telephone call. The ring signal is usually applied at the subscriber's exchange as an ac voltage inserted in series with one of the telephone wires and will pass through either C20 and R20 or C21 and R21 to appear at the top end of R22 (point X in Figure 3) in a rectified and attenuated form. The signal at point X is further attenuated by the potential divider formed by R22 and R23 before being applied to the CMX866 RD input. If the amplitude of the signal appearing at RD is greater than the input threshold (Vthi) of Schmitt trigger 'A' then the N transistor connected to RT will be turned on, pulling the voltage at RT to DVSS by discharging the external capacitor C22. The output of the Schmitt trigger 'B' will then go high, setting bit 14 (Ring Detect) of the DSP Status Register. The on-chip Controller will then respond by setting pin RIN low. The minimum amplitude ringing signal that is certain to be detected is: ( 0.7 + Vthi x [R20 + R22 + R23] / R23 ) x 0.707 Vrms where Vthi is the high-going threshold voltage of the Schmitt trigger A (see section 1.7.1). With R20-22 all 470k as Figure 3, setting R23 to 68k will guarantee detection of ringing signals of 40Vrms and above for DVDD over the range 3 to 5V. R20, 21, 22 R23 R24 470k See text 470k C20, 21 C22 D1-4 0.1F 0.33F 1N4004 Resistors 5%, capacitors 20% Figure 3 Ring Signal Detector Interface Circuit (c) 2004 CML Microsystems Plc 8 D/866/4 V.22 bis Modem with AT Commands CMX866 If the time constant of R24 and C22 is large enough then the voltage on RT will remain below the threshold of the 'B' Schmitt trigger for the duration of a ring cycle. The time for the voltage on RT to charge from DVSS towards DVDD can be derived from the formula: VRT = DVDD x [1 - exp(-t/(R24 x C22)) ] As the Schmitt trigger high-going input threshold voltage (Vthi) has a minimum value of 0.56 x DVDD, then the Schmitt trigger B output will remain high for a time of at least 0.821 x R24 x C22 following a pulse at RD. The values of R24 and C22 given in Figure 3 (470k and 0.33F) give a minimum RT charge time of 100msec, which is adequate for ring frequencies of 10Hz or above. Note that this circuit will also respond to a telephone line voltage reversal. The external host C can distinguish between a Ring signal and a line voltage reversal by measuring the time that pin RIN is low. If the Ring detect function is not used then pin RD should be connected to DVSS and RT to DVDD. 1.4.2 Line Interface A line interface circuit is needed to provide dc isolation and to terminate the line. 2-Wire Line Interface Figure 4a shows a simplified interface for use with a 600 2-wire line. The complex line termination is provided by R13 and C10, high frequency noise is attenuated by C10 and C11, while R11 and R12 set the receive signal level into the modem. For clarity the 2-wire line protection circuits and the connection to RXBN (for on-hook CLI applications) have not been shown. R11 R12 R13 See text 100k 600 C3 C10 C11 Resistors 5%, capacitors 20% See Figure 2 33nF 100pF Figure 4a 2-Wire Line Interface Circuit (c) 2004 CML Microsystems Plc 9 D/866/4 V.22 bis Modem with AT Commands CMX866 The transmit line signal level is determined by the voltage swing between the TXA and TXAN pins, less 6dB due to the line termination resistor R13, and less the loss in the line coupling transformer. Allowing for 1dB loss in the transformer, then with the DSP Tx Mode Register set for a Tx Level Control gain of 0dB (S25 register set to 'xxxxx111') the nominal transmit line levels will be: AVDD = 3.0V -10dBm -10dBm -6 and -8 dBm AVDD = 5.0V -5.5dBm -5.5dBm -1.5 and -3.5 dBm QAM, DPSK and FSK Tx modes (no guard tone) Single tone transmit mode DTMF transmit mode For a line impedance of 600, 0dBm = 775mVrms. See also section 1.7.1.3 In the receive direction, the signal detection thresholds within the CMX866 are proportional to AVDD and are affected by the Rx Gain Control gain setting in the DSP Rx Mode Register (as indicated by the value held in the S26 register). The signal level into the CMX866 is affected by the line coupling transformer loss and the values of R11 and R12 of Figure 4a. Assuming 1dB transformer loss, the Rx Gain Control programmed to 0dB (S26 register set to 'xxxxx111') and R12 = 100k, then for correct operation (see section 1.7.1.3) the value of R11 should be equal to: 500 / AVDD k i.e. 160k at 3.0V, falling to 100k at 5.0V When the RDRVN pin is high impedance (= on-hook = inactive) the auxiliary receive input pin RXBN is internally connected to the RXAN pin. This can be used to increase the Rx gain (required for Type 1 Caller Line Identification reception) by reducing the effective value of R11, as shown in Figures 11 and 12. When the RDRVN pin is low (= off-hook = active) the RXBN pin is not connected. 4-Wire Line Interface Figure 4b shows an interface for use with a 600 4-wire line. The line terminations are provided by R10 and R13, high frequency noise is attenuated by C11 while R11 and R12 set the receive signal level into the modem. Transmit and receive line level settings and the value of R11 are as for the 2-wire circuit. R10, 13 R11 R12 600 See text 100k C3 C11 C12 Resistors 5%, Capacitors 20% See Figure 2 100pF 33nF Figure 4b 4-Wire Line Interface Circuit (c) 2004 CML Microsystems Plc 10 D/866/4 V.22 bis Modem with AT Commands CMX866 1.4.3 Serial Interface The CMX866 is controlled by sending AT commands over the serial interface from an external host C. For simplicity, an asynchronous protocol has been adopted: 9600 baud, 8-bit words, no parity, 1 stop-bit. Since this communications rate exceeds that over the phone line, it is necessary to use CTS flow control to moderate the data rate, so that on average it equals the baud rate for the communications standard adopted. The CTS flow control method provided on the CMX866 will also work with the RTS/CTS handshake protocol used by some Controllers. AT commands and phone numbers need to be stored for future use and the CMX866 provides four internal buffers for phone number and command storage and for data buffering (see Figure 5a). When the external host C is ready to transmit AT commands or data it should take the Request To Send signal active (RTSN pin goes low) and place the information to be sent on the Transmit Data (TXD) pin. When the CMX866 is ready to accept this information from the external host C it will take the Clear To Send signal active (CTSN pin goes low). The information should be sent as 8-bit bytes, encapsulated by a start bit (low) and a stop bit (high). The CMX866 should be presented with continuous mark (stop bits) when the host C has no information to send. As each byte is received it is stored in a 48-byte AT command buffer when in Command mode or in a 16-byte receive data buffer when in Data Transfer mode. The CMX866 will take the CTSN pin high when either buffer is full and will ignore further information on the TXD pin until the on-chip Controller in the CMX866 is ready to accept it. At this time, the CMX866 will once again take the CTSN pin low to signify its readiness to accept more information, providing the RTSN pin is already low. If the external host C does not have an Request To Send signal, the RTSN pin should be permanently wired low. When RTSN is inactive high, CTSN follows RTSN and becomes inactive high, thus there is no data flow from the host C to the CMX866, but data flow from the CMX866 to the host C is allowed. As the incoming AT command is being interpreted, any phone number is identified and stored separately in the 24-byte phone number buffer. When the CMX866 is in Data Transfer mode and it receives a signal from the phone line which exceeds the minimum amplitude threshold, it will attempt to demodulate the signal and place the received data on the RXD pin. At the same time it will make the Data Carrier Detected signal active (DCDN pin goes low). Received data is presented to the RXD pin at 9600 baud (with the same protocol as for transmission, regardless of the format that was used over the phone line), after a complete byte has been demodulated. There is a 24-byte message buffer in the receive path but, as the received data always arrives at slower than 9600 baud, there is no need for a flow control handshake in the receive path. It is assumed that the external host C will absorb all of the data presented to it without the need for flow control and will ignore continuous mark (stop bits) when there is no received data. If the received signal is below the detection threshold or the CMX866 is not in Data Transfer mode, the DCDN and RXD pins will be taken high. If the CMX866 receives a RING signal on the RD and RT pins, such that the detection threshold is exceeded, then the device will forward this condition to the external host C by taking the RIN pin low. This pin follows the output of the ring detector, so will go low for each burst of RING signal. If the CMX866 is in a Powersave or 'Zero-Power' state, it will be woken up and the DSRN pin will go low once the on-chip Controller is ready to receive communications through the serial port. This wake up process takes about 30ms from 'Zero-Power' state, as the VBIAS pin has to charge the external reservoir capacitor and the crystal oscillator has to start up and stabilise before the CMX866 can initialise itself. From the Powersave state this wake up process takes about 10s, as the oscillator and the VBIAS pin are already stable. The DSRN and DTRN pins do not act as a handshake with the external host C. The DSRN pin indicates the operational status of the on-chip Controller (low = ready to communicate with an external host C). The DTRN pin is used for taking the CMX866 out of a Powersave or 'Zero-Power' state. It acts as a device wake up, in the same manner as the RING signal, and becomes active on the high to low transition. A high to low transition on the DTRN pin is ignored if the device is already 'woken up'. If the external host C does not have a DTR signal, the DTRN pin should be permanently wired to the TXD pin. When the CMX866 is in a Powersave or 'Zero-Power' state, the RXD, CTSN, DSRN, DCDN and RIN pins will be permanently high. The condition of the TXD, RTSN and DTRN pins is not important. Depending on the &Dn configuration, if the DTRN pin is taken high at any time whilst the CMX866 is in Data Transfer mode, a fixed, 100ms timeout is started. On completion of the timeout, the CMX866 will (c) 2004 CML Microsystems Plc 11 D/866/4 V.22 bis Modem with AT Commands CMX866 return to Command mode, enabling further AT commands to be sent. If the DTRN pin goes high whilst the CMX866 is in Command mode, the action is ignored. AT commands can be sent providing CTSN and RTSN are low (ie DTRN can be either high or low). A low to high transition on the ESC pin also has the same effect of returning the CMX866 from Data Transfer mode to Command mode, but with immediate effect. The &Dn command configures these options, see section 1.5.4.4 for more details. If the RTSN pin is taken high at any time whilst the CMX866 is in Data Transfer mode, a timeout is started whose value is set in the S28 register (0 = timeout disabled). On completion of the timeout, the CMX866 will return to Command mode and take CTSN high. If the RTSN pin goes high whilst the CMX866 is in Command mode, the CTSN pin goes high and the action on the RTSN pin is ignored. Information transfer can only restart when the RTSN pin is taken low again and the CMX866 responds by taking CTSN low. 1.4.4 RESETN pin The CMX866 has an internal power-up reset function which is activated whenever power is first applied to the device. This reset function resets all of the on-chip Controller registers, including the S-Register settings, and then performs an initialisation sequence which resets the internal DSP and subsequently places it in a powersave state, loads the factory default values into the S-Registers and places the onchip Controller into an operating state. This internal power-up reset function is OR-ed with the RESETN pin. The state of the CMX866, including its outputs, is undefined for approximately 4.7ms, until this reset operation is complete. When the RESETN pin is taken low, the on-chip controller is reset and its program counter held at address $0000. It remains in this condition until the RESETN pin is taken high, at which time the software reset operation described above is performed. The RESETN pin must be held low for at least 5.0s. When the CMX866 first enters the operating state, it reports its configuration as follows: * * * * * * * CMX866 waits for DTRN to go active (low) CMX866 takes the DSRN pin active (low) to indicate its readiness to communicate with an external host C CMX866 waits for RTSN to go active (low) CMX866 sends "CMX866" identification message to external host C (equivalent to the host C issuing an ATI0 command) The on-chip Controller now powers up the DSP part of the CMX866 The DSP is automatically reset then requested to perform an internal diagnostic self-check, which takes about 2.9ms to complete On successful completion, CMX866 sends "DSP checksum OK" identification message to the external host C. If not successful, CMX866 sends "DSP Error" message to the external host C. In the latter case, the CMX866 should be reset again by taking the RESETN pin low The on-chip Controller now powers down the DSP part of the CMX866 The on-chip Controller is now in the Command mode operating state and is ready to accept AT commands from the serial interface, approximately 55ms after DTRN went low CMX866 takes the CTSN pin active (low) to indicate its readiness to communicate with an external host C * * * Note that the on-chip Controller does not perform its own internal diagnostic self-check as this is not considered necessary. (c) 2004 CML Microsystems Plc 12 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5 1.5.1 General Description Internal Structure Internally, the CMX866 consists of a dedicated DSP which is controlled by an on-chip Controller. This Controller is preprogrammed to interpret the AT commands provided by the user into instructions for controlling the dedicated DSP. It also handles the CMX866 power management and other functions. The DSP is preprogrammed with algorithms to implement the various modem functions, but also has Tone Generators and Detectors which are user programmable with AT commands, via the on-chip Controller. The CMX866's DSP transmit and receive operating modes are independently programmable by means of AT commands which write values into the S-Registers. The on-chip Controller then interprets the values in these registers and programs the corresponding registers in the dedicated DSP. The DSP transmit mode can be set to any one of the following: * V.22 bis modem. 2400bps QAM (Quadrature Amplitude Modulation) * V.22 and Bell 212A modem. 1200 bps DPSK (Differential Phase Shift Keying) * V.21 modem. 300bps FSK (Frequency Shift Keying) * Bell 103 modem. 300bps FSK * V.23 modem. 1200 or 75 bps FSK * Bell 202 modem. 1200 or 150 bps FSK * DTMF transmit * Single tone transmit (from a range of modem calling, answer and other tone frequencies) * User programmed tone or tone pair transmit (programmable frequencies and levels) * Disabled The DSP receive mode can be set to any one of the following: * V.22 bis modem. 2400bps QAM * V.22 and Bell 212A modem. 1200 bps DPSK * V.21 modem. 300bps FSK * Bell 103 modem. 300 bps FSK * V.23 modem. 1200 or 75 bps FSK * Bell 202 modem. 1200 or 150 bps FSK * DTMF detect * 2100Hz and 2225Hz answer tone detect * Call progress signal detect * Dual alert tone pair detect (for Caller Line Identification) * User programmed tone or tone pair detect * Disabled The CMX866 can also be set into 'Zero-Power' or Powersave states, which disable all circuitry except for the Ring Detector. The S-Register settings and the CMX866's configuration are remembered when in 'Zero-Power' or Powersave states. The 'Zero-Power' state stops the crystal oscillator and removes power from the VBIAS pin, for minimum power consumption. It takes about 30ms for the CMX866 to become operational from the 'Zero-Power' state. The Powersave state stops the internal clock distribution, but retains power to the crystal oscillator and VBIAS circuit. Consequently, the CMX866 can become operational from this state in about 10s. If the TXD pin is tied to the DTRN pin (to implement a reduced RS232 interface) any activity on the TXD pin will also take the CMX866 into an operational state. In this case, however, data may be corrupted until the CMX866 is fully operational. (c) 2004 CML Microsystems Plc 13 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.2 Operating States and Data Flow The following diagram shows the flow of data in the CMX866: Figure 5a CMX866 Data Flow Diagram (c) 2004 CML Microsystems Plc 14 D/866/4 V.22 bis Modem with AT Commands CMX866 The following state transition chart shows the various modes of operation for the CMX866: Figure 5b CMX866 State Transition Chart (c) 2004 CML Microsystems Plc 15 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.3 Functional Description The CMX866 is a multi-functional integrated modem chip which requires simple telephone line and RS232 interfaces to implement a complete, low-power modem that can be controlled by widely used AT commands. A list of the main features of this product is given below: Function * Set modem line communication functions, software protocol and control characters for AT commands * Select automatic or no fallback from V.22bis to V.22 * Select V.23 or Bell 202 fast turnaround * Return to Command mode by: 1) Issuing an escape sequence: &Tn S15, S16, S18, S21 Dn, DTn, DL, Hn, Xn A, Hn S6, S7, S8, S11, S22, S29 S0, S1, S17 S25, S26 (c) 2004 CML Microsystems Plc 16 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.4 AT Command and Register Set 1.5.4.1 AT Command and S-Register Summary AT Command A A/ Bn Dn ... n or DTn ... n Parameters Re-execute last command n = 0..9 Select Communications Standard n = 0..9, A..D, *,# Dial Command - DTMF dials the subsequent Directory Number , Dial Command Modifier - Delay during dialling - time in S8 register ! Dial Command Modifier- Send a line break - time in S29 register ; Dial Command Modifier - command mode after dialling, no handshake Dial Command - Redial last number n = 0,1 n = 0,1 n=0 n = 0,1 n = 0,1 Command echo, 0=off, 1=on Switch Hook Control, 0=on-hook, 1=off-hook Identification - Returns the modem's product identification V.22bis Fallback to V.22 option, 0=none, 1=automatic Go online in Data mode (from Command mode) Enable(n=0)/Disable(n=1) return of modem result codes Execute V.23 or Bell 202 turnaround if enabled (see S14 and S24) then go online in Data mode S-Register "n" Read - Display specified S Register contents S-Register "n" Write - Write to specified S Register Return result codes as numbers (n=0) or words (n=1) Calling and Response Characteristics Restore factory profile for CMX866 DCD always on (n=0) or DCD follows carrier (n=1) DTR signal procedure Guard Tone Select - Disable (n=0), Enable 550Hz (n=1) or 1800Hz (n=2) User accessible Loopback Tests and Diagnostics Returns current configuration n = 0,1 n = 00..FF n = 00..FF Parameters 0...255 0...255 0-127 0-127 0-127 0-127 2...255 2...255 0...255 1...255 1...255 'Zero-Power' state (n=0) or Powersave state (n=1) DSP Register "n" Read - Display specified DSP Register contents DSP Register "n" Write - Write to specified DSP Register Function Number of rings before answering, 0 = Auto-answer disabled Number of rings received Escape character value Carriage return character value Line feed character value Backspace character value Waiting time in seconds for dial tone or before blind dialling Maximum waiting time in seconds for carrier Pause time in seconds for "," dial modifier Reserved Lost carrier to hang up delay in units of 100ms 700ms Default 2 0 + CR LF BS 4s 50s 2s n=0 n=3 n=1 n=2 n=0 n=0 n=0 n=1 n=1 n=0 n=0 Function Answer Command - Answer and establish a connection when off-hook Default DL En Hn In Nn O Qn RO Sn? Sn=x Vn Xn Z &Cn &Dn &Gn &Tn &V &Zn @Rn? @Rn=x S Registers S0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 n = 0..29 n = 0..29 n =0,1 n = 0..3 n = 0,1 n= 0..2 n = 0..2 n = 0,3..6 (c) 2004 CML Microsystems Plc 17 D/866/4 V.22 bis Modem with AT Commands CMX866 S Registers S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 S23 S24 S25 S26 S27 S28 S29 Bn Register Parameters 5...255 0...255 0...255 0...255 0...255 0...255 0...255 Function DTMF tone duration and interdigit pause duration in units of 10ms Escape code guard time in units of 50ms Reserved General Options Loopback carrier off time in units of 10ms Drop time for loopback in units of 10ms Handshake timeout (Answering) in seconds Loopback timer (0= no timeout) in seconds Reserved for test functions Reserved Default 100ms 1s $92 80ms 60ms 30s 0s 0...255 0...255 0...255 0...255 0...255 0...255 0...255 0...255 0...255 Parameter n 0 1 2 3 4 5 6 7 8 9 Loopback and Power states Calling and response characteristics selection Guard tone selection Equaliser, DCD, DTR status and modulation fallback TX Gain, TX data format RX Gain, RX data format, overspeed (2.3% default) setting Communications Protocol RTSN Timeout for return to Command mode from Data mode in seconds Timed Break Recall period in units of 10ms Communications Protocol (Mapped to S27 register) V.22bis 2400bps QAM V.22 1200bps DPSK V.23 Tx 75bps, Rx 1200bps (Master) V.23 Tx 1200bps, Rx 75bps (Slave) Reserved V.21 300bps FSK Bell 212A 1200bps DPSK Bell 202 Tx 150bps Rx 1200bps Bell 202 Tx 1200bps Rx 150bps Bell 103 300bps FSK Calling and Response Characteristics (Mapped to S22 register) Ignore dial tones and busy tones, return CONNECTxxxx or NO CARRIER Ignore busy tone, wait for dial tone to dial. Return NO DIAL TONE or CONNECT xxxx or NO CARRIER Ignore dial tone. If busy tone detected, return BUSY. Return CONNECT xxxx Return NO DIAL TONE, BUSY, CONNECT xxxx, or NO CARRIER $10 $C0 $00 $A9 $B0 $30 $00 0s 300ms Fallback V.22 Xn Register Parameter n 0 1 2 3 (c) 2004 CML Microsystems Plc 18 D/866/4 V.22 bis Modem with AT Commands CMX866 &Dn Register Parameter n 0 1 2 Ignore DTR signal DTR action (Mapped to S24 register) Go to command state when on to off transition occurs Hang up and go to command state when on to off transition occurs Guard Tone action (Mapped to S23 register) Disabled Enabled 550Hz Enabled 1800Hz Test function (Mapped to S21 register) Terminate test Reserved Reserved Local digital loopback Enable remote request for digital loopback Disable remote request for digital loopback Request remote digital loopback & initiate &Gn Register Parameter n 0 1 2 &Tn Register Parameter n 0 1 2 3 4 5 6 1.5.4.2 General Description of AT Commands Only the AT commands listed above are supported. Valid commands will generate an 'OK' result code (see section 1.5.4.6) and invalid commands will be rejected with an 'ERROR' result code, when command echoing and word result codes are enabled. The on-chip Controller will send a (c) 2004 CML Microsystems Plc 19 D/866/4 V.22 bis Modem with AT Commands CMX866 The escape sequence `+++' (with Guard Time = 1s [see S12 register] before and after the sequence) will cause the CMX866 to enter Command mode from Data Transfer mode and to return an `OK' response. 1.5.4.3 AT Commands in Detail Command A Description Answer Command The CMX866 will go off-hook and attempt to answer an incoming call by establishing a connection with a remote modem. The command is not valid if there is no incoming call and it will return the 'ERROR' result code. Syntax: ATA A/ Re-Execute Previous Command Line Re-executes the last issued command line. This command does not require the AT prefix or a carriage return. If the last issued command line contained several AT commands, each of these will be repeated. Syntax: A/ Bn Select Communications Standard Selects the communications standard specified by the parameter n. Syntax: ATBn Dn or DTn Dial Command This command directs the CMX866 to go off-hook, dial the directory number entered and attempt to establish a connection with a remote modem by going into Data Transfer mode. The n represents an ASCII string composed of dial digits and dial modifiers and must not exceed the 23 character buffer limit. The DTMF tone dialling digits include 0 through 9, A, B, C, D, and the symbols # and *. Loopdisconnect (pulse) dialling is not implemented. For example: ATD9,01621875500 En Echo Command Characters Syntax: ATEn (c) 2004 CML Microsystems Plc 20 D/866/4 V.22 bis Modem with AT Commands CMX866 n=0 Disables the echoing of commands to the external host C. n=1 Enables echoing of commands to the external host C (default). Hn Hook Switch Control Syntax: ATHn "CMX866" (c) 2004 CML Microsystems Plc 21 D/866/4 V.22 bis Modem with AT Commands CMX866 Sn? S-Register Read Command for displaying the contents of an S-Register (See S-Register Table). Syntax: ATSn? Sn=x S-Register Write Command for writing to an S-Register (See S-Register Table). Syntax: ATSn=x Vn Result Code Format Syntax: ATVn Xn Calling Characteristics Determines which set of responses and calling characteristics are used. Syntax: ATXn n=3 If a dial tone is not detected within the time in register S6, a NO DIAL TONE result code is returned. If a busy tone is detected, a BUSY result code is returned. The CMX866 returns a CONNECT xxxx result code when a connection is established, where xxxx is the Tx/Rx line speed, otherwise it returns a NO CARRIER result code (default). Z Factory Reload Reloads the factory default S-Register settings (See S-Register Table). Syntax: ATZ (c) 2004 CML Microsystems Plc 22 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.4.4 Extended AT Commands Command &Cn Description Carrier Detect Determines the action of the DCDN pin. Syntax: AT&Cn &Dn Data Terminal Ready Determines the meaning of the DTRN pin. Syntax: AT&Dn &Gn Guard Tone Select Selects the Guard tone to be transmitted with highband QAM or DPSK. Syntax: AT&Gn &Tn Loopback Connection Instructs the CMX866 to make local or remote loopback connections, or to action a remote request to make loopback connections. Syntax: AT&Tn (c) 2004 CML Microsystems Plc 23 D/866/4 V.22 bis Modem with AT Commands CMX866 Note that if the CMX866 is in Data Transfer mode, an escape sequence must be issued (+++) to return the CMX866 to Command mode before this loopback connection command can be given. The AT&T0, AT&T3 and AT&T6 commands can only be issued when off-hook. The AT&T4 and AT&T5 commands can be issued when either on-hook or off-hook. &V Current Configuration Returns the current CMX866 configuration by reading the S-Registers. The register data is output on the RXD pin in the form (where xxx is decimal data): S00: xxx S01: xxx S02: xxx S03: xxx S04: xxx S05: xxx S06: xxx S07: xxx S08: xxx S09: xxx (c) 2004 CML Microsystems Plc 24 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.4.5 S-Registers The following table gives a more detailed description of the available S-Registers and their functions. The register range, units and default values are also listed. Reg S0 Range 0-255 Units Rings S-Register Description Automatic answer - Number of rings until automatic answer. If the register is zero the modem will not automatically answer. Count incoming rings - This register is read only and contains the number of rings detected by the CMX866. Escape character value - Contains the ASCII decimal value of the escape character. The default setting is an ASCII + and the escape sequence is +++. A value over 127 disables the escape sequence. Carriage return character - Contains the ASCII decimal value of the character recognised as the command line terminator. This character will also be sent at the end of result codes. The default setting is Default 2 S1 0-255 Rings 0 S2 0-127 ASCII Decimal 43 S3 0-127 ASCII Decimal 13 S4 0-127 ASCII Decimal 10 S5 0-127 ASCII Decimal 8 S6 2-255 1s 4 S7 1-255 1s Wait for carrier after dial - Sets the length of time the CMX866 waits for a carrier before returning on-hook. Pause Time for Comma Dial Modifier - Specifies the number of seconds to pause for each comma (,) encountered in a dial string. Reserved 50 S8 0-255 1s 2 S9 1-255 (c) 2004 CML Microsystems Plc 25 D/866/4 V.22 bis Modem with AT Commands CMX866 Reg S10 Range 1-255 Units 100ms S-Register Description Lost carrier to hang up delay - Sets the length of time that the CMX866 waits before hanging up after the loss of a carrier. This allows the CMX866 to distinguish between disturbances that momentarily break the connection and the remote modem hanging up. DTMF tone duration - Defines the duration of DTMF tones for tone dialling. The length of pause between each DTMF tone is the same as this duration time. Escape code guard time - Specifies the minimum time of no data before and after entry of the escape sequence. Reserved General options - provides the following functions: Bit 0 - V.23/Bell 202 Turnaround, 0 Disabled, 1 Enabled Bit 1 - Echo command character, 0 Disables echoing (ATE0), 1 Enables echoing (ATE1) Bit 2 - Result code display, 0 Send responses (ATQ0), 1 Do not send responses (ATQ1) Bit 3 - Word or number responses, 0 Send number responses (ATV0), 1 Send word responses (ATV1) Bit 4 - DSP or S-Register o/p format, 0 Decimal, 1 Hex Bit 5 - Fast Connect, 0 Disabled, 1 Enabled Bit 6 - ESC pin, 0 Disabled, 1 Enabled Bit 7 - Answer/originate operation, 0 Answer (ATA), 1 Originate (ATD) Loopback Carrier Off Time - To terminate a loopback test at a remote modem, the CMX866 turns off the carrier sent to that modem for the time specified in this register. Drop Time for Loopback - If a loopback test is being performed by a remote modem, detection of a drop in the carrier from that modem which exceeds the time set in this register will cause the local loopback to be removed. Handshake Timeout - If the handshake sequence, when answering, exceeds this duration, the handshake will be aborted and the modem will return to Command mode. Loopback Timer - Defines the duration in seconds for which the modem performs diagnostic tests. On timeout, the test is terminated and the modem returns to Command mode. The default value of 0s disables the loopback timer, so that tests will run indefinitely. A test can also be terminated from Command mode at any time by issuing the AT&T0 command, which then returns the modem to Data Transfer mode. Default 7 S11 5-25 10ms 10 S12 0-255 50ms 20 S13 S14 0-255 0-255 Hex 92 S15 0-255 10ms 8 S16 0-255 10ms 6 S17 0-255 1s 30 S18 0-255 1s 0 (c) 2004 CML Microsystems Plc 26 D/866/4 V.22 bis Modem with AT Commands CMX866 Reg S19 S20 S21 Range 0-255 0-255 0-255 Units Reserved Hex S-Register Description Reserved - Reserved for test functions Default Loopback and Power States - controls the operation of remote loopback and operational states: Bit 4 - Remote loopback, 0 Disabled, 1 Enabled (See &Tn command) Bit 6 - Powersave state, 0 Not powersaved, 1 Powersaved Bit 7 - 'Zero-Power' state, 0 Not 'Zero-Power', 1 'Zero-Power' All other bits Reserved Calling and Response Characteristics (see section 1.5.4.1): Bit 4-0 - Reserved Bit 7-5 - Calling and Response Characteristics: 000 Ignore Dial Tone and Busy Tone (ATX0), 100 Ignore Busy Tone, wait for Dial Tone (ATX1), 101 Ignore Dial Tone, wait for Busy Tone (ATX2), 110 Wait for Dial Tone and Busy Tone (ATX3) Guard Tone Selection (see section 1.5.4.1): Bit 5-0 - Reserved Bit 7-6 - Guard Tone Activity: 00 Disabled (AT&G0), 11 Enabled, guard tone = 550Hz (AT&G1) 10 Enabled, guard tone = 1800Hz (AT&G2) Equaliser, DCD and DTR status (see section 1.5.4.1): Bit 0 - Reserved. Permanently set to 1 Bit 1 - Fixed Compromise Equaliser, 0 Enabled, 1 Disabled Bit 2 - Auto-Equaliser, 0 Disabled, 1 Enabled Bit 3 - DCDN pin function, 0 DCDN always low, 1 DCDN follows inverse of carrier Bit 5-4 - DTRN pin function, 00 Ignore DTRN signal (AT&D0), 01 Go to Command mode when low to high transition has been qualified (AT&D1) 10 Go on-hook then go to Command mode when low to high transition has been qualified (AT&D2) Bit 6 - Reserved for use with the V.23 or Bell 202 turnaround function (used by the ATRO command) Bit 7 - Fallback mechanism from V.22bis to V.22 (equivalent to ATN1 command), 0 Disabled, 1 Enabled 10 S22 0-255 Hex C0 S23 0-255 Hex 00 S24 0-255 Hex A9 (c) 2004 CML Microsystems Plc 27 D/866/4 V.22 bis Modem with AT Commands CMX866 Reg S25 Range 0-255 Units Hex S-Register Description Tx Gain, Tx data format on phone line: Bit 2-0 - Tx Gain, 000 (-10.5dB) through to 111 (0dB) in 1.5dB steps Bit 5-3 - Tx Data/Stop bits: 000 (5 data, 1 stop), 001 (5 data, 2 stop), 010 (6 data, 1 stop), 011 (6 data, 2 stop), 100 (7 data, 1 stop), 101 (7 data, 2 stop), 110 (8 data, 1 stop) - default, 111 (8 data, 2 stop) Bit 7-6 - Tx Data Format: 00 (start/stop mode - odd parity), 01 (start/stop mode - even parity), 10 (start/stop mode - no parity) - default, 11 (Synchronous mode) Rx Gain, Rx data format, Rx overspeed on phone line: Bit 2-0 - Rx Gain, 000 (-10.5dB) through to 111 (0dB) in 1.5dB steps Bit 5-3 - Rx Data/Parity bits: 000 (5 data, no parity), 001 (5 data, parity), 010 (6 data, no parity), 011 (6 data, parity), 100 (7 data, no parity), 101 (7 data, parity), 110 (8 data, no parity) - default, 111 (8 data, parity) Bit 7-6 - Rx USART overspeed mode: 00 (start/stop mode 2.3% overspeed) - default, 01 (start/stop mode 1.0% overspeed), 10 (start/stop mode no overspeed), 11 (Synchronous mode) Default B0 S26 0-255 Hex 30 (c) 2004 CML Microsystems Plc 28 D/866/4 V.22 bis Modem with AT Commands CMX866 Reg S27 Range 0-255 Units Hex S-Register Description Communications Protocol: Bit 3-0 - Reserved Bit 7-4 - Communications standard: 0000 (ATB0) Selects ITU-T V.22bis at 2400bps QAM, 0001 (ATB1) Selects ITU-T V.22 at 1200bps DPSK, 0010 (ATB2) Selects ITU-T V.23 with Tx 75bps and Rx 1200bps FSK, 0011 (ATB3) Selects ITU-T V.23 with Tx 1200bps and Rx 75bps FSK, 0100 (ATB4) No function. Reserved for future use, 0101 (ATB5) Selects ITU-T V.21 at 300bps FSK, 0110 (ATB6) Selects Bell 212A at 1200bps DPSK, 0111 (ATB7) Selects Bell 202 with Tx 150bps and Rx 1200bps FSK, 1000 (ATB8) Selects Bell 202 with Tx 1200bps and Rx 150bps FSK, 1001 (ATB9) Selects Bell 103 at 300bps FSK RTSN Timeout - The timeout for validation of a change on the RTSN pin before it is actioned by returning to Command mode from Data Transfer mode. (0 = timeout disabled). Timed Break Recall Period - Sets the length of time that the CMX866 breaks the line before reconnecting it and continuing to dial the directory number. Default 00 S28 0-255 1s 0 S29 0-255 10ms 30 1.5.4.6 Result Codes Numeric Response (Decimal) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 Word Response OK CONNECT RING NO CARRIER ERROR NO DIAL TONE BUSY CONNECT 2400 CONNECT 1200 DUAL TONE DETECT CONNECT 300 CONNECT 1200/75 CONNECT 75/1200 CONNECT 1200/150 CONNECT 150/1200 NYI (Not Yet Implemented) (c) 2004 CML Microsystems Plc 29 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.5 Tx USART A flexible Tx USART is provided for all CMX866 modes. It can be programmed to transmit continuous patterns, Start-Stop characters or Synchronous Data. In both Synchronous Data and Start-Stop modes the data to be transmitted is written by the on-chip Controller into the 8-bit DSP Tx Data Register from which it is transferred to the Tx Data Buffer. If Synchronous Data mode has been selected the 8 data bits in the Tx Data Buffer are transmitted serially in the order in which they are received, ie. b0 being sent first. In Start-Stop mode a single Start bit is transmitted, followed by 5, 6, 7 or 8 data bits from the Tx Data Buffer - b0 first - followed by an optional Parity bit then - normally - one or two Stop bits. The Start, Parity and Stop bits are generated by the USART as determined by the Tx Mode Register settings and are not taken from the DSP Tx Data Register. Figure 6a Tx USART Every time the contents of the DSP Tx Data Register are transferred to the Tx Data Buffer, the Tx Data Ready flag bit of the DSP Status Register is set to 1 to indicate that a new value should be loaded into the DSP Tx Data Register. This flag bit is cleared to 0 when a new value is loaded into the DSP Tx Data Register. The interpretation of this flag is handled automatically by the on-chip Controller. Figure 6b Tx USART Function (Start-Stop mode, 8 Data Bits + Parity) If a new value is not loaded into the DSP Tx Data Register in time for the next DSP Tx Data Register to Tx Data Buffer transfer then the DSP Status Register Tx Data Underflow bit will be set to 1. In this event the contents of the Tx Data Buffer will be re-transmitted if Synchronous Data mode has been selected, or if Start-Stop mode was selected then a continuous Stop signal (1) will be transmitted until a new value is loaded into the DSP Tx Data Register. In all modes the transmitted bit and baud rates are the nominal rates for the selected modem type, with an accuracy determined by the XTAL frequency accuracy. Underspeed transmission is automatically handled by the CMX866 in Start-Stop mode as it inserts extra Stop bit(s) if it has to wait for new data to be loaded into the DSP Tx Data Register. (c) 2004 CML Microsystems Plc 30 D/866/4 V.22 bis Modem with AT Commands CMX866 The optional V.22/V.22 bis compatible data scrambler is enabled in V.22 and V.22bis handshake and data transfer modes. Its function is to invert the next input bit in the event of 64 consecutive ones appearing at its input. The scrambler uses the generating polynomial: 1 + x-14 + x-17 1.5.6 FSK and QAM/DPSK Modulators Serial data from the USART is fed via the optional scrambler to the FSK modulator if V.21, V.23, Bell 103 or Bell 202 mode has been selected or to the QAM/DPSK modulator for V.22, V.22 bis and Bell 212A modes. The FSK modulator generates one of two frequencies according to the transmit mode and the value of current transmit data bit. The QAM/DPSK modulator generates a carrier of 1200Hz (Low Band, Calling modem) or 2400Hz (High Band, Answering modem) which is modulated at 600 symbols/sec as described below: For V.22 and Bell 212A 1200bps DPSK the transmit data stream is divided into groups of two consecutive bits (dibits) which are encoded as a carrier phase change: Dibit (left-hand bit is the first of the pair) 00 01 11 10 Phase change +90 0 +270 +180 (c) 2004 CML Microsystems Plc 31 D/866/4 V.22 bis Modem with AT Commands CMX866 For V.22 bis 2400bps QAM the transmit data stream is divided into groups of 4 consecutive data bits. The first two bits of each group are encoded as a phase quadrant change and the last two bits define one of four elements within a quadrant: First two bits of group (left-hand bit is the first of the pair) 00 01 11 10 Phase quadrant change +90 (e.g. quadrant 1 to 2) 0 (no change of quadrant) +270 (e.g. quadrant 1 to 4) +180 (e.g. quadrant 1 to 3) Figure 7 V.22 bis Signal Constellation 1.5.7 Tx Filter and Equaliser The FSK or QAM/DPSK modulator output signal is fed through the Transmit Filter and Equaliser block which limits the out-of-band signal energy to acceptable limits. In 1200 and 2400 bps FSK, DPSK and QAM modes this block includes a fixed compromise line equaliser which is automatically set for the particular modulation type and frequency band being employed. This fixed compromise line equaliser may be enabled or disabled by bit 1 of the S24 register. The amount of Tx equalisation provided compensates for one quarter of the relative amplitude and delay distortion of ETS Test Line 1 over the frequency band used. 1.5.8 DTMF/Tone Generator In DTMF/Tones mode this block generates DTMF signals or single or dual frequency tones. In QAM/DPSK modem modes it is used to generate the optional 550 or 1800Hz guard tone (see &Gn command and S23 register). 1.5.9 Tx Level Control and Output Buffer The outputs (if present) of the Transmit Filter and DTMF/Tone Generator are summed then passed through the programmable Tx Level Control and Tx Output Buffer to the pins TXA and TXAN. The Tx Output Buffer has symmetrical outputs to provide sufficient line voltage swing at low values of VDD and to reduce harmonic distortion of the signal. The output level is adjusted by bits 0-2 of the S25 register. (c) 2004 CML Microsystems Plc 32 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.10 Rx DTMF/Tones Detectors In Rx Tones Detect mode the received signal, after passing through the Rx Gain Control block, is fed to the DTMF / Tones / Call Progress / Answer Tone detectors. The selection of the four separate detectors is handled automatically by the on-chip Controller: The DTMF detector detects standard DTMF signals. A valid DTMF signal will set bit 5 of the DSP Status Register to 1 for as long as the signal is detected. The output of this detector is not currently used by the on-chip Controller, however, this register can be accessed by the @R command. The programmable tone pair detector includes two separate tone detectors. The first detector will set bit 6 of the DSP Status Register for as long as a valid signal is detected, the second detector sets bit 7, and bit 10 of the DSP Status Register will be set when both tones are detected. By default, this programmable tone pair detector is set to detect the dual alert tone pair (2130Hz and 2750Hz) used on some Type 1 CLI systems. The output of this detector is not currently used by the on-chip Controller, however, this register can be accessed by the @R command. The Call Progress detector measures the amplitude of the signal at the output of a 275 - 665 Hz bandpass filter and sets bit 10 of the DSP Status Register to 1 when the signal level exceeds the measurement threshold. This is handled automatically by the on-chip Controller. When the CMX866 is on-hook, the Call Progress detector can be enabled so that it will detect voice activity arising from a parallel phone connection which is off-hook. The output of the DSP Status Register will need to be monitored by the external host C, using an @R command, for several seconds and decision taken on whether there is voice activity. 10 0 -10 -20 dB -30 -40 -50 -60 0 0.5 1 1.5 2 kHz 2.5 3 3.5 4 Figure 8a Response of Call Progress Filter The Answer Tone detector measures both amplitude and frequency of the received signal and sets bit 6 or bit 7 of the DSP Status Register respectively when a valid 2225Hz or 2100Hz signal is received. This is handled automatically by the on-chip Controller, which looks for either of the Answer Tones. (c) 2004 CML Microsystems Plc 33 D/866/4 V.22 bis Modem with AT Commands CMX866 1.5.11 Rx Modem Filterering and Demodulation When the receive part of the CMX866 is operating as a modem, the received signal is fed to a bandpass filter to attenuate unwanted signals and to provide fixed compromise line equalisation for 1200 and 2400 bps FSK, DPSK and QAM modes. The characteristics of the bandpass filter and equaliser are determined by the chosen receive modem type and frequency band. The fixed compromise line equaliser may be enabled or disabled by bit 1 of the S24 register and compensates for one quarter of the relative amplitude and delay distortion of ETS Test Line 1. The responses of these filters, including the line equaliser and the effect of external components used in Figures 4a and 4b, are shown in Figures 8b-e: 10 0 -10 -20 -30 -40 -50 -60 0 0.5 1 1.5 kHz 2 2.5 3 3.5 4 10 0 -10 -20 -30 -40 -50 -60 0 0.5 1 1.5 kHz 2 2.5 3 3.5 4 dB dB Figure 8b QAM/DPSK Rx Filters 10 0 -10 -20 -30 -40 -50 -60 0 0.5 1 1.5 kHz 2 2.5 3 3.5 4 10 0 -10 -20 -30 -40 -50 -60 0 0.5 Figure 8c V.21 Rx Filters dB dB 1 1.5 kHz 2 2.5 3 3.5 4 Figure 8d Bell 103 Rx Filters Figure 8e V.23/Bell 202 Rx Filters The signal level at the output of the Receive Modem Filter and Equaliser is measured in the Modem Energy Detector block, compared to a threshold value, and the result is automatically handled by the onchip Controller. The output of the Receive Modem Filter and Equaliser is also applied to the FSK or QAM/DPSK demodulator depending on the selected modem type. The FSK demodulator recognises individual frequencies as representing received `1' or `0' data bits: (c) 2004 CML Microsystems Plc 34 D/866/4 V.22 bis Modem with AT Commands CMX866 The QAM/DPSK demodulator decodes QAM or DPSK modulation of a 1200Hz or 2400Hz carrier and is used for V.22, V.22 bis and Bell 212A modes. It includes an adaptive receive signal equaliser (autoequaliser) that will automatically compensate for a wide range of line conditions in both QAM and DPSK modes. It must be enabled when receiving 2400bps QAM by setting bit 2 of the S24 register. The autoequaliser can provide a useful improvement in performance in 1200bps DPSK as well as 2400bps QAM modes, so although it must be disabled at the start of a handshake sequence, it can be enabled as soon as scrambled 1200bps 1s have been detected. Both FSK and QAM/DPSK demodulators produce a serial data bit stream which is fed to the Rx pattern detector, descrambler and USART block (see Figure 9a). In QAM/DPSK modes the demodulator input is also monitored for the V.22 bis handshake `S1' signal. The QAM/DPSK demodulator also estimates the received bit error rate by comparing the actual received signal against an ideal waveform. This estimate is placed in bits 2-0 of the DSP Status Register. However, the estimate is not required for CMX866 operation and so is ignored by the on-chip Controller. 1.5.12 Rx Modem Pattern Detectors and Descrambler See Figure 9a. The 1010.. pattern detector operates only in FSK modes and will set bit 9 of the DSP Status Register when 32 bits of alternating 1's and 0's have been received. The `Continuous Unscrambled 1's' detector operates in all modem modes and will set bits 8 and 7 of the DSP Status Register to 01 when 32 consecutive 1's have been received. The descrambler operates only in DPSK/QAM modes and is enabled automatically by the on-chip Controller. The `Continuous Scrambled 1's' detector operates only in DPSK/QAM modes when the descrambler is enabled and will set bits 8 and 7 of the DSP Status Register to 11 when 32 consecutive 1's appear at the output of the descrambler. To avoid possible ambiguity, the `Scrambled 1's' detector is disabled when continuous unscrambled 1's are detected. The `Continuous 0's' detector will set bits 8 and 7 of the DSP Status Register to 10 when NX consecutive 0's have been received, NX being 32 except when DPSK/QAM Start-Stop mode has been selected, in which case NX = 2N + 4 where N is the number of bits per character including the Start, Stop and any Parity bits. All of these pattern detectors will hold the `detect' output for 12 bit times after the end of the detected pattern unless the received bit rate or operating mode is changed, in which case the detectors are reset within 2ms. The DSP Status Register is automatically polled by the on-chip Controller, which then interprets the results of these pattern detectors. 1.5.13 Rx Data Register and USART A flexible Rx USART is provided for all modem modes. It can be programmed by bits 6 and 7 of the S26 register to treat the received data bit stream as Synchronous data or as Start-Stop characters. In Synchronous mode the received data bits are all sent to the Rx Data Buffer, which is copied into the DSP Rx Data Register after every 8 bits. In Start-Stop mode the USART Control logic looks for the start of each character, then sends only the required number of data bits (not parity) to the Rx Data Buffer. The parity bit (if used) and the presence (c) 2004 CML Microsystems Plc 35 D/866/4 V.22 bis Modem with AT Commands CMX866 of a Stop bit are then checked and the data bits in the Rx Data Buffer copied into the DSP Rx Data Register. Figure 9a Rx Modem Data Paths Whenever a new character is copied into the DSP Rx Data Register, the Rx Data Ready flag bit of the DSP Status Register is set to 1 to prompt the on-chip Controller to read the new data and, in Start-Stop mode, the Even Rx Parity flag bit of the DSP Status Register is updated. In Start-Stop mode, if the Stop bit is missing (received as a 0 instead of a 1) the received character will still be placed into the DSP Rx Data Register and the Rx Data Ready flag bit set, but the DSP Status Register Rx Framing Error bit will also be set to 1 and the USART will re-synchronise onto the next 1 - 0 (Stop - Start) transition. The Rx Framing Error bit will remain set until the next character has been received. Figure 9b Rx USART Function (Start-Stop mode, 8 Data Bits + Parity) If, for any reason, the on-chip Controller has not read the previous data from the DSP Rx Data Register by the time that new data is copied to it from the Rx Data Buffer, then the Rx Data Overflow flag bit of the DSP Status Register will be set to 1. The Rx Data Ready flag and Rx Data Overflow bits are automatically cleared to 0 when the DSP Rx Data Register is read by the on-chip Controller. The handling of these low-level status flags is performed automatically by the on-chip Controller and is transparent to the user. (c) 2004 CML Microsystems Plc 36 D/866/4 V.22 bis Modem with AT Commands CMX866 1.6 1.6.1 Application Notes Hardware Interface The CMX866 can be interfaced to an external host C, as shown in Figure 11, or to an RS232 computer port (via a level shifter IC, to generate 6V), as shown in Figure 12. These are complete phone line interface circuits for operation at VDD = 5.0V. Figure 12 includes the additional gyrator components which may be required for CTR21 compliance. It is recommended that the full, 9-wire interface should be used, where practical. This is illustrated functionally in Figure 10a. In some applications it will be necessary to move the safety barrier to the serial port interface of the CMX866. If opto-couplers are used to achieve the safety isolation required, a reduced RS232 interface, shown in Figure 10b, may be preferred for economic reasons. Figure 10a Full RS232 Link Figure 10b Reduced RS232 Link The TXD signal can be used to wake up the CMX866 from Powersave or 'Zero-Power' states, as shown above. The external host C should ignore CTSN and write a character byte to the CMX866 via the TXD pin, which is connected to the DTRN pin. This will wake up the CMX866 because the DTRN pin is pulled low. The byte written, and any further activity on the TXD pin for up to 30ms when coming out of 'ZeroPower' state (or up to 10s when coming out of Powersave state), will be corrupted. Normal data transfer can commence when the CTSN pin goes low, providing the RTSN pin is already low. If the DTRN pin is not connected to the TXD pin, the TXD signal cannot be used on its own to wake up the CMX866. If the DTRN pin is permanently wired low it will not be possible to wake up the CMX866 from an external host C. Moreover, it will not be possible to put the CMX866 into either a Powersave or 'Zero-Power' state in the first place, so the device will remain permanently operational. (c) 2004 CML Microsystems Plc 37 D/866/4 V.22 bis Modem with AT Commands CMX866 Figure 11 Host C Example (FCC68) (c) 2004 CML Microsystems Plc 38 D/866/4 V.22 bis Modem with AT Commands CMX866 Figure 12 RS232 Level Converter Example (CTR21) (c) 2004 CML Microsystems Plc 39 D/866/4 V.22 bis Modem with AT Commands CMX866 Figures 11 and 12 - Component List: Reference C1, C2 C3, C4, C6 C5, C7 C8 C9 (FCC) C9 (CTR21) C10 (FCC) C10 (CTR21) C11 C12 (FCC) C12 (CTR21) C13 C14 C15 C16 (FCC) C16 (CTR21) C17 D1, D2, D3, D4 D1, D2, D3, D4 D5 D6 D7 F1 Q1, Q2 (FCC) Q1, Q2 (CTR21) Q3 (FCC) Q3 (CTR21) R1 R2 R3 R4 (FCC) R4 (CTR21) R5 (FCC) R5 (CTR21) R6 R7, R8 R9 R10 Value 22pF 100nF 10F 100nF not fitted 2.2F, 16V 33nF 100nF 100pF not used 10F, 50V 100nF 330nF, 250V 330nF 47pF 220pF 100nF not used CBRHD-02 LCA110S PS2701-1 BAS16 C515-1.25 not used FZT605 not used BC846ALT1 100k 100k 620 not used 33k not used 11.5 , 125mW 10k , 0.5W not used 120k 180k 1% 1% Generic Generic 1% 5% Generic Generic 5% Generic ~ 5% 5% 5% MOTOROLA Generic Generic Generic user selectable ~ ZETEX ~ ~ ~ ~ ~ CENTRAL SEMI CLARE NEC Generic BUSSMANN 1.25A slow blow also use a BAS16 diode 20% 20% 20% 20% 10% 10% 10% Generic Generic Syfer 1812J250 Generic Generic Generic Generic (FCC) (CTR21) polarised, electrolytic 20% 20% 20% 20% Generic Generic Generic Generic Tolerance 20% 20% 20% 20% Supplier Generic Generic Generic Generic user selectable replace with wire link non-polarised Comment (c) 2004 CML Microsystems Plc 40 D/866/4 V.22 bis Modem with AT Commands CMX866 Reference R11 (FCC) R11 (CTR21) R12 R13 R14 R15 R16 R17 T1 (FCC) T1 (CTR21) X1 Z1 (FCC) Z1 (CTR21) Z2 Z3 Z4 MAX3241 CMX866 62k 56k 100k 390 5k6 Value Tolerance 1% 1% 1% 1% 1% Supplier Generic Generic Generic Generic Generic Comment optimum value = 64k9 optimum value = 57k6 optimum value = 392 optimum value = 6k04 not used 470k 20k 82111 82107 11.0592MHz not used P6SMB33CAT 3 CMPZDA4V3 CMPZDA18V P3100SC MAX3241 CMX866 ~ ~ ~ ~ ~ ~ MOTOROLA CENTRAL SEMI CENTRAL SEMI TECCOR MAXIM CML 310V SIDACTOR LEVEL CONVERTER MODEM IC 5% 5% ~ ~ 0.01% Generic Generic MIDCOM MIDCOM RALTRON (c) 2004 CML Microsystems Plc 41 D/866/4 V.22 bis Modem with AT Commands CMX866 1.6.2 Calling Modem AT Commands (pull DTRN pin low) ATZ ATS25=x ATS27=x or ATBn ATS26=x ATS23=x or AT&Gn ATS10=x (S12, S14, S24, S28 and S29 registers) General Commands for Initialisation * wake-up CMX866 from 'Zero-Power' state * restore factory defaults * set Tx gain and data format * set communications standard * set Rx gain and data format * set guard time (if required) * set lost carrier to hang-up delay * set other features (as required) Specific Tx Commands * set calling and response characteristics * set DTMF tone duration * set pause time for comma dial modifier * set wait for carrier after dial * set wait time for blind dialling * check correct settings ATS22=x ATS11=x ATS8=x ATS7=x ATS6=x AT&V or ATXn Call Setup * go off-hook and dial directory number ATD 1.6.3 Answering Modem AT Commands (pull DTRN pin low) (see above) General Commands for Initialisation * wake-up CMX866 from 'Zero-Power' state * set features (as required) Specific Rx Commands * set handshake timeout * enable automatic answer * check correct settings ATS17=x ATS0=x AT&V Call Answer * go off-hook and answer an incoming call on RING ATA * progress call and go to data mode when call established. (This is automatic) * return to command mode (c) 2004 CML Microsystems Plc 42 D/866/4 V.22 bis Modem with AT Commands CMX866 1.6.4 RS232 Transaction Sequence A typical RS232 transaction sequence is shown in Figure 13 below: Figure 13 RS232 Transaction Sequence (c) 2004 CML Microsystems Plc 43 D/866/4 V.22 bis Modem with AT Commands CMX866 1.7 1.7.1 Performance Specification Electrical Performance 1.7.1.1 Absolute Maximum Ratings Exceeding these maximum ratings can result in damage to the device. Min. -0.3 -0.3 -50 -20 Max. 7.0 VDD + 0.3 +50 +50 +20 Units V V mA mA mA Supply (VDD - VSS) Voltage on any pin to VSS Current into or out of VDD and VSS pins Current into RDRVN pin (RDRVN pin low) Current into or out of any other pin D1 Package Total Allowable Power Dissipation at Tamb = 25C ... Derating Storage Temperature Operating Temperature D6 Package Total Allowable Power Dissipation at Tamb = 25C ... Derating Storage Temperature Operating Temperature Min. -55 -40 Min. Max. 1000 13 +125 +85 Max. 550 9.0 +125 +85 Units mW mW/C C C Units mW mW/C C C -55 -40 1.7.1.2 Operating Limits Correct operation of the device outside these limits is not implied. Notes Supply (VDD - VSS) Operating Temperature Min. 2.7 -40 Max. 5.5 +85 Units V C (c) 2004 CML Microsystems Plc 44 D/866/4 V.22 bis Modem with AT Commands CMX866 1.7.1.3 Operating Characteristics For the following conditions unless otherwise specified: VDD = 2.7V to 5.5V at Tamb = -40 to +85C, Xtal Frequency = 11.0592MHz 0.01% (100ppm) 0dBm corresponds to 775mVrms. DC Parameters IDD ('Zero-Power' mode) IDD (Powersave mode, VDD = 3.0V) IDD (Powersave mode, VDD = 5.0V) IDD (C operating, DSP powerdown, VDD = 3.0V) IDD (C operating, DSP powerdown, VDD = 5.0V) IDD (C and DSP operating, VDD = 3.0V) IDD (C and DSP operating, VDD = 5.0V) IDD (C and DSP operating, VDD = 3.0V) IDD (C and DSP operating, VDD = 5.0V) Logic '1' Input Level Logic '0' Input Level Logic Input Leakage Current (Vin = 0 to VDD), (excluding XTAL/CLOCK input) Output Logic '1' Level (lOH = 2 mA) Output Logic '0' Level (lOL = -3 mA) IRQN O/P 'Off' State Current (Vout = VDD) RD and RT pin Schmitt trigger input high-going threshold (Vthi) (see Figure 14) RD and RT pin Schmitt trigger input low-going threshold (Vtlo) (see Figure 14) RDRVN `ON' resistance to VSS (VDD= 3.0V) RDRVN `OFF' resistance to VDD (VDD= 3.0V) XTAL/CLOCK Input (timings for an external clock input) 'High' Pulse Width 'Low' Pulse Width Notes 1, 2 1, 2 1, 2 1 1 1, 3 1, 3 1 1 4 4 Min. 70% -1.0 80% 0.56VDD 0.44VDD - 0.6V Notes Min. 30 30 Typ. 3.0 0.6 1.5 1.7 3.7 3.4 6.2 5.0 9.0 50 1300 Typ. Max. 10.0 1.5 3.0 3.5 7.5 7.0 12.5 10.0 18.0 30% +1.0 0.4 1.0 0.56VDD + 0.6V 0.44VDD 70 3000 Max. Units A mA mA mA mA mA mA mA mA VDD VDD A VDD V A V V Units ns ns (c) 2004 CML Microsystems Plc 45 D/866/4 V.22 bis Modem with AT Commands CMX866 Transmit QAM and DPSK Modes (V.22, Bell 212A, V.22 bis) Carrier frequency, high band Carrier frequency, low band Baud rate Bit rate (V.22, Bell 212A) Bit rate (V.22 bis) 550Hz guard tone frequency 550Hz guard tone level wrt data signal 1800Hz guard tone frequency 1800Hz guard tone level wrt data signal Transmit V.21 FSK Mode Baud rate Mark (logical 1) frequency, high band Space (logical 0) frequency, high band Mark (logical 1) frequency, low band Space (logical 0) frequency, low band Transmit Bell 103 FSK Mode Baud rate Mark (logical 1) frequency, high band Space (logical 0) frequency, high band Mark (logical 1) frequency, low band Space (logical 0) frequency, low band Transmit V.23 FSK Mode Baud rate Mark (logical 1) frequency, 1200 baud Space (logical 0) frequency, 1200 baud Mark (logical 1) frequency, 75 baud Space (logical 0) frequency, 75 baud Transmit Bell 202 FSK Mode Baud rate Mark (logical 1) frequency, 1200 baud Space (logical 0) frequency, 1200 baud Mark (logical 1) frequency, 150 baud Space (logical 0) frequency, 150 baud DTMF/Single Tone Transmit Tone frequency accuracy Distortion Transmit Output Level Modem and Single Tone modes DTMF mode, Low Group tones DTMF: level of High Group tones wrt Low Group Tx output buffer gain control accuracy Notes 5 5 6 6 6 Min. 548 -4.0 1797 -7.0 Min. 1647 1847 978 1178 Min. 2222 2022 1268 1068 Min. 1298 2097 389 449 Min. 1198 2197 386 486 Min. -0.2 Min. -4.0 -2.0 +1.0 -0.25 Typ. 2400 1200 600 1200 2400 550 -3.0 1800 -6.0 Typ. 300 1650 1850 980 1180 Typ. 300 2225 2025 1270 1070 Typ. 1200/75 1300 2100 390 450 Typ. 1200/150 1200 2200 387 487 Typ. 1.0 Typ. -3.0 -1.0 +2.0 - Max. 552 -2.0 1803 -5.0 Max. 1653 1853 982 1182 Max. 2228 2028 1272 1072 Max. 1302 2103 391 451 Max. 1202 2203 388 488 Max. +0.2 2.0 Max. -2.0 0.0 +3.0 +0.25 Units Hz Hz Baud bps bps Hz dB Hz dB Units Baud Hz Hz Hz Hz Units Baud Hz Hz Hz Hz Units Baud Hz Hz Hz Hz Units Baud Hz Hz Hz Hz Units % % Units dBm dBm dB dB Notes 6 Notes 6 Notes 6 Notes 6 Notes 7 Notes 7 7 7 7 (c) 2004 CML Microsystems Plc 46 D/866/4 V.22 bis Modem with AT Commands CMX866 Receive QAM and DPSK Modes (V.22, Bell 212A, V.22 bis) Carrier frequency (high band) Carrier frequency (low band) Baud rate Bit rate (V.22, Bell 212A) Bit rate (V.22 bis) Receive V.21 FSK Mode Acceptable baud rate Mark (logical 1) frequency, high band Space (logical 0) frequency, high band Mark (logical 1) frequency, low band Space (logical 0) frequency, low band Receive Bell 103 FSK Mode Acceptable baud rate Mark (logical 1) frequency, high band Space (logical 0) frequency, high band Mark (logical 1) frequency, low band Space (logical 0) frequency, low band Receive V.23 FSK Mode 1200 baud Acceptable baud rate Mark (logical 1) frequency Space (logical 0) frequency 75 baud Acceptable baud rate Mark (logical 1) frequency Space (logical 0) frequency Receive Bell 202 FSK Mode 1200 baud Acceptable baud rate Mark (logical 1) frequency Space (logical 0) frequency 150 baud Acceptable baud rate Mark (logical 1) frequency Space (logical 0) frequency Rx Modem Signal (FSK, DPSK and QAM Modes) Signal level Signal to Noise Ratio (noise flat 300-3400Hz) Notes Min. 2392 1192 Min. 297 1638 1838 968 1168 Min. 297 2213 2013 1258 1058 Min. 1188 1280 2080 Typ. 2400 1200 600 1200 2400 Typ. 300 1650 1850 980 1180 Typ. 300 2225 2025 1270 1070 Typ. 1200 1300 2100 75 390 450 Typ. 1200 1200 2200 150 387 487 Typ. - Max. 2408 1208 Max. 303 1662 1862 992 1192 Max. 303 2237 2037 1282 1082 Max. 1212 1320 2120 76 398 458 Max. 1212 1220 2220 152 397 497 Max. -9 - Units Hz Hz Baud bps bps Units Baud Hz Hz Hz Hz Units Baud Hz Hz Hz Hz Units Baud Hz Hz Baud Hz Hz Units Baud Hz Hz Baud Hz Hz Units dBm dB 9 9 9 Notes Notes Notes 16 16 74 382 442 Notes 16 Min. 1188 1180 2180 16 148 377 477 Notes 10 Min. -45 20 (c) 2004 CML Microsystems Plc 47 D/866/4 V.22 bis Modem with AT Commands CMX866 Rx Modem S1 Pattern Detector (DPSK and QAM modes) Will detect S1 pattern lasting for Will not detect S1 pattern lasting for Hold time (minimum detector `On' time) Rx Modem Energy Detector Detect threshold (`Off' to `On) Undetect threshold (`On' to `Off') Hysteresis Detect (`Off' to `On') response time QAM and DPSK modes 300 and 1200 baud FSK modes 150 and 75 baud FSK modes Undetect (`On' to `Off') response time QAM and DPSK modes 300 and 1200 baud FSK modes 150 and 75 baud FSK modes Rx Answer Tone Detectors Detect threshold (`Off' to `On) Undetect threshold (`On' to `Off') Hysteresis Detect (`Off' to `On') response time Undetect (`On' to `Off') response time 2100Hz detector `Will detect' frequency `Will not detect' frequency 2225Hz detector `Will detect' frequency `Will not detect' frequency Rx Call Progress Energy Detector Bandwidth (-3dB points) See Figure 8a Detect threshold (`Off' to `On) Undetect threshold (`On' to `Off') Detect (`Off' to `On') response time Undetect (`On' to `Off') response time Receive Input Amplifier Input impedance (at 100Hz) Open loop gain (at 100Hz) Rx Gain Control Block accuracy Notes Min. 90.0 5.0 Typ. Typ. Typ. 33.0 18.0 Typ. 36.0 8.0 Typ. Max. 72.0 Max. -43.0 35.0 30.0 60.0 55.0 40.0 80.0 Max. -43.0 45.0 25.0 2160 2000 2285 Max. 665 -37.0 45.0 50.0 Max. Units ms ms Units dBm dBm dB ms ms ms ms ms ms Units dBm dBm dB ms ms Hz Hz Hz Hz Units Hz dBm dBm ms ms Units Moh m V/V dB Notes 10,11 10,11 10,11 10,11 10,11 10,11 10,11 10,11 10,11 Notes 10,12 10,12 10,12 10,12 10,12 Min. -48.0 2.0 10.0 8.0 16.0 10.0 10.0 20.0 Min. -48.0 2.0 30.0 7.0 2050 2160 2335 Notes 10,13 10,13 10,13 10,13 Notes Min. 275 -42.0 30.0 6.0 Min. 10.0 10000 -0.25 +0.25 (c) 2004 CML Microsystems Plc 48 D/866/4 V.22 bis Modem with AT Commands CMX866 DTMF Decoder Valid input signal levels (each tone of composite signal) Not decode level (either tone of composite signal) Twist = High Tone/Low Tone Frequency Detect Bandwidth Frequency Not Detect Bandwidth Max level of low frequency noise (i.e dial tone) Interfering signal frequency <= 550Hz Interfering signal frequency <= 450Hz Interfering signal frequency <= 200Hz Max. noise level wrt. signal DTMF detect response time DTMF de-response time Status Register b5 high time `Will Detect' DTMF signal duration `Will Not Detect' DTMF signal duration Pause length detected Pause length ignored Notes: Notes 10 10 Min. -30.0 -10.0 1.8 14.0 40.0 30.0 - Typ. 25.0 - Max. 0.0 -36.0 6.0 3.5 0.0 10.0 20.0 -10.0 40.0 30.0 15.0 Unit dBm dBm dB % % dB dB dB dB ms ms ms ms ms ms ms 14 14 14 14,15 1. At 25C, not including any current drawn from the CMX866 pins by external circuitry other than X1, C1 and C2. 2. All logic inputs at VSS except for RT, DTRN and RTSN inputs which are at DVDD. 3. DSP is powered up but in a reset state. 4. Excluding RD and RT pins. 5. % carrier frequency accuracy is the same as XTAL/CLOCK % frequency accuracy. 6 Tx signal % baud or bit rate accuracy is the same as XTAL/CLOCK % frequency accuracy. 7. Measured between TXA and TXAN pins with Tx Level Control gain set to 0dB, 1k2 load between TXA and TXAN, at VDD = 3.0V (levels are proportional to VDD - see section 1.4.2). Level measurements for all modem modes are performed with random transmitted data and without any guard tone. 0dBm = 775mVrms. 8. Measured on the 2 or 4-wire line using the line interface circuits described in section 1.4.2 with the Tx line signal level set to -10dBm for QAM, DPSK, FSK or single tones, 6dBm and -8dBm for DTMF tones. Excludes any distortion due to external components such as the line coupling transformer. 9. These are the bit and baud rates of the line signal, the acceptable tolerance is 0.01%. 10. Rx 2 or 4-wire line signal level assuming 1dB loss in line coupling transformer with Rx Gain Control block set to 0dB and external components as section 1.4.2. 11. Thresholds and times measured with random data for QAM and DPSK modes, continuous binary `1' for all FSK modes. Fixed compromise line equaliser enabled. Signal switched between off and -33dBm 12. `Typical' value refers to 2100Hz or 2225Hz signal switched between off and -33dBm. Times measured with respect to the received line signal 13. `Typical' values refers to 400Hz signal switched between off and -33dBm 14. Referenced to DTMF tone of lower amplitude. 15. Flat Gaussian Noise in 300-3400Hz band. 16. For V.23r (Tx1200/Rx75) and Bell 202r (Tx1200/Rx150) the calling modem carrier detect time is typically 1700ms. (c) 2004 CML Microsystems Plc 49 D/866/4 V.22 bis Modem with AT Commands CMX866 3.5 3 2.5 2 Vin 1.5 1 0.5 0 2.5 3 3.5 4 Vdd 4.5 5 5.5 Vthi Vtlo Figure 14 Typical Schmitt Trigger Input Voltage Thresholds vs. VDD 0 -10 -20 -30 dBm -40 -50 -60 -70 10 100 1000 Hz 10000 100000 Bell 202 Figure 15 Maximum Out of Band Tx Line Energy Limits (see note 8) (c) 2004 CML Microsystems Plc 50 D/866/4 V.22 bis Modem with AT Commands CMX866 1.7.2 Packaging Figure 16a 28-pin SOIC (D1) Mechanical Outline: Order as part no. CMX866D1 Figure 16b 28-pin SSOP (D6) Mechanical Outline: Order as part no. CMX866D6 (c) 2004 CML Microsystems Plc 51 D/866/4 V.22 bis Modem with AT Commands CMX866 Handling precautions: This product includes input protection, however, precautions should be taken to prevent device damage from electrostatic discharge. CML does not assume any responsibility for the use of any circuitry described. No IPR or circuit patent licences are implied. CML reserves the right at any time without notice to change the said circuitry and this product specification. CML has a policy of testing every product shipped using calibrated test equipment to ensure compliance with this product specification. Specific testing of all circuit parameters is not necessarily performed. www.cmlmicro.com For FAQs see: www.cmlmicro.com/products/faqs/ For a full data sheet listing see: www.cmlmicro.com/products/datasheets/download.htm For detailed application notes: www.cmlmicro.com/products/applications/ Oval Park, Langford, Maldon, Essex, CM9 6WG - England. 4800 Bethania Station Road, Winston-Salem, NC 27105 - USA. No 2 Kallang Pudding Road, #09 to 05/06 Mactech Industrial Building, Singapore 349307 No. 218, Tian Mu Road West, Tower 1, Unit 1008, Shanghai Kerry Everbright City, Zhabei, Shanghai 200070, China. Tel: +86 21 6317 4107 +86 21 6317 8916 Fax: +86 21 6317 0243 Sales: cn.sales@cmlmicro.com.cn Technical Support: sg.techsupport@cmlmicro.com Tel: +44 (0)1621 875500 Fax: +44 (0)1621 875600 Sales: sales@cmlmicro.com Technical Support: techsupport@cmlmicro.com Tel: +1 336 744 5050, 800 638 5577 Fax: +1 336 744 5054 Sales: us.sales@cmlmicro.com Technical Support: us.techsupport@cmlmicro.com Tel: +65 6745 0426 Fax: +65 6745 2917 Sales: sg.sales@cmlmicro.com Technical Support: sg.techsupport@cmlmicro.com |
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