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CML Microcircuits CMX866 Manual Download Page 48

V.22 bis Modem with AT Commands 

 

CMX866 

 

 

©

 2008 CML Microsystems Plc 

48 

D/866/5 

 

Receive QAM and DPSK Modes  
(V.22, Bell 212A, V.22 bis) 

Notes Min. 

Typ. 

Max. Units 

  Carrier frequency (high band) 

 

2392 

2400 

2408 

Hz 

  Carrier frequency (low band) 

 

1192 

1200 

1208 

Hz 

  Baud rate 

9 

- 

600 

- 

Baud 

  Bit rate (V.22, Bell 212A) 

9 

- 

1200 

- 

bps 

  Bit rate (V.22 bis) 

9 

- 

2400 

- 

bps 

 

Receive V.21 FSK Mode 

Notes 

Min. 

Typ. 

Max. 

Units 

  Acceptable baud rate 

 

297 

300 

303 

Baud 

  Mark (logical 1) frequency, high band 

 

1638 

1650 

1662 

Hz 

  Space (logical 0) frequency, high band 

 

1838 

1850 

1862 

Hz 

  Mark (logical 1) frequency, low band 

 

968 

980 

992 

Hz 

  Space (logical 0) frequency, low band 

 

1168 

1180 

1192 

Hz 

 

Receive Bell 103 FSK Mode 

Notes 

Min. 

Typ. 

Max. 

Units 

  Acceptable baud rate 

 

297 

300 

303 

Baud 

  Mark (logical 1) frequency, high band 

 

2213 

2225 

2237 

Hz 

  Space (logical 0) frequency, high band 

 

2013 

2025 

2037 

Hz 

  Mark (logical 1) frequency, low band 

 

1258 

1270 

1282 

Hz 

  Space (logical 0) frequency, low band 

 

1058 

1070 

1082 

Hz 

 

Receive V.23 FSK Mode 

Notes 

Min. 

Typ. 

Max. 

Units 

  

1200 baud

 

16  

 

   

    Acceptable baud rate  

 

1188 

1200 

1212 

Baud 

    Mark (logical 1) frequency 

 

1280 

1300 

1320 

Hz 

    Space (logical 0) frequency 

 

2080 

2100 

2120 

Hz 

  

75 baud

 

16  

 

   

    Acceptable baud rate  

 

74 

75 

76 

Baud 

    Mark (logical 1) frequency 

 

382 

390 

398 

Hz 

    Space (logical 0) frequency 

 

442 

450 

458 

Hz 

 

Receive Bell 202 FSK Mode 

Notes 

Min. 

Typ. 

Max. 

Units 

  

1200 baud

 

16  

 

   

    Acceptable baud rate  

 

1188 

1200 

1212 

Baud 

    Mark (logical 1) frequency 

 

1180 

1200 

1220 

Hz 

    Space (logical 0) frequency 

 

2180 

2200 

2220 

Hz 

  150 baud

 

16  

 

   

    Acceptable baud rate 

 

148 

150 

152 

Baud 

    Mark (logical 1) frequency 

 

377 

387 

397 

Hz 

    Space (logical 0) frequency 

 

477 

487 

497 

Hz 

 

Rx Modem Signal 
(FSK, DPSK and QAM Modes) 

Notes Min. 

Typ. 

Max. Units 

  Signal level 

10 

-45 

- 

-9 

dBm 

  Signal to Noise Ratio (noise flat 300-3400Hz) 

 

20 

- 

- 

dB 

 

Summary of Contents for CMX866

Page 1: ...e 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 D...

Page 2: ...Result Codes 30 1 5 5 Tx USART 30 1 5 6 FSK and QAM DPSK Modulators 32 1 5 7 Tx Filter and Equaliser 33 1 5 8 DTMF Tone Generator 33 1 5 9 Tx Level Control and Output Buffer 33 1 5 10 Rx DTMF Tones De...

Page 3: ...V 22 bis Modem with AT Commands CMX866 2008 CML Microsystems Plc 3 D 866 5 1 2 Block Diagram Figure 1 Block Diagram...

Page 4: ...Detector not used 9 RESETN I P Schmitt trigger input to an active low reset pin Connect to DVDD if no external reset signal used 10 RXAFB O P The output of the Rx Input Amplifier 11 RXBN I P An altern...

Page 5: ...pts data from the external host C for transmission over the phone line 25 RXD O P The non inverted RD signal used for an RS232 interface with a Level Converter This pin sends data to the external host...

Page 6: ...sion 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 di...

Page 7: ...mmended Power Supply Connections and De coupling ANALOGUE DIGITAL C3 C6 100nF C4 100nF C7 10uF C5 10uF L2 100nH optional see note L1 100nH optional see note Note The inductors L1 and L2 and the electr...

Page 8: ...de 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...

Page 9: ...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 pi...

Page 10: ...d 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 fo...

Page 11: ...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 Car...

Page 12: ...S Registers and places the on chip 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...

Page 13: ...ransmit 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 o...

Page 14: ...2 bis Modem with AT Commands CMX866 2008 CML Microsystems Plc 14 D 866 5 1 5 2 Operating States and Data Flow The following diagram shows the flow of data in the CMX866 Figure 5a CMX866 Data Flow Diag...

Page 15: ...22 bis Modem with AT Commands CMX866 2008 CML Microsystems Plc 15 D 866 5 The following state transition chart shows the various modes of operation for the CMX866 Figure 5b CMX866 State Transition Cha...

Page 16: ...e 1 CLI Rn RR F8 Place the CMX866 into either Zero Power or Powersave states When in these states the CMX866 can be woken up by either 1 activity on the DTRN pin including transmitted data if this is...

Page 17: ...ter n Read Display specified S Register contents Sn x n 0 29 S Register n Write Write to specified S Register Vn n 0 1 Return result codes as numbers n 0 or words n 1 n 0 Xn n 0 3 Calling and Response...

Page 18: ...TX data format B0 S26 0 255 RX Gain RX data format overspeed 2 3 default setting 30 S27 0 255 Communications Protocol 00 S28 0 255 RTSN Timeout for return to Command mode from Data mode in seconds 0s...

Page 19: ...sent to the on chip Controller until the previous result code if enabled has been received Every line of commands except for A and the escape sequence must begin with the AT prefix and be terminated w...

Page 20: ...lects ITU T V 22bis at 2400bps QAM default n 1 Selects ITU T V 22 at 1200bps DPSK n 2 Selects ITU T V 23 with Tx 75bps and Rx 1200bps FSK n 3 Selects ITU T V 23 with Tx 1200bps and Rx 75bps FSK n 4 Re...

Page 21: ...en high see Dn command In Identification Requests the CMX866 to return its product identification information Syntax ATIn CR Modifier Usage n 0 Displays the product identification CMX866 Nn Modulation...

Page 22: ...Characteristics Determines which set of responses and calling characteristics are used Syntax ATXn CR Modifier Usage n 0 The CMX866 will ignore dial tones and busy tones Dial tone wait time is zero an...

Page 23: ...is on DCDN pin is held low Otherwise DCD is off DCDN pin is held high default Dn Data Terminal Ready Determines the meaning of the DTRN pin Syntax AT Dn CR Modifier Usage n 0 DTRN pin is ignored n 1...

Page 24: ...cancel the loopback it is first necessary to return to Command mode by locally issuing a CMX866 escape sequence The AT T0 command can then be given to cancel the loopback Alternatively the ATO command...

Page 25: ...866 to become fully operational from the Zero Power state However the crystal oscillator only takes about 1 4ms to become stable so commands which do not require the analogue parts of the DSP to be st...

Page 26: ...t codes The default setting is CR 13 S4 0 127 ASCII Decimal Line feed character Contains the ASCII decimal value of the character recognised as a line feed This character is ignored if present in a co...

Page 27: ...ses 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 Ans...

Page 28: ...Busy Tone ATX2 110 Wait for Dial Tone and Busy Tone ATX3 C0 S23 0 255 Hex 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...

Page 29: ...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 B0 S26 0 255 Hex Rx Gain Rx data format Rx overspeed on phone l...

Page 30: ...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 00 S28 0 255 1s RTSN Timeout The timeout for validation of a change on t...

Page 31: ...d 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...

Page 32: ...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...

Page 33: ...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 T...

Page 34: ...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...

Page 35: ...n Figures 8b e 60 50 40 30 20 10 0 10 0 0 5 1 1 5 2 2 5 3 3 5 4 kHz dB 60 50 40 30 20 10 0 10 0 0 5 1 1 5 2 2 5 3 3 5 4 kHz dB Figure 8b QAM DPSK Rx Filters Figure 8c V 21 Rx Filters 60 50 40 30 20 10...

Page 36: ...tomatically 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 w...

Page 37: ...ster 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 rec...

Page 38: ...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...

Page 39: ...V 22 bis Modem with AT Commands CMX866 2008 CML Microsystems Plc 39 D 866 5 Figure 11 Host C Example FCC68...

Page 40: ...V 22 bis Modem with AT Commands CMX866 2008 CML Microsystems Plc 40 D 866 5 Figure 12 RS232 Level Converter Example CTR21...

Page 41: ...polarised electrolytic C13 100nF 20 Generic C14 330nF 250V 20 Syfer 1812J250 C15 330nF 20 Generic C16 FCC 47pF 10 Generic C16 CTR21 220pF 10 Generic C17 100nF 10 Generic D1 D2 D3 D4 not used FCC D1 D2...

Page 42: ...00k 1 Generic R13 390 1 Generic optimum value 392 R14 5k6 1 Generic optimum value 6k04 R15 not used R16 470k 5 Generic R17 20k 5 Generic T1 FCC 82111 MIDCOM T1 CTR21 82107 MIDCOM X1 11 0592MHz 0 01 RA...

Page 43: ...TS8 x set wait for carrier after dial ATS7 x set wait time for blind dialling ATS6 x check correct settings AT V Call Setup go off hook and dial directory number ATD number progress call and go to dat...

Page 44: ...bis Modem with AT Commands CMX866 2008 CML Microsystems Plc 44 D 866 5 1 6 4 RS232 Transaction Sequence A typical RS232 transaction sequence is shown in Figure 13 below Figure 13 RS232 Transaction Seq...

Page 45: ...ent into RDRVN pin RDRVN pin low 50 mA Current into or out of any other pin 20 20 mA D1 Package Min Max Units Total Allowable Power Dissipation at Tamb 25 C 740 mW Derating 7 4 mW C Storage Temperatur...

Page 46: ...SP operating VDD 5 0V 1 3 6 2 12 5 mA IDD C and DSP operating VDD 3 0V 1 5 0 10 0 mA IDD C and DSP operating VDD 5 0V 1 9 0 18 0 mA Logic 1 Input Level 4 70 VDD Logic 0 Input Level 4 30 VDD Logic Inpu...

Page 47: ...2222 2225 2228 Hz Space logical 0 frequency high band 2022 2025 2028 Hz Mark logical 1 frequency low band 1268 1270 1272 Hz Space logical 0 frequency low band 1068 1070 1072 Hz Transmit V 23 FSK Mode...

Page 48: ...2225 2237 Hz Space logical 0 frequency high band 2013 2025 2037 Hz Mark logical 1 frequency low band 1258 1270 1282 Hz Space logical 0 frequency low band 1058 1070 1082 Hz Receive V 23 FSK Mode Notes...

Page 49: ...FSK modes 10 11 20 0 80 0 ms Rx Answer Tone Detectors Notes Min Typ Max Units Detect threshold Off to On 10 12 43 0 dBm Undetect threshold On to Off 10 12 48 0 dBm Hysteresis 10 12 2 0 dB Detect Off t...

Page 50: ...n 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 an...

Page 51: ...1 D 866 5 0 0 5 1 1 5 2 2 5 3 3 5 2 5 3 3 5 4 4 5 5 5 5 Vdd Vin Vthi Vtlo Figure 14 Typical Schmitt Trigger Input Voltage Thresholds vs VDD 70 60 50 40 30 20 10 0 10 100 1000 10000 100000 Hz dBm Bell...

Page 52: ...th AT Commands CMX866 2008 CML Microsystems Plc 52 D 866 5 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...

Page 53: ...esponsibility 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 speci...

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