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V.22 bis Modem with AT Commands 

 

CMX866 

 

 

©

 2008 CML Microsystems Plc 

20 

D/866/5 

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 Description 

A 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<CR>

 

 

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<CR> 

 

Modifier Usage

 

n=0

 Selects 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

 Reserved for future use. 

n=5

 Selects ITU-T V.21 at 300bps FSK. 

n=6

 Selects Bell 212A at 1200bps DPSK. 

n=7

 Selects Bell 202 with Tx 150bps and Rx 1200bps FSK. 

n=8

 Selects Bell 202 with Tx 1200bps and Rx 150bps FSK. 

n=9

 Selects Bell 103 at 300bps FSK. 

 

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 *.  Loop-
disconnect (pulse) dialling is not implemented. 

 

For example: 

ATD9,01621875500<CR>

 

 

Modifier Usage

 

n=L 

Re-dial last number. 

n=, 

Delay dial sequence (pause setting contained in S8 register). 

n=! 

Send a timed break recall (duration in S29 register). 

n=; 

Remain in command mode after dialling, no handshake. 

 
 

Содержание CMX866

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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

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

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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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