MSC2121A

MSC2121A OKI | Alldatasheet

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Issue Date: Jul. 16, 2002 MSC2121A 14.4 kbps Full Duplex Modem Chip Set With Built-in Protocols Note: The following notice shall be printed so mewhere in your application such as on its container box; “This Product is licensed under U.S. Patent 4,558,302 and foreign counterparts.” GENERAL DESCRIPTION The MSC2121A is a modem chip-set that provides full duplex data transmission capability of up to 14400 bits/s conforming to ITU-T Recommendation (V.32 bis, V.22 bis, V.22, and V.21) and Bell Standard (212A and 103J), and also provides facsimile transmission capability conforming to as a facsimile activated by FAX Class 1 Command in EIA Standard, as well as the function to set a modem and to control calls originating and terminating with AT Commands and the function as a data modem including error correction and data compression. So, the use of this chip-set enables easy implementation of terminals that have those functions, which are being widely employed in personal computer communication, as a full-duplex modem of 14400 bits/s and as a facsimile reciever and transmitter. In the MSC2121A, no external program memory will be required because the control program codes are stored in the program memories that a general- purpose MCV has. General-purpose SRAMs (which are essential) and EEPROMs (which are removable) should be used for external memories. This chip-set comprises the following two LSIs: MSM66507 General-purpose MCU MSM7564-01 Single-chip modem The above ICs are available in a FLAT or PLCC package. For details, please refer to the individual semiconductor specifications of each IC.

FEATURES

• Communication Modes ITU-T Recommendation V.32bis 14,400/12,000/9,600/ 7,200/4,800 bps Full duplex, SYNC/ASYNC ITU-T Recommendation V.22bis 2,400 bps Full duplex, SYNC/ASYNC ITU-T Recommendation V.22 1,200 bps Full duplex, SYNC/ASYNC ITU-T Recommendation V.21 300 bps Full duplex, ASYNC BELL Standard 212A 1,200 bps Full duplex, SYNC/ASYNC BELL Standard 103J 300 bps Full duplex, ASYNC ITU-T Recommendation V.17 14,400/12,000/9,600 /7,200 bps Half duplex, SYNC ITU-T Recommendation V.29 9,600/7,200 bps Half duplex, SYNC ITU-T Recommendation V.27ter 4,800/2,400 bps Half duplex, SYNC ITU-T Recommendation V.21ch.2 300 bps Half duplex, SYNC
• Command Set Hayes AT commands. EIA/TIA-578 (Class 1) fax commands
• Dial Function DTMF send function (tone dialing) DP send function (pulse dialing): 20 pps, 10 pps (Make/break ratio: 33%, 39%)

¡ Semiconductor MSC2121A FEDL2121A-02

• Error Correction Function ITU-T V.42 (LAP-M) MNP Class 3, 4
• Data Compression Function ITU-T V.42bis MNP Class 5
• Protocol To Support Mobile Telephones: MNP Class 10
• Various Test Functions Various tests including local AC loopback, local DC loopback, remote DC loopback and self- test function
• Transmission Attenuator Function: 0 to 7 dB, (in a 1 dB step)
• +5 V Single Power Supply
• Power Consumption: 900 mW (typical)

¡ Semiconductor MSC2121A FEDL2121A-02 BLOCK DIAGRAM The MSC2121A block diagram is shown below. The MSM66507 performs command processing and control of the various interfaces. The interfaces controlled are the V.24 interface, the LED interface, the SW interface, the modem control interface and the line interface. The MSM7564-01 is a single-chip modem LSI which executes all of the modem standards of the MSC2121A. It performs modulation/demodulation, DTMF signal transmission and call progress tone detection. Auxiliary memory comprises SRAM (32 Kbyte) and EEPROM (2 Kbit). These are respectively used as the internal memory of transmission/reception buffers and as nonvolatile memory for storing internal settings. V.24 interface Line interface LED interface SW interface MSM 66507 MCU MSM 7564-01 MODEM SRAM (32 Kbyte) EEPROM (2 Kbit) MSC2121A Block Diagram

¡ Semiconductor MSC2121A FEDL2121A-02 List of Interface Signals

• V.24 Interface
• Signals for Line Control Transmission data Reception data Request-To-Send Clear-To-Send Data Terminal Ready Data Set Ready Carrier Detect Call Indicator Transmission Timing (DTE source) Transmission Timing (DCE source) Reception Timing Symbol SD RD RTS CTS DTR DSR DCD CI ST1 ST2 RT I/O Input Output Input Output Input Output Output Output Input Output Output Input signal of the transmit data. Mark signal = 1, space signal = 0. Output signal of the receive data. Mark signal = 1, space signal = 0. 1 = Stop receive data. 0 = Send transmit data. 1 = Data transmit disabled. 0 = Data transmit enabled. 1 = Transmit/receive to/from the modem disabled. 0 = Transmit/receive to/from the modem enabled. 1 = Modem is in transmit/receive disabled state. 0 = Modem is in transmit/receive enabled state. 1 = Carrier not detected. 0 = Carrier detected. 1 = No incoming call signal. 0 = Incoming call signal. Transmission timing clock from the DTE. Used in the synchronization mode. Transmission timing clock from the DCE. Used in the synchronization mode. Recieve timing clock. Used in the synchronization mode. ExplanationSignal Name Dial relay Symbol RLY1 I/O Output Dial relay control signal. 1 = Relay ON. (Make) ExplanationSignal Name 0 = Relay OFF. (Break) Hook relay RLY2 Output Line connection relay control signal. 1 = Relay ON. (Make) 0 = Relay OFF. (Break) Incoming call signal input RII Input For input from the NCU unit incoming call signal detection circuit. 1 = No incoming call signal. 0 = Incoming call signal. Speaker SPK Output Speaker control signal. 1 = Speaker ON. 0 = Speaker OFF.

¡ Semiconductor MSC2121A FEDL2121A-02

• Display Signals Auto answer Symbol AA I/O Output Indicates that the modem is in an auto-answer state. 1 = Auto answer state. FunctionSignal Name 0 = Not auto answer state. Error correction mode EC Output Indicates connection to the remote modem made in error correction mode. 1 = Connected in error correction mode. 0 = Connected in normal mode. High speed HS Output Indicates communication at 9,600 bps or higher. 1 = High speed transmission at 9,600 bps or higher. 0 = Low speed transmission at 7,200 bps or lower. Modem ready MR Output Lights when power is turned ON. During the loopback test, cycles ON-OFF in 1 second cycles. 1 = Lamp ON 0 = Lamp OFF

¡ Semiconductor MSC2121A FEDL2121A-02

• Signal Input for Switch Settings Note1: The carrier transmission levels indicate the values at the AOUTP Pin and AOUTN Pin of the MSM7564-01. P2.7 Symbol SW1 Determines the setting of the carrier transmission levels. When P2.7=1, the carrier transmission levels are set by the commands (registers S34 and S35). Refer to registers S34 and S35 requirements for more details. When P2.7=0, the carrier transmission levels are set by the ports (SW2 to SW4). FunctionPort P3.0 SW2 SW3 SW4 SW4 SW3 SW2 Carrier transmission level. (Note1). – 10 dBm – 11 dBm – 12 dBm – 13 dBm – 14 dBm – 15 dBm – 16 dBm – 17 dBm P4.2 SW5 Determines whether the JATE retransmission security function is provided or not. When P4.2=1, the JATE retransmission security function is not provided. When P4.2=0, the JATE retransmission security function is provided. P3.3 P4.1 P4.3 When P2.7=0, the carrier transmission levels are set. SW6 Determines the command set types. When P4.3=1, typeA command set is determined. When P4.3=0, typeB command set is determined. P7.2 SW7 P7.2 should be always set to 0, which is reserved for future use. P7.4 SW8 P7.4 should be always set to 0, which is reserved for future use. P7.5 SW9 Selects the nonvolatile memory types to be used. When P7.5=1, X24C02 ( ) or an equivalent is selected. When P7.5=0, AT59C22 (produced by ATMEL) or an equivalent is selected.

¡ Semiconductor MSC2121A FEDL2121A-02

• List of MCU (MSM66507) Port Assignments Port Number I/O Active Level Input/ output Signal Name AD0 AD7 P0.0 P0.7 Function Address bus (low order) and data bus.to to Output A15 P1.0 P1.7 Address bus (high order) Port Number I/O Active Level Signal Name Function toto SW2P3.0 Input For SW2 signal input. RIIP3.1 Input L For the incoming call signal input from the NCU circuit (Note1). SPKP3.2 Output L For speaker control signal. SW3P3.3 Input For SW3 signal input. SDP3.4 Input For transmission data (connect to P6.6) RTSP3.5 Input L Request to send. RTP3.6 Input Reception timing clock input (from the MSM7564-01). ST2P3.7 Input Transmission timing clock input (from the MSM7564-01). Port Number I/O Active Level Signal Name Function RLY1P2.0 Output H For dial relay control signal. RLY2P2.1 Output H For line connection relay control signal. CIP2.2 Output L Calling indicator DTRP2.3 Input L Data Terminal Ready DSRP2.4 Output L Data Set Ready DCDP2.5 Output L Data Carrier Detect signal. CTSP2.6 Output L Clear to Send. SW1P2.7 Input For SW1 signal input. Port Number I/O Active Level Signal Name Function CE1P4.0 Output MSM7564-01 select signal. SW4P4.1 Input For SW4 signal input. P4.2 Input For SW5 signal input. P4.3 Input For SW6 signal input. MRP4.4 Output For the modem ready indicator signal. HSP4.5 Output H For the high-speed indicator signal. ECP4.6 Output For the error correction mode indicator signal. AAP4.7 Output For the auto answer indicator signal. H H H Port Number I/O Active Level Signal Name Function SW5 SW6

¡ Semiconductor MSC2121A FEDL2121A-02

• Other MCU Signals CSP5.0 Output For non-volatile memory control signal (Note2) CLKP5.1 Output P5.2 Output DI For non-volatile memory control signal (Note2) For non-volatile memory control signal (Note2) Port Number I/O Active Level Signal Name Function RBTMP6.0 Input Reception modulation timing signal from the MSM7564-01. TxD P6.1 Input STSCHG signal (from the MSM7564-01). P6.2 Input Reception data from the MSM7564-01. P6.3 Output Transmission data to the MSM7564-01. RTP6.4 Input Reception timing clock input (from the MSM7564-01). ST2P6.5 Input Transmission timing clock input (from the MSM7564-01). SDP6.6 Input For transmission data. (connect to P34) RDP6.7 Output For reception data. RxD Port Number I/O Active Level Signal Name Function L STSCHG WRP7.0 Output External memory write signal. RDP7.1 Output External memory read signal. P7.2 Input For SW7 signal input. P7.3 Output Clock signal to the MSM7564-01. (3.888MHz) P7.4 Input For SW8 signal input. P7.5 Input For SW9 signal input. R/BP7.6 Input For non-volatile memory control signal (Note2) DOP7.7 Input For non-volatile memory control signal (Note2) L L MCK Port Number I/O Active Level Signal Name Function SW7 SW8 SW9 Pin Name I/O EA Input Connect to +5 V. NMI Input Connect to digital ground. OE Input Connect to digital ground. PSEN Output Not used (open pin). ALE Output Connect to the MSM7564-01 ALE pin. RES Input Connect to system reset signal. Pin Processing

¡ Semiconductor MSC2121A FEDL2121A-02 Note1: If a signal is input to RII under the conditions below, this chip set recognizes it as one incoming call signal. RII CI 150 msec 400 msec One incoming call signal Note2: Each pin assignment to nonvolatile memory type to be used is indicated below.

• When SW9=0, “No nonvolatile memory’’ is automatically identified during initial processing
• If no nonvolatile memory is used, (1) The chip-set is factory shipped after hardware or software is reset. (2) The following commands are invalidated: &w, &z, dial storing s (store dial) Port Number SW9 (7.5)=0 SW9 (7.5)=1 AT59C22 equivalent No non volatile memory X24C02 equivalent DI connect to P7.7 connect to ground DO connect to P5.2 open CS open CSL R/B connect to P5.1 open CLK connect to P7.6 SDA P5.2 P7.7 P5.0 P7.6 P5.1

¡ Semiconductor MSC2121A FEDL2121A-02 COMMAND SPECIFICATIONS

• AT Commands AT commands are explained in Appendix A. Industry standard AT commands are supported.
• EIA/TIA-578 (Class 1) Fax Commands EIA/TIA-578 fax commands are explained in Appendix B. In order to perform facsimile communication, fax commands stipulated by EIA/TIA-578 (Class 1) are supported.
• S-Registers S-registers are explained in Appendix C.
• Command Mode and Data Mode Supplementary explanations of the command mode and data mode are recorded in Appendix
• Loopback Tests and Self Diagnostic Supplementary explanations of the loopback tests and self diagnostic are recorded in Appendix

¡ Semiconductor MSC2121A A-1 FEDL2121A-02 Appendix A AT Commands OVERVIEW AT commands begin with <AT> or <at>. The <character string> up to the carriage return is interpreted as commands, which are executed sequentially. The result code is returned to the DTE. Command character string CR LFAT However, the A, D, Dc, On, Zn, Ax, &Tn and &Zn commands must be placed last in the command string. Even if a command is entered afterwards, any characters up to the return code are ignored. The maximum length of the command character string is 40 characters (spaces <20h> are ignored). Only the backspace function (code can be changed) is valid for deleting an input character. <CR> is the carriage return code (code can be changed). <LF> is the line feed code (can be omitted; code can be changed). Both upper and lower case alpha characters used in commands are recognized, but At or aT are not recognized. When inputting commands, communication with the DTE is handled in asynchronous mode. When AT (at) is input, the terminal speed and character format are automatically determined. TERMINAL SPEED AND CHARACTER FORMAT When the DCE is in the asynchronous command mode, the communication mode with the DTE is as shown below:

• Terminal speed: 300 bps, 1,200 bps, 2,400 bps, 4,800 bps, 7,200 bps, 9,600 bps, 12,000 bps, 14,400 bps, 19,200 bps, 28,800 bps, 38,400 bps, 57,600 bps
• Character format Start bit Data bit Parity bit Stop bit Character length Odd/even None Mark/space None

¡ Semiconductor MSC2121A A-2 FEDL2121A-02 LIST OF AT COMMANDS Note: If n is omitted, it is interpreted as n = 0. Command Function Initial Value Remarks A/ Re-execute the immediately preceding command. A Connect the modem to the line in the answer mode. Bn Selection of ITU-T standard and BELL standard: n = 0: Modem function operates in accordance with the ITU-T standard. n = 1: Modem function operates in accordance with the Bell standard. D Same Force operation into originate mode.

¡ Semiconductor MSC2121A A-3 FEDL2121A-02 The modem dials and operates in the originate mode. Dial Characters Pulse: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, (A, B, C, D, *, # are ignored) Control Characters L P R Sn T Dc Detect silence If during the time set in the S7 register, a continuous 5-second interval of silence is detected after the ring tone, and dial string processing is not detected after that (@), a "BUSY" is returned if the call progress tone is a busy tone, and a "NO ANSWER". Flash The modem goes off hook for 0.5 seconds. Pause Dialing pauses for the time set in the S8 register. After dialing is completed, return to command mode without disconnecting the line Redial the last dialed telephone number If there is an L in the dial string, the last dialed dial string (telephone number) is substituted for the L and dialed. Temporarily sets the subsequent dial string to the pulse dial format Reverse After dialing is completed, the modem starts communication in the answer mode. An interval from after dialing until sending the answer tone can be set by inserting a pause (,) before the reverse (R). If there is an R in the dial string, subsequent chara Dials the telephone number, specified by registration number n, which was stored in nonvolatile memory by the &Zn command. The value for n is specified by 0 to 3 (if there is no specification, it is interpreted as n = 0). If there is an Sn in the dial string and the character after S is 0 to 3, the dial string (telephone number) of the specified registration number is substituted for Sn and dialed. If the character after S is outside of the characters 0 to 3, or if there is Temporarily sets the subsequent dial string to the tone dial format. c is the dial string. The dial string comprises a combination of dial characters and control characters. The maximum number of characters is 40 (D + 39). However, if L or Sn are used, a dial string of greater than 40 characters is possible. L and Sn can store up to 63 and 33 characters, respectively. L is ignored if the telephone numbers are not in memory, such as after a reset or power ON. Sn is ignored if the telephone number is not registered in the registration number of the nonvolatile memory specified by n. If there is an L or Sn in the dial string, the dial string stored in memory is displayed when that L or Sn is executed (however, this is dependent on the Qn command). Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-4 FEDL2121A-02 W J K (Characters other than those above are completely ignored.) Dc Detect a dial tone Regardless of the ATXn command entered, if a dial tone is detected during the time set in the S7 register, the next dial string is processed. If a dial tone is not detected, a "NO DIALTONE" is returned. When MNP Class 10 is enabled, the starting communication carrier speed for the handshaking is performed at 1,200 bps (V.22). [Equivalent to AT*H1 command.] When MNP Class 10 is enabled, the transmission level during communication is changed temporarily according to the line conditions. [Equivalent to the AT)M1 command] J and K are ignored if MNP Class 10 is disabled (AT-N1). Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-5 FEDL2121A-02 En Selects whether to echo when in the command mode. n = 0 The command input characters are not echoed. n = 1 The command input characters are echoed. Hn Controls the connection to the line. n = 0 Set the line OFF (on hook) n = 1 Set the line ON (off hook) In dentification of the DCE. n = 0 Display the product code (14400) n = 1 Display the ROM checksum. n = 2 Perform a ROM check sum and display OK or ERROR. n = 19 Display the ROM version. <CR><LF>Copyright (C) 1995 Oki Electric Industry Co., Ltd.<CR><LF> Mn Controls operation of the monitor speaker. n = 0 The speaker is always OFF n = 1 The speaker is ON from the connection to the line (off hook) until handshaking is completed. n = 2 The speaker is always ON. n = 3 The speaker is ON only during handshaking. Nn Selects the automatic fallback function for the modem-modem communication carrier speed. The maximum communication speed is determined by the S37 register. n = 0 Disables the automatic fallback function n = 1 Enables the automatic fallback function If the automatic fallback function is enabled, the modem automatically falls back to the communication carrier speed of the remote modem when handshaking and retraining. However, if connected in the direct mode, automatic fallback is not performed when retraining regardless of the setting. Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-6 FEDL2121A-02 Selects whether to send the result code. n = 0 Send a result code. n = 1 Do not send a result code. On Return from the on-line command mode to the data mode. n = 0 Switch from the on-line command mode to the data mode. n = 1 When switching from the on-line command mode to the data mode, execute the retraining sequence. If this command is issued from the command state after going off hook (not yet connected to the remote modem), the DCE tests the connection in the mode specified when on hook (D, A, DxxxR commands). P Sets dialing to the pulse dial method. Qn T Sets the dialing mode to tone dialing. Vn Type of result code. n = 0 Short form result code (numeric). n = 1 Long form result code (character string/word). Sets the pointer value for the S-register to the value r.Sr Refer to Appendix C. Returns the contents of the S-register indicated by r.Sr? Sets the contents of the S-register indicated by r to the value d.Sr=d Sets the contents of the S-register indicated by the current pointer value to the value d.=d Returns the contents of the S-register indicated by the current pointer value.? Factory setting is pulse dial. Factory setting is pulse dial. Refer to the section on result codes. Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-7 FEDL2121A-02 Wn Selects the connect result code. n = 0 DTE-DCE terminal speed CONNECT xxxx n = 1 n = 2 Communication carrier speed n = 3 DTE-DCE terminal speed CONNECT xxxx/REL DTE-DCE terminal speed: CARRIER xxxx PROTOCOL : xxxx COMPRESSION : xxxx CONNECT xxxx CARRIER xxxx Carrier speed Protocol Data compression DTE-DCE terminal speed However, when in the direct mode or terminal speed variable mode (AT \\ J1), the communication carrier speed is displayed after the CONNECT display. Displays the DTE-DCE speed and error correction connection. In the normal mode and direct mode, only CONNECT xxxx is displayed. In the terminal speed variable mode (AT \\ J1), the communication carrier speed is displayed after CONNECT. Communication carrier speed: Protocol Data compression 300, 1200, 2400, 4800, 7200, 9600, 12000, 14400 LAPM, ALT, NONE V. 42bis, class5, NONE 300, 1200, 2400, 4800, 7200 9600, 12000, 14400, 19200 28800, 38400, 57600 Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-8 FEDL2121A-02 Xn Selects extended result codes. n = 0 Return basic result codes (result code numbers: 0 to 4, 8). The dial tone and busy tone are not detected and the only connect result code is CONNECT. n = 1 n = 2 n = 3 n = 4 A dial tone is detected by a continuous signal longer than 100 ms within 5 seconds after going off hook. The second dial tone is detected by a continuous signal longer than 100 ms starting from after dialing is completed (starting point of W) and during the time set n the S7 register. After the detection of a busy tone, if the tone signal turns ON and OFF every 500 ms ±150 ms continuously for 3 seconds, it is judged to be BUSY. Command Function Initial Value Remarks Return basic + extended result codes (result code numbers: 0 to 5, 8 to 80). The dial tone and busy tone are not detected. Return basic + extended result codes (result code numbers: 0 to 6, 8 to 80). The busy tone is not detected. Return basic + extended result codes (result code numbers: 0 to 5, 7 to 80). The dial tone is not detected. Return basic + extended result codes (result code numbers: all numbers). Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-9 FEDL2121A-02 &Cn Controls the DCD (CD) signal n = 0 n = 1 Yn Selects the call abort function. n = 0 n = 1 Call Abort Function If an ON ® OFF change is detected in the DTR (ER) signal when an ATH (ATH0) command is received from the DTE, or when an AT&D2 command is set, the following operation is performed: If the modem is in the direct mode with the communication carrier speed at 2,400 bps or lower, a 4-second long space is transmitted to the remote modem, and the line is dropped (invalid when in a mode other than the direct mode). If the communication carrier speed is 4,800 bps or greater, a call abort signal is sent to the remote modem and the line is dropped. If the modem is in the direct mode and the communication carrier speed is 2,400 bps or below, the line is dropped if a long space of 1.6 seconds or greater is received from the remote modem (invalid when in a mode other than the direct mode). If the communication carrier speed is 4,800 bps or greater, the line is dropped, regardless of this setting, if a call abort signal is received from the remote modem. Disables the call abort function. Enables the call abort function. Zn Initializes the DCE the same as when turning on the power supply. n = 0 n = 1 Initializes the DCE with the contents of profile number 0 in nonvolatile memory. Initializes the DCE with the contents of profile number 1 in nonvolatile memory. Command Function Initial Value Remarks The DCD (CD) signal is always ON. The DCD (CD) signal is ON or OFF according to whether a carrier is detected. Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-10 FEDL2121A-02 &Rn Controls the CTS (CS) signal. n = 0 n = 1 Initializes the S-registers and commands to the factory set values.&F Controls the guard tone. n = 0 No guard tone. n = 1 There is a 550 Hz guard tone. n = 2 There is a 1,800 Hz guard tone. &Ln Type of line format used. n = 0 n = 1 0 &Mn Sets the data communication mode. n = 0 Asynchronous communication mode. n = 1 Synchronous mode 1 n = 2 Synchronous mode 2 n = 3 Synchronous mode 3 &Pn Selects the mode of the pulse dial. n = 0 10 pps (39%) USA specification n = 1 10 pps (33%) UK and Japan specifications n = 2 20 pps (33%) Japan specification &Gn &Dn Controls the DCE by the state of the DTR (ER) signal. n = 0 n = 1 n = 2 n = 3 A general telephone switched line is used. A dedicated line is used. The handshake uses only a retraining sequence, and the modem starts sending a carrier signal at the target speed one second after going off hook, regardless of whether the modem is in originate or answer mode. This has a higher priority than the AT\\Nn command. &Sn Controls the DSR signal. n = 0 n = 1 Synchronous. Command Function Initial Value Remarks Ignore the DTR (ER) signal (DTR (ER) signal is considered to be always ON). When in the data mode, the modem switches to the on-line command mode when the DTR (ER) signal changes from ON to OFF. When in the data mode, the modem disconnects the line and switches to the command mode when the DTR (ER) signal changes from ON to OFF. Further, the modem does not auto answer when the DTR (ER) signal is OFF. When in the data mode, the DCE is initialized (the same as when turning the power ON) when the DTR (ER) signal changes from ON to OFF. The DSR (DR) signal is always ON. The DSR (DR) signal is sent in accordance with the ITU-T recommendation for each modem function. When in the data mode, data is output with the delay set in register S26 when an RTS is input. The RTS signal is ignored. Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-11 FEDL2121A-02 &Tn Selects the loopback test mode. n = 0 n = 1 n = 3 n = 4 n = 5 n = 6 n = 7 n = 8 Valid only in direct mode. 0, 4 Terminates the loopback test mode. The DCE loops back the data from the DTE between the modulator unit and the demodulator unit and sends it to the DTE. (Local Analog Loopback test: LAL) The DCE loops back the data received from the remote modem and transmits the data to the remote modem. (Local Digital Loopback test: LDL) The DCE receives data from the remote modem. When a remote digital loopback (RDL) ID signal is received, a verification signal is sent to the remote modem. Afterwards, the data received from the remote modem is looped back by the digital unit and transmitted to the remote modem. When a terminate signal is received from the remote modem, the remote digital loopback test (RDL) is terminated. Even if the remote digital loopback test (RDL) ID signal is received from the remote modem, the DCE ignores it and does not transmit a verification signal to the remote modem. The DCE transmits the remote digital loopback test (RDL) ID signal to the remote modem. Upon reception of the verification signal from the remote modem, the DCE starts the test. If a verification test is not received from the remote modem, ERROR is displayed and the test is stopped. (Remote Digital Loopback test: RDL) The DCE transmits the remote digital loopback test (RDL) ID signal to the remote modem. Upon receiving a verification signal from the remote modem, the DCE transmits specific data in the DCE itself to the remote modem, and the data is looped back by the remote modem. The received specific data is verified, and the errors are counted. When the test is terminated, the error count is displayed. If the verification signal is not received from the remote modem, display ERROR and stop the test. (RDL with self) Specific data from the DCE itself is looped back between the modulator unit and demodulator unit. The specific data is verified and the errors are counted. When the test is terminated, the error count is displayed. (LAL with self) Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-12 FEDL2121A-02 &Un Controls the enabling of trellis coding for ITU-T V.32bis at a 9,600 bps communication carrier speed. n = 0 n = 1 &V Displays the current state of the DCE settings. Displays the current command setting, the S-registers (user, profiles 0, 1) registered in nonvolatile memory, and the transmission level. Refer to the section on display formats. Trellis coding enabled. Trellis coding disabled. Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-13 FEDL2121A-02 Note: If n is omitted, it is interpreted as n = 0. &Yn Selects the user profile number in nonvolatile memory used for the default settings when turning the power ON. n = 0 n = 1 Object S-register numbers: 0, 6 to 10, 12, 14, 18, 21 to 23, 25 to 27, 34 to 48, 40 to 46, 48 &Wn Writes the current contents of the specified S-register to nonvolatile memory. n = 0 n = 1 &Zn = c Writes the character string (c) after the equal sign, as a telephone number, to the nonvolatile memory registration number specified by n. n = 0 n = 1 n = 2 n = 3 The character string c is a maximum of 33 characters. If it is 34 characters or greater, the characters up to the 33rd character are written to nonvolatile memory, and the 34th and beyond are ignored. If c is omitted, the contents of the specified registration number in nonvolatile memory is cleared. The telephone number c conforms to the Dc command. ¥An Selects the maximum block size in MNP reliable mode. n = 0 n = 1 n = 2 n = 3 &Xn Selects the communication clock used in the synchronous mode. n = 0 n = 1 n = 2 Synchronous When turning the power ON, initialize with the profile number 0. When turning the power ON, initialize with the profile number 1. n = 0 Writes to user profile number 0. n = 1 Writes to user profile number 1. Write to nonvolatile memory number 0. Write to nonvolatile memory number 1. Write to nonvolatile memory number 2. Write to nonvolatile memory number 3. The maximum block size is 64 bytes. The maximum block size is 128 bytes. The maximum block size is 192 bytes. The maximum block size is 256 bytes. Use ST2 from the modem. Use ST1 from the terminal. Use the receive clock RT from the modem. Command Function Initial Value Remarks (clear)

¡ Semiconductor MSC2121A A-14 FEDL2121A-02 Note: If n is omitted, it is interpreted as n = 0. Sends a break signal to the remote modem. n = 0 n = 1 to 9 When in the data mode of the normal or reliable modes, this functions as a command which transmits a break to the remote modem. If in the data mode of the direct mode, an ERROR is returned. Note: Normal Mode A break (space) signal is sent to the line for an interval set by n on the transmit side. The receive side receives the break signal and the modem sends a break signal to the DTE for a fixed time of 300 ms. V.42/V.42bis Modes The break information is delivered in accordance with the break processing (\\Kn) and break length (\\Bn) on the transmit side. The break processing is executed on the receive side according to the frame received from the remote modem. The break signal to the DTE is sent in accordance with the break length information of the frame from the remote modem (100 to 900 ms). MNP4/MNP5 Modes When transmitting, only the break processing mode (\\K) is delivered. When receiving, break processing is performed according to the information from the remote modem. The break signal to the DTE is fixed at 300 ms. ¥Bn Valid only when in normal mode and reliable mode. Transmits a 300 ms break signal (long space). Transmits an n ´ 100 ms break signal (long space). The default value of this command is 0. Values set subsequently are stored in internal memory, but are not included in the S-registers and are not stored in nonvolatile memory. Therefore, the following explanations are for a break transmission by means of \\Bn. However, even if a break signal is received directly from the DTE, the \\Bn value at that time is used. Command Function Initial Value Remarks

¡ Semiconductor MSC2121A A-15 FEDL2121A-02 Note: If n is omitted, it is interpreted as n = 0. ¥Cn Selects the automatic determination in auto reliable mode. n = 0 n = 1 n = 2 Valid only in the answer mode when the AT\\N3 or AT\\N7 command (auto reliable mode) is set. The receive data is not buffered. If there is no reliable request even after 8 seconds have elapsed, the modem connects in normal mode. Two-hundred bytes or 8 seconds of receive data is buffered. If a reliable request is received during that time, the data in the buffer is discarded and the modem connects in reliable mode. If a reliable request is not received, the modem connects in normal mode and sends the data in the buffer to the DTE. The receive data is not buffered. If an auto reliable fallback character is received, or if there is no reliable request even after 8 seconds have elapsed, the modem connects in normal mode. Refer to the section on display formats. ¥F Displays all telephone numbers registered in nonvolatile memory and the last dialed telephone number. ¥Gn Sets the flow control with the remote modem. n = 0 n = 1 Valid only when in normal mode. Command Function Initial Value Remarks No flow control. Flow control based on XON/XOFF codes.

¡ Semiconductor MSC2121A A-16 FEDL2121A-02 Note: If n is omitted, it is interpreted as n = 0. ¥Kn Sets the processing of the break signal.

• If a break signal (long space) is received from the DTE: a: In the data mode state of the normal/reliable mode n = 4 n = 5 b: In the on-line command mode state of the normal/reliable mode (includes break processing based on the AT\\Bn command from the DTE). n = 4, 5 After processing the break signal, the modem remains in the on-line command mode state. c: Data mode state of direct mode. n = 4 n = 5 Break signals from the DTE are ignored in the on-line command state when in the direct mode.
• If a break signal (long space) is received from the remote modem while in the data mode of the normal mode: n = 4, 5 The modem switches to the on-line command state without transmitting a break signal to the remote modem. The modem transmits a break signal after transmitting he data remaining in the transmit buffer to the remote modem (nondestructive, nonexpedited). The modem transmits the break information after transmitting the data remaining in the transmit buffer to the remote modem (nondestructive, nonexpedited). The modem immediately transmits a break signal to the remote modem and switches to the on-line command mode state. The modem immediately transmits a break signal to the remote modem and remains in the data mode. The modem transmits a break signal (long space) after sending the data remaining in the receive buffer to the DTE (nondestructive, nonexpedited). ¥Jn Sets the DTE-DCE terminal speed. n = 0 n = 1 0 The DTE-DCE terminal speed is fixed. When in the command mode, the speed is in accordance with the terminal speed. Follows the communication carrier speed at the time when the connection is completed. The DTE needs to reset the terminal speed according to the "CONNECT xxxx" speed displayed. Valid only in the normal mode and reliable mode. Command Function Initial Value Remarks

¡ Semiconductor MSC2121A A-17 FEDL2121A-02 Note: If n is omitted, it is interpreted as n = 0. ¥Kn Even if a break signal (long space) is received from the remote modem while in the on-line mode, it is ignored.

• If a frame for a break signal is received from the remote modem while in the data mode of the reliable mode, processing is performed according to the commands in that frame. If a frame for a break signal is received from the remote modem while in the on-line command mode, it is processed when the modem returns to the data mode state.
• If a break signal (long space) is received from the remote modem while in the data mode of the direct mode, the break signal (long space) is sent, as is, to the DTE. Even if a break signal (long space) is received from the remote modem while in the on-line command mode, it is ignored. Command Function Initial Value Remarks

¡ Semiconductor MSC2121A A-18 FEDL2121A-02 Note: If n is omitted, it is interpreted as n = 0. ¥Nn Sets the operation of the modem. n = 0 n = 1 n = 2 n = 3 n = 4 n = 5 n = 6 n = 7 ¥Sn Displays the current DCE settings. n = 0 n = 1 ¥Qn Selects the DTE-DCE flow control. n = 0 n = 1 n = 2 n = 3 Invalid when in direct mode. ¥Tn Sets the inactivity timer when in reliable mode. n = 1 to 90 (min); n = 0 indicates no timer function. If, for the above time setting, no transmit data is input from the local DTE and there is also no receive data from the remote modem, the line is dropped. Refer to the section on display formats. Modem operates in normal mode (with buffering). V.42 and MNP are not used. Modem operates in direct mode (without buffering). V.42 and MNP are not used. The DTE needs to reset the terminal speed according to the speed displayed in "CONNECT xxxx." Modem operates in V.42/MNP reliable mode. The modem tries to connect using V.42 and MNP, in that order. If it cannot connect, it drops the line. Modem operates in V.42/MNP auto reliable mode. The modem tries to connect using V.42 and MNP, in that order. If it cannot connect, the modem connects in direct mode if the \\J1 command is set. Otherwise, it connects in normal mode. The modem operates in V.42 reliable mode. If it cannot connect in V.42, it drops the line. The modem operates in V.42 reliable mode without using the detection phase. If it cannot connect in V.42, it drops the line. The modem operates in MNP reliable mode. If it cannot connect in MNP, it drops the line. The modem operates in MNP auto reliable mode. The modem tries to connect in MNP. If it cannot connect, it connects in direct mode if the \\J1 command is set. Otherwise, it connects in normal mode. No flow control. Bidirectional flow control based on XON/XOFF codes. Unidirectional flow control from the DCE side based on the CTS (CS) signal line. Bidirectional flow control based on the CTS (CS) signal line and RTS (RS) signal line. Command Function Initial Value Remarks Display first screen. Display second screen.

¡ Semiconductor MSC2121A A-19 FEDL2121A-02 Note: If n is omitted, it is interpreted as n = 0. ¥Xn Sets the transparency of the XON/XOFF codes from the DTE. n = 0 n = 1 Valid when AT\\Q1 is set in normal mode. %En Sets whether auto retraining is performed. n = 0 n = 1 %R Displays the current contents of all S-registers. %Cn Sets whether data is compressed. n = 0 n = 1 %Ac Sets the MNP fallback character. c = 0 to 127 Set by a decimal ASCII code.

0 Used when setting

AT\\C2 in MNP mode. Refer to the section on display formats. Command Function Initial Value Remarks The XON/XOFF codes from the DTE are not transmitted to the remote modem. The XON/XOFF codes from the DTE are transmitted to the remote modem. Data is not compressed. Data is compressed by V.42bis or MNP Class 5. No auto retraining. Auto retraining.

¡ Semiconductor MSC2121A A-20 FEDL2121A-02 –Nn Sets whether MNP Class 10 is enabled. n = 0 n = 1 –Kn Sets whether extended MNP service is enabled. n = 0 n = 1 MNP Class 10 is enabled. The settings of the -Kn, *Hn, and ) Mn commands become enabled. MNP Class 10 is disabled. The settings of the -Kn, *Hn, and ) Mn commands are ignored and treated as -K0, *H0 and )M0. Extended MNP service disabled. Extended MNP service enabled. The originate-side modem monitors the MNP detection pattern (MDP) in the V.42 detection phase. The answer-side modem transmits the MDP after ODP detection, thus making MNP protocol negotiation possible. Further, the V.42bis compression function can be used in the MNP connection state. *Hn Selects the communication carrier speed when handshaking. n = 0 n = 1 Connects at the communication carrier speed set in the DCE and performs protocol negotiation. First connects at a communication carrier speed of 1,200 bps (V.22) when handshaking, and performs protocol negotiation. If the line conditions are judged to be good by the DCE itself, the communication carrier speed is changed to 2,400 bps (V.22bis). If the line conditions are still good, the communication carrier speed is changed to 4,800 bps (V.32bis). In the same manner, the communication carrier speed is changed to 7,200 bps (V.32bis), 9,600 bps (V.32bis), 12,000 bps (V.32bis) and 14,400 bps (V.32bis). Data communication is started. (Initial Speed-up Shift Function) Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-21 FEDL2121A-02 )Mn Sets the variation of the transmission level during communication. n = 0 n = 1 DCE does not change the transmission level during communication. DCE changes the transmission level during communication according to the line conditions. If the DCE is used in a mobile telephone, etc., the demodulation state information of the remote modem is received and, based on that information, the transmission level is changed to one most suitable for the remote modem. Command Function Initial Value Remarks Note: If n is omitted, it is interpreted as n = 0.

¡ Semiconductor MSC2121A A-22 FEDL2121A-02 RESULT CODES When the DCE is in asynchronous command mode result codes are returned to the DTE as commands are executed. There are two types of result codes which can be selected by the Vn command. Further, the Qn command selects whether to return result codes. The following shows the format of the two types of result codes. Numeric characters Character string Character string Numeric character string CR LFCR CR LF

¡ Semiconductor MSC2121A A-23 FEDL2121A-02 LIST OF RESULT CODES Character String (Word) Meaning Commands are executed normally; modem returns to command mode state. Connection is established; modem switches from command mode to data mode. Carrier not detected; carrier dropped. The connection is established at a DTE - DCE terminal speed of 1,200 bps. Dial tone not detected. Busy signal detected; dial oscillation spacing is inadequate. Silence state not detected by the @ parameter. Ring signal detected. Command abnormal; there is an error in the command parameter. Connection established at a DTE-DCE terminal speed of 2,400 bps. Connection established at a DTE-DCE terminal speed of 4,800 bps Connection established at a DTE-DCE terminal speed of 7,200 bps Connection established at a DTE-DCE terminal speed of 9,600 bps Connection established at a DTE-DCE terminal speed of 12,000 bps Connection established at a DTE-DCE terminal speed of 14,400 bps Connection established at a DTE-DCE terminal speed of 19,200 bps Connection established at a DTE-DCE terminal speed of 28,800 bps Connection established at a DTE-DCE terminal speed of 38,400 bps Connection established at a DTE-DCE terminal speed of 57,600 bps Connection established at a DTE-DCE terminal speed of 1,200 bps (with error correction) Connection established at a DTE-DCE terminal speed of 2,400 bps (with error correction) Numeric Character Connection established at a DTE-DCE terminal speed of 4,800 bps (with error correction) Connection established at a DTE-DCE terminal speed of 7,200 bps (with error correction) Connection established at a DTE-DCE terminal speed of 9,600 bps (with error correction) Connection established at a DTE-DCE terminal speed of 12,000 bps (with error correction) Connection established at a DTE-DCE terminal speed of 14,400 bps (with error correction) Connection established at a DTE-DCE terminal speed of 19,200 bps (with error correction) OK CONNECT NO CARRIER ERROR CONNECT 1200 NO DIALTONE BUSY NO ANSWER CONNECT 2400 RING CONNECT 4800 CONNECT 9600 CONNECT 19200 CONNECT 1200/REL CONNECT 2400/REL CONNECT 4800/REL CONNECT 9600/REL CONNECT 19200/REL CONNECT 720012 CONNECT 1440015 CONNECT 1200014 CONNECT 5760019 CONNECT 3840018 CONNECT 2880017 CONNECT 7200/REL25 CONNECT 14400/REL28 CONNECT 12000/REL27 22-32 Error Correction Mode *: The speed display xxxx of "CONNECT xxxx" and "CARRIER xxxx," "PROTOCOL: xxxx" and "COMPRESSION: xxxx" are determined by the Xn and Wn commands.

¡ Semiconductor MSC2121A A-24 FEDL2121A-02 The Class 5 MNP standard is used for data compression. The V.42bis ITU-T standard is used for data compression. Data compression not used. COMPRESSION : class 5 COMPRESSION : V.42bis COMPRESSION : NONE Error correction protocol not used. The V.42 LAP-M ITU-T standard is used for the error correction protocol. The Class 4 MNP standard is used for the error correction protocol. PROTOCOL : NONE PROTOCOL : LAPM PROTOCOL : ALT Connection established at a communication carrier speed of 300 baud. (V.21/Bell 103J) Connection established at a communication carrier speed of 1,200 baud. (V.22/Bell 212A) Connection established at a communication carrier speed of 2,400 baud. (V.22bis) CARRIER 300 CARRIER 1200 CARRIER 2400 Connection established at a communication carrier speed of 48,00 baud. (V.32) Connection established at a communication carrier speed of 7,200 baud. (V.32bis) Connection established at a communication carrier speed of 9,600 baud. (V.32/V.32bis) CARRIER 4800 CARRIER 7200 CARRIER 9600 Connection established at a communication carrier speed of 12,000 baud. (V.32bis) Connection established at a communication carrier speed of 14,400 baud. (V.32bis) CARRIER 12000 CARRIER 14400 The Class 10 MNP standard is used for the communication protocol. The Class 4 MNP standard is used for the error correction protocol. PROTOCOL : ALT+CELLULAR Character String (Word) Meaning Numeric Character CONNECT 57600/REL32 CONNECT 38400/REL31 CONNECT 28800/REL30 Connection established at a DTE-DCE terminal speed of 28,800 bps (with error correction) Connection established at a DTE-DCE terminal speed of 38,400 bps (with error correction) Connection established at a DTE-DCE terminal speed of 57,600 bps (with error correction) *: The speed display xxxx of "CONNECT xxxx" and "CARRIER xxxx," "PROTOCOL: xxxx" and "COMPRESSION: xxxx" are determined by the Xn and Wn commands.

¡ Semiconductor MSC2121A A-25 FEDL2121A-02 DISPLAY FORMAT

• The following is displayed by executing the AT&V command. DTE SPEED & CHARACTER FORMAT : 9600 bps 8bit Non-Parity 1Stop-bit B0 E1 M1 N1 Q0 V1 W0 X4 &C0 &D0 &G0 &L0 &M0 &P1 &S0 &T4 &U0 &Y0 %C1 %E1 \\A3 \\C0 \\G0 \\J0 \\K5 \\N3 \\Q2 \\X0 -N1 -K0 *H0 )M0 S00 = 000 S01 = 000 S02 = 043 S03 = 013 S04 = 010 S05 = 008 S06 = 004 S07 = 050 S08 = 002 S09 = 006 S10 = 014 S12 = 050 S14 = 170 S18 = 000 S21 = 004 S22 = 244 S23 = 059 S25 = 005 S26 = 001 S27 = 000 S36 = 007 S37 = 000 S38 = 020 S39 = 064 S40 = 055 S41 = 153 S42 = 024 S43 = 000 S44 = 000 S46 = 136 S48 = 007 S49 = 000 ACTIVE- : PROFILE STORED- : PROFILE No.0 STORED- : PROFILE No.1 LEVEL : REMAIN : OK B0 E1 M1 N1 Q0 V1 W0 X4 &C0 &D0 &G0 &L0 &M0 &P1 &S0 &T4 &U0 %C1 %E1 \\A3 \\C0 \\G0 \\J0 \\K5 \\N3 \\Q2 \\X0 -N1 -K0 *H0 )M0 S00 = 000 S06 = 004 S07 = 050 S08 = 002 S09 = 006 S10 = 014 S12 = 050 S14 = 170 S18 = 000 S21 = 004 S22 = 244 S23 = 059 S25 = 005 S26 = 001 S27 = 000 S36 = 007 S38 = 020 S39 = 064 S40 = 055 S41 = 153 S42 = 024 S43 = 000 S44 = 000 S46 = 002 S48 = 007 S49 = 000 B0 E1 M1 N1 Q0 V1 W0 X4 &C0 &D0 &G0 &L0 &M0 &P1 &S0 &T4 &U0 %C1 %E1 \\A3 \\C0 \\G0 \\J0 \\K5 \\N3 \\Q2 \\X0 -N1 -K0 *H0 )M0 S00 = 000 S06 = 004 S07 = 050 S08 = 002 S09 = 006 S10 = 014 S12 = 050 S14 = 170 S18 = 000 S21 = 004 S22 = 244 S23 = 059 S25 = 005 S26 = 001 S27 = 000 S36 = 007 S38 = 020 S39 = 064 S40 = 055 S41 = 153 S42 = 024 S43 = 000 S44 = 000 S46 = 002 S48 = 007 S49 = 000 TX CARRIER = -15dBm PRODUCTION = MSC2121A VER = 1.00
• The following is displayed by executing the AT\\F command. STORED DIAL (&Z0) = 03-1234-5678 STORED DIAL (&Z1) = STORED DIAL (&Z2) = STORED DIAL (&Z3) = LAST DIAL = OK
• The following is displayed by executing the AT%R command. REG DEC HEX S00 000 00H S01 000 00H S02 043 2BH S03 013 0DH S04 010 0AH S05 008 08H S06 004 04H S07 050 32H S08 002 02H S09 006 06H OK REG DEC HEX S00 014 0EH S11 - - - - - - S12 050 32H S13 - - - - - - S14 170 AAH S15 - - - - - - S16 000 00H S17 - - - - - - S18 000 00H S19 - - - - - - REG DEC HEX S20 - - - - - - S21 004 04H S22 244 F4H S23 059 3BH S24 - - - - - - S25 005 05H S26 001 01H S27 000 00H S28 - - - - - - S29 - - - - - - REG DEC HEX S30 - - - - - - S31 - - - - - - S32 - - - - - - S33 - - - - - - S34 015 0FH S35 009 09H S36 007 07H S37 000 00H S38 020 14H S39 064 40H REG DEC HEX S40 055 37H S41 153 99H S42 024 18H S43 000 00H S44 000 00H S45 000 00H S46 002 02H S47 - - - - - - S48 007 07H S49 000 00H

¡ Semiconductor MSC2121A A-26 FEDL2121A-02

• The following is displayed by executing the AT\\Sn command. Display of the first screen [AT\\S or AT\\S0] DTE Speed DCE Speed DCE Type Modem Type Line Mode Auto Answer Dial Mode Dial Speed Command Echo Result Code Extended CONNECT Extended Result Speaker Control DCD Control DTR Control DSR Control OK 9600 Off-line DATA ITU-T GSTN Off Pulse 33% 10PPS On On AT+FCLASS=0 ATB0 AT&L0 S0=000 ATP AT&P1 ATE1 ATV1 ATW0 ATX4 ATM1 AT&C0 AT&D0 AT&S0 Display of the second screen [AT\\S1] Modem Mode DTE Speed Adjust Block Size Break Control Break length Auto Buffer Fall-Back Code Flow (DTE-DCE) Flow (DCE-DCE) Pass Xon/Xoff Watch timer Data Compression V. 32bis trellis Cellular OK Auto V. 42/MNP Off 256 CTS Off Off Off On On Off AT\\N3 AT\\J0 AT\\A3 AT\\K5 AT\\B003 AT\\C0 AT%A000 AT\\Q2 AT\\G0 AT\\X0 AT\\T000 AT%C1 AT&U0 AT-N1 S-REGISTER SETTINGS The S-register can display and change the register contents by means of the following command examples: Example 1 ATS0 = 4: Sets the S0 register to 4. Example 2 ATS0: Stores 0 in the register pointer. AT = 4: Sets 4 to the register specified at the register pointer (S0). Example 3 ATS0?: Displays the contents of the S0 register. Example 4 AT?: Displays the current value of the register pointer stored in memory. Note: If AT = ? is executed, the register number, pointed to by the register pointer currently stored in memory, is set to 0, and that set value (0) is displayed.

¡ Semiconductor MSC2121A A-27 FEDL2121A-02 MNP CLASS 10 OPERATION The MNP Class 10 protocol has four main functions for performing modem communication in a state which is best suited to the line conditions.

• Initial Speed-up Shift Function This function is enabled by setting the AT*H1 command. If AT*H0 is set, the modem performs handshaking with the remote modem at the communication carrier speed set in the DCE, and then performs protocol negotiation. If AT*H1 is set, hand shaking is performed with the remote modem at a communication carrier speed of 1,200 bps (V.22), since this speed performs well even if line noise is present and improves the probability of connecting properly even with poor line conditions. The modem performs protocol negotiation. Afterwards, both modems judge the line condition by means of the reception condition. If the line conditions are judged to be unsuitable when the communication carrier speed is at 2,400 bps (V.22bis), the modem starts data communication as is, at a communication carrier speed of 1,200 bps. If the line conditions are satisfactory, the communication carrier speed is shifted upwards to 2,400 bps and both modems judge the line conditions by means of the reception condition. If the line conditions are judged to be unsuitable when the communication carrier speed is at 4,800 bps (V.32bis), the modem starts data communication as is, at a communication carrier speed of 2,400 bps. If the line conditions are satisfactory, the communication carrier speed is shifted upwards to 4,800 bps and both modems judge the line conditions by means of the reception condition. The above operation is performed for 4,800 bps (V.32bis), 9,600 bps (V.32bis), 12,000 bps (V.32bis) and 14,400 bps (V.32bis), and data communication is performed at the highest communication carrier speed suited to the current line conditions.
• Robust Auto Reliable Function The DCE performs the following processing during protocol negotiation in order to raise the protocol connectivity as much as possible, even if the line conditions are poor. a) If in originate mode: * If there is no response from the remote modem to a link request frame sent, the DCE retransmits the link request frame a maximum of 15 times at 2 second intervals. * The link verification frame is transmitted twice during negotiation. * The link disconnect frame is transmitted twice in order to refuse the link establishment. b) If in answer mode: * If even one SYN code is detected in the data received from the remote modem, the link establishment timer is increased to 30 seconds. * The link disconnect frame is transmitted twice in order to refuse the link establishment.

¡ Semiconductor MSC2121A A-28 FEDL2121A-02

• Aggressive Adaptive Packet Size Function If a data error is generated in a frame due to line noise, etc. during data communication, the DCE reduces the frame size (shortens the frame transmission time) and holds the qualitative drop in the transmission throughput to a minimum by actively changing the frame size. Thus, data communication is performed in a state best suited to the given line conditions. The DCE monitors the frequency with which data errors are generated and executes this function in cases such as when the line conditions change gradually.
• Dynamic Speed Shift Function During the protocol negotiation, the DCE learns which modem standards the remote modem supports, and freely changes to those modem standards during data communication. The DCE monitors the frequency with which data errors are generated and executes this function in cases such as when the line conditions change suddenly. For example, if a sudden line degradation is detected during data communication at a communication carrier speed of 14,400 bps (V.32bis), the DCE requests a change to a communication carrier speed of 12,000 bps (V.32bis), thus rapidly dealing with the poor line condition. Further, conversely, if an improvement in the line condition is detected during data communication at a communication carrier speed of 12,000 bps, the DCE requests to the remote modem a return to a communication carrier speed of 14,400 bps, thus raising the qualitative transmission throughput.

¡ Semiconductor MSC2121A B-1 FEDL2121A-02 Appendix B EIA/TIA-578 (Class 1) Facsimile Commands OVERVIEW The EIA/TIA-578 (Class 1) fax commands are added to the AT command set, and begin with <AT> or <at>, the same as for AT commands. The <character string> up to the carriage return is interpreted as commands and executed. The result code is returned to the DTE. If multiple commands are sent in the same character string, commands are separated by a colon ":" (3Bh). To switch the modem from the data modem to the Class 1 fax mode, the AT+FCLASS=1 command is executed. To return to the data modem, the AT+FCLASS=0 command must be executed. The command structure and result codes conform to the AT command set. When inputting commands, communication with the DTE is handled in asynchronous mode, the same as for AT commands. When AT (at) is input, the DTE-DCE terminal speed and character format are automatically determined. To execute Class 1 fax communication, application software (G3 fax communication software) is used which conforms to the EIA/TIA-578 (Class 1) fax command standards. DTE-DCE TERMINAL SPEED AND CHARACTER FORMAT The DTE-DCE terminal speed and character format are the same as for AT commands when in the EIA/TIA-578 command mode. However, to execute fax communication, the DTE-DCE terminal speed must be 19,200 bps or greater, and the character format must have 1 start bit, 8 data bits, no parity, 1 stop bit and a character length of 10. LIST OF EIA/TIA-578 (CLASS 1) FAX COMMANDS Command Function Initial Value Remarks + FCLASS = ? Returns all service classes supported by the DCE. Parameter: <0, 1> 0 = Data communication 1 = Fax communication (Class 1 fax commands) + FCLASS? Returns the service class currently set in the DCE. 0 = Data communication. 1 = Fax communication (Class 1 fax commands). + FCLASS = n Switches the DCE to the specified service class. n = 0 Data communication. n = 1 Fax communication (Class 1 fax commands). Note: If n and t are not specified, it results in an error.

¡ Semiconductor MSC2121A B-2 FEDL2121A-02 Note: If n and m are not specified, it results in an error. +FTM=m +FRM=m +FTH=m +FRH=m +FLO=n *1: Refer to the "Specification of the Modulation/Demodulation Method" section regarding the setting of the modulation/demodulation method. +FTM=? +FRM=? +FTH=? +FRH=? +FLO=? +FLO? +FTS=t +FRS=t Command Function Initial Value Remarks Stops transmission and returns the OK result code after the specified time. Specified time = t x 10 ms; t = 0 to 255 Detects a continuous silence for the specified time and returns the OK result code. Specified time = t x 10 ms; t = 0 to 255 Transmits fax data by the modulation method specified by m. Returns all fax data modulation methods supported by the DCE. Parameter: <24, 48, 72, 73, 74, 96, 97, 98, 121, 122, 145, 146> Receives the fax data by the demodulation method specified by m. Returns all fax data demodulation methods supported by the DCE. Parameter: <24, 48, 72, 73, 74, 96, 97, 98, 121, 122, 145, 146> Transmits the HDLC format by the modulation method specified by m. Returns all HDLC format modulation methods supported by the DCE. Parameter: <3, 24, 48, 72, 73, 74, 96, 97, 98, 121, 122, 145, 146> Receives HDLC format by the demodulation method specified by m. Returns all HDLC format demodulation methods supported by the DCE. Parameter: <3, 24, 48, 72, 73, 74, 96, 97, 98, 121, 122, 145, 146> Returns all DTE-DCE flow control methods, when in fax communication mode, supported by the DCE. Parameter: <0, 1> 0 = Bidirectional flow control based on XON/XOFF codes. 1 = Bidirectional flow control based on the CTS (CS) signal line and RTS (RS) signal line. Returns the DTE-DCE flow control method, when in fax communication mode, currently set by the DCE. 0 = Bidirectional flow control based on XON/XOFF codes. 1 = Bidirectional flow control based on the CTS (CS) signal line and RTS (RS) signal line. Sets the DTE-DCE flow control methods, when in fax communication mode, in the DCE. 0 = Bidirectional flow control based on XON/XOFF codes. 1 = Bidirectional flow control based on the CTS (CS) signal line and RTS (RS) signal line.

¡ Semiconductor MSC2121A B-3 FEDL2121A-02 Note: If n and m are not specified, it results in an error. SPECIFICATION OF MODULATION/DEMODULATION METHOD The m which specifies the modulation/demodulation method in the +FTM=m, +FRM=m, +FTH=m, +FRH=m commands must be specified using the codes indicated in the table below. Further, if m is set to a question mark "?" (e.g., +FTH=?), the modem returns the codes of all supported modulation/demodulation methods to the DTE.

• List of modulation/demodulation methods used by EIA/TIA-578 (Class 1) fax commands. Dc Dials and performs fax transmission. The CNG signal transmission and the +FRH=3 command are automatically added to the Dc command of the AT command. A Connects the DCE to the line in the fax receive mode. The CED signal transmission and the +FTH=3 command are automatically added to the A command of the AT command. H Disconnects the telephone line (goes on hook). If this command is executed during transmission/reception, the telephone line is disconnected (goes on hook) after stopping that transmission/reception. Command Function Initial Value Remarks Code Moduration/ Demoduration on Method Communication Speed 121 122 145 146 V.21 ch.2 V.27 ter V.27 ter V.29 V.17 V.17 w/st V.29 V.17 V.17 w/st V.17 V.17 w/st V.17 V.17 w/st It is essential to specify by the +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Specify by the +FTM, +FRM, +FTH and +FRH commands. Required Conditions 300 bps 2400 bps 4800 bps 7200 bps 7200 bps 7200 bps 9600 bps 9600 bps 9600 bps 12000 bps 12000 bps 14400 bps 14400 bps

¡ Semiconductor MSC2121A B-4 FEDL2121A-02 RESULT CODES The result codes to the EIA/TIA-578 (Class 1) commands operate under the same conditions as those for the result codes of the AT commands. However, "NO CARRIER" (numeric character 3) does not mean that the modem changes to the on hook state. FAX COMMUNICATION PROTOCOL If executing facsimile communication using EIA/TIA-578 (Class 1) fax commands, the DTE side must be responsible for creating and managing the modulation/demodulation method, HDLC frame configuration, various signal procedures, methods, various signal times and intervals as stipulated in ITU-T Recommendation T.30 which is the facsimile communication protocol. This is the same for message data: the DTE must be responsible for creating and decoding the message data in the format stipulated by ITU-T Recommendation T.4 (MH, MR conversion) or T.6 (MMR conversion). Numeric Character Character String (Word) +F4 OK CONNECT RING NO CARRIER ERROR NO DIALTONE BUSY +FCERROR The command executed normally and the modem returns to the command mode state. The modem entered the data transmission state. Data input/output is performed. A ring signal was detected. A receive carrier was not detected. Or, since the receive carrier stopped, data reception ends. However, this does not mean that the modem has changed to the on hook state. The command is abnormal or there is an error in the command parameters. Or, the command ended abnormally. The modem returns to the command mode state. There is an abnormality in the HDLC frame. Or, data is not input from the DTE during transmission even after 5 seconds have elapsed. A dial tone was not detected. A busy tone was detected. The dial interval is insufficient. A signal was received other than one specified by the AT+FRM=x or AT+FRH=x command. Meaning

¡ Semiconductor MSC2121A B-5 FEDL2121A-02 HDLC FRAME DATA The +FTH=m command performs the following processing on the HDLC frame data input from the DTE, and transmits the data to the remote fax by the specified modulation method. Recognize the <DLE><ETX> codes as the end of data input. Replace the <DLE><DLE> codes with one <DLE> code. Delete the <DLE> code and the next character. Perform the frame check sequence and add the 2-byte FCS. Insert the HDLC zero bit. Continuously transmit the HDLC flag. The +FRH=m command performs the following processing on the HDLC frame data received from the remote fax by the specified modulation method. Delete the HDLC flag. Delete the HDLC zero bit. Perform the frame check sequence and verify the 2-byte FCS. However, the 2-byte FCS is not deleted. Replace each <DLE> code with <DLE><DLE> codes. Add the <DLE><ETX> codes as an end of data transmission. MESSAGE DATA The +FTH=m command performs the following processing on the message data input from the DTE, and transmits the data to the remote modem by the specified modulation method. Recognize the <DLE><ETX> codes as the end of data input. Replace the <DLE><DLE> codes with one <DLE> code. Delete the <DLE> code and the next character. The +FRH=m command performs the following processing on the message data received from the remote fax by the specified modulation method, and sends the data to the DTE. Replace each <DLE> code with <DLE><DLE> codes. Add the <DLE><ETX> codes as an end of data transmission. Note: The following recommendations, at a minimum, must be understood and followed if using the EIA/TIA-578 (Class 1) fax commands. ITU-T T.4 Standardization of group 3 facsimile apparatus for document transmission. ITU-T T.6 Facsimile coding schemes and coding control functions for group 4 facsimile apparatus. ITU-T T.30 Proc edures for document facsimile transmission in the general switched telephone network. EIA/TIA-578 Service Class 1 Asynchronous Facsimile DCE Control Standard.

¡ Semiconductor MSC2121A B-6 FEDL2121A-02

¡ Semiconductor MSC2121A C-1 FEDL2121A-02 Appendix C S-Registers OVERVIEW In this modem, the memory referenced as a variable or state (status), used for the main environment settings known as the S-registers, is arranged in RAM. When the power is turned on, only the S-registers marked with an asterisk "*" on the List of S- Registers are copied from non-volatile memory to the relevant S-registers, making it possible to automatically set the environment. Further, the contents and initial value of each S-register are recorded in the List of S-registers and Bit-mapped S-Registers. LIST OF S-REGISTERS Registers marked with an asterisk "*" are stored in non-volatile memory. Set values with input ranges outside of 0 to 255 are forced to the maximum/minimum value when set. The functioning and operation of the modem cannot be guaranteed if S-registers other than the ones listed below are written to or read from.

¡ Semiconductor MSC2121A C-2 FEDL2121A-02 S-Register No. Range Initial ValueUnit Function *S0 0 to 255 0 Count S1 0 to 255 0 Count 0 to 127 43 ASCII 0 to 127 13 ASCII 0 to 127 10 ASCII 4 to 20 4 Seconds 1 to 50 50 Seconds 0 to 255 2 Seconds 1 to 255 6 1/10 Second 1 to 255 141/10 Second — 170 — —0 — 0 to 255 0 Seconds —4 — — 244 — —6 3 — 0 to 255 51/100 Second —0 — *S6 *S7 *S8 *S9 *S10 *S14 S16 *S18 *S21 *S22 *S23 *S25 *S27 Number of ring signals for the auto answer mode; 0 = auto answer OFF. Number of ring signals received. Escape sequence code. Carriage return code. Line feed code. Back space code. Pause time from off hook until the start of dialing. Allowable time until connection is established. Pause time of comma (,) when dialing Carrier detect time. Carrier loss detect time; 255 does not automatically go on hook. Bit-mapped option register. Bit-mapped option register. Timer for testing. Bit-mapped option register. Bit-mapped option register. Bit-mapped option register. Minimum time of DTR(ER) OFF detection. Delay time from RTS to CTS. Bit-mapped option register. Attenuation level of the data carrier output. Attenuation level of the DTMF (tone) output. Fallback option selection. Maximum DCE line speed setting: 0 = based on the S23 and S45 registers. Time until line disconnect: 255 = line does not disconnect. Bit-mapped option register. Bit-mapped option register. Bit-mapped option register. Bit-mapped option register. Fallback character in the auto reliable mode. Inactivity timer of the \\Tn command: 0 = no timer function. Display of DTE-DCE terminal speed: Enabled when S23.3-1 = 7. Protocol and data compression specification: Enabled when S48 = 0. Protocol negotiation specification. Bit-mapped option register. 0 to 5 5 dB*S34 0 to 5 3 dB*S35 0 to 7 7 —*S36 0 to 11 0 —*S37 0 to 255 20 Seconds*S38 —6 4 —*S39 —5 5 —*S40 — 153 —*S41 —2 4 —*S42 0 to 127 0 ASCII*S43 0 to 90 0 Minutes*S44 0 to 32 32 —*S45 0, 7, 128 7 —*S48 —0 —*S49 2—*S46 0 to 138 0 to 32, 127 8ASCIIS5 0 to 255 11/100 Second*S26

¡ Semiconductor MSC2121A C-3 FEDL2121A-02 General S-Registers Default: 0 Profile: Yes Default: 0 Profile: No Default: 43 Profile: No Default: 13 Profile: No Default: 10 Profile: No Default: 8 Profile: No Default: 4 Profile: Yes Default: 50 Profile: Yes Default: 2 Profile: Yes Default: 6 Profile: Yes S10 Default: 14 Profile: Yes

• Specifies the number of ring signals to be received when auto answering.
• Specify in the range of 0 to 255 (Units: Number of rings).
• 0 specifies no auto answer.
• 1 to 255 specifies the number of ring signals received until the start of auto answer.
• Counts the number of ring signals received when there is an incoming call.
• This register clears 8 seconds after the ring signals stop.
• Specifies the escape sequence code character.
• Specify in the range of 0 to 127 in ASCII code (decimal).
• The default "43" displays a "+" code.
• Specifies the carriage return code character.
• The specified character is used in commands and result codes.
• Specify in the range of 0 to 127 in ASCII code (decimal).
• Uses the default <CR> code (ASCII 13).
• Specifies the line feed code character.
• The specified character is used in commands and result codes.
• Specify in the range of 0 to 127 in ASCII code (decimal).
• Uses the default <LF> code (ASCII 10).
• Specifies the backspace code character.
• The specified character is used in commands.
• Specify in the range of 0 to 32, 127 in ASCII code (decimal).
• Uses the default <BS> code (ASCII 8).
• Sets the pause time from off hook to the start of dialing.
• Specify in the range of 4 to 20 (Units: Seconds).
• Used when dial tone detection is not performed during dialing.
• Specifies the maximum time until a carrier signal is detected.
• Disconnects the line if a carrier signal is not detected within the specified time.
• In originate mode: the time from the end of dialing until carrier signal detection. In answer mode: the time from off hook until carrier signal detection.
• Specify in the range of 1 to 50 (Units: Seconds).
• Specifies the pause time of the dial control character (comma ",") used in the ATD command.
• Specify in the range of 0 to 255 (Units: Seconds).
• No pause when set to 0.
• Specifies the carrier signal detection time.
• If the carrier signal duration is shorter than the specified time, it is not detected.
• Specify in the range of 1 to 255 (Units: 1/10 second).
• Specifies the carrier signal loss detection time. If a carrier signal loss longer than the specified time is detected, the line is automatically disconnected.
• If 255 is specified, automatic line disconnect is not performed. Therefore, the DTE must go on hook at the DTR(ER) signal or by the H command.
• Specify in the range of 1 to 255 (Units: 1/10 second). Register No. Function

¡ Semiconductor MSC2121A C-4 FEDL2121A-02 S18 Default: 0 Profile: Yes S25 Default: 5 Profile: Yes S26 Default: 1 Profile: Yes S34 Default: 5 Profile: Yes S35 Default: 3 Profile: Yes S36 Default: 7 Profile: Yes

• Specifies the measurement time of the loopback test.
• Specify in the range of 0 to 255 (Units: Seconds).
• Specifies the timespan to detect that DTR(ER) is OFF.
• Specify in the range of 0 to 255 (Units: 1/100 second).
• The delay time until the CTS (CS) signal is turned ON when the RTS(RS)signal changes from ON to OFF.
• Specify in the range of 0 to 255 (Units: 1/100 second).
• Sets the attenuation level for the data carrier output line.
• Specify in the range of 0 to 5 (Units: dB).
• Sets the attenuation level for the DTMF (tone) output line.
• Specify in the range of 0 to 5 (Units: dB).
• Specifies the fallback options.
• This register operates when the S48 register is 128, and the V.42 link could not be connected.
• If an invalid value is specified, the value itself is accepted, but actual operation takes place as though the default was input.
• Specify in the range of 0 to 7. 0: DCE disconnects the line. 1: DCE establishes a direct mode connection. 2: Reserved. 3: DCE establishes a normal mode connection. 4: The DCE tries to make an MNP link connection. If the connection fails, the line is disconnected. 5: The DCE tries to make an MNP link connection. If the connection fails, then a connection is established in direct mode. 6: Reserved. 7: The DCE tries to make an MNP link connection. If the connection fails, then a connection is established in normal mode. Register No. Function

¡ Semiconductor MSC2121A C-5 FEDL2121A-02 S37 Default: 0 Profile: Yes S38 Default: 20 Profile: Yes S43 Default: 0 Profile: Yes

• Specifies the maximum communication carrier speed of the DCE.
• When S40.5 = 0, tries to connect to the remote modem at the specified communication carrier speed. When S40.5 = 1, tries to connect with the remote modem at a high communication carrier speed which is supported by both modems, but not exceeding the range of the specified communication carrier speed.
• If an invalid value is specified, the value itself is accepted, but actual operation takes place as though the default was input.
• Specify in the range of 0 to 13. 0: Communication carrier speed is specified according to the local DTE terminal speed. Based on bits 3, 2, 1 of the S23 register and the S45 register: S23 bits: 1: V.21 2: V.21 or Bell 103J 3: V.21 or Bell 103J 5: V.22 or Bell 212A 6: V.22bis or Bell 224 7: V.32 8: V.32bis 9: V.32 or V.32bis 10: V.32bis 11: V.32bis
• Specifies the time until the line is disconnected.
• When in error correction mode if a disconnect command is received, or the DTR(ER) goes from ON to OFF, or data appears in the buffer, the DCE will lose its data, or it will wait the specified amount of time, disconnect the line and discard the data.
• If a value from 0 to 254 is specified, waits the specified amount of time before disconnecting the line, or sends all data.
• If a value of 255 is specified, the line is not disconnected until all the data is sent.
• Specify in the range of 0 to 255 (Units: Seconds).
• Specifies the fallback character used in the auto reliable mode.
• Specify by the AT%Ac command.
• Specify in the range of 0 to 127 ASCII code (decimal). Register No. Function V.21 or Bell 103J V.22 or Bell 212A V.22bis or Bell 224 V.32 V.32 or V.32bis and S45 = 8, V.32bis and S45 = 16, V.32bis and S45 = 17 or greater, V.32bis 300 bps 1200 bps 2400 bps 4800 bps 7200 bps 9600 bps 12000 bps 14400 bps 300 bps 300 bps 300 bps 1200 bps 2400 bps 4800 bps 7200 bps 9600 bps 12000 bps 14400 bps

¡ Semiconductor MSC2121A C-6 FEDL2121A-02 S44 Default: 0 Profile: Yes S45 Default: 32 Profile: Yes S46 Default: 2 Profile: Yes S48 Default: 7 Profile: Yes

• Sets the inactivity timer.
• If 0 is specified the timer does not function.
• When connecting in reliable mode, if there is no data transmission or reception even if a time longer than the specified time has elapsed, the line is disconnected.
• Set by the AT\\Tn command.
• Specify in the range of 0 to 90 (Units: minutes).
• Displays the DTE-DCE terminal speed.
• Set by automatic recognition of "AT" or "SET."
• When bits 1 to 3 of the S23 register are all "1," this register is enabled, and the DTE-DCE terminal speed is displayed.
• Displayed by a numeric value in the range of 0 to 32. 0 Terminal speed is indicated by bits 1 to 3 of the S23 register. 8: 7,200 bps 16: 12,000 bps 17: 14,400 bps 19: 19,200 bps 23: 28,800 bps 27: 38,400 bps 32: 57,600 bps
• Specifies the communication protocol and data compression when the S48 register is specified as "0."
• If an invalid value is specified, the value itself is accepted, but actual operation takes place as though the default was input.
• Displayed by a numeric value in the range of 0 to 138. 0: Only normal mode connection. 1: Only MNP Class 3, 4 connection. 2: Only LAPM or V.42bis connection. 3: Only MNP Class 5 connection. 136: Only LAPM connection. 138: Only V.42bis connection.
• Sets the negotiation of the communication protocol with the remote modem.
• For negotiation with the remote modem, this register is referred to with maximum priority, and the communication protocol of the link connection is determined based on this register.
• Specify as 0, 7 or 128. 0: Communication protocol of the link connection is determined by the S46 register. 7: Communication protocol of the link connection is determined by the AT\\Nn command. 128: Communication protocol of the link connection is determined by the AT\\Nn command. However, if the link connection fails with V.42, the modem operates according to the S36 register. Register No. Function

¡ Semiconductor MSC2121A C-7 FEDL2121A-02 Bit-mapped S-Registers S14 Default: 170 Profile: Yes S16 Default: 0 Profile: No Register No. FunctionBit Position Bit State RelevantCommands Reserved (bit state is "0").

• No echo back when in command mode.
• Echo back when in command mode.
• Result codes.
• No result codes.
• Digit form result code (numeric).
• Word form result code (character string).
• Pulse dialing speed 10 pps.
• Pulse dialing speed 20 pps.
• Sets tone dialing as the default.
• Sets pulse dialing as the default. Reserved (bit state is "0").
• Answer mode.
• Originate mode.
• Local analog loopback test (LAL) disabled.
• Local analog loopback test (LAL) enabled. Reserved (bit state is "0").
• Local digital loopback test (LDL) disabled.
• Local digital loopback test (LDL) enabled.
• The RDLB from the remote modem stops.
• The RDLB from the remote modem is in operation.
• Remote digital loopback test (RDL) disabled.
• Remote digital loopback test (RDL) enabled.
• RDL disabled by the self diagnostic.
• RDL enabled by the self diagnostic.
• LAL disabled by the self diagnostic.
• LAL enabled by the self diagnostic. Reserved (bit state is "0"). Reserved (bit state is "0"). Reserved (bit state is "0").
• Responds to the RTS(RS) and controls the CTS(CS).
• Ignores the RTS(RS).
• Ignores the DTR(ER).
• Returns to the command mode by DTR(ER) ON ® OFF.
• Disconnects the line by DTR(ER) ON ® OFF.
• Initializes by DTR(ER) ON ® OFF.
• The DCD(CD) is always ON. The DCD(CD) depends on the presence of the receive carrier.
• The DSR(DR) is always ON. The DSR(DR) follows the various ITU-T recommendations.
• Line does not disconnect by a break signal.
• Line disconnects by a break signal. T P &T0 &T1 &T0 &T3 &T0 &T6 &T0 &T7 &T0 &T8 4, 3 0, 0 0, 1 1, 0 1, 1 S21 Default: 4 Profile: Yes 7 0 &D0 &D1 &D2 &D3 &C0 &C1 &S0 (&T4)* 6 &S1 &P0, &P1 &P2 D A &R0

¡ Semiconductor MSC2121A C-8 FEDL2121A-02 3, 2 6, 5, 4 0, 0 0, 1 1, 0 1, 1 0, 0, 0 1, 0, 0 1, 0, 1 1, 1, 0 1, 1, 1 S22 Default: 244 Profile: Yes S22 Default: 244 Profile: Yes Reserved (bit state is "0"). Reserved (bit state is "0").

• Monitor speaker is always OFF.
• Monitor speaker is ON until a carrier signal is detected.
• Monitor speaker is always ON.
• Monitor speaker is ON only during handshake.
• Returns a basic result code. Reserved. Reserved. Reserved.
• Returns a basic + extended (no busy or dial detection).
• Returns a basic + extended (no busy tone detection).
• Returns a basic + extended (no dial tone detection).
• Returns a basic + extended (all functions are enabled).
• Uses pulse dialing with make/break ratio of 39%.
• Uses pulse dialing with make/break ratio of 33%.
• Refuses remote digital loopback test.
• Permits remote digital loopback test.
• Local DTE terminal speed: 0 ~ 300 bps. Reserved.
• Local DTE terminal speed: 1,200 bps.
• Local DTE terminal speed: 2,400 bps.
• Local DTE terminal speed: 4,800 bps.
• Local DTE terminal speed: 9,600 bps. Reserved. Local DTE terminal speed is displayed by the S45 register.
• Even parity.
• Space parity.
• Odd parity.
• Mark or no-parity.
• No guard tone
• 550 Hz guard tone.
• 1,800 Hz guard tone. Reserved. 7 0 &P0 &P1, &P2 3, 2, 1 0, 0, 0 1, 1, 0 1, 1, 1 0, 0 0, 1 1, 0 1, 1 0, 0, 1 0, 1, 0 0, 1, 1 1, 0, 0 1, 0, 1 5, 4 7, 6 0, 0 0, 1 1, 0 1, 1 &T5 &T4 &G0 &G1 &G2 0, 0, 1 0, 1, 0 0, 1, 1 Register No. FunctionBit Position Bit State Relevant Commands

¡ Semiconductor MSC2121A C-9 FEDL2121A-02 2, 1, 0 S39 Default: 64 Profile: Yes 6 –N0 –N1 0, 0 0, 1 1, 1

• Specifies the asynchronous mode
• Specifies synchronous mode 1.
• Specifies synchronous mode 2.
• Specifies synchronous mode 3.
• Specifies general public switched line.
• Specifies dedicated line. Reserved (bit state is "0").
• ST2 clock setting.
• ST1 clock setting.
• RT clock setting.
• Not used.
• Modem operation based on ITU-T recommendations.
• Modem operation based on BELL standards. Reserved (bit state is "0"). Reserved (bit state is "000").
• Extended MNP is disabled.
• Extended MNP is enabled.
• Connects at the specified communication carrier speed. Connects at a communication carrier speed of 1,200 bps (V.22).
• Does not change transmission level during communication.
• Changes transmission level during communication.
• MNP 10 protocol is enabled.
• MNP 10 protocol is disabled. Reserved (bit state is "0"). 1, 0 S27 Default: 0 Profile: Yes &M0 &L0 &L1 1, 0 &M1 &M2 &M3 –K0 –K1 *H0 *H1 )M0 )M1 5, 4 0, 0 0, 1 1, 1 1, 0 &X1 &X2 &X0 Register No. FunctionBit Position Bit State Relevant Commands

¡ Semiconductor MSC2121A C-10 FEDL2121A-02 4, 3 0, 1 1, 0 1, 1 0, 1 S41 Default: 153 Profile: Yes 6, 5 %E0 %E1 \\G01 0, 0 0, 0 1, 0 1, 1 7 0 \\G1 \\X0 \\X1 \\A0 \\A1 \\A2 \\A3 \\C0 \\C1 \\C2 %C0 %C1

• Uses normal mode.
• Uses direct mode.
• Uses reliable mode.
• Uses auto reliable mode. Reserved.
• Uses break mode 4.
• Uses break mode 5. Reserved.
• Inhibits auto fallback function.
• Enables auto fallback function.
• Reports terminal speed.
• Reports communication carrier speed, protocol data compression and terminal speed.
• Reports communication carrier speed.
• Report appends to the terminal carrier speed whether there is error correction (/REL).
• No auto retrain.
• Auto retrain.
• Does not perform flow control between the modem and the remote modem.
• Performs flow control based on XON/XOFF codes.
• Does not send XON/XOFF codes to the remote modem. Sends XON/XOFF codes to the remote modem (transparent).
• Maximum block length is 64 bytes.
• Maximum block length is 128 bytes.
• Maximum block length is 192 bytes.
• Maximum block length is 256 bytes.
• No buffering.
• Buffers until an SYN or ODP is received, until 200 characters are received, or until 8 seconds of reception.
• Received data is discarded until the auto reliable fallback character is received, or until a maximum of 8 seconds of reception. Reserved.
• No data compression.
• Data compression. S40 Default: 55 Profile: Yes 0, 0 1, 0 0, 1 1, 0 1, 1 7, 6 4, 3, 2 1, 0, 0 1, 1, ´ 0, 0 0, 1 0, ´, ´ 1, 0 \\N0 \\N1 \\N2, 4 to 6 \\N3, \\N7 \\K4 1 N1 0 N0 1, 1 W3 1, 0, 1 \\K5* Register No. FunctionBit Position Bit State Relevant Commands

¡ Semiconductor MSC2121A C-11 FEDL2121A-02 2, 1, 0 S49 Default: 0 Profile: Yes (Bits 7 and 6 cannot be written to a profile.) 0, 0, 0* 1, 1, 1 1, 1, 0 0, 1, 0 1, 0, 1 1, 0, 0 0, 1, 1 0, 0, 1 +FCLASS=0 +FCLASS=1 7, 6 0, 1 0, 0 1, 1 1, 0 * +FAA=0 +FAA=1 5, 4 3, 2 0, 0 0, 1 1, 0 1, 1 \\Q0 \\Q1 \\Q2 \\Q3 \\J0 \\J1 S42 Default: 24 Profile: Yes 7 0

• V.32bis at 9,600 bps; trellis coding.
• V.32bis at 9,600 bps; no trellis coding. Reserved. Reserved.
• No flow control between the DTE and the modem.
• Flow control based on XON/XOFF codes.
• Flow control based on the CTS(CS) signal of the modem.
• Flow control based on the CTS(CS)/RTS(RS) signals. Reserved.
• Flow control based on XON/XOFF codes.
• Flow control based on the CTS(CS)/RTS(RS) signals. Reserved. Reserved (bit state is "0"). Terminal speed during communication is the same as during commands.
• Terminal speed during communication matches the carrier speed.
• Data modem using asynchronous AT commands.
• Facsimile DCE using Class 1 fax commands. Reserved. Reserved. Reserved. Reserved. Reserved. Reserved. Reserved (bit state is "0"). Reserved (bit state is "0"). Reserved (bit state is "0").
• FAX/DATA automatic switching disabled.
• FAX/DATA automatic switching enabled. Reserved. Reserved. Bits 3 and 2 are only valid when in data modem mode. Bits 5 and 4 are only valid in facsimile DCE mode. 0, 0 0, 1 +FLO=0 1 &U1 &U0 1, 1 1, 0 +FLO=1 Register No. FunctionBit Position Bit State Relevant Commands

¡ Semiconductor MSC2121A C-12 FEDL2121A-02

¡ Semiconductor MSC2121A D-1 FEDL2121A-02 Appendix D Command Mode and Data Mode OVERVIEW The modem has two general states: command mode and data mode. Since the command mode performs asynchronous communication with the terminal, it is more accurately called the asynchronous command mode. The data mode refers to the state in which the modem connects the line to the remote equipment and in which data can be transmitted/ received. ASYNCHRONOUS MODE Power ON Modem initializationRI ON/OFF RING RING detection ATS0=<n> ATZ DTR is ignored Asynchronous command mode Line ON ATA S0 £ S1 AT0 ATD ATH1 ATH0 Line ON Line ON Line ON Line OFF ATX<n> Call progress tone detection Dialing Key abort Key abort Key abort NO DIALTONE NO ANSWER BUSY NO CARRIERHandshake carrier detection S7 timer exceeded CONNECT Carrier loss AT & D2 DTR ON ® OFF Asynchronous data mode Escape sequence +++ AT & D1 DTR ON ® OFF AT & D3 DTR ON ® OFF

• Originate Mode The modem dials by the ATD (ds) command. If there is a response from the remote equipment and the modem connects successfully, the CONNECT result code is returned indicating that the modem has switched to the data mode.
• Answer Mode To set the auto answer mode, enter a command such as ATS0=2. With this command, the modem will auto answer if 2 rings are received. To set the manual answer mode, enter the ATS0=0 command. After verifying the ring, enter the ATA command to answer the call. If the modem connects with the remote equipment, a CONNECT result code is returned indicating that the modem has switched to the data mode.
• Switch From Data Mode to Command Mode If DTR ON®OFF is detected by & D1 mode, the OK result is returned indicating that the modem has returned to the command mode. At this point, commands can be used freely with the modem still connected to the line.
• Switch From Command Mode to Data Mode By inputting the ATO command, the CONNECT result code is returned indicating that the modem has switched to the data mode again.
• Drop the Line Connection (ATH0 command) Normally, the ATH0 command is input in the state where the modem has switched to the command mode. The line is turned OFF and the OK result code is returned. At this point, the remote side detects the carrier loss, turns the line OFF and returns the NO CARRIER result code. At this point, some garbage characters may accompany the signal and change to a result code. If both sides input the ATY1 command to each other beforehand, the line disconnect operates by sending a break signal. The remote side can thus drop the line normally with an OK result code.
• Drop the Line Connection (DTR) If the AT&D2 command is set, the line is disconnected if the DTR makes a transition from ON to OFF, and the modem returns to the command mode.
• DTR Function By entering the AT&D<n> command, the modem performs the functions shown in the figure at left.

¡ Semiconductor MSC2121A D-2 FEDL2121A-02 SYNCHRONOUS MODE This modem can utilize the synchronous mode in addition to the asynchronous mode. There are three types of synchronous modes which are called synchronous mode 1, synchronous mode 2 and synchronous mode 3. The synchronous mode is basically controlled by changes in the DTR state of the DTE. However, only synchronous mode 1 uses the asynchronous command mode up until the line is connected. After the line is connected, the modem switches to the synchronous mode. This mode is therefore called the synchronous/asynchronous mode. In synchronous modes 2 and 3, the command mode functions are enabled if the line is not connected when DTR is in the OFF state. Note: If synchronous mode 2 or 3 is already set, take care that the power ON sequence is correct and that the connection cable is not unplugged. When the modem power is turned ON, this mode is entered and changes in the DTR are detected. If, at this time, the DTR transitions from OFF to ON, originate operation begins. Generally, the modem is powered ON after the DTE is set up. DTEs such as asynchronous type data terminals, personal computers, etc., can use the three synchronous modes. However, they must have a synchronous communication function for after the line is connected. Synchronous modes 2 and 3 can use synchronous type DTEs. RS-232C related commands which do not function in the synchronous mode are AT&C<n>, AT&D<n> and AT&S<n>. The AT&R<n> command functions only in synchronous mode. The time set in S25 is in units of seconds if the DTR state is detected immediately after the line is connected in synchronous mode 1. Otherwise, S25 is used as the delay time for detecting the change in DTR from ON to OFF, and the unit is 1/100 second. The time set in S26 is the delay time from RTS ON until CTS ON. S26 functions if AT&R0 is set. The result of the line connection in synchronous mode depends on changes in the DSR, DCD and CTS signals. Synchronous mode communication is possible when all three of these signals are in the ON state. Further, the AT&X<n> command is set beforehand to select which signal is used for each transmission clock. The setup of each mode is set by the AT&M<n> command. Overview of Synchronous Mode 1 (SYNC/ASYNC mode) Connections are made in the same manner as the asynchronous mode, for both originate and answer modes. A result code is also returned when making a connection (CONNECT xxxx, NO CARRIER, RING). The conditions for dropping the line are if DTR changes from ON to OFF, or if the carrier is not detected for longer than S10. Overview of Synchronous Mode 2 When the DTR changes from OFF to ON, the modem dials the telephone number in nonvolatile memory. Answering is similar to the asynchronous mode, but is also related to DTR. Namely, if DTR is left in the ON state, the modem auto answers if S0 is not 0 and the ring count S0 = S1. The result codes and key abort do not function. (For convenience, the DTE is assumed to be an asynchronous type if the AT00V1 state is set; the result codes will then function.) The conditions for dropping the line are the same as for synchronous mode 1.

¡ Semiconductor MSC2121A D-3 FEDL2121A-02 Overview of Synchronous Mode 3 Dialing is performed by an auxiliary telephone instrument and the connection is made when DTR changes from OFF to ON. Other aspects are the same as for synchronous mode 2.

¡ Semiconductor MSC2121A D-4 FEDL2121A-02 SYNCHRONOUS MODE 1 Power ON Modem initializationRI ON/OFF RING RING detection ATS0=<n> ATZ DTR is ignored Asynchronous command mode Line ON S0 £ S1 ATD Line ON Line OFF ATX<n> Call progress tone detection Dialing Key abort Key abort Key abort NO DIALTONE NO ANSWER BUSY NO CARRIERHandshake carrier detection S7 timer exceeded CONNECT DSR, DCD, CTS ON Synchronous data mode Originate mode Carrier loss DTR ON ® OFF DTR OFF Enters DTR state after S20 seconds Answer mode DTR ON

• Setup Synchronous mode 1 is set by the AT&M1 command, and appropriate settings are made with the ATX<n> and ATQ<n> commands according to the intended purpose. With ATQ1, result codes are returned but communication is completely in asynchronous mode. Set the S25 register to a value suitable for the following purposes (factory setting is 5 seconds). If switching from the asynchronous mode to the synchronous mode is performed on the application side, the DTR may momentarily turn OFF. However, in order not to recognize this change as signal to drop the line, the DTR state is inspected S25 seconds after the connection is completed. The DTR is ignored in the asynchronous command mode state. However, since the ON/OFF changes of the DTR affect the connection, the DTR is generally set to the ON state ahead of time when making a connection.
• Originate Mode The number is dialed by the ATD<ds> or ATDS command. The modem switches to the synchronous mode upon completing the connection to the remote modem. However, the DTR state is inspected after the time set in S25 has elapsed. If the state is OFF, the line is dropped and the modem returns to the asynchronous command mode.
• Answer Mode If <n> in the ATS0=<n> command is not 0, and the modem receives <n> rings, the modem will auto answer the call. The modem switches to the synchronous data mode when the connection with the remote modem is completed (there is no S25 function).
• Drop the Line If the carrier is not detected for the time set in S10 (factory setting: 1.4 seconds), or if the modem detects a DTR change from ON to OFF, the modem drops the line and returns to the asynchronous command mode. If S10 = 255, the line is not dropped due to a carrier loss. At this point, the carrier state can be monitored by the CD LED. Further, a change in the DTR from ON to OFF is not recognized for the time set in S25 (factory setting: 100 seconds).
• Drop the Connection State [TN: "Drop" should probably be "Observe"] If the modem is in the ATX4, ATQ0 or ATV1 state, result codes such as RING, BUSY, NO DIALTONE, CONNECT 1200, CONNECT 2400 and NO CARRIER are returned in the asynchronous mode. DSR turns ON upon receiving an answer tone from the remote modem.DCD turns ON when the data carrier is detected. The CD LED also turns ON. The CTS turns ON if the RTS of the DTE is ON. The operation of RTS and CTS is related to the AT&R<n> command. If n = 0, the CTS turns ON with a delay of time as set in S26 (factory setting: 100 seconds) after RTS turns ON. If n = 1, the CTS is always ON during synchronous data mode, regardless of RTS. DSR, DCD and CTS are all ON in states where synchronous communication is possible.

¡ Semiconductor MSC2121A D-5 FEDL2121A-02 SYNCHRONOUS MODE 2 Power ON Modem initializationRI ON/OFF RING RING detection ATS0=<n> ATZ Command enabled by DTR OFFAsynchronous command mode Line ON S0 £ S1 Line ON Line OFF ATX<n> Call progress tone detection Dialing NO DIALTONE NO ANSWER BUSY NO CARRIERHandshake carrier detection S7 timer exceeded CONNECT DSR, DCD, CTS ON Synchronous data mode Carrier loss ON®OFF DTR ON DTR ON®OFF DTR OFF®ON

• Setup Synchronous mode 2 is set by the AT&M2 command. The telephone number of the remote modem is written to nonvolatile memory by the AT&Z<ds> command. If this mode is always used, store the current settings in nonvolatile memory by the required command string). By storing the current settings, the S registers are automatically set to the values stored in nonvolatile memory the next time power is turned ON, thus setting this mode. To change the settings or test using new ones, set the DTR to the OFF state and use the asynchronous command mode to make the changes. With ATQ0E1, the result codes are returned and the commands are echoed back. Further, if setting the modem as mentioned above, the result code notations in the figure to the left will differ from the normal codes.
• Originate Mode This mode dials the stored telephone number when the DTR changes from OFF to ON. At this point, the line noise can be heard on the monitor speaker if the ATL2M1 command is set. If the line does not connect normally, the line is turned OFF and the modem returns to the asynchronous state.
• Answer Mode The modem is set to the auto answer mode by the ATS0=<n> command. When DTR is ON, the modem starts auto answer when the ring count reaches n (S0 = S1). If S0 > S1, DTR turns OFF and the modem stops auto answering 8 seconds after the last ring. Conversely, if a ring is received even if DTR is turned OFF, the modem auto answers if DTR is turned ON again within 8 seconds. After this interval is exceeded, turning DTR ON starts the originate mode.
• Drop the Line Same as for synchronous mode 1.
• Observe the Connection State Same as for synchronous mode 1.

¡ Semiconductor MSC2121A D-6 FEDL2121A-02 SYNCHRONOUS MODE 3 Power ON Modem initializationRI ON/OFF RING RING detection ATS0=<n> ATZ Command enabled by DTR OFFAsynchronous command mode Line ON S0 £ S1 Line ON Line OFF ATX<n> Call progress tone detection Dialing NO DIALTONE NO ANSWER BUSY NO CARRIERHandshake carrier detection S7 timer exceeded CONNECT DSR, DCD, CTS ON Synchronous data mode Carrier loss ON®OFF DTR ON DTR ON®OFF Dialing by telephone instrument DTR OFF ®ON

• Setup Synchronous mode 3 is set by the AT&M3 command. If this mode is always used, store the current settings in nonvolatile memory by the the required command string). By storing the current settings, the S registers are automatically set to the values stored in nonvolatile memory the next time power is turned ON, thus setting this mode. To change the settings or test using new ones, set the DTR to the OFF state and use the asynchronous command mode to make the changes. With ATQ0E1, the result codes are returned and the commands are echoed back. Further, if setting the modem as mentioned above, the result code notations in the figure to the left will differ from the normal codes.
• Originate Mode The DTR is turned OFF beforehand. Dial the remote modem using an auxiliary telephone instrument. The connection will start when the DTR changes from OFF to ON. At this point, the line noise can be heard on the monitor speaker if the ATL2M1 command is set. If the line does not connect normally, the line is turned OFF and the modem returns to the asynchronous state.
• Answer Mode Same as for synchronous mode 1.
• Drop the Line Same as for synchronous mode 1.
• Observe the Connection State Same as for synchronous mode 1.

¡ Semiconductor MSC2121A D-7 FEDL2121A-02 DEDICATED LINE MODE In addition to data communication using general telephone lines, this modem has the following data communication functions for dual-line dedicated lines. By selecting the dedicated line mode with the AT&L1 command, the modem has the same functions as the general telephone line mode except that the operation for originating and answering calls is different. However, since there is no automatic speed response (fallback) function when answering, set both modems to the same speed before making connection. Asynchronous Mode and Synchronous Mode 1 Select the dedicated line mode by the AT&L1 command. The connection is made by the originating side inputting the ATD command and the answering side inputting the ATA command at about the same time. Synchronous Modes 2, 3 Select the dedicated line mode by the AT&L1 command. The originating side sets the S0 register to 0. The answering side sets the S0 to a value other than 0. Connection is made by setting DTR from OFF to ON at about the same time.

¡ Semiconductor MSC2121A D-8 FEDL2121A-02

¡ Semiconductor MSC2121A E-1 FEDL2121A-02 Appendix E Loopback Tests and Self Diagnostic OVERVIEW As stated previously in the section on command explanations, there are five types of test functions which can be performed. Further, by using a test timer, testing can be performed for arbitrarily times. The purpose of the tests is to check whether transmitted data is looping back normally. The results can be used as a diagnostic tool. Test Preparation First check that the terminal and modem and the telephone lines are connected properly, finish setting up the equipment, and then turn the power on. If using a personal computer as a terminal, perform the required preparation (communication speed, formatting, etc.). First, input the ATZ command. "ATZ" should echo back on the terminal screen, and the result code "OK" should be displayed. The terminal and modem are now in a normal state. If they are not in this state, check the connections and settings again. When any of the test modes are executing, the MR-LED display flickers in approximately 1 second intervals. Local Analog Loopback Test (&T1) This test can test the line from the terminal to the internal modem. Modulator Demodulator TXD RXD Reference Example (1): If a test timer is not used. Terminal ATS18 = 0&T1 Begin test. OKI ELECTRIC Input freely and it will be echoed back, as is. COMPANY +++ Escape sequence. Modem OK Returns to command mode. Terminal AT&T0 Input test end command. Modem OK Test ends. Reference Example (2): If a test timer is used. Terminal ATS18 = 50&T1 Set the test timer to 50 seconds and begin the test. OKI ELECTRIC Input freely and it will be echoed back, as is. COMPANY (In this interval, 50 seconds elapse.) Modem OK Test ends.

¡ Semiconductor MSC2121A E-2 FEDL2121A-02 Local Analog Loopback Self-Test (&T8) This test is not input from the terminal. A 1:1, 0/1 alternating pattern is automatically input to the TXD inside the modem, and the errors are counted by the receiver unit. If an error is generated, it is counted. (If a command is input during the test, the test is temporarily interrupted until processing is completed.) TXD RXD Modulator Demodulator Reference Example (1): If a test timer is not used and no errors occur. Terminal ATS18 = 0&T8 Begin test. (During this time, pause only for an appropriate interval.) AT&T0 Test ends. Modem 000 There were 0 errors. OK Reference Example (2): If a test timer is not used and 7 errors occur. Terminal ATS18 = 0&T8 Begin test. (During this time, pause only for an appropriate interval.) AT&T0 Test ends. Modem 007 There were 7 errors. OK Reference Example (3): If a test timer is used and no errors occur. Terminal ATS18 = 10&T8 Set the test timer to 10 seconds and begin the test. (In this interval, 10 seconds elapse.) Modem 000 There were 0 errors. OK Reference Example (4): If a test timer is used and 7 errors occur. Terminal ATS18 = 10&T8 Set the test timer to 10 seconds and begin the test. (In this interval, 10 seconds elapse.) Modem 007 There were 7 errors. OK

¡ Semiconductor MSC2121A E-3 FEDL2121A-02 Remote Digital Loopback Test (&T6) If the remote modem is the same type as the main unit, a remote digital loopback test can be performed with the local modem. (This function is not available at 300 bps.) TXD RXD TXD RXD Telephone LineLocal Remote Demodulator Modulator Modulator Demodulator As preparation for this test, match up the communication modes for both the local and remote modems. (The communication speed should either be 1200 or 2400 bps.) Input AT&T4 at the remote side, so that there will be a response to the remote digital loopback test request. (The AT&T5 command, conversely, is the setting for no response to the request.) This test is performed in the connected state (on-line), so the usual method is to connect the line. After the test, the modem can return to the on-line data mode by the AT0 command. The explanations in the following reference examples start from after the modem goes on-line. Reference Example (1): If a test timer is not used. Terminal +++ Escape sequence. OK Changes to command mode. ATS18 = 0&T6 Begin test. OKI ELECTRIC Enter arbitrary characters freely and those characters will be COMPANY echoed back, as is. +++ Escape sequence. Modem OK Changes to command mode. Terminal AT&T0 Input test end command. Modem OK Test ends. Reference Example (2): If a test timer is used Terminal +++ Escape sequence. OK Changes to command mode. ATS18 = 30&T6 Set test timer to 30 seconds and begin test. OKI ELECTRIC Enter arbitrary characters freely and those characters will be COMPANY echoed back, as is. (In this interval, 30 seconds elapse.) Modem OK Test ends.

¡ Semiconductor MSC2121A E-4 FEDL2121A-02 Remote Digital Loopback Self-Test (&T7) This test differs from the remote digital loopback test only on the point that the modem internal data is used, the same as for the local analog loopback self test, instead of using the terminal input data. Perform test preparation in the same manner. (If a command is input during the test, the test is temporarily interrupted until processing is completed.) TXD RXD TXD RXD Telephone LineLocal Remote Demodulator Modulator Modulator Demodulator Reference Example (1): If a test timer is not used and no errors occur. Terminal +++ Escape sequence. Modem OK Changes to command mode. Terminal ATS18 = 0&T7 Set test timer to 0 and begin test. (Pause for an appropriate interval.) AT&T0 Input test end command. Modem 000 No errors. OK Test ends. Reference Example (2): If a test timer is not used and 7 errors occur. Terminal +++ Escape sequence. Modem OK Changes to command mode. Terminal ATS18 = 0&T7 Set test timer to 0 and begin test. (Pause for an appropriate interval.) AT&T0 Input test end command. Modem 007 7 errors occur. OK Test ends. Reference Example (3): If a test timer is used and no errors occur. Terminal +++ Escape sequence. Modem OK Changes to command mode. Terminal ATS18 = 30&T7 Set test timer to 30 seconds and begin test. (In this interval, 30 seconds elapse.) Modem 000 No errors. OK Test ends.

¡ Semiconductor MSC2121A E-5 FEDL2121A-02 Reference Example (4): If a test timer is not used and 7 errors occur. Terminal +++ Escape sequence. Modem OK Changes to command mode. Terminal ATS18 = 30&T7 Set test timer to 30 seconds and begin test. (In this interval, 30 seconds elapse.) Modem 007 7 errors occur. OK Test ends. The Remote Digital Loopback Test and The Remote Side State During Self-Testing For both test modes, input the AT&T4 command on the remote side beforehand, as it must be set to respond to the request. It can be known via the S-register (16) bit 3 if this test is being performed on the remote side. Reference Example (Remote Side) Terminal +++ Escape sequence. Modem OK Changes to command mode. Terminal ATS167 Modem 008 Since bit 3 of S16 is ON, the modem knows that testing is taking place on the local side. OK Reference example of the AT&T5 command input on the remote side, with testing on the local side. Terminal +++ Escape sequence. Modem OK Changes to command mode. Terminal AT&T6 Remote digital loopback test begins. (The time set in S7 elapses.) Modem NO CARRIER Connection failure. OK If, for causes outside of this test, a loop is not configured, a result code (NO CARRIER) is returned to the modem.

¡ Semiconductor MSC2121A E-6 FEDL2121A-02 Local Digital Loopback Test (&T3) In this test, data transmitted from the remote modem is digitally looped back in the local modem, and returned to the remote modem. Perform the same preparation for this test as for the remote digital loopback test. TXD RXD TXD RXD Telephone LineLocal Remote Demodulator Modulator Modulator Demodulator Reference Example: (In this case, the test type can also be used. However, it is not practical, since input for the test is done at the remote side. The general method is not to use a test timer, but to perform the test by making telephone contact.) Terminal +++ Escape sequence. Modem OK Changes to command mode. Terminal ATS18 = 0&T8 Set test timer to 0 and begin test. Modem OK Enters loopback. (In this interval, the characters entered at the remote terminal are echoed back to the local display.) Terminal AT&T0 Input test end command. Modem OK Test ends. (If AT0 is input, the modem returns to the on-line data mode.) &T4 and &T5 Commands The &T4 command sets the response to the request from the remote modem for a remote digital loopback test. The &T5 command sets the opposite.

¡ Semiconductor MSC2121A F-1 FEDL2121A-02 Appendix F Application Circuit Diagrams CIRCUIT DIAGRAMS Application Circuit Diagram 1 This application circuit diagram is for an MSC2121A modem chip set. The IC pin numbers vary according to the IC package used. Please refer to the individual IC data sheets. Application Circuit Diagram 2 This application circuit diagram is for an MSC2121A modem chip set evaluation board. * The evaluation board has onboard EPROM for the microcomputer program, but this is not needed in the actual chip set since it is built into the microcomputer. * The evaluation board is for evaluating the modem chip set. * Do not use on actual lines. (JATE approval in Japan not obtained.) * These circuit diagrams are evaluation board circuit diagrams. Performance other than the function checks and performance evaluation of the modem chip set is not guaranteed.

¡ Semiconductor MSC2121A F-2 FEDL2121A-02 AOUTPAOUTP AOUTPAOUTN AINPAINP AINNAINN SGSG +5 VA 1 mF1 mF 10 mH VDDA GNDA 1 mF1 mF 10 mH VDDP GNDP BTD CKOEN CPUTYPE SLEEP TI9 VDD GND TO3 TI RESET SOM SYCR XYCK ST1 ST2 RT RBTM SRD STD5 MCK ALE WR RD AOD ADA CE0 CE1 MSM7564-01 VDD GND OE WE D A CE 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 P7.1 RD WRP7.0 ALE P7.3 OE AI0 to 9 TxD RxD RBTM RT ST2 P3.6 P3.7 P7.7 P7.6 DI CLK CS GND VCC DO R/B ORG AT59C22

2 KBit E2PROM

P4.0 10 pF P3.4 P6.6 P6.7 P3.5 P2.6 P2.3 P2.4 P2.5 P2.2 OSC0 OSC1 P2.0 P2.1 P3.1 P3.2 P7.5 P7.4 P7.2 P4.3 VREF EA VDD VDD VDD GND GND AGND NMI RESET 31.104 MHz MSM66507 SD RD RTS CTS DTR DSR CD CI RT ST2 ST1 RLY1 RLY2 RII SPK AA EC HS MR SW9 SW8 SW7 SW6 RESET A8 to 15

32 KByte RAM

61 STSCHG

P4.2SW5 P4.1SW4 P3.3SW3 P3.0SW2 P2.7SW1 51 kW

¡ Semiconductor MSC2121A F-3 FEDL2121A-02 Application Circuit Diagram 2 (1/3)

59 XYCK

55 SYCR

52 SOM

(4/4) 133VDDP 138GNDP 8VDDA 139GNDA 5 VA 21BTD 32CKOEN 46CPUTYPE 131TI9 1265 1014 773 542 151 VDD C10 1325 904 473 262 91 1088 1247 1236 425TI 394 403 GND RESETTO367 0129 1127 211 TI ST117 ST257 RT682 RBTM363 STSCHG624 RD615 SD136 SLEEP35 MCK134 ALE50 WR RD19 0102 199 296 394 492 588 685 783 AOA ADA 0 81 1 106 2 79 3 76 4 75 5 103 6 74 7 107 CE0 CE1 MSM7564-01 32VCC 30CE2 C7 2A16 16GND 7 21 6 20 5 19 4 18 3 17 2 15 1 14 0 13 D OE WE 29 1 MSM51257 012 111 210 39 48 57 66 75 A CE1 227 30 P4.0 63 6 29 5 28 4 26 3 25 2 23 1 21 0 20 PSEN 132 51k 51k 136 134 130 138 ALE P7.3 3 115 6TxD 2 114 5RxD 1 112 4STSCHG 0 111 3RBTM 4 117 2RT 5 118 1ST2 61P3.6 P3.7 12P7.7 0143P7.6 GND V CC DI CLK CS 4 DO R/B ORG 380 278 177 AT59C22 H JP1 51k 93,95,96,98,99,101 102,104 to 10631 L AI0 to 9 OE EA RESET AGND108 GND124 GND54 NMI81 VDD91 VDD88 VDD16 VREF 110 P2.7 P3.0 P3.3 P4.1 4576 4777 5178 6479 SW1 SW2 SW3 SW4 13747 14046 14145 6644 SW 7 SW 8 SW 9 SW 5 36743SW 6 6921 7122 7423 MR HS EC 77624AA P3.2 P3.1 P2.1 5025 4826 3527 SPK RII RLY2 P2.03328RLY1 129 127 X110 pF 10 pF 31.104 MHz OSC1 OSC0 P2.23833CI P2.54334 P2.44135 CD DSR P2.34036DTR P2.64437CTS P3.55838RTS P6.712139RD P6.612040SD 57 P3.4 49, 50 13 to 16 7 to 10 C1 + 11, 12 17 to 20

5 VAC2 +

(2/4) PSEN67

3.888 MHz

D CN1 (3/4) RESET CN1 (1/4) C11

¡ Semiconductor MSC2121A F-4 FEDL2121A-02 Application Circuit Diagram 2 (2/3) +5 VA 17 to 205VD 5VA GND A GND D 15 66 14 65 13 64 12 63 11 62 10 61 9 60 8 59 7 58 6 57 5 56 4 55 3 54 2 53 1 52 0 51 A A U/2 VCC VPP PGM A16 CE GND 7 20 195 184 173 152 141 130 D OE PSEN 67 75 77 74 6 73 5 72 4 71 3 70 2 69 1 68 0 D 1AOUTP AOUTP 2AOUTN AOUTN 5AG AG 3AINP AINP 4AINN AINN 26RI RII 28RLY1 RLY1

27 RLY2

+ C416 V 2.2 m R26 51k 1S1588 SD CN1 RD RTS CTS DTR DSR CD CI ST1 ST2 RT SG RA2 RA1 MR AA EC HS OH SD RD CD CN2 11, 12 7 to 10 13 to 16, 49, 59 MSM27C101ZB

¡ Semiconductor MSC2121A F-5 FEDL2121A-02 Application Circuit Diagram 2 (3/3) LINE TEL 250V 0.1mC33 B H C R27 7.5k D5S1WBA ZD1 RD13E (B2) R28 100 ZD2 RD13E PC2 (1/2)TLP521 2 VR1 C32 50V 10m BP D6S1WBA 2SC1214 R33 20R32 2SC 1214 1000P C35 R31 10k R30 PC1 (2/2) TLP521 R29 27k ZD3 RD13E C34 3.3m 25 V 671-8264 D2C26 0.033m R12 442 R11 100 R10 22k C25 100P R43 20k R13 51k 22k LMC662CN 10kR8 C24 100P 51k C23 430P 430PC37 C22 51k 27k 1000PC20 LMC662CN 51k 51k R4 27k 1+ 2 –C21 0.1m 16 V 10m R16 330PC28 27k 2 LMC662CN R14 300 1000P C27 8.2k R15 C29 R18 22k R17 22k R21 47k PC2 (2/2)4 TLP521 R20 100+ 16 V 2.2m R19 10k HCO4 R22 47k PC1 (1/2) TLP521 1S1588K1 +12 V + 10m C36 RV1 50k +R23 ABIL3N 10m SPK 100m C6C37 R2410 0.033m C30 0.1m 4 +12 V 25 V 100m 25 V 100m 1 to 3 GND CX1 to 3 + 25 V 100m 3, 4 1, 2 6 +12 V –12 V GND +5 V+5 VA 5 to 7 CX4 to 6 8, 9 CN3 ABILBN AOUTP AOUTN AG AINP AINN RII RLY1 RLY2 SPK

REVISION HISTORY

No. Date Previous Edition Current Edition

Description

FEDL2121A-02 Oct. 1999 – – Second edition 1 1 Added “Note” FEDL2121A-03 July 12, 2002 – – Added “Revision History”

1. The information contained herein can change without notice owing to product and/or technical improvements. Before using the product, please make sure that the information being referred to is up-to-date. 2. The outline of action and examples for application circuits described herein have been chosen as an explanation for the standard action and performance of the product. When planning to use the product, please ensure that the external conditions are reflected in the actual circuit, assembly, and program designs. 3. When designing your product, please use our product below the specified maximum ratings and within the specified operating ranges including, but not limited to, operating voltage, power dissipation, and operating temperature. 4. Oki assumes no responsibility or liability whatsoever for any failure or unusual or unexpected operation resulting from misuse, neglect, improper installation, repair, alteration or accident, improper handling, or unusual physical or electrical stress including, but not limited to, exposure to parameters beyond the specified maximum ratings or operation outside the specified operating range. 5. Neither indemnity against nor license of a third part y’s industrial and intellectual property right, etc. is granted by us in connection with the use of the product and/or the information and drawings contained herein. No responsibility is assumed by us for any infringement of a third party’s right which may result from the use thereof. 6. The products listed in this document are intended for use in general electronics equipment for commercial applications (e.g., office automation, communicati on equipment, measurement equipment, consumer electronics, etc.). These products are not authorized for use in any system or application that requires special or enhanced quality and reliability characteristics nor in any system or application where the failure of such system or application may result in the loss or damage of property, or death or injury to humans. Such applications include, but are not limited to , traffic and automotive equi pment, safety devices, aerospace equipment, nuclear power control, medical equipment, and life-support systems. 7. Certain products in this document may need government approval before they can be exported to particular countries. The purchaser assumes the responsibility of determining the legality of export of these products and will take appropriate and necessary steps at their own expense for these. 8. No part of the contents contained herein may be reprinted or reproduced without our prior permission. Copyright 2002 Oki Electric Industry Co., Ltd.