3M55bl6 DOOSTBG IEXR EXAR XR-2942 XR-2942 Fax/Data
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XR-2942
XR-2942 Fax/Data Microcontroller
J.-vS-^-'W
XR-2942 dedicated microcontroller that provides command control XR-2900 Fax/Data modem chip set. XR-2942 provides control CCITT recommended V.42 error detection, including LAPM protocols, with class data compression included greater compatibility. Also supported CLASS (EIA PN2388) standard 'AT+F' extended command set.
system architecture XR-2942 allows actual command sets 'AT', 'AT+F', MNP, LAPM reside external XR-2942, allowing ease customization. Exar provides these command sets designer modify requirements design.
XR-2942 operates from single volt power supply, offering power consumption through CMOS technology.
FEATURES*
Group Send/Receive
Compatibility with Available Applications Software
Error Free Data Transfer:
DATA Mode
Increased Data Throughput Data Compression
4800 Throughput 'AT' Command Control
2388 (CL2) Standard Commands ('AT
Easily Modified, Exar Supplied Commands 'ATTAT+F'/M P/V.42
Possible Chip Upgrade V.42bis (XR-2943) *(Apply when used with XR-2900 Fax/Data modem chip set)
APPLICATIONS
Error Free Fax/Data Modem Applications Stand-Alone Fax/Data Modems Smart Modems
Laptop Modems (Send Receive Data) Networked Machines
ASSIGNMENT
P1.0
Pt.4
p,5[!
INTO
XTAL1 OGND
-ct-
XR-2942
(For other assignments, refer this datasheet)
ORDERING INFORMATION
Part Number Package Operating Temperature
XR-2942CP Plastic XR-2942CJ PLCC
XR-2942CQ
ABSOLUTE MAXIMUM RATINGS
-0.3V -0.7V (VDD +0.3V)
Power Supply Input Voltage Input Current (any input)
Power Dissipation (Package Limitation)
Derate above
Storage Temperature Range
SYSTEM DESCRIPTION
XR-2942, when coupled XR-2900 Fax/Data modem chip set, allows implementation Group fax/2400 V.22bis modem. With P/V.42 operation included data mode, error-free operation provided.
XR-2942 just family controller options XR-2900 Fax/Data modem chip set, including:
FUNCTION 'AT' 'AT+F 'ATVAT+F7V.42/MNP 'AT'/"AT+F'/V.4 2/V.42bis/MN
CONTROLLER 8031 XR-2942 XR-2943
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ELECTRICAL CHARACTERISTICS
Test Conditions: FCLK 11,0592MHz +0.05%, unless otherwise specified.
SYMBOL PARAMETERS UNITS CONDITIONS
Power Supply Voltage
Power Supply Current
Input High Voltage (Except XTAL1 RST)
Input High Voltage XTAL
Output High Voltage Ports 1,2,3
Output High Voltage Port (External Mode) ALE, PSEN -400
Output Voltage 0.45 Ports 1,2,3,
Output Voltage 0.45 Port ALE. PSEN
Input High Current (Leakage) 0.45V iVDD
Input Current 0.45V
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SYSTEM OPERATION
typical application utilizing XR-2942 support XR-2900 Fax/Data chip set, shown Figure XR-2900 provides complete modem data pump function for:
CCITT V.29 9600, 7200 4800BPS
V.27ter 4800 2400 V.22bis 2400 V.22 1200
*V.23(mode 1200/75 V.21(Ch Bell 212A 1200
Supported XR-2321 Command control supported XR-2942 for:
Microcom Error Correction Microcom Data
Compression LAPM CCITT Recommended V.42
Error Correction 'AT' Industry Standard
EIA2388 (CL2)
Commands
Although XR-2942 does provide complete command control, actual commands various modes reside external EPROM 27256,
Byte. With this architecture Exar supplied command set, maximum flexibility offered. command used customer tailored particular design.
unique architecture utilized XR-2900 command controller allow same hardware (Printed Circuit Board (PCB)) support several different types Fax/Data modems. changing available pin-to-pin compatible microcontrollers, Fax/Data modem types listed Table possible with same printed circuit board. mode types changed n-C, EPROM supported command sets SRAM size change and/or elimination also required. each case Exar provides complete production worthy command sets which used easily modified meet specific application requirements. software modifications, Tables list XR-2942 memory mapping, indicating customer usable regions.
Externat memory modifications requiring ji.C (XR-2942) support will need entry/re-entry point information. This point important XR-2942 contains program memory with Exar proprietary V.42/MNP5 Auto Data Select functions accessible externally (fusible link protected) available Exar customers. Auto Fax/Data select external EPROM, however source code provided this routine.
2400 Microcontroller External Memory Requirements (Bytes)
Data Mode Part Number EPROM SRAM
8031 (Generic ROMLESS jiP) 8k/32k
MNP5/V.42 XR-2942 8K/32K
V.42bis XR-2943
Table 1.2900 Modem Options iiC. EPROM, Requirements
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ENTRY POINTS MEMORY MAPPING
SPDJNM 0069H Speed Conversion Pro-
Status Mode Setting Memory Locations gram Jump-In Point.
Status Location Description INLSPDM 006CH Speed Conversion
SPD_FLG 20H.7 Speed Conversion Enable Initialization Routine.
Flag. V21_IN_1 006FH Speed
Break Prescaler Timer Conversion Timer Set-Up.
BK_TMR Break Timer EC_MAIN 0080H Calling Main Pro-
(Only Normal Mode) gram. This only
MRCVP2 803BH Disconnect Check Auto-Reliable Fallback Mode.
location wnicn inmate program. K^^^H
PASS_B 9D14H Escape Code Checking
Byte Speed Conversion XR-2942Re-Entry Points
Mode. Function Location Description
SPEED 9D15H Speed Indicator C000H Power
Modes. C003H Interrupt
0-19200 C006H Timer
9600 C009H Interrupt
4800 C00CH Timer
2400 C00FH Serial Port Interrupt
1200 C012H Timer
MNP_OUT C015H Program
Z_BUF 9D16H Auto Reliable Fallback Intermediate Point
Character. CHK070S C01BH 'ESC' Jump
BACK 9D1AH Starting Address Point
Command Buffer Back-up. DISCONNECT C01EH Disconnect
OPT_P 9D50H Output Port Selection Option (F0FF 40FFH). ON_LOOPS C021H Auto-Reliable Fallback Point.
This Parameter SPD_OUTS C024H Speed Conversion Jump
Initialized Immediately Point.
After Power V21JNS C027H Call Speed Conversion
constantly monitored BPS.
Module. SPD_TXD C02AH TXDATA Modem
9E22H Reliable Link Indicator Chip.
RETRAN 24H.0 RETRANSMISSION SPD_RXD C02DH RXDATA From Modem Chip.
Function Call Locations V.42bis/V.42/ l_TXSYNTT C030H CRC-CCITT
Program Entry Points CALCULATION ROUTINE
Function Location Descri ption LRXSYNTT C033H RXCRC-16
SCTINT 0006H Interrupt Jump-In Point. CALCULATION ROUTINE
SCRINT 0016H Interrupt Jump-In Point. LTXASYN16 C036H CRC-16
SPINT_1 0026H Serial Port Interrupt CALCULATION ROUTINE
Jump-In Point. LRXASYN16 C039H CRC-16
0030H Exar Copyright Message. CALCULATION ROUTINE
P_ECRAM_ 0060H After Escape l_SNDREL C03CH SENDING RESULT
Re-Entry Point. CODE SUBROUTINE
MSG_CPY 0063H Exar Copyright Calling Subroutine. LMNPINIT C03FH PARAMETER INITIALIZATION ROUTINE
MNPJN 0066H Program Immediate l_V42INIT C042H PARAMETER
Re-Entry Point modify- INITIALIZATION ROUTINE
Program. LSETURMNP C045H UART SETTING
ROUTINE
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Locations
stack 'AT' program starts from OCOH page occupies bytes space. Internal page bytes page bytes free indicator space.
externa! data memory follows:
Error Control 8000H-8FFFH
Data Compression Buffer 9000H-93FFH
FAX/Remote Access 9400H-95FFH
Available 9600H-97FFH
V.42 9800H-98FFH
Break Buffer 9A00H-9AFFH
Buffer 9B00H-9BFFH
Buffer 9C00H-9CFFH
Misc. Registers 9D00H-9DFFH
Backup 9E00H-9EFFH Buffer
11)'AT' Backup 9F00H-9FFFH Buffer
BTLZ Compression C000H-FFFFH Dictionary
Note: Before jumping into program control code will backup entire bytes into external RAM. addition, before jumping program will backup entire bytes into external RAM.
Miscellaneous register function list provided below. option code control allows firmware engineer change factory defaults source code, then reassemble.
OPTION LOCATION PARAMETER COMMAND DESCRIPTION
0pt_0 9D09H Non-MNP
Reliable Mode
Auto _reliable Mode
Opt_1 9D0AH Normal XON/XOFF
Used
Unidirectional RTS/CTS
Xon/Xoff Pass Through
Xon/Xoff Send Only
Bidirectional RTS/CTS
Disable Flow Control
Opt_2 9D0BH Disable Speed Conversion
(BITO) Enable Speed Conversion
Opt_2 9D0BH Disable Serial port rate adjust
(BIT1) Enable Serial port rate adjust
Opt_2 9D0BH Disable modem port flow control
(BIT2) Enable modem port flow control
XON/XOFF
(for normal mode only)
Opt_2 9D0BH Parity checking XON/XOFF
(BIT3) Ignore parity checking
XON/XOFF
Opt_2 9DOB Used
(BIT4)
Opt_2 9D0BH Used
(BIT5)
Opt_2 9D0BH V.42 Mode
(BIT6) Mode
Opt_2 9D0BH Disable Data Compression
(BIT7) Enable Data Compression
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OPTION LOCATION PARAMETER COMMAND DESCRIPTION
Opt_3 9D0CH Block size transmit, 64bytes bytes bytes bytes
Opl_4 9D0DH Xmit break during normal mode data mode, n=100ms
Opt_5 9D0EH Expedited, Destructive Expedited, Non-destructive Non-expedited, Non-destructive
Opt_6 9D12 (81H) Originate Reliable Link
Opt_6 9D12H 9D12H Accept Reliable Switch Reliable Link
Opt_7 9D13 (BITO) connect indicator other speed
Opt_8 Opt_8 Opt_8 Opt_8 Opt_8 Opt_8 9D0FH 9D0FH (BIT3.2) 9D0FH (BIT4) 9D0FH (BIT5) 9D0FH (BIT6) 9D0FH (BIT7) \Q0-\Q4 \Q5,\Q6 Standard Result code form Result code Auto-reliable buffer Auto-reliable buffer fall back character Stream mode Block mode \Q5, tumoff V.42 only negotiation Eliminate V.42
Opt_9 9D10H Auto-reliable fallback character
Opt_A 9D11H Inactivity Timer
Opt_B 9D51H (BIT4) Default Clear Buffer after disconnect
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Interrupt Vectors
XR-2942 brings interrupt vectors external program. This allows easy customer modification service routines suit particular application. interrupt vectors XR-2942 follows:
LJMP ONS; Jump Power
Routine
INTO: Interrupt
OUT_SCT
SCTINT1
SCTINT
INTO: Interrupt
INT1:
OUT_SCR
SCRINT
INT1: Interrupt
SER: Port Interrup
OUT_SP
SPINT
FFFFH
8000H
IFFFH
'AT'/'AT&P Firmware (27C256)
Masked LAPM Code (XR-2942)
0000H
Note: 27C256 Byte EPROM Table XR-2942
TJNT2:
LJMP
;Timer Interrupt
XR-2942 PROGRAM/DATA MEMORY MAPS
Tables show memory maps XR-2942. should noted that without separate CS(chip select) XR-2902 XR-2321, there would overlap address locations.
indicated Table bytes EPROM assigned 'AT' command firmware. This section located between 8000H FFFFH.
LAPM, MNP2-4 MNP5 code masked microcontroller (XR-2942), resides bytes memory, between address locations OOOOH and1FFFH.
Table shows map, which space between OOOOH 002CH address locations used modem chip address. Table shows modem chip (XR-2902) address assignment. Included addressing XR-2321 XR-2100. These chips optional system design, added where V.21 V.23/V.21 standards required. XR-2321 provides both V.23 V.21 data standards, while XR-2100 provides only V.21. XR-2321 XR-2100 datasheets details.
FFFFH
A000H 8000H
002DH OOOOH
V.42/MNP5 Data SRAM
Modem Chip Address
A15=1 A14=0
Table XR-2942
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MODEM CHIP ADDRESS
XR-2902 OOOOH -001FH A15=0
A5=0
XR-2321 0028H 002CH A5=1
A15=0
XR-2100 0028H 0029H A5=1
Table Modem
Also space between 9FFFH assigned V.42 MNP5 data data. Ideations between AOOOH FFFFH, well locations between 002FH 7FFFH available ports such LED, EIA, etc.
y.42 OPERATION
XR-2942 when coupled with XR-2900 Fax/Data modem chip allows implementation group error-free, increased throughput 2400 data modem. gain understanding V.42/MNP modes data operation, following basic information been included. basic understanding error correction techniques, flow control, speed buffering, data compression will allow designer better understand V.42/MNP5 modems capabilities best utilize them. excellent reference 'Data Compression*. Gilbert Held. publisher Wiley.
V.42 CCITT recommended error correction protocol which allows asynchronous DTE's (Data Terminal Equipment) communicate error-free with other such equipped modems.
actual error detection protocol used V.42 HDLC (High-level Data Link Control) based protocol called LAPM, Link Access Procedure Modems. additional detailed information beyond following basic description, refer CCITT Recommendations, Series "Data Communication Over Telephone Network'. latest version known 'Blue Book' (Blue Covers) Series, dated 1988 (Melbourne), recent update from 'Red Book'.
V.42 Basic Operation/Features
HDLC-based error correction protocol-LAPM
Asynchronous (Async 'start/stop') Communication error free
Chip Address
Actual line transmission synchronous (sync)- start stop bits (stripped from data), however initial handshake, subsequent modem handshake asynchronous
Error Detection
Data sent 'frames' blocks with nominal size (default) Octets (Octet bit) data frames
Start/Stop elimination from data creates actual data throughput improvement, roughly 120% nominal. 2400 becomes about 2900
Encoded information added data frame receiver 'decode' determine block error free. 16-bit cyclic redundancy (CRC) methods used data encoded information indicate correct data recognize imperfect data frame
Retransmission (automatic) determined imperfect frames ensure perfect data received
V.42 operation found virtually identical (specifically variable parameters) that reliable normal modes operation. this reason command also used V.42 variables control.
OPERATION
MNP, Microcom Networking Protocol developed Microcom, Inc., modem manufacturer. Since conception, been constant, state update/improvement. this reason 'classes' operation emerged signify each major update improvement.
Relative V.22bis 2400 modems, dass level become 'standard'. used with modes operation, mentioned before HDLC framing techniques used.
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CLASSES
(Throughput data based 2400 line speed).
Class half duplex protocol included many designs. Throughput about 1690 BPS. XR-2942 does support this class.
Class Asynchronous operation with byte orient data formatting. Throughput rough nominal about 2000 BPS.
Class Conversion synchronous, oriented data handling transmitted blocks consisting characters. Throughput about 108% 2600 BPS.
Class Basic characters same Class block size dynamic, Bytes, (flexible size based data transmission quality). Throughput 120% 2900 BPS.
Class Includes Class with data pression techniques added. pression effectiveness dependent type data, typical throughput enhancements 200% 4800BPS.
ERROR CORRECTION
Modem users have come expect sophisticated circuitry like automatic adaptive equalization varying phone characteristics retrain modes ensuring continued optimal performance. These techniques dramatically improve performance characteristics which quantified measurements, probability errors when modem signal presence noise.
previously mentioned techniques aimed improving modem data pump through analog digitally synthesized) circuitry. Techniques becoming popular only improving, virtually eliminating data errors through protocols implemented modems command microcontroller (jxC). Prior these 'hardware' based schemes, error correction provided applications software available, such X-MODEM Kermit asynchronous file transfer. mainframe environments, SDLC HDLC schemes were used.
Software based error correction schemes however have their disadvantages. important being reduced data throughput. throughput performance varies, schemes reduce data transfer below nominal rate. Typical values common, equating only about 2400 connection.
hardware based error correction protocols supported XR-2942 data mode those specified CCITT LAPM, MNP. These schemes convert asynchronous data transmitted synchronous format (start stop bits stripped) packet-oriented protocol. Throughput values again vary, however typical values 108% lower Class 120% Class LAPM. These equate roughly 2600 2900 2400 modems.
Actual error correction based adding information block-oriented data, through 16-bit (Cyclic Redundancy Check) calculation. receiving side calculates values each block found incorrect, retransmission that block will requested.
Typical frame sizes LAPM Octets (8-bit start/stop stripped characters).
DATA COMPRESSION
CCITT recommendation V.42 only specifies error correction modes, provided LAPM 2-4. Modem controller protocols have advanced point where addition providing error-free data transfer, they also offer other significant enhancements. very significant enhancement addition data compression operation. Simply put, this technique substantially enhances data throughput modem.
This data compression scheme, although specifically part V.42 recommendation, been included XR-2942 serve only further enhancement XR-2942 based modems.
Class protocol data compression.
most accepted protocol this function. CCITT recommendations adding data compression mode V.42, called V.42bis. upcoming XR-2943 will support future CCITT recommended BTLZ data compression.
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data compression offers XR-2900 Fax/Data modem chip roughly 100% increase throughput data mode), 200% nominal. This translates maximum modem throughput 2400 4800 text file.
techniques utilize scheme which abbreviates redundant data characters much higher transmission efficiency throughput increase. Because dependency redundant characters, amount improvement will vary. Typical improvement values range 125%, 4200 5400 2400 modem link.
FLOW CONTROL
previously outlined, method regulating flow data transmitted necessary when data rates exceed line rates. Figure illustrates basic modem connection helps illustrate where flow controls
control under hardware software control.
HARDWARE FLOW CONTROL
Hardware Flow Control allows modem tower raise (Clear Send) line DTE. This provides ON/OFF control data flow from modem. modem data buffer becomes full lowers line stop transmit data flow allow modem "catch-up".
SOFTWARE FLOW CONTROL
alternative hardware flow control control software, known Xon/Xoff. This accomplished special characters inserted into data stream start stop data flow. Control (AQ) used start restart data flow Control (AS) stop dataflow.
Three different variations Xon/Xoff control modes are:
Send Only
Normal
Passthrough
SPEED 300BPS 19.2
LINE SPEED 300/1200/2400 DATA 9600/7200/4800/2400
IXQft
MODEM
MODEM
EXAR
2900 V.42
MNPS/ Fax/
V.42 Data
RXI^
^RTS
CTS^
LINE
V.29 V.27ter V.22bte
Figure Basic Modem Connection XR-2942 V.42/MNP FUNCTIONS COMMANDS
XR-2942 with external EPROM provides control following major functions:
FUNCTION DESCRIPTION
Command Control 'AT+F' Commands Level Level V.42 (LAPM) Speed Conversion Provides Command Control Provides control functions Provides error correction 100% perfect data transfer. Allows roughly 100% increase (4800 V.22bis mode) data throughput, through data compression techniques. 100% perfect data transfer Maintain 19,200 (terminal) speed 9600 line speeds, both LAPM/MNP non-error correcting connections.
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Application Software Interface
firmware XR-2942 (combined masked supporting code) supports working document Telecommunication Industry Association Fax/Data modems, assigned part number 2388. level support service Class which places most CCITT T.30 command functions modem (XR-2901, XR-2902 XR-2942). Figure indicates approximate division between modem (DCE) (DTE).
command section XR-2942 data sheet defines commands, responses functions firmware supplied with XR-2942. possible send those commands XR-2900 system hand, visually monitor responses send receive data proper format. However, XR-2900 modem system effectively, best application software package that automatically monitors response strings acts accordingly.
general application software would required perform:
ASCII Bitmap Conversion
Bitmap Conversion
TIFF Bitmap Conversion
PICT Bitmap Conversion
imbedded system, such text editor, above list could reduced include only ASCII Bitmap conversion. Because ASCII encoded, information font, italics, bold, underline,
other word processor options lost. expected that either communication packages will start recognizing some Word processor options, integration word processors communication software such seen today. second step perform:
Dimensional Coding
Dimensional Coding
CCITT specification.
Figure shows process taking text encoding dimensionally using CCITT Huffman codes. entire line must total 1728 picture elements pels. application software will need convert from files pels line containing 1728 more.
Vertical dimension, either (dots inch) 1968 would selected. This would determine number scan lines needed page well determine quality reproduced image. dimensional Huffman encoding supported. Both these modes would need enabled using (vertical resolution) (data format) subparameter +FDIS command.
AUTO Fax/Data Negotiate: XR-2942 supports 2388 Class standard auto Fax/Data negotiation. Figure shows flow this process proceed. entire process requires less than seconds permitting compatible with machines data modems available today.
T.30 XR-2900
Data Pump
"Physical Layer"
(Application Software) (Modem Firmware)
Figure T.4/T.30 Partitioning DCE/DTE
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Rgure Auto Fax/Data Negotiation Answer Mode
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T.30 Description
CCITT T.30 specification intended standardize signaling between machines. This permits group card machine communicate with another also meeting standard.
T.30 specification defines transmission reception process into five steps phases:
Phase Call Establishment
Phase Negotiation data rate, capabilities
both machines
Phase Message (Page) Transmission Phase Post Message (Page) Transmission; confirm send; possibly more pages Phase Call Release (Hang
Figure provides general flow chart process.
Phase CCITT T.30 specification establishes that modem answering line data modem. uniqueness this handshake allows ability feature switching between data modes with XR-2900 Fax/Data modem chip set. addition, optional identification called calling unit takes place using CCITT V.21 modulation demodulation. data framed (synchronous) ensure reliable communication this point, even extremely poor phone line. taking this extra step CCITT provided means negotiate (during Phase data rate lower rate, required. This utilized application software developer security mode: correct response provided, session ended this point.
Phase exchange information capabilities modems, again using V.21 channel synchronous transmission reception. Information such scanning speed, number dimensions Huffman encoding, grey scale encoding sent this time.
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Phase also includes phasing training process modem data pump. calling (originating) modem transmits bi-phase signal proper baud rate transmission (2400 symbols/second 9600 BPS) allow called (answering) modem adjust group delay distortion well gain loss line. successful, failure train (FTT) sent from called modem calling modem using framing described above. calling modem tries next lower speed. Once this process successful, called modem confirms that programmed receive.
sending page information occurs during Phase maximum negotiated data rate (9600 XR-2900).
Phase confirmation message receiving page. This usually indicates that page been received properly. this time optional multiple pages signal sent. another page sent received, phase repeated.
Phase disconnects phone line hook).
XR-2942 supports automatic call establishment, felt that manual process practical Fax/Data product where interaction between host computer perform file conversion encoding) modem needed. However this does preclude manual automatic process, using external dialer starting application program send (off hook immediate wait Phase begin).
process similar when receiving call. However, with Exar proprietary Fax/Data auto select, modem will determine during phase whether machine/card data modem calling. Details this provided this datasheet.
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PHASEC PHASED
|RECEIVE REMOTE CAPABILITIES
SEND LOCAL CAPABILITIES
SELECT
NEXT
SPEED
ENDOFPAGE
CONFIRMATION
DISCONNECTFRAME
Figure CCI7T T.30 Process Sequence (Transmit Single Page)
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PROTOCOL NEGOTIATION
XR-2942, data mode, supports error correcting reliable modes operation only LAPM, also MNP2-4 type protocols. Also, although data compression operation specified CCITT V.42 specifications, been included through increased compatibility. Because these multiple protocols supported, XR-2942 offers protocol negotiation modes:
AT\M0 Default Mode
This command selects automatic protocol negotiation mode. First LAPM negotiation will attempted. possible, MNP2-4.5 operation will negotiated. highest possible class operation will negotiated (depending upon setting command). remote modem does support error correction, normal 2400 (or1200/300 BPS) operation will supported.
AT\M1
This command will disable LAPM operation. Here only non-error correcting modes operation will supported.
following command summary XR-2942. Provided are:
Data Mode
Basic Connection/Dialing Commands
Dialing Modifiers
Standard Hayes 'AT' Command
Register Descriptions/Functions. These registers used controlling value function various 'AT' commands.
MNP/LAPM Commands. entire list represents command set. Most commands also apply LAPM, with exceptions indicated.
Mode
Extended Commands 2388 (Class operation
responses
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COMMAND DESCRIPTION RANGE SIZE
Execute previous command, without striking <CR>
Attention
Answer Immediate
ATBO V.22 mode
ATB1 Bell 212A mode DEFAULT
ATB2 V.23 mode
Dial Command
ATDP Dial Using pulse dial
ATDT Dial Using DTMF tone dial DEFAULT
following modifiers will dial using previously used technique (pulse tone),
command added after (dial) command.
ATDW Wait Dial Tone Period Register
ATD@ Quiet Answer: Wait Seconds Silence Before Dialing
ATD! Hookflash: Commonly Used Systems
ATDR Reverse Answer Mode
ATDS=n Dial Stored Number when
ATD/ Wait 0.125 Seconds
ATD; Return Command Mode After Dialing
ATD, Pause Time Register
ATEO Command Echo Disabled
ATE1 Command Mode Echo Enabled DEFAULT
ATHO Hook (Open Relay)
ATH1 Hook (Close Relay)
Identification Code
AIdentification Code
ATI2 "OK" Response Checksum Verifies
ATI3 EXAR EPROM Revision Date
ATLO Lowest Volume Setting
ATL1 Same ATLO
ATL2 Medium Volume Setting DEFAULT
ATL3 Maximum Volume
ATMO Speaker Always
ATM1 Speaker Until Carrier Detected DEFAULT
Speaker Always
ATM3 DTMF Tones Heard, Speaker Until Carrier Detected
Originate Immediate Return Data Mode
AT01 Request Retrain When V.22bis Mode
ATQO Provide Result Codes DEFAULT
ATQ1 Disable Result Code
ATSn? Provide Register Value
ATSn= Register Value
ATVO Terse (and Verbose) Responses, affected
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NUMERIC DESCRIPTION RANGE -SIZE
Command Executed
CONNECT Connection
RING Ring Signal Detected
CARRIER Carrier Signal Detected
ERROR Error
CONNECT 1200 Connection 1200
DIALTONE DialTone Detected
BUSY Busy Signal Detected
ANSWER Silence Detected
CONNECT 2400 Connection 2400
CONNECT 4800 Connection 4800
CONNECT 9600 Connection 9600
CONNECT 19200 Connection 19200
CONNECT 1200/REL Class Link
CONNECT 1200/REL Class Link
CONNECT 2400/REL Class Link
CONNECT 2400/REL Class Link
CONNECT 1200/V.42 V.42 Link
CONNECT 2400/V.42 V.42 Link
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COMMAND DESCRIPTION RANGE SIZE
ATV1 Verbose Response DEFAULT. ATVO Responses
ATXO Enable Result Codes
ATX1 Enable Result Codes 0-5,10
ATX2 Enable Result Codes 0-6,10
ATX3 Enables Result Codes
ATX4 Enables Result Codes 0-10 DEFAULT
ATYO Disable Long Space Disconnect DEFAULT
ATY1 Enable Long Space Disconnect
ATZO Software Reset, Restore Register from profile location NVRAM
ATZ1 Restore Registers From Profile Location NVRAM
AT&CO Carrier Line Always Forced DEFAULT
AT&C1 Carrier Line Follows Data Carrier
AT&DO Always DEFAULT
AT&D1 Modem Goes Command Mode When Goes
AT&D2 Modem Goes HOOK Returns Command Mode When Goes
AT&D3 Modem Initializes When Goes
AT&F Fetch Registers From EPROM Factory Default
AT&GO Guard Tone DEFAULT
AT&G1 Guard Tone Enabled
AT&G2 1800 Guard Tone Enabled
AT&JO RJ-11 Select DEFAULT
AT&KO Flow Control Disabled
AT&K1 Function
AT&K2 Function
AT&K3 RTS/CTS Flow Control Default
AT&K4 Xon/Xoff Flow Control
AT&K5 Xon/Xoff Pass Through
AT&LO Switched Line Select DEFAULT
AT&L1 Leased Line Select
AT&MO Asynchronous Mode DEFAULT
AT&M1 Synchronous Mode With Asynchronous Dial
AT&M2 Synchronous Mode Dial Stored Number Immediately
AT&M3 Synchronous Mode With Controlling Data/Talk
AT&PO Make/Break Ratio Pulse Dialing DEFAULT
AT&P1 Make/Break Ratio Pulse Dialing
AT&QO Direct mode (same Hayes)
AT&Q1 Same
AT&Q2 Same
AT&Q3 Same
AT&Q5 Error Control Mode
AT&Q6 Normal Mode
AT&RO Clear Send (CTS) Follows DEFAULT
AT&R1 Always
AT&SO Data Ready (DSR) Always DEFAULT
AT&S1 Normal
AT&TO Terminate Test Progress DEFAULT
AT&T1 Initiate Local Analog Loopback Time Register
AT&T2 Defined
AT&T3 Initiate Digital Loopback Time Register
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GDDS^SO HEXR
XR-2942
T-75-33-90
COMMAND DESCRIPTION RANGE SIZE
AT&T4 (Not Supported)
AT&T5 Disable Remote Digital Loopback (RDLB) Response
AT&T6 Initiate RDLB
AT&T7 Initiate RDLB with Self Test
AT&T8 Initiate with Self Test (for Direct Normal Mode only)
AT&WO Write User Profile into NVRAM
AT&W1 Write User Profile into NVRAM
AT&XO Modem Provides Transmit Clock
AT&X1 Supplies Transmit Clock (Not Supported)
AT&X2 Slave Clock Mode (Not Supported)
AT&YO Power Recall User Profile
AT&Y1 Power Recall User Profile
AT&V List Configuration both Active Stored
AT&Z m=An Store Telephone Number into NVRAM (XL93C46)
where: number location (0-3)
(pulse Tone)
telephone number
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EXAR C0RP 3422blfl 0005^51
XR-2942_
T-75-33-90
COMMAND LAPM Yes/No DESCRIPTION/RANGE SIZE FUNCTION
Normal
Direct
2-5/Reliable
2-5/Auto Reliable
AT\N4 V.42 Mode
V.42 Mode Auto Reliable
V.42 Reliable
V.42 Auto Reliable
Characters Transmit Block Size
AT\A1 Characters
AT\A2 Characters
Characters
AT%An 0-127 ASCII Auto-Reliable Fallback
Character
Stream Link Block
AT\L1 Block Link (Stream Mode)
=\L0
Initiate Reliable Link After Originate Reliable Link
Escape Command Independent
Modem Initial mode (ANS ORG)
Accept Reliable after Escape Accept Reliable Link
Command request from Initiator Link
Establish Reliable Link Switch Reliable Mode
after Connecting Normal Mode
Switch Normal Mode Switch Normal Mode
After Establishing Reliable Link
Compression Disabled Compression On/Off Control
%C1* Compression Enabled
Standard Non-MNP Result Codes Result Code Form
Modified Result Codes
Listed Below)
ATVBn (100ms Increments) Transmit Break
Used Normal Mode Normal Data Mode
Default Error Control Mode
Always 300ms
Does buffer Data Default Auto-Reliable Buffer
Break Control
Buffers Data Answering
Modem until Characters
(Non-Sync) Returned
AT\C2 Does Buffer Data Answering
Modem, according fall back
"Destructive" signaling regardless Break Control
sequence data sent received; Reliable Data Mode
data process time destroyed
AT\K3 "Expedited" signaling regardless
sequence data sent received;
data integrity maintained
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XR-2942
T-75-33-90
COMMAND LAPM Yes/No DESCRIPTION RANGE SIZE FUNCTION
sequence" signaling data sent
received; data integrity
maintained ahead after break
KO,2,4 Supported
(Will equal selected)
0-90 Inactivity Timer
(disable)
%D0* Hang without clearing buffer
Clear receive buffer before hang
Functional Interface Protocol
Rate Adjust Disabled Speed Conversion
Control Disable
AT\J1 Rate Adjust Enabled Modem Port Rate
Adjustment
AT\S List Profiles
Disables Modem Port Flow Control Modem Port
AT\G1 Sets Modem Port Flow Control Flow Control
Xoff
Does Pass Xoff Xoff Pass
Remote Modem Through Control
Passes Xoff
Remote Modem
AT\QO Disable Flow Control Serial Port Flow Control
AT\Q1 Bidirectional Xoff Enabled
Unidirectional Hardware
Control
AT\Q3 Bidirectional Hardware Control
Unidirectional /Xoff Send Only
Keep until connect unidirectional
hardware flow control
Keep until connect bidirectional
hardware flow control
Functional Clear Serial Port
Speed Serial Port
Ignores Parity Special Characters Check Parity
AT-P1 Processes Special Characters Only
they have Correct Parity
Note: Denotes Default Condition
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XR-2942
T-75-33-90
Command Above
STANDARD RESULT CODESWO MODIFIED RESULT CODES
Verbose Numeric Verbose Numeric
CONNECT CONNECT 1200 CONNECT 2400 CONNECT 4800 CONNECT 9600 CONNECT 19200 CONNECt 1200 CONNECT 2400 CONNECT 1200/V.42 CONNECT 2400/V.42
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3422blfl
XR-2942
T-75-33-90
REGISTER FUNCTION
Number Rings Answer: Default answer)(stored)
Ring Count: Stores Number Rings: Resets After Every Call
Escape Code Character: Default (ASCII "+")
Carriage return Character: Default
Line Feed Character: Default
Back Space Character: Default
Walt Dial Tone: Default (seconds) (minimum setting)
Wait Carrier After Dial: Default (seconds)
Duration Delay Comma: Default (seconds)
Carrier Detect Response Time: Default (seconds)
Loss Carrier Response Time Default (seconds)
Touch Tone Duration: Default (milliseconds)
Escape Code Guard Time: Default (second)
Reserved
Mapped Register: Stored NVRAM (XL93C46)
Reserved
Echo
Result Codes
Numeric Result Codes
Always
Tone/Pulse Dialing
Reserved
Answer/Originate
Reserved
Test Register
BitO
Reserved
Local Digital Loopback
Remote Digital Loopback (Not Supported)
Initiate Remote Test
Initiate Remote Test With Self Test
Analog Loopback With Self Test
Reserved
Reserved
Test Time Stored NVRAM (XL93C46) Default (seoonds)
Reserved
Reserved
Mapped Register Stored NVRAM (XL93C46) READ ONLY
BitO RJ11 Jack
Used
Function
Function
Function
Function
Always True Default
Off, Forces Command State
Off, Forces Modem Offline
Modem Initializes With (ATZ)
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XR-2942
REGISTER NUMBER REGISTER FUNCTION
Carrier Status
Bit6
Guard Tone Select
Function
Guard Tone Default
Guard Tone
1800 Guard Tone
Reserved
Option Mapped Register
Determines Speaker Volume
Speaker Volume
Medium pefault
High
Determines Speaker Status
RiL2 BiL2 Speaker Status
Always
Until Carrier Detected Default
Always
Except Dialing
Determine Response Messages
Message
Basic Message
Extended with Connect 1200 Connect 2400
Extended with Dial Tone'
Extended with 'Busy'
Extended with Messages Default
Determines Hook/On Hook (Make/Break) Ratio Pulse Dialing
Ratio
39/61 (USA Canada) Default
33/67 Hong Kong)
Option Mapped Register
(LSB) Supported
Used
1200
2400
480Q
9600
19200
38400(reserved)
Determines Parity Transmitting Receiving Data
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XR-2942
T-75-33-90
REGISTER NUMBER REGISTER FUNCTION
Bit4 Parity
Even Default
Space/None
Mark
Determines Guard Tone Frequency
(Used European Applications)
Bite Guard Tone fHzi
Disabled Default
1800
Reserved
Used
Delay (Stored NVRAM) Default (seconds)
Delay (Synchronous Mode Only) Default (milliseconds)
Mapped Register STORED NVRAM
BitO
Transmission Mode
BitO Function
Asynchronous Mode Default
Synchronous Mode
Synchronous Mode
Synchronous Mode
Reserved
Reserved
Transmission Mode
Function
Internal Modem Clock Used Default
Supplied Clock
Slave Clock Mode
Same
CCITT Bell Handshaking Standard
CCITT
Bell (including V.22bis) Default
Reserved
S28-35 Reserved
Negotiate Failure Fallback (Affected
Bits
Hang
Attempt standard asynchronous connection (&Q0)
Attempt asynchronous connection using automatic speed
buffering (&Q6)
Attempt V.42 Alternative Protocol connection (MNP compatible);
negotiation fails, attempt standard asynchronous connection
Attempt V.42 Alternative Protocol connection (MNP compatible);
negotiation fails attempt standard asynchronous connection
Supported
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XR-2942_^75-33-90
REGISTER NUMBER REGISTER FUNCTION
Supported
Reserved
Supported
Supported
S43-45 Reserved
Protocol Selection: Bits LAPM only (V.42)
Supported
Feature Negotiation Action Negotiation disabled; presume remote modem configured capabilities necessary connection selected with Negotiation enabled, originating modem remains silent during detection phase. connections with modems; defeats connection sequence with other V.42 modems Negotiation enabled Negotiation disabled; forces fallback options specified taken immediately
Break Handling: Affected commands "Expedited" signaling regardless sequence data sent received; data integrity maintained "Destructive" signaling regardless sequence data sent received; data process time destroyed sequence" signaling data sent received; data integrity maintained ahead after break
Supported
Special Notes regarding registers above AT/n Commands.
Changes register values above will effect profile display AT/n Commands. AT/n Commands however, modify setting registers.
intended that user application software package will only method register Commands) effect error control functions. combination could result unpredictable behavior.
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XR-2942
*T-75-33-90
COMMANDS
following list commands supported XR-2900. They follow Aug. 20,1990 standard PN-2388 (class
commands listed used string length characters, always proceeded "AT". example, "AT&D2E1 V0+FCLASS=2<CR>" valid command sequence. semicolon(;) must used separate commands.
DESCRIPTION RESPONSE COMMENTS
+FCLASS Establish Class integer values
Data mode
mode
+FCLASS=? Provides service Class list
+FCLASS? Service Class Setting Indicates latest setting
Default Parameters Each number's location
+FDCC=VR, Capability string represents function
listed below:
+FDCS=VR, Current Session
Parameters
+FDIS=VR, Parameters Session Vertical Resolution
(dots/inch)
Rate (modulation)
2400 V.27ter
4800 V.27
7200 V.29
9600 V.29
Page Width
1728 PIXELS
2048 pixels
2432 pixels
1216 pixels
pixels
Page Length
A4,297
unlimited
Data Format
Modified Huffman
Supported
Supported
ErrorFree Mode
Disable
Supported
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XR-2942 t-75-33-90
COMMAND DESCRIPTION RESPONSE COMMENTS
Binary File Transfer
Disable
Supported
Scan Time
+FLID "Local Local String character alpha numeric
string identification
space, ASCI 32-127
+FCR Capability Receive will receive, will
+FCR answer handshake
+FCQ Copy Quality Supported
+FBUG Debug Mode: HDLC Frame
FMINSP =0,1, Minimum Transmit Speed 0:2400,1:4800, 7200,
9600
+FBOR Order (DCE DTE) First
+FBOR First
+FDR Begin Phase Reception CONNECT Beginning file noted
DC2(12H) character
+FAA Auto Answer Mode only communication
+FAA Auto Fax/Data determination
+FDT Begin Sending Page CONNECT Marks beginning Phase
data
+FHPS=0,1 Handshake Protocol 0:OK
Error
+FET=0,2 page Supported
Indicates additional pages
another page parameter
changes
RESPONSES from XR-2900 FIRMWARE:
following lists valid responses expected from XR-2942 firmware. standardization these responses allows Application software verify that particular mode been entered monitoring transmission reception process easier.
RESPONSE DESCRIPTION COMMENTS
+FCON connection Occurs after V.21 flags received
+FCSI: Called Station Report being Received (originate)
+FTSI: Transmit Station
+FDIS: Session Negotiation Parameters Uses format shown Commands Section
+FDCS: Report Frame Information Format same -i-FDIS command
+FET:0, Post Page Message Response Another Page coming same document
Supported
more pages documents
+FPTS:1, Message Confirmation
quality
+FHNG:0 Call terminated status Normal proper connections
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DDDSTbO
XR-2942
APPLICATIONS INFORMATION
XR-2942 shown typical "stand-alone" application modem schematic. XR-2942 provides command controller function XR-2900 Fax/Data modem chip set. data operation modem operates error-free through LAPM modes offer increased throughput with XR-2321 device included adds CCITT V.21 V.23 modes, optional eliminated designs requiring these modes.
Detailed information XR-2900 available XR-2900 Fax/Data modem chip datasheet.
Layout Hints
order XR-2942 provide optimal support best performance modem, some design hints/rules should followed.
Locate XR-2902 near section
provide short transmit receive carrier input path, away from digital control lines.
Maintain separate analog digital grounds/ power lines back power supply.
Bypass (capacitor decouple) XR-2901, XR-2902, XR-2942 power supplies with both 0.01 ceramic 0.47jjF tantalum capacitors near their actual pins. Ensure analog/digital supplies bypassed their respective ground.
Crystal parallel resonant type. Typical loading capacitors 18pF.
T-75-33-90
SYSTEM PERFORMANCE
Performance error-correcting modem (data mode) major areas.
DATA PUMP PERFORMANCE
With error-detection capabilities turned off, integrity data pump pass data presence impairments. Most often major specification measured here probability data errors with receive carrier impaired noise, (bit error rate) (Signal-to-Noise ratio).
Figure shows circuit Figure measured with test set-up Figure
ERROR CONTROLLER PERFORMANCE
XR-2942, when LAPM modes provides control detection required yield perfect data transfer (Data Modem mode).
Beyond error correction, throughput, data transfer rate, another important parameter modems overall performance.
LAPM Modes specifically provided increased throughput. However additional benefit their error-detecting schemes roughly increase throughput. Using 'Quick Brown Fox.' pattern, both LAPM modes yielded better than throughput increase. V.22bis mode used this test, with actual throughput better than 2900 measured.
Data Compression Included XR-2942 allows roughly 100% throughput increase over modems nominal data rate. previously discussed, throughput performance varies with different types data. Figure shows data various data patterns. Figure illustrates test set-up used measuring circuit Figure
performance shown XR-2900 performance/ compatibility summary bulletin.
3-195
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XR-2942
T-75-33-90
Conditions:
2400 (Data Modem Mode)
Originate Mode
RXCAR -40dBM
5KHz Noise Bandwidth
Hgure 8.2400 Data Mode (Non-Error Correcting)
Noise Worse-Case
Line
Figure Data Quality Test Set-up
3-196
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EXAR CORP
3M22bia DOOSTbe
IEXR
XR-2942
T-75-33-90
-6000 -5760
"5520
220-
170160
FILES PASSED
-5280
6040
4800
4560
4320
-4080
GRAPH TYPE PATTERN BYTES FILE
"QUICK BROWN FOX" 10044
MICROHEX 31530
PROGRAM 26627
MIXED 31530
-3360
Figure Effective Data Throughput
RUNNING THROUGHPUT PROGRAM'
XR-2900 V.4-2
MOOEM
ASYNC MOOEM
NETWORK SIMULATOR
ASYNC MODEM
TERMINAL
(asynchronous Performance Tester), also contains data files used during measurement. Productof Concord Data Systems. Simulates line impaimsnt attenuation condi Hons.
Figure MNP5 Throughput Measurement Test (Data Mode)
3-197
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XR-2942
34S2blfi bfil HIEXR
mmmmmrnNi^iPiiMra
P1.5 P1.6
rxdE
["6* TXpf? INTO INT1
[44] [43] [42]
XR-2942CQ FLAT PACK
|12||13||14| |15[ |17| |18||19| |20||21||22|
P0.4
P0.5
P0.6
PSEN
P2.7
P2.6
P.2.5
3-198
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