CH1786A Family of Ultra Small 2400bps Modems
INTRODUCTION
  • UL 1950 Edition 3 and CSA C22.2 950 Listed.
  • The CH1786A represents the next generation of full
  • UL File Number: E251266.
  • function, FCC Part 68 approved 2400bps modems in
  • AT Command structure with extensions.
  • the CH1786 Family. These modems provide a fast,
    easy and flexible way to integrate a modem into any
  • 1500 VAC RMS isolation barrier minimum, 2122V
  • OEM product while utilizing the minimum amount of
    peak surge protection minimum.
    PCB space (1.01”x 1.27”x 0.52”).
    The CH1786A
  • Error Correction.
  • family only requires two external interfaces: a ITU-T
  • Fast Connect (V.22).
  • V.24 serial interface that can be routed directly to a
  • Single 5 volt operation.
  • UART, and a Tip and Ring interface which goes
  • Caller ID (optional).
  • directly to an RJ-11 jack for the PSTN line connection.
  • Low power operation with automatic reduced power
  • The CH1786A can be controlled with industry standard
    standby mode.
    AT commands and, hence, is compatible with
    available industry communication software. DTE
  • Zero Power (optional).
  • speed conversion allows commands and data to be
  • Automatic
  • adaptive
    and
    fixed
    compromise
    sent at rates that differ from the modem connection
    equalization.
    speed.
    In most cases, the CH1786A can be used
  • Size: 1.01”x 1.27”x 0.52” (nominal).
  • interchangeably with the CH1786. See Attachment I
  • NVRAM allows storage of custom configurations
  • for equivalency comparisons and differences by
    and telephone numbers.
    product.
    All
    CH1786A
    modems
    support
    asynchronous
    operation at 2400bps, 1200bps, and 300bps to both
    Bell and ITU-T standards.
    The CH1786A also
    supports
    Fast
    Connect
    and
    LAPM/MNP
    Error
    Correction.
    The resident PSTN line interface, or Data Access
    Arrangement (DAA), while being FCC approved, is
    also Industry Canada CS-03 Part I Registered.
    Further, the CH1786A can be approved in other
    countries that require 1500VAC RMS isolation
    requirements per UL 1950 Edition 3.
    The CH1786A family of modems operate off a single
    5-volt supply. The low power operation and automatic
    standby mode make these modems ideally suited for
    Figure 1. Functional Block Diagram of CH1786A.
    portable equipment. In addition, their small physical
    size affords maximum flexibility in equipment design.
    DESCRIPTION OF FUNCTIONAL BLOCKS
    CH1786A comes with FCC Part 68 approval and is
    AND DISCUSSION OF BASIC OPERATIONS
    shipped from the factory with an FCC Part 68 label
    Figure 1 contains a functional block drawing of the
    indicating
    the
    registration
    number
    and
    ringer
    CH1786A. The CH1786A is a highly integrated, full-
    equivalent. This label should be prominently displayed
    function
    modem,
    comprised
    of
    a
    modulator/
    on the end product.
    demodulator, controller, NVRAM and an FCC Part 68
    approved and UL 1950 Edition 3/CSA C22.2 950 listed
    PSTN line interface.
    FEATURES
  • Supports Standards ITU-T V.22bis, V.22, Bell 212,
  • Modulation/Demodulation and Modem Controller.
    and Bell 103.
    These functions are provided by a monolithic modem
  • FCC Part 68 approved:
  • integrated circuit.
    This IC has built-in facilities to
    US:B46MM07BCHXXXXAYY
    accommodate integrated AT command control and
  • Industry Canada CS-03 Part I Registered:
  • contains the necessary resident interfaces for general
    IC:176A-CHXXXXAY
    communication and routing to the DAA.
    2006 Cermetek Microelectronics, Inc.
    Page 1
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Telephone Line Interface or DAA. The CH1786A
    SUPPORT FEATURES
    AT Command Set. A 50-character command line is
    supported. The command line starts with AT and may
    contain standard or enhanced commands.
    The
    commands are compatible with EIA Document
    TR302.2/88-08006.
    Serial Host Interface. The serial interface is a V.24
    (EIA-232) compatible interface. Ten Bits total: 1 start
    bit, 1 stop bit, and eight data bits which can be either
    eight bits with no parity or seven odd or even with
    parity. The start bit is LOW going. RXD and TXD data
    is non-inverted. See pin description in Table 2.
    Figure 2. Voice/ Data Port Control
    Speaker Interface.
    The SPK output reflects the
    receiver analog input and provides a signal that can be
    family of modems is designed to meet 1500VAC RMS
    used to monitor call progress. The SPK signal can
    isolation and provide 2122V peak surge protection.
    drive a 300 load directly. Typically, the SPK signal
    Consequently, the CH1786A satisfies U.S. FCC Part
    is input into an audio power amplifier and the amplifier,
    68 and Industry Canada CS-03 Part I requirements,
    in turn, drives the speaker coil.
    The speaker is
    and will meet other international approval agency
    activated with the ATMn command.
    The speaker
    requirements that specify these levels of isolation.
    volume is adjusted using the ATLn command, where n
    is 0, 1, 2, or 3. Increasing numbers correspond to
    With the exception of the U.S., most countries
    higher volume.
    Figure 5 indicates one method of
    (including Canada) require submission of the final
    driving an external 8 speaker.
    product or system containing the CH1786A to the
    appropriate governing regulatory agency for approval.
    Phone Control. Cermetek’s CH1786A contains a pin
    Typically this is accomplished by submitting the final
    called Voice or Data (V/D). The V/D pin toggles high
    end product to an independent test house or
    when the modem goes off hook. This pin can be used
    consultant for evaluation. The test house or consultant
    to activate a relay which can switch a telephone on or
    then
    forwards
    the
    test
    results and
    applicable
    off the Tip and Ring incoming PSTN lines.
    This
    documents to the regulatory agency. Call Cermetek
    feature allows any telephone associated with the
    for a list of suggested consultants.
    CH1786A to be disconnected when a data call is in
    progress, thereby preventing the data from being
    Non-Volatile RAM (NVRAM). The NVRAM present
    disturbed by an inadvertent telephone pick-up. See
    on the CH1786A is sufficient to store up to two user
    Figure 2.
    customized modem profile configurations.
    The
    AT&Wn command will store the active modem
    Speed and Parity Selection. Prior to call initiation,
    configuration in the selected NVRAM profile by
    the host controller trains the modem to the host speed
    specifying either an n of 0 or 1. The CH1786A is
    (2400, 1200 or 300bps) and parity (odd, even, mark,
    delivered with Factory Default setup parameter values
    space, or none) via a host-initiated training sequence.
    pre-stored in NVRAM profile 0.
    This training also sets the speed of the data for
    originate calls. The CH1786A will automatically adjust
    The
    AT&Yn
    command
    selects
    the
    modem
    to the originator’s speed when answering calls.
    configurations to be automatically recalled and made
    active upon a reset or power up. The ATZn command
    The CH1786A matches the host’s parity when it
    immediately recalls and activates a stored profile
    returns status messages to the host. During a data
    configuration. Refer to Tables 4, 5 and 6 for storable
    connection, however, the modem passes parity
    S-Registers and available commands.
    through without interpretation or alteration.
    The NVRAM can save up to four telephone numbers
    Sleep Mode. To minimize power consumption, the
    with up to 31 digits or modifiers in each telephone
    CH1786A includes a power down feature called Sleep
    number.
    The AT&Zn=s command will store s, the
    Mode.
    When
    activated,
    the
    CH1786A
    will
    telephone number dial string. The individual NVRAM
    automatically enter Sleep Mode after 1 to 255 seconds
    telephone number storage locations are selected by
    of inactivity. The inactivity delay is selected using the
    specifying an n of 0, 1, 2, or 3.
    The ATDTS=n
    ATS24 command and defaults to 0 which will disable
    command will cause the modem to dial the stored
    this feature.
    The CH1786A returns to normal
    telephone number in location n.
    operation when a ring signal is received or upon an
    input low signal on the TXD pin. A SLEEP output
    signal is available to control power to external devices.
    2006 Cermetek Microelectronics, Inc.
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    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    In Figure 5, a FET controlled by the SLEEP signal
    found
    on
    the
    Cermetek
    web
    site
    located
    at
    turns off the external speaker amplifier when the
    http://www.cermetek.com.
    CH1786A enters Sleep Mode. In Sleep Mode, power
    is reduced to about 1/3 of normal operating power.
    Answer Tone. A ITU-T (2100 Hz) or Bell (2225Hz)
    answer tone is generated depending on the selected
    Zero Power Mode. The “P” versions of the CH1786A
    configuration.
    Refer to “AT Commands and S-
    Family supports Zero Power Mode operation. If an
    Registers” for a more detailed discussion.
    application calls for zero power during standby
    periods, this feature allows the power to the CH1786A
    Data Encoding. The data encoding conforms to ITU-
    to be switched off using external circuitry and then
    T recommendations V.22bis or V.22, or Bell212A, or
    reapplied when the CH1786A’s RI pin becomes active.
    103, depending on the selected configuration. Refer
    The CH1786A can thus be powered down to zero.
    to “AT Commands and S-Register” for a more detailed
    discussion.
    Referring to Figure 3, the controller activates the relay
    switch, supplying power (+5V) to the CH1786A. In this
    Line Equalization. Transmitter and receiver digital
    configuration, the ring signal is used to “wake up” the
    filters compensate for delay and amplitude distortion
    CH1786A when the CH1786A is in the zero power
    during operation on nominal phone lines. In addition,
    state.
    automatic adaptive equalization in the receiver
    minimizes the effects of inter symbol interference.
    Transmission Speed.
    In normal operation, the
    originating modem initiates the call and attempts to
    connect to the answering modem at a speed
    established by the originating modem’s controller prior
    to call initiation.
    This is referred to as the Initial
    CH1786A-P
    Trained Rate. Upon receiving the call, the answering
    modem will attempt to connect to the originating
    modem at its Initial Trained Rate. If these two rates
    are identical, the connection is made. If the speeds
    differ, the answering modem must adjust its rate or
    terminate the call. Table 1 indicates the connection
    rate when the calling modem’s Initial Trained Rate and
    answering modem’s Trained Rate are different.
    Error Correction. The CH1786A supports LAPM and
    MNP error correction. Error correction is enabled via
    the \Nn command. Enabling error correction overrides
    &Qn and sets S36 and S48 values.
    Refer to
    Cermetek, “AT Commands and S-Registers”, for a
    Figure 3. Zero Power Operation.
    more detailed discussion.
    As indicated in Figure 2, the user connects an external
    Table 1. Connection Rates.
    pull-up resistor (Cermetek recommends 30k ohms) to
    Connection Rate Resulting
    an active 5V source thereby providing a small current
    Answering Modem
    When Calling Modem Initial
    to the CH1786A through the RI pin when the CH1786A
    Initial Trained Rate
    Rate Is:
    is powered down (i.e., no power applied to the VCC
    300
    1200
    2400
    pin).
    An internal blocking diode provides supply
    isolation.
    300
    300
    1200
    1200
    1200
    300
    1200
    1200
    The pins of the CH1786A will be in an undefined state
    when powered is switched off. This must be taken into
    2400
    300
    1200
    2400
    consideration to assure that no unwanted signals are
    presented to the CH1786A during power down.
    NOTE
    A 2400-baud connection rate will only result if both
    Guard Tone. A guard tone of 550 Hz or 1800 Hz can
    modems are initially set at 2400 baud.
    be generated at 6 dB or 9 dB below the transmit level,
    respectively, by using the &Gn command. For a more
    detailed discussion, refer to Cermetek Document 613-
    Ring Indicator (RI). The RI pin follows the frequency
    0001, “AT Commands and S-Registers”, which can be
    of the ring signal and toggles low when the CH1786A
    detects an incoming call. The ring signal is typically 20
    to 30 Hz and is on for 2 seconds and off for 4 seconds.
    2006 Cermetek Microelectronics, Inc.
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    Document No. 607-0019 Revision A8 (03/06)
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    CH1786A Family of Ultra Small 2400bps Modems
    Although not TTL compliant, the RI pin can,
    schematic indicating one possible configuration for
    nonetheless, be utilized to activate external circuitry
    voice/ tone utilization.
    including the external RST pin.
    Typically, voice communication would precede data
    +MS Command.
    The user may override the
    communications.
    For this case, the following
    automatic data rate function of the HS modems. This
    commands should be used to configure the CH1786A
    is accomplished by executing the +MS command.
    (Refer to Figure 4):
    This command allows the user to specify the desired
    data modulation protocol. Further, the +MS command
    Enter: ATS0=0<CR>
    Disables auto-answer
    may be used to force a desired data rate and/or
    Result: OK
    restrict the allowed data rate.
    The supported
    modulation schemes are listed above.
    Enter: ATS7=255<CR>
    Disables data-carrier time
    Result: OK
    out
    The
    following
    examples
    establish
    the
    V.22bis
    modulation scheme:
    Enter: ATS10=255<CR> Disables lost-carrier time
    Result: OK
    out
    Enter:
    AT+MS=V22B
    Result:
    OK
    WARNING
    This is identical to the following explicit +MS
    The CH1786A has been FCC Part 68 and Industry
    command:
    Canada CS-03 Part I approved as a data modem
    only.
    Utilization of the Voice/DTMF Tone Port
    Enter:
    AT+MS=V22B,0,300,1200,300,1200
    requires further registration.
    FCC and Industry
    Result:
    OK
    Canada will require that the system, including the
    CH1786A and the handset or DTMF transceiver,
    adhere to Part 68 and CS-03 Part I rules.
    NOTE
    The minimum transmission rate is not stored and will
    default to 300bps upon execution of reset or upon
    The
    following
    command
    sequences
    illustrate
    power up.
    implementation
    of
    common
    Voice/Tone
    Port
    applications.
    Refer to, “AT Commands and S-Registers”, for a more
    1. To answer a voice call.
    detailed discussion of the +MS command.
    (a) Enter: ATH1<CR>
    Result: OK
    Power Supply. The CH1786A modem module is a
    (b) Drive V.INJ. HIGH to activate relay.
    complex set of sub-systems.
    During the course of
    (c) Begin voice conversation.
    normal operation the CH1786A decodes analog
    signals from the telephone line that are in the millivolt
    2. To switch to data mode.
    range. Steps must be taken by the user to guarantee
    (a) Drive V.INJ. LOW
    that power supply noise on all supply lines, including
    (b) At the originate modem:
    ground, does not exceed 50 mV peak to peak. Any
    Enter: ATX1<CR>
    frequency between 20 kHz and 150 kHz must be less
    Result: OK
    than 500 micro volts peak.
    If necessary, use
    dedicated power and ground planes.
    Failure to
    3. To disconnect (hang-up) a voice call or a data call.
    provide such operating conditions could cause the
    (a) Enter: ATH<CR>
    CH1786A to malfunction or to function erratically.
    Result: OK
    The CH1786A requires a single +5V ±5% supply. It is
    4. Place a call to 1234567 using the CH1786A’s
    recommended that by-pass capacitors be placed on
    DTMF tone generator, then use VOICE mode for
    the power supply as close to the modem’s supply input
    voice communications.
    Note that the CO
    as practical.
    It’s recommended a 10 µ F Tantalum
    command disables carrier generation.
    capacitor in parallel with a 0.01 µF ceramic capacitor
    (a) Enter: ATDT1234567;C0<CR>
    be used.
    Result: OK
    (b) Drive V.INJ. HIGH
    Voice/DTMF Tone Injection Port.
    The CH1786A
    provides two pins to allow the user to share the
    telephone line interface associated with the modem for
    MODEM CONTROL
    voice and DTMF applications.
    Figure 4 contains a
    The CH1786A modem may be controlled by sending
    serial ASCII command sequences. The commands
    2006 Cermetek Microelectronics, Inc.
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    Document No. 607-0019 Revision A8 (03/06)
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    CH1786A Family of Ultra Small 2400bps Modems
    are sent to the modem serially on the TXD pin. After
    Training the Modem. Each modem must be trained
    execution of a received command, the modem returns
    to match its host’s speed and parity so that it is able to
    a serial status message that can be read on pin RXD.
    recognize serial asynchronous commands sent to it by
    This message indicates command completion status.
    the host’s is UART. The host must retrain the modem
    Refer to Table 3 for a complete list of status
    each time a reset pulse is applied on RST or after a
    messages.
    RESET serial command has been issued.
    Modem Training Command Sequence.
    The
    CH1786A is trained by sending it the following
    sequence:
    Enter: AT<CR>
    Result: OK
    Where: A and T may be either upper or lower case but
    must be the same case.
    <CR> represents carriage return
    The AT sequence is referred to as an attention
    sequence. The CH1786A will respond with one of the
    following status messages, depending on whether it is
    optioned for Terse (abbreviated) or Verbose (English)
    status messages.
    Figure 4. Voice/Tone Injection.
    Result: 0<CR> (Terse)
    or
    Result:
    <CR><LF>OK<CR><LF> (Verbose)
    IMPORTANT NOTE
    Where:
    <CR> represents carriage return (ASCII 13
    Although every effort has been made to design the
    or HEX 0D).
    CH1786A products to be fully and completely
    <LF> represents line feed (ASCII 10 or HEX
    compatible with the existing CH1786 family, there are
    0A).
    some minor differences.
    Refer to Table 14 for
    equivalency information and refer to Attachment I for
    After responding with an OK, the CH1786A is in idle
    a summary of product differences.
    mode and is ready to accept additional commands.
    An alternate attention sequence A/ may be sent which
    behaves much like the AT sequence except that it
    INITIALIZING THE MODEM
    causes the previously entered command specified with
    Before commands may be sent to the CH1786A, the
    an AT prefix to be executed. When given, both the AT
    CH1786A must be initialized. Initialization is a two
    and A/ must be in upper case ASCII. No carriage
    step activity consisting of:
    return is needed for the A/ command.
    1. Hard Reset. This is accomplished by applying a
    hardware reset pulse to pin RST or by switching
    THE COMMAND FORMAT
    the power off and then back on.
    Typical commands consist of three elements: the
    attention sequence, the commands themselves, and a
    2. Initial modem training.
    The CH1786A must be
    terminating carriage return.
    trained to the host’s speed and parity (odd, even,
    mark, space or none).
    AT[commands]<CR>.
    These activities are briefly described below.
    Where: AT represents attention sequence.
    [Commands] represents command strings.
    Reset. Upon applying power to the CH1786A, the
    <CR> represents carriage return (ASCII 13 or
    CH1786A automatically generates an internal reset
    HEX 0D).
    pulse. The user may also reset the modem externally
    by applying a high-going reset pulse to the RST pin for
    When entering commands to the modem, the
    at least 10ms after the +5V power supply has
    backspace character-control-H (ASCII 8 or HEX 08)
    stabilized. Delay sending commands to CH1786A for
    may be used to edit mistakes. AT and A/ may not be
    200ms after reset has been initiated to allow the
    edited.
    Multiple commands may be placed in the
    CH1786A time to properly reconfigure.
    command line. A command line may be as long as 40
    characters, excluding the letters AT .
    By way of
    example, the command below instructs the CH1786A
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    CH1786A Family of Ultra Small 2400bps Modems
    to configure itself to not echo characters when in
    AT COMMAND APPLICATIONS
    command mode E0 and then put itself in answer mode
    Dialing A Phone Number. The Dial command takes
    A .
    the form Dn , where n is a string of characters. In the
    Enter: ATE0A<CR>
    simplest form, n will be only the digits of the phone
    Result: OK
    number to be dialed.
    AT Command Set. The available command set is
    Example: Dial number.
    divided into four types of commands: dial modifiers,
    Enter:
    ATD1234567<CR>
    basic commands, ampersand and percent commands.
    Result:
    OK
    Refer to the complete list in Table 5.
    In response to this command, the CH1786A dials the
    AT Command Data Rate. With the serial interface,
    telephone number “123-4567” and then waits for a
    the rate is speed sensed for parity and format.
    carrier from the distant modem.
    If no carrier is
    detected within a given time (the default time is 30
    seconds), the CH1786A automatically releases the line
    THE STATUS MESSAGES
    and sends a NO CARRIER result code. If a carrier is
    The CH1786A responds with a status message after
    detected, the CH1786A gives a CONNECT result code
    each command is executed.
    This status message
    and goes on-line, permitting communication with the
    may either be a numeric code (Terse Result Code)
    distant modem.
    followed by a carriage return; or a carriage return and
    line feed with a message in English (Verbose Result
    The Dial Command may also be issued without a
    Code) followed by a carriage return and line feed.
    telephone number. ATD causes the modem to pick up
    the telephone line without dialing a number.
    Various status code subsets are enabled with the Xn
    command. Where n=0, 1, 2, 3, 4 establishes the result
    Pause During Dialing. When placing a call from an
    codes allowed to be sent from the CH1786A to the
    office with a telephone connected to a PBX, it may be
    DTE.
    necessary to dial an access code (usually the digit 9)
    to get an outside line.
    Inserting a comma in the
    telephone number instructs the modem to pause for a
    NOTE
    specific length of time. The factory set default pause
    The CH1786A is factory set to X4, which allows all
    time is 2 seconds.
    result codes.
    Example: Dial 9,pause, dial number.
    Enter:
    ATDT9,1234567<CR>
    MODEM STATES
    Result:
    OK
    The CH1786A can be in either command mode or data
    Multiple commas may be used to generate integer
    mode. When the modem is idle, it is in command
    multiples of the specified delay time.
    mode by default and will recognize commands. When
    data transmission is in progress, the CH1786A is in
    Originate a Call in Answer Mode. The D command
    the data mode state and will not recognize commands.
    forces the modem into originate mode.
    To call an
    To force the CH1786A to recognize commands, the
    originate-only modem, dial the number and set the
    host must send an escape sequence to the CH1786A
    modem to answer mode via the R command (reverse
    forcing it out of data mode and into command mode.
    originate). This is done by including an R at the end of
    the telephone number.
    The escape sequence consists of a “guard time” (a
    period where no characters are sent to the modem),
    Example: Change modem from original-only to answer
    followed by 3 escape characters, followed by another
    mode.
    guard time. The guard time is set by register S12.
    Enter:
    ATDT1234567R<CR>
    The escape character code is set in register S2. At
    Result:
    OK
    power-up, the guard time is set to 1 second minimum,
    and the escape character is set as “+.” There is no
    Multiple commas may be used to generate integer
    minimum delay between characters but the maximum
    multiples of the specified delay time.
    delay is set by register S12.
    Redial Last Number.
    The repeat command is a
    The CH1786A will stay off-hook with its carrier on after
    convenient way to execute the previously entered
    the escape sequence is received. It will return an OK
    command line.
    status message when it is ready to accept commands.
    The CH1786A may be put into data mode by issuing
    Example: Use A/ , the repeat command, to redial the
    the command ATO<CR> .
    last telephone number dialed.
    2006 Cermetek Microelectronics, Inc.
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    CH1786A Family of Ultra Small 2400bps Modems
    Enter:
    A/
    (telephone
    number).
    ASCII
    data
    is
    Result:
    ATDT1234567R<CR> Previous command
    presented.
    OK
    line executed
    2
    Enables
    Caller
    ID
    with
    unformatted
    Return to Command State.
    Use ; to return to
    presentation to the DTE.
    The data is
    command mode offer dialing.
    presented
    in
    a
    continuous
    string.
    Example: Touch-tone dial 9, pause, dial number,
    HEXADECIMAL data is presented.
    return to Command.
    Enter:
    ATDT9,1234567;<CR>
    Refer to Application Note # 174, Caller ID Feature For
    Result:
    OK
    CH1786A, CH179XA and CH2056A Modems, for
    additional information and examples.
    V.22 Fast Connect.
    The CH1786A supports non-
    standard V.22 fast connect protocols.
    This feature
    The AT+VRID command affects the format of the data
    reduces the connect time to 3-4 seconds. However, to
    provided by the PSTN Caller ID services for the last
    utilize the fast connect protocol, this protocol must be
    received call. The DTE is presented this data once
    supported by both modems. Further, the DCE speed
    every time the +VRID command is executed.
    must be set to 1200 baud (i.e., V.22).
    Enter: AT+VRID=n<CR>
    To setup the CH1786A to connect utilizing Fast
    Result: Data Stream from most recent call
    Connect, execute the following commands:
    Where n is a decimal number corresponding to the
    Enter: AT+MS=V22,0,300,1200,300,1200<CR>
    selected option as described below.
    Result: OK
    0
    Reports
    Caller
    ID
    with
    formatted
    Enter: $F2<CR>
    presentation to the DTE.
    The data is
    Result: OK
    presented the data items in a <Parameter
    This forces the CH1786A to communicate using the
    Description> <Value> pair format.
    The
    V.22 protocol and to attempt to connect using Fast
    expected pairs are: date, time, name, and
    Connect. If Fast Connect is not supported by the other
    caller code (telephone number).
    modem, the CH1786A will connect using the standard
    V.22 protocol.
    1
    Reports
    Caller
    ID
    with
    unformatted
    presentation to the DTE.
    Caller ID (CID). The “C” versions of the CH1786A
    Family supports Caller ID.
    The +VCID command
    Refer to Application Note # 174, Caller ID Feature For
    controls reporting and presentation of the data
    CH1786A, CH179XA and CH2056A Modems, for
    provided by the PSTN Caller ID services.
    Data is
    additional information and examples.
    presented to the DTE between the first and the second
    ring indication. This command affects the data format
    IMPORTANT NOTE
    for incoming calls as the call is being received.
    Caller ID (CID) requires that the PSTN service
    provider supply the required data.
    The Caller ID
    Enter:
    AT+VCID=n&W0&W1<CR>
    feature will report the NULL string if the CID service
    Result:
    OK<CR><LF>
    is not activated by the PSTN service provider.
    IMPORTANT NOTE
    Automatic Answering. The S0 register controls the
    The &W0 (or &W1 ) command, as appropriate per
    number of rings that must occur before the CH1786A
    the specification of &Y0 (or &Y1 ), must be executed
    answers a incoming call. The register may range in
    before the +VCID command will be implemented by
    value from 0 to 255.
    the CH1786A.
    To set the CH1786A to not answer any incoming calls,
    Where n is a decimal number corresponding to the
    executed the following command:
    selected option as described below.
    Enter:
    ATS0=0<CR>
    0
    Disable Caller ID reporting. (Default.)
    Response OK
    1
    Enables
    Caller
    ID
    with
    formatted
    When S0 is set to 0, the modem will not auto-answer.
    presentation to the DTE.
    The data
    To set the CH1786A to answer after 3 rings, execute
    presented is in a <Parameter Description>
    the following command:
    <Value> pair format.
    The expected pairs
    are: date, time, name, and caller code
    Enter:
    ATS0=3<CR>
    Response OK
    2006 Cermetek Microelectronics, Inc.
    Page 7
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Figure 5.
    CH1786A block diagram illustrating typical feature implementations: V/D control, RJ-11
    connection, speaker for call progress monitoring, serial port connection, external reset, +5V and GND.
    2006 Cermetek Microelectronics, Inc.
    Page 8
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 2. CH1786A Pin Descriptions
    PIN
    NAME
    TYPE
    FUNCTION
    1
    RING
    I/O
    RING . Directly connects to the telephone line’s Ring lead through a user supplied
    RJ-11C jack.
    2
    TIP
    I/O
    TIP . Directly connects to the telephone line’s Tip lead through a user supplied RJ-
    11C jack.
    3
    RXA
    O
    ANALOG VOICE INJECTED . Receive Signal. Let float if not used.
    4
    TXA
    I
    ANALOG VOICE INJECTED . Transmit Signal. Let float if not used
    5
    SPK
    O
    SPEAKER . Audio output for speaker. See speaker control schematic in Figure 5.
    6
    NC
    -
    No connection.
    7
    NC
    -
    No connection.
    8
    SLEEP
    O
    SLEEP . Active LOW. A LOW indicates CH1786A is in low power idle mode. Used
    to control power to other devices. See Figure 5. Register S24 is the sleep timer
    register. When the CH1786A is inactive for a period of time specified by S24, the
    CH1786A will power down by about 1/3 of its normal operating power. During
    power down, all I/O lines become undefined. Default is (ATS24=0) disabled.
    9
    NC
    -
    No connection.
    10
    TXD
    I
    TRANSMIT DATA . Active Low. Serial Transmit data input. Marking or a binary 1
    condition is transmitted when a HIGH is asserted.
    11
    RXD
    O
    RECEIVE DATA . Active Low. Serial Receive data output. Received marking or
    binary 1 condition is indicated by HIGH.
    12
    V/D
    O
    VOICE/DATA . Used to switch between telephone and modem line use. In a typical
    application, V/D active HIGH opens the normally closed voice injection relay and
    disconnects the handset from the telephone line. HIGH indicates the CH1786A is
    off-hook and online. Therefore, this pin also reflects the state of the off-hook relay
    of the CH1786A. See Figure 2. Let float if not used.
    13
    DTR
    I
    DATA TERMINAL READY . Active LOW. Switching off DTR can either return
    modem to command state, disconnect phone call, or reset modem. DTR should be
    set LOW when not used.
    14
    DSR
    O
    DATA SET READY . Active LOW. LOW indicates handshaking with a remote
    modem is in progress, and/ or the data carrier of a remote modem has been
    detected.
    15
    RI
    O
    RING INDICATION. This signal follows the frequency of the ringing signal and is
    normally about 20 to 40 Hz for 2 seconds on with 4 seconds off. This pin is also
    used for Zero Power option. See Figure 3.
    16
    CTS
    O
    CLEAR-TO SEND . Active LOW. Used for hardware Flow Control of data.
    17
    DCD
    O
    DATA CARRIER DETECT . Active LOW. LOW indicates a data carrier from a
    remote modem is detected. Must be enabled using the &C1 command.
    18
    NC
    -
    No Connection.
    19
    VCC
    -
    POWER SUPPLY . 5 volts + 5%
    20
    GND
    -
    GROUND . Note: Noise should be less than 50mV peak to peak.
    21
    RST
    I
    RESET . Active HIGH. This input must be asserted HIGH for at least 10 ms to reset
    the modem. RESET is then returned LOW for normal operation. If no system reset
    is available, let this pin float. Input impedance of driving circuit should be <10K.
    22
    NC
    I
    No Connection.
    2006 Cermetek Microelectronics, Inc.
    Page 9
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 3. S-Register Summary.
    Firmware
    Factory
    Register
    Function
    Range
    Units
    Saved
    Defaults
    Defaults
    S0
    Rings to Auto-Answer
    0-255
    rings
    *
    000
    001
    S1
    Ring Counter
    0-255
    rings
    000
    000
    S2
    Escape Character
    0-255
    ASCII
    *
    043
    043
    S3
    Carriage Return Character
    0-127
    ASCII
    013
    013
    S4
    Line Feed Character
    0-127
    ASCII
    010
    010
    S5
    Backspace Character
    0-255
    ASCII
    008
    008
    S6
    Wait Time before Dial Tone or Blind Dialing
    2-255
    s
    *
    002
    002
    S7
    Wait Time for Carrier, Silence or Dial Tone
    1-255
    s
    *
    050
    050
    S8
    Pause Time for Dial Delay Modifier
    2-255
    s
    *
    002
    002
    S9
    Carrier Detect Response Time
    1-255
    0.1s
    *
    006
    006
    S10
    Carrier Loss Disconnect Delay
    1-255
    0.1s
    *
    014
    014
    S11
    DTMF Tone Duration
    50-255
    0.001s
    *
    085
    085
    S12
    Escape Prompt Delay
    0-255
    0.02s
    *
    050
    050
    S13
    Reserved
    -
    -
    000
    000
    S14
    General Bit Mapped Options Status
    -
    -
    *
    146 (92H)
    146 (92H)
    S15
    Reserved
    -
    -
    000
    000
    S16
    Test Mode Bit Mapped Options Status (&T)
    -
    -
    000
    000
    S17
    POS Option
    -
    -
    000
    000
    S19
    Reserved
    -
    -
    000
    000
    S20
    Reserved
    -
    -
    000
    000
    S21
    V.24/General Bit Mapped Options Status
    -
    -
    052 (34H)
    100 (74H)
    S22
    Speaker/Results Bit Mapped Options Status
    -
    -
    117 (75H)
    117 (75H)
    S23
    General Bit Mapped Options Status
    -
    000
    000
    S24
    Sleep Inactivity Timer
    0-255
    s
    000
    000
    S25
    Delay to DTR off
    0-255
    0.01s
    005
    005
    S26
    RTS-to-CTS Delay
    0-255
    0.01s
    001
    001
    S27
    General Bit Mapped Options Status
    -
    -
    073 (49H)
    074 (4AH)
    S28
    General Bit Mapped Options Status
    -
    -
    000
    000
    S29
    Flash Dial Modifier
    0-255
    0.01s
    070
    070
    S30
    Disconnect Inactivity Timer
    0-255
    10ms
    000
    000
    S31
    General Bit Mapped Options Status
    -
    -
    192 (C0H)
    192 (C0H)
    S36
    LAPM Failure Control
    -
    -
    *
    007
    007
    S37
    Line Connection Speed
    -
    -
    000
    000
    S38
    Delay Before Forced Hang-up
    0-255
    s
    020
    020
    S39
    Flow Control Bit Mapped Options Status
    -
    -
    003
    003
    S40
    General Bit Mapped Options Status
    -
    -
    *
    104 (68H)
    104 (68H)
    S41
    General Bit Mapped Options Status
    -
    -
    *
    195 (C3H)
    192 (C0H)
    S43-S45
    Reserved
    -
    -
    -
    -
    S46
    Data Compression Control
    -
    -
    *
    138
    136
    S48
    V.42 Negotiation Control
    -
    -
    007
    007
    S82
    LAPM Break Control
    -
    -
    000
    000
    S86
    Call Failure Reason Code
    0-26
    -
    021
    021
    S91
    PSTN Transmit Attenuation Level
    0-15
    dBm
    011
    011
    S92
    FAX Transmit Attenuation Level
    0-15
    dBm
    011
    011
    S95
    Result Code Messages Control
    -
    -
    *
    000
    000
    S210
    V.34 Symbol Rate
    0-255
    -
    141 (8CH)
    141 (8CH)
    NOTES:
    1. Parameters indicated with a (*) in the Saved column may be stored in User Profile n=0, 1 by executing
    the appropriate &Wn command.
    2. A stored Profile is a subset of allowed parameters and is comprised of those parameters displayed
    with the &V command.
    3. Factory Default values that are different from the Firmware Default values are highlighted in BOLD .
    4. Restore Factory Default values using Zn command.
    5. Restore Firmware Default values using &Fn command
    2006 Cermetek Microelectronics, Inc.
    Page 10
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 4. Extended Result Code Summary.
    Table 4.
    Extended Result Code Summary
    Result Code Form
    n is ATXn
    (Continuation).
    Command
    Result Code Form
    n is ATXn
    Terse
    Verbose or Long
    0
    1
    2
    3
    4
    Command
    or
    Terse
    Verbose or Long
    0
    1
    2
    3
    4
    Short
    or
    +F4
    +FCERROR
    X X X X X
    Short
    0
    OK
    X X X X X
    80
    +ER: ALT
    X
    X
    X
    X
    X
    1
    CONNECT
    X X X X X
    81
    +ER: ALT-CELLULAR
    X
    X
    X
    X
    X
    2
    RING
    X X X X X
    83
    LINE IN USE
    X
    X
    X
    X
    X
    3
    NO CARRIER
    X X X X X
    85
    OFF-HOOK
    X
    X
    X
    X
    X
    4
    ERROR
    X X X X X
    INTRUSION
    5
    CONNECT 1200
    1
    X X X X
    86
    LINE
    REVERSAL
    X
    X
    X
    X
    X
    6
    NO DIAL TONE
    3
    3
    X X X
    DETECTED
    7
    BUSY
    3
    3
    3
    X X
    87
    NO LINE
    X
    X
    X
    X
    X
    8
    NO ANSWER
    X X X X X
    91
    CONNECT 31200
    9
    CONNECT 0600
    1
    X X X X
    130
    +ILRR
    X
    X
    X
    X
    X
    10
    CONNECT 2400
    1
    X X X X
    134
    +MCR: B103
    X
    X
    X
    X
    X
    11
    CONNECT 4800
    1
    X X X X
    135
    +MCR: B212
    X
    X
    X
    X
    X
    12
    CONNECT 9600
    1
    X X X X
    136
    +MCR: V21
    X
    X
    X
    X
    X
    13
    CONNECT 7200
    1
    X X X X
    137
    +MCR: V22
    X
    X
    X
    X
    X
    14
    CONNECT 12000
    1
    X X X X
    138
    +MCR: V22B
    X
    X
    X
    X
    X
    15
    CONNECT 14400
    1
    X X X X
    139
    +MCR: V23
    X
    X
    X
    X
    X
    16
    CONNECT 19200
    1
    X X X X
    139
    +MCR: V23C
    X
    X
    X
    X
    X
    17
    CONNECT 38400
    1
    X X X X
    140
    +MCR: V32
    X
    X
    X
    X
    X
    18
    CONNECT 57600
    1
    X X X X
    141
    +MCR: V32B
    X
    X
    X
    X
    X
    19
    CONNECT 115200
    1
    X X X X
    210
    +MRR: 25333
    X
    X
    X
    X
    X
    20
    CONNECT 230400
    X X X X X
    211
    +MRR: 26667
    X
    X
    X
    X
    X
    22
    CONNECT
    1
    X X X X
    212
    +MRR: 25333
    X
    X
    X
    X
    X
    75TX/1200RX
    213
    +MRR: 22666
    X
    X
    X
    X
    X
    23
    CONNECT
    1
    X X X X
    214
    DIGITAL
    LINE
    X
    X
    X
    X
    X
    1200TX/75RX
    DETECTED
    24
    DELAYED
    4
    4
    4
    4
    X
    25
    MESSAGE-WAITING
    X X X X X
    IMPORTANT NOTE
    32
    BLACKLISTED
    4
    4
    4
    4
    X
    An “X” in a column indicates that the message
    33
    FAX
    X X X X X
    (either the long form if verbose, or the value only
    35
    DATA
    X X X X X
    for short form) will be generated when that
    39
    +MRR: 75
    X X X X X
    particular value of “n” (shown at the top of the
    40
    +MRR: 300
    X X X X X
    column) has been selected by the use of ATXn . A
    42
    +MRR: 600
    X X X X X
    numeral indicates which less explicit message
    44
    +MRR: 1200/75
    X X X X X
    (verbose or short form) will be output for that X
    45
    +MRR: 75/1200
    X X X X X
    option.
    46
    +MRR: 1200
    X X X X X
    47
    +MRR: 2400
    X X X X X
    48
    +MRR: 4800
    X X X X X
    The Serial Interface Lines. The CH1786A supports a
    49
    +MRR: 7200
    X X X X X
    full EIA-232E/V.24 serial interface. Signal levels are
    50
    +MRR: 9600
    X X X X X
    TTL rather than EIA-232E level compatible, which
    51
    +MRR: 12000
    X X X X X
    allows direct connection of the CH1786A to the host
    52
    +MRR: 14400
    X X X X X
    UART without the need for level translation circuitry.
    66
    +DR: ALT
    X X X X X
    See Table 2 for a complete pin description.
    The
    67
    +DR: V42B
    X X X X X
    CH1786A is controlled by sending it serial commands
    68
    +DR: V44
    X X X X X
    over TXD and it’s status determined by monitoring the
    69
    +DR: None
    X X X X X
    serial status messages returned on
    70
    +ER: NONE
    X X X X X
    RXD. DTR is optionally used to reset, terminate calls
    77
    +ER: LAPM
    X X X X X
    or return CH1786A to command mode.
    All other serial interface lines may be utilized for the
    convenience of a particular application but are not
    2006 Cermetek Microelectronics, Inc.
    Page 11
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 5. AT Command Summary.
    Table 5. AT Command Summary (Continuation).
    Command Function
    Command
    Function
    A/
    Re-execute command
    &D0
    Modem ignores DTR
    A
    Go off-hook and attempt to answer call
    &D1
    Modem assumes command state
    B0
    Select CCITT connection at 300 or
    &D2
    Modem
    hangs
    up,
    assumes
    1200bps
    command state and disables auto-
    B1
    Sect Bell connection at 300 or 1200bps
    answer
    Dn
    Dial modifier where n is one or more of
    &D3
    Modem assumes initialization state
    the following:
    &F0
    Restore Factory configuration 0
    P
    Pulse Dial
    &F1
    Restore Factory configuration 1
    T
    Touch Tone Dial
    &G0, 1, 2
    Guard Tone Options
    W
    Wait for Dial Tone
    &K0
    Disable DTE/DCE flow control
    ;
    Return to Command State
    &K1,2
    Not Supported
    @
    Wait for Quiet Answer Command
    &K3
    Enable RTS/CTS DTE/DCE flow
    !
    Flash Hook
    control
    ,
    Pause
    &K4
    Enable XON/XOFF DTE/DCE flow
    0-9/ABCD Dial Digits/Characters & wait
    control
    for credit card dial tone
    &K5
    Enable transparent XON/XOFF flow
    ^
    Toggles calling tone
    control
    L
    Redial last number
    &P0, 1, 2, 3
    Make to Break Ratio Options
    *,#
    Star digit – tone dialing
    &Q0
    Select direct asynchronous mode
    S=n
    Dial the number and store in
    &Q1,2,3,4
    Not Supported
    Directory, n= 0 to 3
    &Q5
    Modem negotiates an error corrected
    E0
    Disable command echo
    link
    E1
    Enable command echo
    &R0
    CTS tracks RTS
    H, H0
    Initiate a hang-up sequence
    &R1
    CTS always on
    H1
    If on-hook, go off-hook and enter
    &S0
    DSR always on
    command mode
    &S1
    DSR
    active
    after
    answer
    tone
    L0
    Set low speaker volume
    detected and inactive after loss of
    L1
    Set low speaker volume
    carrier
    L2
    Set medium speaker volume
    &T0
    Terminate Loopback Test
    L3
    Set high speaker volume
    &T1
    Initiate Loopback Test
    M0
    Speaker off
    \Bn
    Send break of n x 100 msec (n=0 to
    M1
    Speaker on during hand shaking and
    9)
    speaker off while receiving carrier
    \N0
    Select normal speed buffered mode
    M2
    Speaker on during hand shaking and
    \N1
    Select direct mode
    while receiving carrier
    \N2
    Select reliable mode
    M3
    Speaker off during dialing and receiving
    \N3
    Select auto reliable mode
    carrier
    and
    speaker
    on
    during
    answering
    \N4
    Force LAPM mode
    O0
    Go on-line
    \N5
    Force MNP mode
    O1
    Go
    on-line
    and
    initiate
    a
    retrain
    \V0
    Connect messages are controlled by
    sequence
    the command settings X, W, and
    S95
    Sn
    Select S Register n
    \V1
    Connect messages are displayed in
    Sn=m
    Write value m to S Register n
    the single line format
    Sn?
    Read the value of S Register n
    MODULATION COMMANDS
    ?
    Returns Last addressed S Register
    +MS
    Select modulation
    value
    V0
    Short Form Result Code Option
    +MCR=n
    Carrier protocol n reporting
    V1
    Long Form Result Code Option
    +MR=n
    Select
    extended
    Modulation
    X1, X2,
    Result Code Reporting Options
    Reporting of +MCR and +MRR to
    X3, X4
    DTE
    +++
    Escape Code Sequence
    +MRR=m, n
    Report Transmit m and Receive n
    Z0, Z1
    The
    modem
    performs
    soft
    reset.
    DCE rates to DTE
    Restore stored profile 0 or 1 after reset
    CALLER ID COMMANDS
    &C0
    Force DCD active regardless of the
    +VCID
    Select data presentation format n (0-
    carrier state
    2) for incoming calls.
    &C1
    DCD to follow the carrier state
    2006 Cermetek Microelectronics, Inc.
    Page 12
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 5. AT Command Summary (Continuation).
    Fax Modes. The CH1786A Product Family supports
    Command
    Function
    Send and Receive FAX. The modes and rates are
    +VRID
    Select data presentation format n (0-
    determined by the AT+F commands. Refer to Table
    1)
    for
    most
    recently
    received
    6A.
    incoming call.
    ERROR CORRECTING COMMANDS
    FAX modem processing is explicitly defined in ITU-
    %C0
    Disable data compression
    TV.29,
    ITU-TV.27,
    ITU-TV.21
    and
    ITU-T
    V.17
    %C1
    Enable MNP 5 data compression
    recommendations.
    All
    modulation,
    wave-form
    spectrum, and data processing functions conform to
    %C2
    Enable V.42bis data compression
    the appropriate specifications.
    %C3
    Enable both V.42bis and MNP 5
    compression
    STORED PROFILE COMMANDS
    PHONE LINE CONNECTION GUIDELINES
    &V
    Display current configuration
    1. The CH1786A must be mounted in the final
    &W0
    Store the active profile in NVRAM
    assembly such that it is isolated from exposure to
    profile 0
    any hazardous voltages within the assembly.
    &W1
    Store the active profile in NVRAM
    Adequate separation and restraint of cables and
    profile 1
    cords must be provided.
    &Y0
    Recall stored profile 0 upon power
    up
    2. The circuitry from the CH1786A to the telephone
    &Y1
    Recall stored profile 1 upon power
    line interface must be provided in wiring that
    up
    carries
    no
    other
    circuitry
    other
    than
    that
    &Zn=x
    Store dial string x (31 digits max) to
    specifically allowed in the FCC rules (such as A
    location n (0-3)
    and A1 leads).
    MNP10 COMMANDS
    -K0
    Disable MNP 10 extended services
    3. Connection to phone line should be made through
    -K1
    Disable MNP 10 extended services
    an RJ-11C jack.
    -K2
    Disable MNP 10 extended services
    FAX COMMANDS
    4. PCB traces from the modem’s RING and TIP pins
    +FCLASS=n
    Service Class
    to the RJ-11C jack must be 0.1 inch spacing or
    +F<cmd>?
    Report
    active
    configuration
    for
    greater to one another and 0.2 inch spacing or
    specified command cmd
    greater to all other traces. The traces should have
    +F<cmd>=?
    Report
    capabilitied
    for
    specified
    a nominal width of 0.020 inches or greater.
    command cmd
    +FAA=n
    Data/Fax Auto Answer
    5. The RING and TIP PCB traces should be as short
    +FLO
    Flow Control
    as possible and oriented to prevent coupling other
    +FMI?
    Report Manufacturer ID
    high speed or high frequency signals present on
    +FMM?
    Report Model ID
    the host circuit PCB.
    +FMR?
    Report Revisions ID
    +FRM=n
    Receive Data with n protocol
    6. No additional circuitry other than that shown in
    +FTM=n
    Transmit Data with n protocol
    Figure 6 may be connected between the modem
    +FRH=n
    Receive Data with HDLC Framing
    module and the RJ-11C jack.
    Doing so will
    with n protocol
    invalidate the FCC approval.
    +FTH=n
    Transmit Data with HDLC Framing
    7. Surge protection is provided internally. (See
    with n protocol
    Figure 6). This is mandatory to maintain FCC Part
    +FTS=n
    Stop Transmission and Wait
    68 conveyed approval.
    FAST CONNECT COMMANDS
    $F0
    Normal connection (Default)
    8. The CH1786A, the RJ-11C jack, the interfacing
    $F1,3,4
    Not Supported
    circuitry and all PCB traces in between, must be
    $F2
    V.22 Fast Connect
    contained on a PCB with a 94 V-0 flammability
    IDENTIFICATION COMMANDS
    rating.
    I0
    Reports product code
    I3
    Reports firmware Identification code
    9. The supplied FCC registration label must be
    applied visibly on the outside of the product.
    required by the CH1786A depending on user’s
    10. The product’s User Manual must provide the user
    initialization string.
    Unused outputs (from modem)
    with instructions for connection and use as
    should be left unconnected. Unused inputs should be
    recommended in the FCC Registration Section
    set to the proper logic level. See Table 2.
    below.
    2006 Cermetek Microelectronics, Inc.
    Page 13
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    CH1786A HANDLING AND ASSEMBLY
    notice is recommended and should be included in the
    RECOMMENDATIONS
    end product’s user manual.
    The CH1786A contains static-sensitive components
    and should only be handled by personnel and in areas
    that are properly protected against static discharge.
    FOR YOUR USER’S MANUAL
    The two recommended mounting techniques for
    The FCC Part 68 rules require the following (or
    physically connecting the CH1786A to a PCB are
    equivalent) be provided to the end user of equipment
    discussed below.
    containing a DAA.
    Direct Soldering.
    The CH1786A may be wave
    Type of Service . The (insert end product name) is
    soldered.
    All CH1786A products are hermetically
    designed to be used on standard device telephone
    sealed and will not be harmed by industry standard
    lines. It connects to the telephone line by means of a
    wave soldering processes.
    standard jack called the USOC RJ-11C (or USOC
    RJ45S). Connection to telephone-company-provided
    Socketing.
    The socketing approach to mounting
    coin service (central office implemented systems) is
    eliminates cleaning and desoldering concerns. When
    prohibited. Connection to party lines service is subject
    the socket is used, it must make a solid connection to
    to state tariffs.
    all pins.
    Failure to do so will cause unreliable or
    intermittent operation. Also, steps should be taken to
    Changes in Attestation Procedure for Plugs and
    assure that the module remains tightly seated in the
    Jacks. (Name of applicant) attests that the network
    socket during shipping. Cermetek recommends using
    interface plugs or jacks used on this equipment comply
    sockets from Samtec. See Application Note # 130,
    with and will continue to comply with the mechanical
    Summary of Recommended Suppliers.
    requirements specified in Part 68, sub-part F,
    specifically the dimensions, tolerances and metallic
    plating requirements.
    The compliance of these
    connectors will be assured by purchase specifications
    and incoming inspection.
    Documentation of such
    specifications and/ or inspections will be provided to
    the FCC within 30 days of their request for the same.
    Telephone Company Procedures. The goal of the
    telephone company is to provide you with the best
    service it can. In order to do this, it may occasionally
    be necessary for them to make changes in their
    equipment, operations or procedures.
    If theses
    changes might affect your service or the operation of
    your equipment, the telephone company will give you
    notice, in writing, to allow you to make any changes
    necessary to maintain uninterrupted service.
    Figure 5.
    Speaker Control Circuit: Optional to
    In certain circumstances, it may be necessary for the
    allow for call progress monitoring.
    telephone company to request information from you
    concerning the equipment which you have connected
    to your telephone line. Upon request of the telephone
    FCC REGISTRATION
    company, provide the FCC registration number and
    All products in the CH1786A family are registered with
    the ringer equivalence number (REN); both of these
    the FCC (Federal Communications Commission)
    items are listed on the equipment label. The sum of all
    under Part 68.
    To maintain the validity of the
    of the REN’s on your telephone lines should be less
    registration, you must serve notice to the end user of
    than five in order to assure proper service from the
    the products of several restrictions the FCC places on
    telephone company. In some cases, a sum of five
    the modem and its use.
    may not be useable on given line.
    Consult your
    telephone provider.
    In addition to restriction notification, the FCC requires
    that Cermetek make all repairs to all products in the
    If Problems Arise .
    If any of your telephone
    CH1786A family.
    If repairs are necessary after
    equipment is not operating properly, you should
    installation of the CH1786A in the end product and the
    immediately remove it from your telephone line, as it
    end product has been delivered to the end user, the
    may cause harm to the telephone network.
    If the
    end product must be returned to the end product
    telephone company notes a problem, they may
    supplier where the CH1786A can be removed and
    temporarily discontinue service. When practical, they
    then forward to Cermetek for repair. The following
    will notify you in advance of this disconnection.
    If
    2006 Cermetek Microelectronics, Inc.
    Page 14
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    advance notice is not feasible, you will be notified as
    Minimum DTR pulse width =0.1 seconds
    soon as possible.
    Ring count =01
    Escape code character =43
    When you are notified, you will be given the
    Carriage return character =13
    opportunity to correct the problem and informed of
    Line feed character =10
    your right to file a complaint with the FCC. Contact
    Back space character =08
    your local telephone service provider if you have nay
    Duration of wait for dial tone =02 seconds
    questions about your phone line.
    Duration of wait for carrier after dialing =30 seconds
    Duration of dial pulse (comma)=02 seconds
    In the event repairs are ever needed on the (insert
    Carrier detect response time =0.1 seconds
    your product name), they should be performed by
    Escape code guard time =1 second
    (insert your company name) or an authorized
    Length of use after comma =2.0 seconds
    representative of (insert your company name).
    For
    Last carrier to hang up delay =0.1 seconds
    information contact: (insert your company address).
    DTMF interdigit delay =0.1 seconds
    Sleep mode inactivity time = off
    Long space disconnect disabled
    DEFAULT STATUS, PERFORMANCE, AND
    V.22B selected
    SPECIFICATIONS
    Factory Defaults. The following is a summary of the
    Factory Pre-Configuration. Cermetek pre-configures
    Default Configuration Profile installed by Cermetek
    the CH1786A modems with the following command
    Microelectronics, Incorporated, prior to delivery of the
    set:
    CH1786A.
    Enter: AT+MS=V22B,1,300,2400,300,2400<CR>
    Async mode selected
    Result: OK
    2400bps
    Even parity
    Enter:
    Auto answer enabled
    ATS0=1%C0&C1&D0&S1&Q6\N0&Y0&W0<CR>
    Command echo ON
    Result: OK
    Error correction OFF
    All result codes enabled –extended
    Wait for dial tone before dialing =2 seconds
    IMPORTANT NOTE
    Detects busy signal
    Full word result codes
    If the AT&F, AT&F0 or AT&F1 commands are
    Pulse dial make/break ratio =39/61
    executed by the user, the Factory Pre-configuration
    DSR enabled
    commands specified above must be executed after
    Modem enabled DTR
    the AT&F, AT&F0 or AT&F1 commands to ensure
    DCD enabled
    proper configuration setup of the CH1786A
    Speaker enabled but off when receiving carrier
    Speaker volume set to low
    Guard tones disabled
    2006 Cermetek Microelectronics, Inc.
    Page 15
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    All models except
    CH1786AL and CH1786AN
    Figure 6.
    PSTN Line Interface for all CH1786A Products. CH1786AL and CH1786AN models do NOT
    contain internal Surge Protection (Dashed Box 2). The purchaser MUST be provide external
    surge protection to maintain conveyed FCC Part 68 approval.
    1. Current Limiting PSTN Protection Line Device.
    For severe environments, use an external three
    Current limiting devices are mandatory to meet UL
    terminal device with an earth ground as is shown in
    safety standards. To maintain conveyed FCC Part
    dashed Box 3.
    68 approval, the current limiting components
    identified as F1 and F2 in dashed Box 1 must also
    4. EMI/RFI Suppression.
    survive FCC Part 68 surge testing.
    Refer to
    Suppression of emitted EMI/RFI is recommended
    Cermetek Application Note #126, Supplemental
    and is typically required to obtain FCC part 15 A
    PSTN Line Protection, for more details. Refer to
    and/or B approval. EMI/RFI suppression circuitry is
    Application Note # 130, Summary of Recommend
    also used to suppress reception of externally
    Suppliers, for a list of suppliers and associated part
    generated EMI/RFI signals, such as strong radio
    numbers.
    signals, should the CH1786A be located near a
    source of such signals.
    Although no external
    A resettable/repairable fuse (rated at 0.15 amps) is
    EMI/RFI noise suppression circuitry is required to
    preferred because it resets automatically upon
    maintain
    conveyed
    FCC
    Part
    68
    approval,
    removal of the current flow. Non-resettable devices
    additional suppression may be added as described
    are also acceptable.
    Although CS-03 Part 1
    below without adversely affecting FCC Part 68
    (Canada) follows the requirements of FCC Part 68
    approval.
    (USA),
    Cermetek
    recommends
    contacting
    a
    certified independent lab to verify compliance in the
    specific application.
    A. To provide adequate EMI/RFI suppression, the
    capacitor/inductor network contained in dashed
    2. Over Voltage and Lightning Protection.
    Box 5 should be located as close to the RJ-11C
    Surge Protection is provided by internal circuitry
    Jack as possible. Further, this network should
    contained within all CH1786A models except
    be provided with an excellent ground path to the
    CH1786AL and CH1786AN. No additional external
    chassis.
    components are required to maintain conveyed
    FCC Part 68 approval for all models EXCEPT
    B. Capacitors C1 and C2 should not exceed
    CH1786AL and CH1786AN.
    0.005 µ f. They must have a rating of 1.5KV and
    typically are 0.001 µ f ± 20%. Inductors L1 and
    For CH1786AL and CH1786AN, the required surge
    L2 may be either individual inductors or a dual
    protection (identified as D1 in Dashed Box 2) must
    inductor. Refer to Application Note #130 for a
    be supplied externally. The purchaser must include
    list of suppliers. For UL applications, choose
    some form of surge protection as described herein
    capacitors and inductors that are UL 1950
    to maintain conveyed FCC Part 68 approval. Refer
    Edition 3 listed.
    The actual values of the
    to Application Note # 130 for a list of suppliers.
    components used may vary depending on the
    end product design and the nature of the EMI/
    3. Optional External Over Voltage and Lightning
    RFI.
    Consult an FCC Part 15 consultant, if
    Protection.
    required.
    In most environments, the internal two terminal
    surge suppressor (see dashed Box 3) is adequate.
    2006 Cermetek Microelectronics, Inc.
    Page 16
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 7. CH1786A System Data Mode Compatibility Specifications.
    Parameter
    Specification
    Parameter
    Specification
    Asynchronous
    2400, 1200 600 bps character
    Receive Carrier
    Originate 2400Hz ± 7Hz
    asynchronous.
    Frequencies
    Answer
    1200Hz ± 7Hz
    0-300 bps asynchronous
    V.22 bis, V.22,
    212A
    Asynchronous
    Speed
    TXD may differ +1%, -2.5%
    Bell 103
    Answer
    ‘space’ 2020Hz ±
    Range
    from modem output. Offsets
    7Hz
    will be corrected by adding/
    Answer
    ‘mark’
    2225Hz ±
    deleting stop bits.
    7Hz
    Originate ’space’
    1070Hz ±
    7Hz
    Originate ‘mark’
    1270Hz ±
    7Hz
    Asynchronous Format
    8,9,10 bits, including start,
    Receiver
    OFF to ON threshold –43
    stop, parity.
    Sensitivity
    dBm
    ON to OFF threshold –48
    dBm
    Telephone Line Interface
    Two-wire
    full
    duplex
    over
    Billing Delay
    2.0 to 3.0 seconds (T a =25°C)
    public switched network. On-
    chip hybrid and billing delay
    timers.
    Modulation
    V.22 bis, 16 point QAM at 600
    Hysteresis
    2 dB minimum
    baud. V.22 and 212A, 4 point
    DPSK at 600 baud.
    103
    Binary phase coherent FSK.
    Self
    Test
    Pattern
    Alternate ‘ones’ and ‘zeros’
    Line
    Fixed
    compromise
    Generator
    and error detector, to be used
    Equalization
    equalization,
    transmit.
    along with most loopbacks. A
    Adaptive
    equalizer
    for
    number
    indicating
    the
    bit
    PSK/QAM, receive.
    errors detected is sent to DTE.
    Transmit
    Carrier
    Originate 1200Hz ± .01%
    Diagnostic
    Local analog loopback. &T1
    Frequencies
    V.22
    bis,
    Answer
    2400Hz ± .01%
    Available
    Local analog loopback.
    V.22, 212A
    Must be used with error
    correction off (AT&Q6).
    Bell 103
    Originate ’space’
    1070Hz ±
    Call Progress
    With speaker or quiet screen
    .01%
    Tones Detected
    messages (No dial tone,
    Originate ‘mark’
    1270Hz ±
    busy, ring, modem answer
    .01%
    tone and voice).
    Answer
    ‘space’ 2025Hz ±
    Computer
    IBX PC/XT/AT bus
    .01%
    Interface
    compatible with an
    Answer
    ‘mark’
    2225Hz ±
    8250/16450/16550A UART
    .01%
    as a serial controller.
    2006 Cermetek Microelectronics, Inc.
    Page 17
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 8. CH1786A Electrical Specifications.
    Parameter
    Description
    Min.
    Typ.
    Max.
    Units
    V CC
    Positive Supply Voltage- Noise less than 50mV
    4.75
    5.0
    5.25
    V
    I CC Off Hook
    Nominal Operating Current when modem is OFF Hook
    61
    67
    mA
    I CC On Hook
    Nominal Operating Current when modem is ON Hook
    58
    64
    mA
    I CCPD
    Power Down Current @
    0.0
    mA
    2
    V CC = 5.5V when modem is in Power Down Mode
    I RIPD
    Current Supplied into RI pin when in Power Down
    11.0
    uA
    2
    Mode @ V CC = 5.5V
    1
    V IH
    High Level Input Voltage
    2
    Vcc+.
    V
    5
    1
    V IL
    Low Level Input Voltage
    0
    0.8
    V
    I IN
    Input Leakage Current (TXD, DTR, RTS)
    -10
    +10
    uA
    I LO
    Leakage Current DCD, HS, RXD, SLEEP, DSR
    -10
    +10
    uA
    VT+
    Positive Hysteresis Threshold for RESET pin
    3.0
    V
    VT-
    Negative Hysteresis Threshold for RESET pin
    1.33
    V
    1
    V OH
    High Level Output Voltage (I OH = 2.0mA)
    2.4
    V
    1
    V OL
    Low Level (I OL = - 2.0mA)
    0.4
    V
    Test conditions: VCC = 5V ± 10%, Temp = 0 ° C to 70 ° F (unless otherwise stated).
    Notes:
    1. Output Load = 50 pF ± one TTL.
    2. With recommended 30k ohm external resistor. Maximum external resistor range: 10k to 100k ohm.
    Table 9. CH1786A Electrical Specifications.
    Parameter
    Minimum
    Typical
    Maximum
    Units
    Comments
    DC Off Hook Impedance
    125
    312
    Ohms
    @16 to 80 ma
    Trans Hybrid Loss
    25
    dB
    600 Ohm, RXA, TXA
    Ring Voltage Detect
    25VAC
    35VAC
    V RMS
    Typically riding on 48VDC
    Line Loop Current-
    16
    80
    mA
    (Off-Hook)
    Return Loss @ 1000Hz
    15
    dB
    600 Ohm
    Ring Detect Frequencies
    14
    20
    35
    Hz
    Receiver Insertion Gain
    -0.5
    0.0
    +0.5
    dBm
    600 Ohm- Data Mode
    Transmit Power
    -17.2
    -13.0
    -9.5
    dBm
    Into 600 Ohm Load
    (Adjustable with S91)
    First Character After Reset
    0.5
    1.0
    5
    sec
    Delay
    Inter Character Delay
    20
    50
    msec
    Between all command
    characters
    Command Delay
    100
    200
    msec
    Between all AT commands
    Maximum Reset Drive
    0
    10K
    Ohms
    Minimum Reset Pulse
    10
    msec
    If user supplied
    Duration
    2006 Cermetek Microelectronics, Inc.
    Page 18
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 10. Other Performance Specifications.
    Parameter
    Minimum
    Typical
    Maximum
    Units
    Comments
    DTMF total power
    -5.3
    -5.6
    --5.8
    dBm
    Into 600 ohm load
    DTMF Twist (Balance)
    2
    3
    dB
    DTMF Tone Duration
    50
    85
    255
    ms
    85ms default
    Pulse Dialing Rate
    8
    10
    20
    pps
    10pps default
    Pulse Dialing Make/
    39/61
    %
    US, Canada default
    Break
    Pulse Interdigit Interval
    700
    3000
    ms
    789ms default
    Guard Tone Frequency
    1800
    Hz
    Referenced to High Channel
    Transmit
    Guard Tone Amplitude
    -9
    dB
    Referenced to High Channel
    Transmit
    High Channel Transmit
    -1
    dB
    Referenced to Low channel,
    Amplitude
    Guard tone enabled
    nd
    Guard Tone 2
    -40
    dB
    Harmonic Distortion
    Call Progress
    205
    720
    Hz
    @ -20 dBm received tone
    Passband Frequency
    Wait Time for Dial tone
    2
    255
    sec
    Two second default
    Return loss @ 1000Hz
    15
    dB
    T r =600 Ω
    Table 11. Analog Characteristics.
    Name
    Type
    Characteristic
    Value
    SPK
    O(DF)
    Minimum Load
    300 Ω
    Maximum Capacitive Load
    0.01µ
    Output voltage
    1.65± .6V
    2006 Cermetek Microelectronics, Inc.
    Page 19
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 12. CH1786A Pin Functions.
    PACKAGE CONNECTION TABLE
    PIN NO.
    FUNCTION
    PIN NO.
    FUNCTION
    1
    RING
    12
    V/D
    2
    TIP
    13
    DTR
    3
    RXA
    14
    DSR
    4
    TXA
    15
    RI
    5
    SPK
    16
    CTS
    6
    NC
    17
    DCD
    7
    NC
    18
    NC
    8
    SLEEP
    19
    VCC
    9
    NC
    20
    GND
    10
    TXD
    21
    RST
    11
    RXD
    22
    NC
    Figure 7.
    CH1786A Physical Dimensions.
    2006 Cermetek Microelectronics, Inc.
    Page 20
    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    Table 13A. Summary CH1786A Family of Non-RoHS Compliant Products.
    Model
    Summary of Features
    Operating Temperature
    CH1786A
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed
    0°C to + 70°C
    CH1786A-C
    Full Function with Caller ID (CID), 2400bps, FCC Part 68
    0°C to + 70°C
    Approved, UL 1950 Listed
    CH1786A-L
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed,
    0°C to + 70°C
    No EEPROM, No Internal Surge Protection
    CH1786A-N
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed,
    0°C to + 70°C
    No EEPROM, No Internal Surge Protection, No 2-4 Wire
    Converter Circuit (i.e., No Voice Inject Capability)
    CH1786A-P
    Full Function with Zero Power Down, 2400bps, FCC Part 68
    0°C to + 70°C
    Approved, UL 1950 Listed
    CH1786A-CP
    Full Function with Caller ID (CID) and Zero Power Down,
    0°C to + 70°C
    2400bps, FCC Part 68 Approved, UL 1950 Listed
    CH1786A ET
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed
    -40°C to +85°C
    CH1786A ET-C
    Full Function with Caller ID (CID), 2400bps, FCC Part 68
    -40°C to +85°C
    Approved, UL 1950 Listed
    CH1786A ET-P
    Full Function with Zero Power Down, 14.4kbps, FCC Part 68
    -40°C to +85°C
    Approved, UL 1950 Listed
    CH1786A ET-CP
    Full Function with Caller ID (CID) and Zero Power Down,
    -40°C to +85°C
    2400bps, FCC Part 68 Approved, UL 1950 Listed
    Table 13B. Summary CH1786A Family of RoHS Compliant Products.
    Model
    Summary of Features
    Operating Temperature
    CH1786AR
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed
    0°C to + 70°C
    CH1786AR-C
    Full Function with Caller ID (CID), 2400bps, FCC Part 68
    0°C to + 70°C
    Approved, UL 1950 Listed
    CH1786AR-L
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed,
    0°C to + 70°C
    No EEPROM, No Internal Surge Protection
    CH1786AR-N
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed,
    0°C to + 70°C
    No EEPROM, No Internal Surge Protection, No 2-4 Wire
    Converter Circuit (i.e., No Voice Inject Capability)
    CH1786AR-P
    Full Function with Zero Power Down, 2400bps, FCC Part 68
    0°C to + 70°C
    Approved, UL 1950 Listed
    CH1786AR-CP
    Full Function with Caller ID (CID) and Zero Power Down,
    0°C to + 70°C
    2400bps, FCC Part 68 Approved, UL 1950 Listed
    CH1786AR ET
    Full Function, 2400bps, FCC Part 68 Approved, UL 1950 Listed
    -40°C to +85°C
    CH1786AR ET-C
    Full Function with Caller ID (CID), 2400bps, FCC Part 68
    -40°C to +85°C
    Approved, UL 1950 Listed
    CH1786AR ET-P
    Full Function with Zero Power Down, 2400bps, FCC Part 68
    -40°C to +85°C
    Approved, UL 1950 Listed
    CH1786AR ET-CP
    Full Function with Caller ID (CID) and Zero Power Down,
    -40°C to +85°C
    2400bps, FCC Part 68 Approved, UL 1950 Listed
    2006 Cermetek Microelectronics, Inc.
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    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    ATTACHMENT I
    Page 1 of 2
    Table 14. Cross Compatibility Comparison Chart.
    Old (non “A”) Model
    Equivalent New Model
    Comments
    CH1786
    CH1786A
    Standard CH1786A. No Options needed.
    CH1786LC
    CH1786A-L
    No EEPROM, No Internal Surge Protection.
    CH1786ET/PD
    CH1786A-ET
    Standard extended temp CH1786A. No
    or
    options needed if Power Down not required.
    CH1786A ET-P
    Standard extended temp CH1786A with
    Power Down option.
    CH1786NH
    CH1786A-N
    No EEPROM, No Internal Surge Protection,
    No 2-4 wire circuitry (i.e., No voice inject
    capability).
    Table 15. Summary of differences between CH1786 and CH1786A products.
    ITEM
    CH1786
    CH1786A
    PIN CONFIGURATION
    PIN 18
    HS. LOW indicates 2400bps operation.
    Not Supported. No Connect.
    IDENTIFICATION COMMANDS
    ATI0 . Product Code.
    242
    14400
    ATI1 . ROM Checksum.
    192
    042
    ATI2 . Checksum
    OK
    OK
    Verification.
    ATI3 . Identify
    current
    AFES-C2501-H0
    CX81802-V32
    firmware code.
    MODEM OPERATION COMMANDS
    Long Space Disconnect.
    ATYn command supports:
    Not Supported.
    n=0
    Disables long space disconnect
    (default).
    n=1
    Enables long space disconnect.
    On-Line Echo Character.
    ATFn command supports:
    Not Supported.
    n=0 Returns ERROR result code.
    n=1
    Returns OK result code (default).
    Test and Diagnostic.
    AT&Tn command supports:
    AT&Tn command supports:
    n=0
    Terminates test in progress.
    n=0
    Terminates test in progress.
    n=1 Initiates Analog loopback.
    n=1
    Initiates Analog loopback.
    n=2
    Returns ERROR.
    n=2-8 Not Supported.
    n=3
    Initiates local Digital loopback.
    n=4
    Enables
    Digital
    loopback
    acknowledgement from remote RDL.
    n=5
    Disables
    Digital
    loopback
    acknowledgement from remote RDL.
    n=6
    Initiates remote Digital loopback.
    n=7
    Initiates remote Digital loopback
    with self test.
    n=8 Initiates local Analog loopback
    with self test.
    NOTE:
    The identification code returned when the I0 , I1 , I3 commands are executed may vary, depending on
    manufacture date.
    2006 Cermetek Microelectronics, Inc.
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    Document No. 607-0019 Revision A8 (03/06)
    Cermetek Microelectronics, Inc.
    CH1786A Family of Ultra Small 2400bps Modems
    ATTACHMENT I
    Page 2 of 2
    Table 14. Summary of differences between CH1786 and CH1786A products (Continued).
    ITEM
    CH1786
    CH1786A
    FAX OPERATION COMMANDS
    Flow Control.
    AT+FF command supports:
    AT+FLO command supports:
    n=0
    Disable
    enhanced
    flow
    n=0 XON/XOFF and RTS/CTS flow control turned off
    control (default). EIA-578 standard.
    (default).
    n=1
    Enables
    enhanced
    flow
    n=1 XON/XOFF flow control on in both directions.
    control.
    n=2 Use RTS for flow control of modem by DTE; use CTS
    flow control of DTE by modem.
    Transmit Test Data.
    +FTTn=m command.
    Not Supported.
    Receive Test Data.
    +FRTn command.
    Not Supported.
    NVRAM
    Stored Telephone
    36 digits (maximum)
    31 digits (maximum)
    Number Length
    STORED PARAMETERS
    Retrieval of factory
    Execute AT&F or AT&F1 to retrieve
    Execute AT&F, AT&F0 or AT&F1 to retrieve Firmware
    default profiles.
    Firmware Default setup parameters.
    Default setup parameters. To restore the CH1786A to the
    CH1786 default configuration, the following commands
    MUST be executed after executing the AT&F, AT&F0 or
    AT&F1 commands:
    Enter:
    AT+MS=V22B,1,300,2400,300,2400<CR>
    Result: OK
    Enter:
    ATS0=1%C0&C1&D0&S1&Q6\N0&Y0&W0<CR>
    Result: OK
    Cermetek reserves the right to make changes in specifications at any time and without notice. The information furnished by
    Cermetek in this publication is believed to be accurate and reliable. However, Cermetek assumes no responsibility for its use, or for
    any infringements of patents or other rights of third parties resulting from its use. No license is granted under any patents or patent
    rights of Cermetek.
    Cermetek provides the user with a FCC (USA) and IC (Canada) Approved or device. However, Cermetek does not have influence
    over nor knowledge of the specific user application environment. Therefore, for FCC and IC Approved or Approvable devices, the
    user assumes all risk for maintaining compliance to registration.
    Printed in U.S.A
    1390 BORREGAS AVNUE | SUNNYVALE CA 94089 | LOCAL: 408-752-5000 | TOLL FREE: 1-800-882-6271 | FAX: 408-752-5004
    CERMETEK WEB SITE: http://www.cermetek.com | EMAIL: sales@cermetek.com
    2006 Cermetek Microelectronics, Inc.
    Page 23
    Document No. 607-0019 Revision A8 (03/06)