EV8680 datasheet(28/39 Pages) CMLMICRO

28 / 39 page

Evaluation Kit for CMX868

EV8680

UM8680/2

1.6.5.3 Negotiation and Data Transfer

Modem negotiation (handshaking) may be aborted by pushing any key prior to entering data transfer

mode.

During data transfer mode the user can revert to on-line AT command mode by typing the escape

code sequence (+++).

The escape code guard time (based on S12) must have expired to

successfully access this mode. Whilst in on-line AT command mode the board to remote modem

connection may be aborted by typing ATH0 (instructs modem to go on-hook). Alternatively the user

can enter relevant AT commands or return to data transfer mode by using the ATO command.

The firmware only supports asynchronous data transfer.

Receiver USART overspeed settings specified in S-Register, S26, only apply to DPSK/QAM operating

modes.

Transmitter Guard Tone settings specified in S-Register, S23, only apply to DPSK/QAM answering

modes.

If the carrier is lost (during data transfer) or negotiation is aborted by the user, the firmware will send

the General Reset Command to the CMX868 evaluation device. This action will cause the EV8680

evaluation board to hang up and powersave the CMX868 device.

The data transfer firmware does not contain any retrain code. This process is sometimes performed

by modems when signal distortion or line noise is detected which may threaten data integrity.

The receive auto equaliser function can be enabled via the S24 register. This S24 register setting only

applies to DPSK modes of operation. The CMX868 firmware for V22bis always enables the receive

auto equaliser half way through the negotiation phase.

1.6.5.4 Example AT Commands for Hayes Optima 336 Modem (not supplied) Setup

V.22bis Protocol - AT&FB30X1Q0E1V1L0N0W2S37=6S95=42

V.22 Protocol - AT&FB0X1Q0E1V1L0N0W2S37=5S95=42

1.6.6

Example EV8680 Modem Tests

1.6.6.1 Set up EV8680 to Automatically Answer a V.22 Call from a Remote Modem

1. Select V.22 communication standard (default is V.22 bis).

Command : ATB1<CR>

2. Select the required Guard Tone setting using the AT&Gn command (default is none).

3. Enable/Disable Fixed Compromise Equalisers by writing to S-Register, S24 (default is enabled).

4. Configure CMX868 Transmitter by writing to S-Register, S25.

5. Configure CMX868 Receiver by writing to S-Register, S26.

6. Set Automatic Answer S-Register (S0) to 5 rings.

Command : ATS0=5<CR>

EV8680 Datasheet(PDF) 28 Page - CML Microcircuits