AN93

Table 142. AT Commands Provided to Support SIA Level-3 Protocol Communication (Continued)

AT Command

Modem Function

Remarks

 

 

 

AT+F1

Enable B103 Receiver for Data Block

Modem enables FSK receiver, waits for >12T marks

 

reception.

to be detected, then sends CONNECT message to

 

 

DTE to indicate a received Data Block follows.

 

 

Modem will stay in this mode indefinitely until an AT

 

 

command is issued by DTE. It is usually a

 

 

+F3(ACK), +F4(NACK) or +F5(ACK followed by

 

 

Data Block transmission) command.

 

 

Note1: Modem will wait for up to 1 second to detect

 

 

>12T marks before unclamping RXD. After 1 sec-

 

 

ond RXD will be unclamped regardless.

 

 

Note 2: The +F1 command can be used to resume

 

 

SIA protocol communication after a voice listen-in or

 

 

V.32bis interruption.

 

 

 

AT+F2

Enable tonal ACK/NACK detection.

Detect and report ACK or NACK to DTE.

 

 

‘OK’ for ACK and ‘ERROR’ for NACK.

 

 

A NACK will be reported if no valid signal is

 

 

detected within 2.5 seconds.

 

 

 

AT+F3

Transmit Tonal ACK

Transmit Space for 600 ms. Send ‘OK’ prompt to

 

 

DTE when done.

 

 

 

AT+F4

Transmit Tonal NACK

Transmit Mark for 600 ms. Send ‘OK’ prompt to

 

 

DTE when done.

 

 

 

AT+F5

Transmit Tonal ACK with reverse chan-

Transmit Space for 600 ms, followed by Mark for

 

nel command.

180 ms. Then send CONNECT to DTE to indicate

 

 

modem is ready to accept data.

AT+F6

Abort current Data Block Reception or

This command is useful for exception handling,

 

Transmission.

such as timeout. If the FSK transmitter was on, +F6

 

 

shuts it off. FSK reception is aborted and modem

 

 

returns to the AT command mode.

 

 

 

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Rev. 1.3

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Silicon Laboratories SI2493/57/34/15/04, SI2494/39 manual AT+F1, AT+F2, AT+F3, AT+F4, AT+F5, AT+F6