AN93

Table 39. Basic AT Command Set (Continued)

 

 

 

Command

 

Action

 

 

 

Synchronous access mode control options

 

ASpecifies action taken if an underrun condition occurs

 

during transparent sub-mode

 

 

0 = Modem transmits 8-bit SYN sequences (see

 

+ESA[G]) on idle.

 

BSpecifies action taken if an underrun condition occurs

 

after a flag during framed sub-mode

 

 

0 = Modem transmits 8-bit HDLC flags on idle.

 

CSpecifies action taken if an underrun or overrun condition

 

occurs after a non-flag during framed sub-mode

 

 

0 = Modem transmits abort on underrun in middle of

+ESA =

frame.

A,B,C,D,E,F,G

 

1 = Modem transmits flag on underrun in middle of frame

 

 

and notifies host of underrun or overrun.

 

DSpecifies V.34 half duplex operation. This parameter should

 

not be used.

 

E – Specifies CRC polynomial used while in framed sub-mode

 

 

0 = CRC generation checking disable

 

 

1 = 16-bit CRC generation and checking is performed by the

 

modem

 

F – Specifies NRZI encoding and decoding

 

 

0 = NRZI encoding and decoding disabled

 

G – Defines 8-bit SYN

 

 

255 = Fixed at 255 (marks)

 

 

 

Class 1 Mode Enable.

 

X

Mode

+FCLASS = X

0

Off

 

1

Enables support for V.29 Fast Connect mode.

 

8

Enables voice mode.

 

256

SMS mode

 

 

 

Class 1 Receive Carrier.

 

X

Mode

 

2

Detect V.21 (980 Hz) tone for longer than 100 ms, then

 

 

send answer tone

+FRM = X

 

(2100/2225 Hz) for 200 ms.

 

95

V.29 short synchronous.

 

96

V.29 full synchronous.

 

200

Returns to data mode prepared to receive an SMS mes-

 

sage.

 

 

 

 

Rev. 1.3

67

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Silicon Laboratories SI2494/39 Specifies action taken if an underrun condition occurs, During transparent sub-mode, Frame