ST75C540 datasheet(48/84 Pages) STMICROELECTRONICS

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VIII.2.5.2 - Default Optional Status in Fax Mode

While in Fax Modem mode the format of the STAOP word is as follows :

Optional Status Words in MODEM Mode

Add.

Name

Bit

543

$0C

STAOP0

SPEED

(2)(5)

SPVAL

(1)(5)

$0D

STAOP1

STAQUAS

$0E

STAOP2

PNSUCs

PRDETs

PNDETs

SCR1s

PRs

PNs

P2s

P1s

$0F

STAOP3

TDT19

TDT18

TDT17

TDT16

DTMF_DIGIT

(4)

Notes : 1. SPVAL is active in V.33 receiver only at the same time as the rising transition of the SCR1s signal. When SPVAL is set, it indicates

that the SPEED bits contain the Data speed information.

2. SPEED is valid in V.33 receiver only it can have 2 values, after the SCR1s signal goes high : 1000 for 14400bps and 0111 for

12000bps.

3. The STAOP2 Bit reflects the progression of the Synchronisation.

4. Only valid in V.21 Channel 2 Receive mode.

The STAOP2 Bits have the following meanings :

STAOP2 in Fax Modem Mode

Name

Position

Description

P1s

Unmodulated carrier sequence. Optional, used for echo protection.

P2s

Continuous 180

° phase reversal sequence

PNs

Equalizer trainning sequence

PRs

V.33 and V.17 rate sequence

SCR1s

Continuous scrambled 1 sequence

PNDETs

Turned on after PN sequence detection

PRDETs

Turned on after PR sequence detection (V.33 and V.17 only)

PNSUCs

Turned on after succesfull training of the receive equalizer. When on at the end of the

synchronization, the transmition BER is statisticaly bellow 10ppm.

VIII - STATUS DESCRIPTION (continued)

ST75C530 - ST75C540

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