ST75C520 datasheet(14/45 Pages) STMICROELECTRONICS

14 / 45 page

V.2 - Command Set

The Command Set has the following attractive

features :

- user friendly with easy to remember mnemonics,

- possibility of straightforward expansion with new

commands to suit specific customer require-

ments,

- easy upgrade of existing software using previous

modem based SGS-THOMSON products.

The command set has been designed to provide

the necessary functional control on the ST75C520.

Each command is classified according to its syntax

and the presence/absence of parameters. In the

case of a parametric command, parameters must

first be written into the dual port RAM before the

command is issued. Acknowledge and error report

is issued for each command entered.

V.2.1 - Command Set Summary

V.2.1.1 - Operational Control Commands

INIT

Initialize. Initialize the modem engine.

Set all parameters to their default values

and wait for commands of the control

processor. Non parametric command.

IDT

Identify. Return the product identification

code. Non parametric command.

SLEEP

Turn to low power mode, the ST75C520

enters the low power mode and stops its

crystal oscillator to reduce power

consumption. In this mode all the clocks

are stopped and the dual RAM is

unreachable.

HSHK

Handshake. Begins the handshake

sequenc e. The

modem engi ne

generates all the sequences defined in

the ITU-T recommendations. A status

report indicates to the control processor

the state of the handsha ke. This

command only applies to modes where

a handshake sequence is defined. A

CONF command must have been issued

prior to the use of HSHK. Non parametric

command.

STOP

FAX S to p. Stop FAX Half-dup le x

transmitter. Non parametric command.

SYNC

FAX Synchronize. Start/Stop of FAX

Hal f- du ple x r ec ei ver. P ar ame t r ic

command.

CSE

Clear Status Error. Selectively clears the

Error status byte SYSERR. Parametric

command.

SETGN

Set Gain. This command sets the global

gain factor, which is used for the transmit

samples. Parametric command.

V.2.1.2 - Data Communication Commands

XMIT

Tra n sm i t

D a ta.

S tar t/sto p

t he

transmission of data in parallel mode.

After a XMIT command, the ST75C520

sends the data contained in its dual port

RAM.

SERIAL Select Serial or Parallel Mode. This

command selects the data source, i.e.

either parallel or serial. The parallel

mode uses a part of the dual port RAM

as a double buffer. The serial mode uses

the serial synchronous I/O. Parametric

command.

FORM

Selects the Transmission Format (only in

para l le l m ode). Th is c omma nd

configures the data interface for both

receiver and transmitter according to the

selected da ta fo rmat. Parametr ic

command (HDLC or synchronous). In

s er ial m ode, f o r m at i s al wa y s

synchronous.

V.2.1.3 - Memory Handling Commands

Memory Write. This command is used to

write an arbitrary 16-bit value into the

writable memory location currently

specified by a parameter. Parametric

command.

Memory Read. This command allows the

controller to read any of the ERAM or

CROM (ST75C520 memory spaces)

l oc a ti on w it ho ut in t er ru pt in g t h e

processor. Parametric command.

Complex Read. This command allows

the controller to read at the same time

the real and imaginary part of a complex

value stored in a double ERAM or

CROM location. This feature is very

interesting for eye pattern software

control and for equalization monitoring.

This command insures that the real and

imaginary parts are sampled in the

memory at the same time (integrity).

Parametric command.

ST75C520

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