STLC5464 datasheet(27/83 Pages) STMICROELECTRONICS

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III.3.2 - GCI and V* Protocol

A TDM can carry 8 GCI channels or V* channels. The monitor and S/C bytes always stand at the same

position in the TDM in both cases.

CGI Channel 0

CGI Channel 1 to Channel 6

CGI Channel 7

TS0

TS1

TS2

TS3

TS28

TS29

TS30

TS31

MON

S/C

MON

S/C

III - FUNCTIONAL DESCRIPTION (continued)

The GCI or V* channels are composed of 4 bytes

and have both the same general structure.

MON

S/C

B1, B2 : Bytes of data. Those bytes are not

affected by the monitor and CI protocols.

MON

: Monitor channel for operation and

maintenance information.

S/C

: Signalling and control information.

Only Monitor handshakes and S/C bytes are dif-

ferent in the three protocols :

ISDN V* S/C byte

C/I 4 bits

ISDN GCI S/C byte

C/I 4 bits

Analog GCI S/C byte

C/I 6 bits

CI : The Command/Indicate channel is used for

activation/deactivation of lines and control

functions.

D : These 2 bits carry the 16 kbit/s ISDN basic

access D channel.

In GCI protocol, A and E are the handshake bits

and are used to control the transfer of information

on monitor channels.The E bit indicates the trans-

fer of each new byte in one direction and the A bit

acknowledges this byte transfer in the reverse di-

rection.

In V* protocol, there isn’t any handshakemode.The

transmitter has only to mark the validity of the

Monitor byte by positioning the E bit (T is not used

and is forced to ”1”).

For more information about the GCI and V*, refer

to the General Interface Circuit Specification (is-

sue1.0, march 1989) and the France Telecom

Specification about ISDN Basic Access second

generation (November 1990).

III.3.3 - Structure of the Treatment

GCI/V* TDM’s are connected to DIN 4 and DIN 5.

The D channels are switched through the matrix

towards the output 7 and the HDLC receiver. The

Monitor and S/C bytes are multiplexed and sent to

the CI and Monitor receivers (see Figure 11 on

Page 28).

In transmission, the S/C and Monitor bytes are

recombined by multiplexing the information pro-

vided by the Monitor,C/I and the HDLC Transmitter.

Like in reception,the D channel is switched through

the matrix.

III.3.4 - CI and Monitor Channel Configuration

Monitor channel data is located in a time slot ; the

CI and monitor handshakebits are in the next time

slot.

Each channel can be defined independently. A

table with all the possible configurations is pre-

sented hereafter (Table 13).

Table 13 : C/I and MON Channel Configuration

C/I validated or not

CI For analog subscriber (6 bits)

CI For ISDN subscriber (4 bits)

Monitor validated

or not

Monitor V*

Monitor GCI

Note : A mix of V* and GCI monitoring can be performed for two

distinct channels in the same application.

III.3.5 - CI and Monitor Transmission/Reception

Command

The reception of C/I and Monitor messages are

managed by two interrupt queues.

In transmission, a transmit command register is

implemented for each C/I and monitor channel (16

C/I transmit command registers and 16 Monitor

transmit command registers). Those registers are

accessible in read and write modes by the micro-

processor.

STLC5464

27/83

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