MTC-20172-PC AMI Semiconductor, Inc., MTC-20172-PC Datasheet - Page 56

• Manufacturer Part Number: MTC-20172-PC
• Description: S Interface Circuit for ISDN (SIC)
• Manufacturer: AMI Semiconductor, Inc.

6.3 The B-Channels on
The B-channels are 64 kbit/s. They
are transparent channels used for a
point-to-point switched connection.
Idle B-channels are often forced at all
binary 1.
In other interface devices, the direction
of the B-channels can be reversed on
the GCI data pins. This is not possible
in the MTC-20172 SIC.
Also, the position of the GCI B-
channels can be moved to alternative
positions. This is not possible with
MTC-20172 SIC.
Fig. 6.5 : Explanation of Notation of the SDL Diagrams
the GCI bus
6.4 The D-Channels on
The D-channel contains HDLC
messages.
In NT/LT-S mode the D-channel is
exchanged transparently with the S-
bus.
In TE/LT-T mode there is a D-channel
access protocol on the S-bus, which
limits the transport of the D-channel to
the S-bus, see 5.7.
The TIC bus protocol used by other
divices for D-channel Access control in
an intelligent NT is NOT supported,
see 5.8.
the GCI bus
46
MTC-20172
Data Sheet & Reference Manual
Rev. 1.1 February 1997
6.5 The Command/
The S-bus transceiver must be put in a
defined state according to CCITT
I.430. This happens partially under its
own control and under supervision of
an external controller.
In the C/I channel, commands to and
state indications from the MTC-20172
SIC are exchanged with a control
element (µ-controller) or with an other
uplink or downlink ISDN circuit.
The state diagram of the C/I channel,
the possible commands and
indications, and the internal reaction of
the S-transceiver are all defined in the
GCI standards, which allow a simple
interconnection of uplink and downlink
ISDN elements. Unfortunately, a few
dialects of the C/I exist.
Moreover, some unused commands
and indications can be used for other
purposes (e.g.maintenance/monitoring)
and can be chosen according to the
component manufacturer.
In MTC-20172 SIC, two version
of the C/I command channel are
implemented:
1) The V* version
The C/I channel works according to
the Mietec MTC-2072 SIC. It can be
linked to the MTC-2071 UIC (4B3T) of
MIETEC and the IEC of Siemens at the
NT. The MTC-20172 SIC is fully
compatible, with a few extra
commands available.
2) The GCI version
The C/I channel is compatible with
many other devices. It can be linked to
the UID of ST/NSC and to the 2B1Q
U-device of Siemens.
Compared to the V* version, GCI
incorporates minor changes and
additions. Some commands are coded
with binary numbers differently from
Indication (C/I)
Channel