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PEB 20321
PEF 20321
IOM
-2 Interface
Data Sheet
190
2001-02-14
8.1
The IOM
-Revision-2 (IOM
-2) standard defines an industry standard serial bus for
interconnecting telecommunications ICs. The standard covers line card, NT1, and
terminal architectures for ISDN and analog loop applications.
In digital telephone switches, an inter-chip communication bus is often used to connect
the codec/filter ICs to the switch backbone. Typically, a separate serial bus is used
between each codec/filter IC and a line-card controller IC. The line card controller
provides the connection to the switch backbone, as well as an interface to the
microprocessor that controls the line card. The inter-chip bus structures that were used
in this single channel per line pre-ISDN (Integrated Services Digital Network) telephone
equipment are not well-suited for the 2 B + D structure of ISDN.
To address this problem, four major European telephone equipment manufacturers
jointly defined a new interface bus. These four companies, Alcatel, Italtel, Plessey, and
Siemens invented a bus structure that satisfied the requirements of both ISDN and
analog applications. The General Circuit Interface, or GCI, is an evolution of the ISDN
Oriented Modular Interface (IOM
) invented by Siemens. The GCI was designed with
the specific needs of interconnecting components on switch line cards. As such, it is not
well-suited for terminal and NT1 applications. As a result, a terminal version of the
interface has been designed. The terminal version has been designated the Special
Circuit Interface T, or SCIT. The GCI line card and SCIT terminal bus specifications
combined form the IOM
Revision 2 standard (IOM
-2).
The MUNICH32X contains an integrated IOM
-2 handler for driving ISDN Layer-1
devices via the serial PCM interface. In this mode, the PCM interface has a structure and
features of the IOM
-2 interface:
It is compatible with the IOM
-2 industry standard for line cards/trunk cards
(supporting the Monitor and C/I communication channels),
Figure 73
.
Its 4 lines correspond to TXD/DU, RXD/DD, DCL, FSC of other ISDN devices.
The data rate is programmable up to 4.096 Mbit/s.
The clock frequency is either equal to the data rate, or twice the data rate. By default
it is equal to the data rate.
General Features