Serial Management Controllers (Smcs); Overview; Using Idl With The Smcs; Using Gci With The Smcs - Motorola MC68302 User Manual

Communications Processor (CP)
by the M68000 core before setting the STR bit so that received replies may be easily recog-
nized by the software.

4.7 SERIAL MANAGEMENT CONTROLLERS (SMCS)

The SMC key features are as follows:
• Two Modes of Operation:
—IDL—SMC1 supports the maintenance channel and SMC2 supports
the auxiliary channel
—GCI (IOM-2)—SMC1 supports the monitor channel and SMC2 supports the C/I
channel
• Full-Duplex Operation
• Local Loopback Capability for Testing

4.7.1 Overview

The SMCs are two synchronous, full-duplex serial management control (SMC) ports. The
SMC ports may be configured to operate in either Motorola interchip digital link (IDL) or gen-
eral circuit interface (GCI) modes. GCI is also known as ISDN oriented modular 2 (IOM-2).
See 4.4 Serial Channels Physical Interface for the details of configuring the IDL and GCI in-
terfaces. The SMC ports are not used when the physical serial interface is configured for
PCM highway or NMSI modes.

4.7.1.1 Using IDL with the SMCs

In this mode, SMC1 transfers the maintenance (M) bits of the IDL to and from the internal
RAM, and SMC2 transfers the auxiliary (A) bits to and from the internal RAM. The CP gen-
erates a maskable interrupt upon reception/transmission of eight bits. The SMC1 and SMC2
receivers can be programmed to work in hunt-on-zero mode, in which the receiver will
search the line signals for a zero bit. When it is found, the receiver will transfer data to the
internal RAM.

4.7.1.2 Using GCI with the SMCs

In this mode, SMC1 controls the GCI monitor channel.
SMC1 Transmission
The monitor channel is used to transfer commands to the layer-1 component. The
M68000 core writes the data byte into the SMC1 Tx BD. SMC1 will transmit the data on
the monitor channel.
The SMC1 channel transmitter can be programmed to work in one of two modes:
Transparent Mode
In this mode, SMC1 transmits the monitor channel data and the A and E control bits
transparently into the channel. When the M68000 core has not written new data to
the buffer, the SMC1 transmitter will retransmit the previous monitor channel data
and the A and E control bits.
4-138 MC68302 USER'S MANUAL MOTOROLA