MC68302 Datasheet, PDF (138/480 Pages) Motorola, Inc – Integrated Multiprotocol Processor User’s Manual

Communications Processor (CP)
have to be contiguous in the PCM highway, but rather can be separated by other time slots.
Also, PCM channel time slots need not be an even multiple of eight bits in envelope mode.
Although not shown in the figure, it is also possible to route multiple PCM channels to a sin-
gle SCC, causing the SCC to process one higher speed data stream.
The PCM highway interface also supports the RTS signals. They will be asserted (just like
in NMSI mode) when an SCC desires to transmit over the PCM highway and will stay as-
serted until the entire frame is transmitted (regardless of how many time slots that takes).
The RTS signal that asserts corresponds to the SCC that desires to transmit. The RTS sig-
nals may be useful in debugging but are not required for proper PCM highway operation. If
the RTS signals are not needed, they can be ignored or reassigned as parallel I/O.
1 CLOCK
CYCLE SYNC PRIOR
L1SY0
L1SY1
8-BIT ENVELOPE
L1SY0
L1SY1
DATA ROUTING
CH-1
CH-2
CH-3
Figure 4-9. Two PCM Sync Methods
4-18
MC68302 USER’S MANUAL
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