MC68000 MOTOROLA [Motorola, Inc], MC68000 Datasheet - Page 130

• Manufacturer Part Number: MC68000
• Manufacturer: MOTOROLA [Motorola, Inc]

Communications Processor (CP)
When using the IDL or GCI buses, additional control functions in the frame structure are re-
quired. These functions are supported in the MC68302 through two SMC channels: SMC1
and SMC2. (For other matters relating to the SMCs, refer to 4.7 Serial Management Con-
trollers (SMCs)).
The serial interface also supports two testing modes: echo and loopback. Echo mode pro-
vides a return signal from the physical interface by retransmitting the signal it has received.
The physical interface echo mode differs from the individual SCC echo mode in that it can
operate on the entire multiplexed signal rather than just on a particular SCC channel (which
may further have particular bits masked). Loopback mode causes the physical interface to
receive the same signal it is transmitting. The physical interface loopback mode checks
more than the individual SCC loopback mode; it checks the physical interface and the inter-
nal channel routes.
Refer to Figure 4-5 for the serial channels physical interface block diagram.
M68000 DATA BUS
SIMASK
SIMODE
MASK REGISTER
MODE REGISTER
TO SMC1
TO SMC2
TO SCC1
TO SCC2
TO SCC3
MUX
MUX
MUX
PHYSICAL INTERFACE BUS
TIME-SLOT
LAYER-1 BUS
ASSIGNER
INTERFACE
SCC2
SCC3
ISDN INTERFACE OR SCC1
Figure 4-5. Serial Channels Physical Interface Block Diagram
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MC68302 USER’S MANUAL
MOTOROLA