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Chapter 30
Serial Management Controllers
300
300
The two serial management controllers (SMCs) are full-duplex ports that can be conÞgured
independently to support one of three protocolsÑUART, transparent, or general-circuit
interface (GCI). Simple UART operation is used to provide a debug/monitor port in an
application, which allows the SCCs to be free for other purposes. The SMC in UART mode
is not as complex as the SCC in UART mode. The SMC clock can be derived from one of
the four internal baud rate generators (BRGs) or from an external clock pin. However, the
clock should be a 16´ clock.
In totally transparent mode, the SMC can be connected to a TDM channel (such as a T1
line) or directly to its own set of pins. The receive and transmit clocks are derived from the
TDM channel, the internal BRGs, or from an external 1´ clock. The transparent protocol
allows the transmitter and receiver to use the external synchronization pin. The SMC in
transparent mode is not as complex as the SCC in transparent mode.
Each SMC supports the C/I and monitor channels of the GCI bus, for which the SMC
connects to a time-division multiplex (TDM) channel in the serial interface (SI).
Chapter 21, ÒSerial Interface,Ó describes GCI interface conÞguration.
The SMCs support loopback and echo modes for testing. The SMC receiver and transmitter
are double-buffered, corresponding to an effective FIFO size (latency) of two characters.
Figure 30-1 shows the SMC block diagram.
MOTOROLA
Chapter 30. Serial Management Controllers
30-1
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