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Communication Processor Module
MOTOROLA
MPC823 USER’S MANUAL
16-381
SMC
COMMUNICATION
16
PROCESSOR
MODULE
16.11.5.1 DISABLING THE ENTIRE SMC TRANSMITTER. Follow these steps to fully
enable or disable the SMC transmitter:
1. Issue the STOP TRANSMIT command. This command is recommended when a serial
management controller is transmitting data since it stops transmission smoothly. If a
serial management controller is not transmitting, then this command is not required.
Furthermore, if you overwrite the TBPTR or the INIT TX PARAMETERS command is
executed, this command is not required.
2. Clear the TEN bit in the SMCMR. This disables the SMC transmitter and puts it in a
reset state.
3. Make modifications. You can make modifications to the SMC transmit parameters,
including the parameter RAM. If you prefer to switch protocols or restore the SMC
transmit parameters to their initial state, issue the INIT TX PARAMETERS command.
4. Issue the RESTART TRANSMIT command. You must do this if you did not issue the
INIT TX PARAMETERS command in step 3.
5. Set the TEN bit in the SMCMR. Transmission now begins using the TX buffer
descriptor that the TBPTR value pointed to as soon as the R bit is set in the TX buffer
descriptor.
16.11.5.2 DISABLING PART OF THE SMC TRANSMITTER. Follow this shorter
sequence if you prefer to reinitialize the transmit parameters to the state they had after reset.
1. Clear the TEN bit in the SMCMR.
2. Issue the INIT TX PARAMETERS command and make any additional modifications.
3. Set the TEN bit in the SMCMR.
16.11.5.3 DISABLING THE ENTIRE SMC RECEIVER. Follow these steps to fully enable
or disable the receiver:
1. Clear the REN bit in the SMCMR. Reception is aborted immediately, which disables
the SMC receiver and puts it in a reset state.
2. Make modifications to the SMC receive parameters, including the parameter RAM. If
you prefer to switch protocols or restore the SMC receive parameters to their initial
state, issue the INIT RX PARAMETERS command.
3. Issue the CLOSE RX BD command. You must do this if you did not issue the INIT RX
PARAMETERS command in step 2.
4. Set the REN bit in the SMCMR. Reception begins immediately using the RX buffer
descriptor that the RBPTR pointed to if the E bit is set in the RX buffer descriptor.