Communication Processor Module
MOTOROLA
MPC823e REFERENCE MANUAL
16-391
SMC
COMMUNICATION
16
PROCESSOR MODULE
16.11.5.1 DISABLING THE ENTIRE SMCx TRANSMITTER.
Follow these steps to fully
enable or disable the SMCx transmitter:
1. Issue the
STOP TRANSMIT
command. This command is recommended when a serial
management controller is transmitting data since it stops transmission smoothly. This
command is not required if a serial management controller is not transmitting, if you
overwrite the TBPTR or if you execute the
INIT TX PARAMETERS
command.
2. Clear the TEN bit in the SMCMR. This disables the SMCx transmitter and puts it in a
reset state.
3. Modify the SMCx transmit parameters, including the parameter RAM. If you prefer to
switch protocols or restore the SMCx 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. When the R bit is set in the TX buffer descriptor,
transmission begins using the TX buffer descriptor indicated by the TBPTR value.
16.11.5.2 DISABLING PART OF THE SMCx TRANSMITTER.
Follow this shorter
sequence if you prefer to reinitialize the transmit parameters to the state they were in 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 SMCx 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 SMCx receiver and puts it in a reset state.
2. Modify the SMCx receive parameters, including the parameter RAM. If you prefer to
switch protocols or restore the SMCx 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. When the E bit is set in the RX buffer descriptor,
reception begins immediately using the RX buffer descriptor indicated by the RBPTR.
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