Serial Management Controllers (SMCs)
MOTOROLA
MC68360 USER’S MANUAL
7-275
NOTES
The modification of parameter RAM does not require a full dis-
abling of the SMC. See the parameter RAM description for de-
tails on when parameter RAM values may be modified.
If the user desires to disable all SCCs, SMCs, and SPI, then the
CR may be used to reset the entire CP with a single command.
7.11.5.1 SMC TRANSMITTER FULL SEQUENCE.
For the SMC transmitter, the full dis-
able and enable sequence is as follows:
1. STOP TRANSMIT command. This command is recommended if the SMC is currently
in the process of transmitting data since it stops transmission in an orderly way. If the
SMC is not transmitting (e.g., no Tx BDs are ready), then the STOP TRANSMIT com-
mand is not required. Furthermore, if the TBPTR will be overwritten by the user or the
INIT TX PARAMETERS command will be 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. The user may make modifications to the SMC transmit parame-
ters including the parameter RAM. If the user desires to switch protocols or restore the
SMC transmit parameters to their initial state, the INIT TX PARAMETERS command
may now be issued.
4. RESTART TRANSMIT command. This command is required if the INIT TX PARAME-
TERS command was not issued in step 3.
5. Set the TEN bit in the SMCMR. Transmission will now begin using the Tx BD pointed
to by the TBPTR value as soon as the Tx BD R-bit is set.
7.11.5.2 SMC TRANSMITTER SHORTCUT SEQUENCE.
A shorter sequence is possible if
the user desires to reinitialize the transmit parameters to the state they had after reset. This
sequence is as follows:
1. Clear the TEN bit in the SMCMR.
2. INIT TX PARAMETERS command. Any additional modifications may now be made.
3. Set the TEN bit in the SMCMR.
7.11.5.3 SMC RECEIVER FULL SEQUENCE.
For the receiver, the full disable and enable
sequence is as follows:
1. Clear the REN bit in the SMCMR. Reception will be aborted immediately. This disables
the receiver of the SMC and puts it in a reset state.
2. Make modifications. The user may make modifications to the SMC receive parameters
including the parameter RAM. If the user desires to switch protocols or restore the
SMC receive parameters to their initial state, the INIT RX PARAMETERS command
may now be issued.
3. CLOSE Rx BD command. This command is required if the INIT RX PARAMETERS
command was not issued in step 2.
4. Set the REN bit in the SMCMR. Reception will now begin immediately using the Rx