Processor Users Manual

26-10 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
26.2.4.4 SMC Receiver Shortcut Sequence
This shorter sequence reinitializes receive parameters to their state after reset.
1. Clear SMCMR[REN].
2. Issue an
INIT RX PARAMETERS command and make any additional changes.
3. Set SMCMR[REN].
26.2.4.5 Switching Protocols
To switch the protocol that the SMC is executing without resetting the board or affecting
any other SMC, use one command and follow these steps:
1. Clear SMCMR[REN] and SMCMR[TEN].
2. Issue an
INIT TX AND RX PARAMETERS COMMAND to initialize transmit and receive
parameters. Make any additional SMCMR changes.
3. Set SMCMR[REN, TEN]. The SMC is now enabled with the new protocol.
26.2.5 Saving Power
When SMCMR[TEN, REN] are cleared, the SMC consumes little power.
26.2.6 Handling Interrupts in the SMC
Follow these steps to handle an interrupt in the SMC:
1. Once an interrupt occurs, read SMCE to identify the interrupt source. The SMCE
bits are usually cleared at this time.
2. Process the TxBD to reuse it if SMCE[TXB] is set. Extract data from the RxBD if
SMCE[RXB] is set. To send another buffer, set TxBD[R].
3. Execute the rÞ instruction.
26.3 SMC in UART Mode
SMCs generally offer less functionality and performance in UART mode than do SCCs,
which makes them more suitable for simpler debug/monitor ports instead of full-featured
UARTs. SMCs do not support the following features in UART mode.
¥R
TS, CTS, and CD signals
¥ Receive and transmit sections clocked at different rates
¥ Fractional stop bits
¥ Built-in multidrop modes
¥ Freeze mode for implementing flow control
¥ Isochronous operation (1´ clock)
¥ Interrupts on special control character reception
¥ Ability to transmit data on demand using the TODR
¥ SCCS register to determine idle status of the receive signal
¥ Other features for the SCCs as described in the GSMR