Motorola MPC8260 - Manual (Page 942)

33-18 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
remains open. If the master sends 5 or more bytes, the TxBD is closed after the Þfth byte.
If the master sends 16 bytes and negates SPISEL, the RxBD is closed without triggering an
out-of-buffers error. If the master sends more than 16 bytes, the RxBD is closed (full) and
an out-of-buffers error occurs after the 17th byte is received.
33.10 Handling Interrupts in the SPI
The following sequence should be followed to handle interrupts in the SPI:
1. Once an interrupt occurs, read SPIE to determine the interrupt source. Normally,
SPIE bits should be cleared at this time.
2. Process the TxBD to reuse it and the RxBD to extract the data from it. To transmit
another buffer, simply set TxBD[R], RxBD[E], and SPCOM[STR].
3. Execute an rÞ instruction.