MPC823 datasheet(27/74 Pages) MOTOROLA

27 / 74 page

Communication Processor Module

MOTOROLA

MPC823 REFERENCE MANUAL

16-405

12. Initialize the RX buffer descriptor. Assume the RX data buffer is at 0x00001000 in main

memory. Write 0xB000 to RX_BD_Status, 0x0000 to RX_BD_Length (not required),

and 0x00001000 to RX_BD_Pointer.

13. Initialize the TX buffer descriptor. Assume the TX data buffer is at 0x00002000 in main

memory and contains five 8-bit characters. Then write 0xB000 to TX_BD_Status,

0x0005 to TX_BD_Length, and 0x00002000 to TX_BD_Pointer.

14. Write 0xFF to the SMCE–UART register to clear any previous events.

15. Write 0x17 to the SMCM–UART register to enable all possible serial management

controller interrupts.

16. Write 0x00000010 to the CIMR so SMC1 can generate a system interrupt. The CICR

must also be initialized.

17. Write 0x4820 to SMCMR to configure normal operation (not loopback), 8-bit

characters, no parity, 1 stop bit. Notice that the transmitter and receiver are not

enabled yet.

18. Write 0x4823 to SMCMR to enable the SMC1 transmitter and receiver. This additional

write ensures that the TEN and REN bits are enabled last.

16.11.6.16 HANDLING INTERRUPTS IN THE SMCx UART CONTROLLER. Follow

these steps to handle an interrupt in a serial management controller:

1. Once an interrupt occurs, read the SMCE–UART register to discover the cause of the

interrupt. To clear the SMCE bits, write ones to them.

2. Process the TX buffer descriptor to reuse it if the TX bit is set in the SMCE–UART

SMCE–UART. To transmit another buffer, set the R bit in the TX buffer descriptor.

3. Clear the SMCx bit in the CISR.

4. Execute the rfi instruction.

Note: After 5 bytes are transmitted, the TX buffer descriptor is closed. The receive

buffer is closed after 16 bytes are received. Any data received after 16 bytes

causes a busy (out-of-buffers) condition since only one RX buffer descriptor is

prepared.

MPC823 датащи(PDF) 27 Page - Motorola, Inc