Freescale Semiconductor MPC8260 - Manual (Page 768)

SCC BISYNC Mode
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
23-18 Freescale Semiconductor
After ETX, a BCS is expected; then the buffer should be closed. Hunt mode should be entered when a line
turnaround occurs. ENQ characters are used to stop sending a block and to designate the end of the block
for a receiver, but no CRC is expected. After control character reception, set SCCM[RCH] to reenable
interrupts for each byte of data received.
23.17 SCC BISYNC Programming Example
This BISYNC controller initialization example for SCC2 uses an external clock. The controller is
configured with RTS2, CTS2, and CD2 active. Both the receiver and transmitter use CLK3.
1. Configure port D pins to enable TXD2 and RXD2. Set PPARD[27,28] and PDIRD[27] and clear
PDIRD[28] and PSORD[27,28].
2. Configure ports C and D pins to enable RTS2, CTS2 and CD2. Set PPARD[26], PPARC[12,13]
and PDIRD[26] and clear PDIRC[12,13], PSORC[12,13], and PSORD[26].
3. Configure port C pin 29 to enable the CLK3 pin. Set PPARC[29] and clear PDIRC[29] and
PSORC[29].
4. Connect CLK3 to SCC2 using the CPM mux. Write 0b110 to CMXSCR[R2CS] and
CMXSCR[T2CS].
5. Connect the SCC2 to the NMSI (its own set of pins). Clear CMXSCR[SC2].
6. Assuming one RxBD at the beginning of dual-port RAM followed by one TxBD, write RBASE
with 0x0000 and TBASE with 0x0008.
7. Write 0x04a1_0000 to CPCR to execute INIT RX AND TX PARAMETERS . This updates RBPTR and
TBPTR to the new values of RBASE and TBASE.
8. Write RFCR and TFCR with 0x10 for normal operation.
9. Write MRBLR with the maximum number of bytes per receive buffer. For this case, assume 16
bytes, so MRBLR = 0x0010.
10. Write PRCRC with 0x0000 to comply with CRC16.
11. Write PTCRC with 0x0000 to comply with CRC16.
12. Clear PAREC for clarity.
13. Write BSYNC with 0x8033, assuming a SYNC value of 0x33.
14. Write DSR with 0x3333.
15. Write BDLE with 0x8055, assuming a DLE value of 0x55.
16. Write CHARACTER1 with 0x6077, assuming ETX = 0x77.
Table 23-15. Control Characters
Control Characters E B H
ETX 0 1 1
ITB 0 1 0
ETB 0 1 1
ENQ 0 0 0
Next entry 0 X X