Motorola MPC8260 User Manual

20-22

MOTOROLA

Table 20-13 describes UART SCCS Þelds.

The following initialization sequence is for the 9,600 baud, 8 data bits, no parity, and stop
bit of an SCC in UART mode assuming a 66-MHz system frequency. BRG1 and SCC2 are
used. The controller is conÞgured with RTS2, CTS2, and CD2 active; CTS2 acts as an
automatic ßow-control signal.

1. ConÞgure port D pins to enable TXD2 and RXD2. Set PPARD[27,28] and 

PDIRD[27] and clear PDIRD[28] and PSORD[27,28]. 

2. ConÞgure 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. ConÞgure BRG1. Write BRGC1 with 0x0001_035A. The DIV16 bit is not used and 

the divider is 429 (decimal). The resulting BRG1 clock is 16

´ the preferred bit rate.

4. Connect BRG1 to SCC2 using the CPM mux. Clear CMXSCR[RS2CS,TS2CS].

5. Connect the SCC2 to the NMSI. Clear CMXSCR[SC2].

6. Write RBASE and TBASE in the SCC2 parameter RAM to point to the RxBD and 

TxBD tables in dual-port RAM. Assuming one RxBD at the start of dual-port RAM 
followed by one TxBD, write RBASE with 0x0000 and TBASE with 0x0008.

7. Write 0x04A1_0000 to CPCR to execute the 

INIT

 

RX

 

AND

 

TX

 

PARAMS

 command for 

SCC2. This command updates RBPTR and TBPTR of the serial channel with the 
new values of RBASE and TBASE.

8. Write RFCR with 0x10 and TFCR with 0x10 for normal operation.

9. Write MRBLR with the maximum number of bytes per Rx buffer. For this case, 

assume 16 bytes, so MRBLR = 0x0010.

10. Write MAX_IDL with 0x0000 in the parameter RAM to disable the maximum idle 

functionality for this example.

11. Set BRKCR to 0x0001 so 

STOP

 

TRANSMIT

 commands send only one break character.

12. Clear PAREC, FRMEC, NOSEC, and BRKEC in parameter RAM.

13. Clear UADDR1 and UADDR2. They are not used.

14. Clear TOSEQ. It is not used.

0Ð6

Ñ

Reserved, should be cleared.

7

ID

Idle status. Set when RXD has been a logic one for at least a full character time.
0 The line is not idle.
1 The line is idle.