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Serial Communication Controllers (SCCs)
MC68360 USER’S MANUAL
controller is configured with the RTS4, CTS4, and CD4 pins active. The CLK7 pin is used
for both the BISYNC receiver and transmitter.
1. The SDCR (SDMA Configuration Register) should be initialized to $0740, rather than
being left at its default value of $0000.
2. Configure the port A pins to enable the TXD4 and RXD4 pins. Write PAPAR bits 6
and 7 with ones. Write PADIR bits 6 and 7 with zeros. Write PAODR bits 6 and 7
with zeros.
3. Configure the port C pins to enable RTS4, CTS4, and CD4. Write PCPAR bit 3 with
one and bits 10 and 11 with zeros. Write PCDIR bits 3, 10, and 11 with zeros.
Write PCSO bits 10 and 11 with ones.
4. Configure port A to enable the CLK7 pin. Write PAPAR bit 14 with a one. Write
PADIR bit 14 with a zero.
5. Connect the CLK7 pin to SCC4 using the SI. Write the R4CS bits in SICR to 110.
Write the T4CS bits in SICR to 110.
6. Connect the SCC4 to the NMSI (i.e., its own set of pins). Clear the SC4 bit
in the SICR.
7. Write $0740 to the SDCR to initialize the SDMA Configuration Register.
8. Write RBASE and TBASE in the SCC parameter RAM to point to the Rx BD and Tx
BD in the dual-port RAM. Assuming one Rx BD at the beginning of dual-port RAM,
and one Tx BD following that Rx BD, write RBASE with $0000 and TBASE with
$0008.
9. Program the CR to execute the INIT RX & TX PARAMS command for this channel.
For instance, to execute this command for SCC1, write $0001 to the CR. This com-
mand causes the RBPTR and TBPTR parameters of the serial channel to be updated
with the new values just programmed into RBASE and TBASE.
10. Write RFCR with $18 and TFCR with $18 for normal operation.
11. Write MRBLR with the maximum number of bytes per receive buffer. For this case,
assume 16 bytes, so MRBLR = $0010.
12. Write PRCRC with $0000 to comply with CRC16.
13. Write PTCRC with $0000 to comply with CRC16.
14. Clear PAREC for the sake of clarity.
15. Write BSYNC with $8033, assuming a SYNC value of $33.
16. Write BDLE with $8055, assuming a DLE value of $55.
17. Write CHARACTER1–8 with $8000. They are not used.
18. Write RCCM with $E0FF. It is not used.
19. Initialize the Rx BD. Assume the Rx data buffer is at $00001000 in main memory.
Write $B000 to Rx_BD_Status. Write $0000 to Rx_BD_Length (not required—
done for instructional purposes only). Write $00001000 to Rx_BD_Pointer.
20. Initialize the Tx BD. Assume the Tx data buffer is at $00002000 in main memory
and contains five 8-bit characters. Write $BD20 to Tx_BD_Status. Write $0005 to
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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