Freescale Semiconductor, Inc.
Serial Communications Interface (SCI)
SCI registers
Table 5-1. Example SCI baud rate control values
Crystal frequency (EXTAL)
12 MHz
Target
baud
rate
8 MHz
16 MHz
Dec
Hex
Dec
Hex
Dec
Hex
value
value
2272
1666
833
416
208
104
52
value
value
value
value
4545
3333
1666
833
416
208
104
52
110
150
$08E0
$0682
$0341
$01A0
$00D0
$0068
$0034
$001A
$000D
3409
2500
1250
625
312
156
78
$0D51
$09C4
$04E2
$0271
$0138
$009C
$004E
$0027
$0014
$11C1
$0D05
$0682
$0341
$01A0
$00D0
$0068
$0034
$001A
$000D
300
600
1200
2400
4800
9600
19200
38400
26
39
13
20
26
13
5.8.2 SCCR1 — SCI control register 1
State
on reset
Address bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
LOOP
SCI 1 control 1 (SCCR1)
$0072
WOMS
0
M
WAKE ILT
PE
PT 0000 0000
S
The SCCR1 register provides the control bits that determine word length
and select the method used for the wakeup feature.
LOOPS — SCI loop mode enable
1 = SCI transmit and receive are disconnected from TXD and RXD
pins, and transmitter output is fed back into the receiver input.
0 = SCI transmit and receive operate normally.
Both the transmitter and receiver must be enabled to use the LOOP
mode. When the LOOP mode is enabled, the TXD pin is driven high
(idle line state) if the transmitter is enabled.
WOMS — Wired-OR mode for SCI pins (PD1, PD0)
1 = TXD and RXD are open drains if operating as outputs.
0 = TXD and RXD operate normally.
MC68HC11P2 — Rev 1.0
Technical Data
Serial Communications Interface (SCI)
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