MPC555
/
MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-45
14.8.2 SCI Control Register 0
SCCxR0 contains the SCIx baud rate selection field and two bits controlling the clock
source. The baud rate must be set before the SCI is enabled. The CPU can read and
write SCCxR0 at any time.
Changing the value of SCCxR0 bits during a transfer operation can disrupt the trans-
fer. Before changing register values, allow the SCI to complete the current transfer,
then disable the receiver and transmitter.
14.8.3 SCI Control Register 1
SCCxR1 contains SCIx configuration parameters, including transmitter and receiver
enable bits, interrupt enable bits, and operating mode enable bits. The CPU can read
or write this register at any time. The SCI can modify the RWU bit under certain cir-
cumstances.
Changing the value of SCCxR1 bits during a transfer operation can disrupt the trans-
fer. Before changing register values, allow the SCI to complete the current transfer,
then disable the receiver and transmitter.
SCCxR0 —
SCI Control Register 0
0x30 5008
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
OTHR
LNK-
BD
0
SCxBR
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
Table 14-23 SCCxR0 Bit Descriptions
Bit(s)
Name
Description
0
OTHR
This bit is reserved and should always be programmed to 0.
1
LNKBD
This bit is reserved and should always be programmed to 0.
2
—
Reserved
3:15
SCxBR
SCI baud rate. The SCI baud rate is programmed by writing a 13-bit value to this field. Writing a
value of zero to SCxBR disables the baud rate generator. Baud clock rate is calculated as fol-
lows:
where SCxBR is in the range of 1 to 8191.
SCI Baud Rate
f
SYS
32
SCxBR
×
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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