MC68HC11F1MFN2 FREESCALE [Freescale Semiconductor, Inc], MC68HC11F1MFN2 Datasheet - Page 44

• Manufacturer Part Number: MC68HC11F1MFN2
• Description: Technical Summary 8-Bit Microcontroller
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

9.2 SCI Registers
TCLR — Clear Baud Rate Counters (TEST)
Bit 6 — Not implemented. Reads always return zero and writes have no effect.
RCKB — SCI Baud-Rate Clock Check (TEST)
SCP[2:0] — SCI Baud Rate Prescaler Selects
SCR[2:0] — SCI Baud Rate Selects
44
BAUD — Baud Rate
RESET:
SCP[2:0]
NOTES:
These bits determine the baud rate prescaler frequency. Refer to Table 21 and Figure 11.
These bits determine the receiver and transmitter baud rate. Refer to Table 22 and Figure 11.
The prescaler bits SCP[2:0] determine the highest baud rate, and the SCR[2:0] bits select an additional
binary submultiple (divide by 1, 2, 4,..., through 128) of this highest baud rate. The result of these two
dividers in series is the 16X receiver baud rate clock. The SCR[2:0] bits are not affected by reset and
can be changed at any time. They should not be changed, however, when an SCI transfer is in progress.
X11
101
1. A blank table cell indicates that an uncommon rate results.
X00
001
X10
SCR[2:0]
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
TCLR
Bit 7
Clock By
Internal
0
Divide
13
1
3
4
9
SCP2
Prescaler By
4.0 MHz
XTAL =
6
0
62500
20833
15625
4800
Divide
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Freescale Semiconductor, Inc.
128
16
32
64
1
2
4
8
For More Information On This Product,
Table 21 Baud Rate Prescaler Selection
SCP1
4.9152 MHz
5
0
XTAL =
76800
25600
19200
Table 22 Baud Rate Selection
5908
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Prescaler
Output =
4800
4800
2400
1200
600
300
150
75
—
SCP0
4
0
8.0 MHz
XTAL =
125000
41667
31250
9600
—
Prescaler
Output =
RCKB
9600
9600
4800
2400
1200
Prescaler Output
600
300
150
10.0 MHz
75
3
0
XTAL =
156250
52083
38400
12019
—
SCR2
Baud Rate
Prescaler
12.0 MHz
Output =
XTAL =
187500
U
2
62500
46875
14423
20830
19200
19200
9600
4800
2400
1200
600
300
150
1
SCR1
16.0 MHz
XTAL =
250000
83333
62500
19200
U
1
Prescaler
—
Output =
38400
38400
19200
9600
4800
2400
1200
600
300
20.0 MHz
MC68HC11F1/FC0
SCR0
XTAL =
312500
104167
MC68HC11FTS/D
Bit 0
76800
24038
U
—
Prescaler
Output =
76800
76800
38400
19200
9600
4800
2400
1200
600
24.0 MHz
XTAL =
375000
125000
93750
28846
$x02B
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