mc68hc11f1cpu3 Freescale Semiconductor, Inc, mc68hc11f1cpu3 Datasheet - Page 94

• Manufacturer Part Number: mc68hc11f1cpu3
• Description: Mc68hc11f1 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

OR — Overrun Error Flag
NF — Noise Error Flag
FE — Framing Error
Bit 0 — Not implemented
7.6.5 Baud Rate Register
BAUD — Baud Rate
TCLR — Clear Baud Rate Counters (Test)
SCP[1:0] — SCI Baud Rate Prescaler Selects
7-8
RESET:
SCP1
OR is set if a new character is received before a previously received character is read
from SCDR. Clear the OR flag by reading SCSR and then reading SCDR.
NF is set if majority sample logic detects anything other than a unanimous decision.
Clear NF by reading SCSR and then reading SCDR.
FE is set when a zero is detected where a stop bit was expected. Clear the FE flag by
reading SCSR and then reading SCDR.
Always reads zero
Use this register to select different baud rates for the SCI system. The SCP[1:0] bits
select the prescaler rate for the SCR[2:0] bits. Together, these five bits provide multi-
ple baud rate combinations for a given crystal frequency. Normally, this register is writ-
ten once during initialization. The prescaler is set to its fastest rate by default out of
reset, and can be changed at any time. Refer to Table 7-1 and Table 7-2 for normal
baud rate selections.
Refer to the SCI baud rate generator block diagram.
0
0
1
1
Prescaler
0 = No overrun
1 = Overrun detected
0 = Unanimous decision
1 = Noise detected
0 = Stop bit detected
1 = Zero detected
SCP0
TCLR
Bit 7
0
1
0
1
0
Divide Internal
—
Clock By
6
0
Table 7-1 Baud Rate Prescaler Selection
Freescale Semiconductor, Inc.
13
1
3
4
For More Information On This Product,
SERIAL COMMUNICATIONS INTERFACE
SCP1
5
0
Go to: www.freescale.com
62500
20833
15625
4800
4.0
SCP0
4
0
4.9152
76800
25600
19200
5907
RCKB
3
0
Crystal Frequency (MHz)
125000
41667
31250
9600
8.0
SCR2
U
2
187500
62500
46875
14423
SCR1
12.0
U
1
TECHNICAL DATA
25000
83332
62500
19200
SCR0
16.0
Bit 0
U
MC68HC11F1
312500
104165
78125
24000
$102B
20.0