MC68HC908AT32 Datasheet, PDF (161/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

I/O Registers
SCP1 and SCP0 — SCI Baud Rate Prescaler Bits
These read/write bits select the baud rate prescaler divisor as shown in Table 16-6. Reset clears SCP1
and SCP0.
SCP[1:0]
00
01
10
11
Table 16-6. SCI Baud Rate Prescaling
Prescaler Divisor (PD)
1
3
4
13
SCR2 – SCR0 — SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in Table 16-7. Reset clears
SCR2–SCR0.
Table 16-7. SCI Baud Rate Selection
SCR[2:1:0]
000
001
010
011
100
101
110
111
Baud Rate Divisor (BD)
1
2
4
8
16
32
64
128
Use the following formula to calculate the SCI baud rate:
Baud rate = _{6----4-----f×}--C--P--r--y-D--s---t-_×-a---l-B----D---
where:
f_Crystal = crystal frequency
PD = prescaler divisor
BD = baud rate divisor
Table 16-8 shows the SCI baud rates that can be generated with a 4.194-MHz crystal.
MC68HC908AT32 Data Sheet, Rev. 3.1
Freescale Semiconductor
161