MC68HC908AS32A Datasheet, PDF (187/280 Pages) Freescale Semiconductor, Inc – Microcontrollers

I/O Registers
SCR2 – SCR0 — SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in Table 14-7. Reset clears
SCR2–SCR0.
Table 14-7. 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 = ---------f--C----r--y---s---t--a---l--------
64 × PD × BD
where:
f_Crystal = crystal frequency
PD = prescaler divisor
BD = baud rate divisor
Table 14-8 shows the SCI baud rates that can be generated with a 4.9152-MHz crystal.
MC68HC908AS32A Data Sheet, Rev. 2.0
Freescale Semiconductor
187