MC908AP32CFBE Datasheet, PDF (207/324 Pages) Freescale Semiconductor, Inc – The following revision history table summarizes changes contained in this document. For your convenience, the page number designators have been linked to the appropriate location.

Table 12-7. SCI Baud Rate Prescaling
SCP1 and SCP0
00
01
10
11
Prescaler Divisor (PD)
1
3
4
13
I/O Registers
SCR2–SCR0 — SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in Table 12-8. Reset clears
SCR2–SCR0.
Table 12-8. IRSCI Baud Rate Selection
SCR2, SCR1, and SCR0
000
001
010
011
100
101
110
111
Baud Rate Divisor (BD)
1
2
4
8
16
32
64
128
Use this formula to calculate the SCI baud rate:
baud rate = ^{S-----C----I---c---l--o---c---k-----s---o---u---r--c---e--}
16 × PD × BD
where:
SCI clock source = f_BUS or CGMXCLK
(selected by CKS bit)
PD = prescaler divisor
BD = baud rate divisor
Table 12-9 shows the SCI baud rates that can be generated with a 4.9152-MHz bus clock when f_BUS is
selected as SCI clock source.
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
207