Datasheet

Serial Communications Interface Module (SCI)
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
134 Freescale Semiconductor
SCP1 and SCP0 — SCI Baud Rate Prescaler Bits
These read/write bits select the baud rate prescaler divisor as shown in Table 12-6. Reset clears SCP1
and SCP0.
SCR2–SCR0 — SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in Table 12-7. Reset clears
SCR2–SCR0.
Use this formula to calculate the SCI baud rate:
where:
f
BAUDCLK
= baud clock frequency
PD = prescaler divisor
BD = baud rate divisor
Table 12-8 shows the SCI baud rates that can be generated with a 4.9152-MHz CGMXCLK frequency.
Table 12-6. SCI Baud Rate Prescaling
SCP[1:0] Prescaler Divisor (PD)
00 1
01 3
10 4
11 13
Table 12-7. SCI Baud Rate Selection
SCR[2:1:0] Baud Rate Divisor (BD)
000 1
001 2
010 4
011 8
100 16
101 32
110 64
111 128
Baud rate
f
BAUDCLK
64 PD BD××
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