Serial Communications Interface (SCI)
Technical Data MC68HC908AZ60A — Rev 2.0
280 Serial Communications Interface (SCI) MOTOROLA
SCP1 and SCP0 — SCI Baud Rate Prescaler Bits
These read/write bits select the baud rate prescaler divisor as shown
in Table 18-9. 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 18-10. Reset clears SCR2–SCR0.
Use the following formula to calculate the SCI baud rate:
where:
f
Crystal
= crystal frequency
PD = prescaler divisor
BD = baud rate divisor
Table 18-9. SCI Baud Rate Prescaling
SCP[1:0] Prescaler Divisor (PD)
00 1
01 3
10 4
11 13
Table 18-10. 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
Crystal
64 PD BD××
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