mc68hc908gr16 Freescale Semiconductor, Inc, mc68hc908gr16 Datasheet - Page 171

• Manufacturer Part Number: mc68hc908gr16
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

PDS2–PDS0 — Prescaler Divisor Select Bits
PSSB4–PSSB0 — Clock Insertion Select Bits
Use the following formula to calculate the ESCI baud rate:
where:
Table 14-11
Freescale Semiconductor
These read/write bits select the prescaler divisor as shown in
These read/write bits select the number of clocks inserted in each 32 output cycle frame to achieve
more timing resolution on the average prescaler frequency as shown in
PSSB4–PSSB0.
Frequency of the SCI clock source = f
BPD = Baud rate register prescaler divisor
BD = Baud rate divisor
PD = Prescaler divisor
PDFA = Prescaler divisor fine adjust
ESCIBDSRC in the CONFIG2 register)
shows the ESCI baud rates that can be generated with a 4.9152-MHz bus frequency.
The setting of ‘000’ will bypass not only this prescaler but also the prescaler
divisor fine adjust (PDFA). It is not recommended to bypass the prescaler
while ENSCI is set, because the switching is not glitch free.
Baud rate =
PS[2:1:0]
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
Table 14-9. ESCI Prescaler Division Ratio
MC68HC908GR16 Data Sheet, Rev. 5.0
Frequency of the SCI clock source
64 x BPD x BD x (PD + PDFA)
Bus
or CGMXCLK (selected by
NOTE
Prescaler Divisor (PD)
Bypass this prescaler
2
3
4
5
6
7
8
Table
14-9. Reset clears PDS2–PDS0.
Table
14-10. Reset clears
I/O Registers
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