s908qc16vdse Freescale Semiconductor, Inc, s908qc16vdse Datasheet - Page 146

• Manufacturer Part Number: s908qc16vdse
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Enhanced Serial Communications Interface (ESCI) Module
PDS2–PDS0 — Prescaler Divisor Select Bits
PSSB4–PSSB0 — Clock Insertion Select Bits
Use the following formula to calculate the ESCI baud rate:
where:
Table 13-10
146
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
SCI clock source = bus clock or BUSCLKX4 (selected by ESCIBDSRC in the configuration register)
BPD = Baud rate register prescaler divisor
BD = Baud rate divisor
PD = Prescaler divisor
PDFA = Prescaler divisor fine adjust
shows the ESCI baud rates that can be generated with a 4.9152-MHz bus frequency.
Reset:
Read:
Write:
The setting of ‘000’ will bypass this prescaler. Do not bypass the prescaler
while ENSCI is set, because unexpected results may occur.
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 4
PDS2
Bit 7
0
Baud rate =
Figure 13-17. ESCI Prescaler Register (SCPSC)
PDS[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 13-8. ESCI Prescaler Division Ratio
PDS1
6
0
Frequency of the SCI clock source
PDS0
64 x BPD x BD x (PD + PDFA)
5
0
PSSB4
NOTE
4
0
Prescaler Divisor (PD)
Bypass this prescaler
PSSB3
3
0
2
3
4
5
6
7
8
Table
PSSB2
2
0
13-8.
PSSB1
Table
1
0
13-9.
Freescale Semiconductor
PSSB0
Bit 0
0