MC68HC908GZ8 Datasheet, PDF (247/344 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Enhanced Serial Communications Interface (ESCI) Module
I/O Registers
NOTE:
PDS2–PDS0 — Prescaler Divisor Select Bits
These read/write bits select the prescaler divisor as shown in
Table 19-10. Reset clears PDS2–PDS0.
The setting of ‘000’ will bypass this prescaler. It is not recommended to bypass the
prescaler while ENSCI is set, because the switching is not glitch free.
Table 19-10. ESCI Prescaler Division Ratio
PS[2:1:0]
000
001
010
011
100
101
110
111
Prescaler Divisor (PD)
Bypass this prescaler
2
3
4
5
6
7
8
PSSB4–PSSB0 — Clock Insertion Select Bits
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 Table 19-11. Reset clears PSSB4–PSSB0.
Use the following formula to calculate the ESCI baud rate:
Baud rate = _{6----4-----×}-----B----P----D------_×-----B----fD--B----u_×---s--₍--P-----D-----+-----P-----D-----F----A----₎
where:
f_Bus = Bus frequency
BPD = Baud rate register prescaler divisor
BD = Baud rate divisor
PD = Prescaler divisor
PDFA = Prescaler divisor fine adjust
Table 19-12 shows the ESCI baud rates that can be generated with a 4.9152-MHz
bus frequency.
MC68HC908GZ8
MOTOROLA
Enhanced Serial Communications Interface (ESCI) Module
For More Information On This Product,
Go to: www.freescale.com
Data Sheet
247