Panasonic MN101C77C - Manual (Page 243)

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Chapter 6 8-bit Timers
8-bit PWM Output
(5) Set the "H" period of PWM output to the timer
0 compare register (TM0OC).
The setting value is set to 256 / 4 = 64 (x'40'),
because it should be the 1/4 duty of the full
count (256).
At that time, the timer 0 binary counter
(TM0BC) is initialized to x'00'.
(6) Set the TM0EN flag of the TM0MD register to
"1" to operate timer 0.
Setup Procedure
(5) Set the period of PWM "H" output.
TM0OC (x'3F52') = x'40'
(6) Start the timer operation.
TM0MD (x'3F54')
bp3 :TM0EN = 1
Description
TM0BC counts up from x'00'. PWM source waveform outputs "H" till TM0BC reaches the setting
value of the TM0OC register, and outputs "L" after that. Then, TM0BC continues counting up, and
PWM source waveform outputs "H" again, once overflow happens, and TM0BC restarts counting up
from x'00'. TM0IO pin outputs the PWM source waveform with 1 count clock delay.
The initial setting of PWM output is changed from "L" output to "H" output at the selection of
PWM operation by the TMnPWM flag of the TMnMD register.