Chapter 8
8-bit Timer
8-bit PWM Output VIII - 25
8.6 8-bit PWM Output
8.6.1 Operation (Timer 0, Timer 2 and Timer 4)
8-bit PWM Output Operation
Timer 0, Timer 2 and Timer 4 have PWM function. a PWM waveform with a given duty cycle is generated by set-
ting TMnOC to "High" period of the PWM duty. And the period of the PWM is the time of the full count overflow
of the 8-bit timer.
For PWM output pins, refer to Table:8.1.1.
Count Timing of PWM Output (at Normal)
Figure:8.6.1 Count Timing of PWM Output (at Normal)
When TMnPOP bit is "0":
• (A) PWM output is "High" while TMnBC counts up from "0x01" to the setting value of TMnOC.
• (B) PWM output changes to "Low" when TMnBC matches the setting value of TMnOC, then TMnBC contin-
ues counting up until it overflows.
..
As for the initial setting, the PWM output is changed from "Low" to "High" when setting the
TMnMD.TMnPWM (when TMnPOP bit = 0) to select the PWM operation.
..
N
N+1 N+2 FE
FF
Count
clock
TMnEN
bit
Compare
register
Binary
counter
Interrupt
request
00 01 N+1N-1
N
00 01 N-1
N
TMnIO output
(PWM output)
(A)
(B)
PWM basic waveform (overflow time of binary counter)
Time set in the compare register
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