ISD94100 Series Technical Reference Manual
Sep 9, 2019
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Rev1.09
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Figure 6.7-13 PWM Prescale Waveform in Up Count Type
6.7.6.2
PWM Counter
PWM supports three counter types operation: up count, down count and up-down count types.
6.7.6.3
Up Count Type
When PWM counter is set to up count type, CNTTYPE (TIMERx_PWMCTL[2:1]) is 0x0, it starts
up-counting from zero to PERIOD (TIMERx_PWMPERIOD[15:0]). The current counter value can
be read from the CNT (TIMERx_PWMCNT[15:0]). PWM generates a zero point event when both
counter and prescale counts to 0. PWM generates a period point event when the counter counts to
PERIOD and prescale counts to 0. Figure 6.7-14
shows an example of PWM up count type, where
PWM period time is (1) * (1) * TMRx_PWMCLK.
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PWM Period
PWM Period
PERIOD = 5
PERIOD = 8
PWM Period
PERIOD = 8
zero point event
period point event
PWMCNT
(TIMERx_PWMCNT[15:0])
PWMCNTEN
(TIMERx_PWMCTL[0])
Figure 6.7-14 PWM Up Count Type
6.7.6.4
Down Count Type
When PWM counter is set to down count type, CNTTYPE (TIMERx_PWMCTL[2:1]) is 0x1, it starts
down-counting from PERIOD to zero, current counter value can be read from CNT
(TIMERx_PWMCNT[15:0]). PWM generates a zero point event when both counter and prescale
counts to 0. PWM generates a period point event when the counter counts to PERIOD and prescale
counts to 0. Figure 6.7-15
is an example of PWM down count type, where PWM period time is
(1) * (1) * TMRx_PWMCLK.
