STM32W108CB datasheet(171/278 Pages) STMICROELECTRONICS

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General-purpose timers

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10.1.6

PWM input mode

This mode is a particular case of input capture mode. The procedure is the same except:

●

Two ICy signals are mapped on the same TIy input.

●

These two ICy signals are active on edges with opposite polarity.

●

One of the two TIyFP signals is selected as trigger input and the slave mode controller

is configured in reset mode.

For example, to measure the period in the TIMx_CCR1 register and the duty cycle in the

TIMx_CCR2 register of the PWM applied on TI1, use the following procedure depending on

CK_INT frequency and prescaler value:

●

Select the active input for TIMx_CCR1: write the CC1S bits to 01 in the TIMx_CCMR1

●

Select the active polarity for TI1FP1, used both for capture in the TIMx_CCR1 and

counter clear, by writing the CC1P bit to 0 (active on rising edge).

●

Select the active input for TIMx_CCR2 by writing the CC2S bits to 10 in the

TIMx_CCMR1 register (TI1 selected).

●

Select the active polarity for TI1FP2 (used for capture in the TIMx_CCR2) by writing the

CC2P bit to 1 (active on falling edge).

●

Select the valid trigger input by writing the TS bits to 101 in the TIMx_SMCR register

(TI1FP1 selected).

●

Configure the slave mode controller in reset mode by writing the SMS bits to 100 in the

TIMx_SMCR register.

●

Enable the captures by writing the CC1E and CC2E bits to 1 in the TIMx_CCER

Figure 34.

PWM input mode timing

STM32W108CB Datasheet(PDF) 171 Page - STMicroelectronics