Pwm Input Mode (Only For Tim9/12); Figure 175. Pwm Input Mode Timing - ST STM32F207 Series Reference Manual

Advanced arm-based 32-bit mcus

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General-purpose timers (TIM9 to TIM14)

PWM input mode (only for TIM9/12)

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

Two ICx signals are mapped on the same TIx input.

These 2 ICx signals are active on edges with opposite polarity.

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

is configured in reset mode.

For example, the user can measure the period (in TIMx_CCR1 register) and the duty cycle

(in TIMx_CCR2 register) of the PWM applied on TI1 using 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 TIMx_CCR1 and counter

clear): program the CC1P and CC1NP bits to '00' (active on rising edge).

Select the active input for TIMx_CCR2: write the CC2S bits to '10' in the TIMx_CCMR1

Select the active polarity for TI1FP2 (used for capture in TIMx_CCR2): program the

CC2P and CC2NP bits to '11' (active on falling edge).

Select the valid trigger input: write the TS bits to '101' in the TIMx_SMCR register

(TI1FP1 selected).

Configure the slave mode controller in reset mode: write the SMS bits to '100' in the

TIMx_SMCR register.

Enable the captures: write the CC1E and CC2E bits to '1' in the TIMx_CCER register.

1. The PWM input mode can be used only with the TIMx_CH1/TIMx_CH2 signals due to the fact that only

TI1FP1 and TI2FP2 are connected to the slave mode controller.

reset counter

RM0033 Rev 9

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