STM32W108HB datasheet(91/179 Pages) STMICROELECTRONICS

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STM32W108CB, STM32W108HB

General-purpose timers

Doc ID 16252 Rev 2

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Figure 24 gives an overview of the external trigger input block.

Figure 24.

External trigger input block

For example, to configure the up-counter to count each 2 rising edges on ETR, use the

following procedure:

●

As no filter is needed in this example, write TIM_ETF = 0000 in the TIMx_SMCR

●

Set the prescaler by writing TIM_ETPS = 01 in the TIMx_SMCR register.

●

Select rising edge detection on ETR by writing TIM_ETP = 0 in the TIMx_SMCR

●

Enable external clock mode 2 by writing TIM_ECE = 1 in the TIMx_SMCR register.

●

Enable the counter by writing TIM_CEN = 1 in the TIMx_CR1 register.

The counter counts once each 2 ETR rising edges.

The delay between the rising edge on ETR and the actual clock of the counter is due to the

resynchronization circuit on the ETRP signal.

Figure 25.

Control circuit in external clock mode 2

8.1.4

Capture/compare channels

Each capture/compare channel is built around a capture/compare register including a

shadow register, an input stage for capture with digital filter, multiplexing and prescaler, and

an output stage with comparator and output control.

STM32W108HB Datasheet(PDF) 91 Page - STMicroelectronics