Figure 210. Control Circuit In External Clock Mode 1 - STMicroelectronics STM32WL5 Series Reference Manual

General-purpose timer (TIM2)
Note: The capture prescaler is not used for triggering, so it does not need to be configured.
4. Select rising edge polarity by writing CC2P=0 and CC2NP=0 and CC2NP=0 in the
TIMx_CCER register.
5. Configure the timer in external clock mode 1 by writing SMS=111 in the TIMx_SMCR
register.
6. Select TI2 as the input source by writing TS=00110 in the TIMx_SMCR register.
7. Enable the counter by writing CEN=1 in the TIMx_CR1 register.
When a rising edge occurs on TI2, the counter counts once and the TIF flag is set.
The delay between the rising edge on TI2 and the actual clock of the counter is due to the
resynchronization circuit on TI2 input.
Counter clock = CK_CNT = CK_PSC
External clock source mode 2
This mode is selected by writing ECE=1 in the TIMx_SMCR register.
The counter can count at each rising or falling edge on the external trigger input ETR.
Figure 211
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Figure 210. Control circuit in external clock mode 1

TI2
CNT_EN
Counter register
TIF
gives an overview of the external trigger input block.
RM0453 Rev 5
34
Write TIF=0
35 36
RM0453
MS31087V2