Figure 62. Ti2 External Clock Connection Example - ST STM32F100 Series Reference Manual

Advanced arm-based 32-bit mcus

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For example, to configure the upcounter to count in response to a rising edge on the TI2

input, use the following procedure:

Configure channel 2 to detect rising edges on the TI2 input by writing CC2S = '01' in

the TIMx_CCMR1 register.

Configure the input filter duration by writing the IC2F[3:0] bits in the TIMx_CCMR1

Select rising edge polarity by writing CC2P=0 in the TIMx_CCER register.

Configure the timer in external clock mode 1 by writing SMS=111 in the TIMx_SMCR

Select TI2 as the trigger input source by writing TS=110 in the TIMx_SMCR register.

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

The capture prescaler is not used for triggering, so the user does not need to configure it.

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.

Figure 62. TI2 external clock connection example

TI2F_Falling

RM0041 Rev 6

Advanced-control timer (TIM1)

(internal clock)

External clock

External clock

Internal clock

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