Figure 69. Ti2 External Clock Connection Example; Figure 115. Control Circuit In Normal Mode, Internal Clock Divided By 1 - ST STM32F102 Series Reference Manual

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General-purpose timer (TIMx)

Counter clock = CK_CNT = CK_PSC

External clock source mode 1

This mode is selected when SMS=111 in the TIMx_SMCR register. The counter can count

at each rising or falling edge on a selected input.

Figure 116. TI2 external clock connection example

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

input, use the following procedure:

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

The capture prescaler is not used for triggering, so you don't need to configure it.

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 input source by writing TS=110 in the TIMx_SMCR register.

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.

COUNTER REGISTER

TI2F_Falling

32 33 34 35 36

01 02 03 04 05 06 07

external clock

external clock

internal clock

(internal clock)

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