RM0016 datasheet(153/467 Pages) STMICROELECTRONICS

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RM0016

16-bit advanced control timer (TIM1)

261

Procedure

Use the following procedure to configure the up-counter and, for example, to count in

response to a rising edge on the TI2 input:

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

TIM1_CCMR2 register.

Configure the input filter duration by writing the IC2F[3:0] bits in the TIM1_CCMR2

Note: The capture prescaler is not used for triggering, so it does not need t o be

configured. The CC2S bits do not need to be configured either as they only select the

input capture source.

Select rising edge polarity by writing CC2P = 0 in the TIM1_CCER1 register.

Configure the timer in external clock mode 1 by writing SMS = 111 in the TIM1_SMCR

Select TI2 as the input source by writing TS = 110 in the TIM1_SMCR register.

Enable the counter by writing CEN = 1 in the TIM1_CR1 register.

When a rising edge occurs on TI2, the counter counts once and the trigger flag is set (TIF bit

in the TIM1_SR1 register) and an interrupt request can be sent if enabled (depending on the

TIE bit in the TIM1_IER register).

The delay between the rising edge on TI2 and the actual reset of the counter is due to the

resynchronization circuit on TI2 input.

Figure 46. Control circuit in external clock mode 1

RM0016 데이터시트(PDF) 153 Page - STMicroelectronics