RM0312 datasheet(131/275 Pages) STMICROELECTRONICS

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RM0312

16-bit general purpose timer (TIM2/TIM3)

170

When an input capture occurs:

•

The TIMx_CCR1 register gets the value of the counter on the active transition.

•

The input capture flag (CC1IF) is set (interrupt flag). The overcapture flag CC1OF is

also set if at least two consecutive captures occured while the flag was not cleared.

•

An interrupt is generated depending on the CC1IE bit.

To handle the overcapture event (CC1OF flag), it is recommended to read the data before

the overcapture flag. This is to avoid missing an overcapture which could happen after

reading the flag and before reading the data.

Note:

It is not possible to send an IC interrupt without actually capturing the counter value in the

TIMx_CCRx register. Nevertheless, it is possible to generate the capture event by software

by setting the corresponding CCiG bit in the TIMx_EGR register.

PWM input signal measurement

This mode is a particular case of input capture mode. The procedure is the same except:

•

Two ICi are mapped on the same TIi input.

•

These 2 ICi are active on edges with opposite polarity.

•

One of the two TIiFP is selected as trigger input and the clock/trigger controller is

configured in trigger reset mode.

Figure 52. PWM input signal measurement

IC1

IC2

IC1

IC2

IC1: Period measurement

in TIMx_CCR1 register.

Reset counter.

IC2: Duty Cycle

measurement in

TIMx_CCR2 register

PWM Input

Signal

TIMx_ARR

Time

value

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