One of channels’ input signals (CIx) can be chosen from the TIMERx_CHx signal or the
Excusive-OR function of the TIMERx_CH0, TIMERx_CH1 and TIMERx_CH2 signals. First,
the channel input signal (CIx) is synchronized to TIMER_CK domain, and then sampled by a
digital filter to generate a filtered input signal. Then through the edge detector, the rising and
falling edge are detected. You can select one of them by CHxP. One more selector is for the
other channel and trig, controlled by CHxMS. The IC_prescaler make several the input
events generate one effective capture event. On the capture event, CHxVAL will restore the
value of Counter.
So, the process can be divided to several steps as below:
Step1: Filter configuration. (CHxCAPFLT in TIMERx_CHCTL0)
Based on the input signal and requested signal quality, configure compatible
CHxCAPFLT.
Step2: Edge selection. (CHxP/CHxNP in TIMERx_CHCTL2)
Rising or falling edge, choose one by CHxP/CHxNP.
Step3: Capture source selection. (CHxMS in TIMERx_CHCTL0)
As soon as you select one input capture source by CHxMS, you have set the channel
to input mode (CHxMS! = 0x0) and TIMERx_CHxCV cannot be written any more.
Step4: Interrupt enable. (CHxIE and CHxDEN in TIMERx_DMAINTEN)
Enable the related interrupt to get the interrupt and DMA request.
Step5: Capture enables. (CHxEN in TIMERx_CHCTL2)
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