Input Capture Rising Edge IRQ Triggers A Update Event IRQ

[oli]

Posted on February 04, 2015 at 17:46

Hello

I'm using the Update Event (UEV) of TIM1 to count the CNT overflows (CNT > ARR). I'm using the capture compare IRQ of TIM1 on channel 1 to catch the rising edges of an input signal. Now I've got a strange thing: On each time the TIM1 captures a rising edge it triggers the capture compare interrupt and the UEV interrupt. The input signal and the CNT overflow are not syncron so this can not be a reason. This behaviour is not mentioned at the manual and the register description. Has anyone an idea why this happens and if possible how  divide this two interrupts? Thanks #input-capture #update-event #stm32-input-capture-update-even

[waclawek.jan]

Posted on February 04, 2015 at 17:55

Which STM32 model?

Do you check for the source of interrupt in the ISR(s)? Don't you use reset slave mode triggered by the same CC? JW

[oli]

Posted on February 04, 2015 at 19:40 Yes, I'm checking the interrupt source at the ISR. What do you mean with ''by the same CC''? Capture Compare? I'm just doing input capture at channel 1 and counting the CNT overflows on UEV. What I could not find out was why I do get the UEV on a input capture and if it is a correct function what is the cause and the sense of it . This behaviour is not described at the manual. And what I need to know is if it is possible to avoid a UEV at a input capture event.

[oli]

Posted on February 04, 2015 at 19:43 Sorry. I've forgotten : it is a stm32f4

[waclawek.jan]

Posted on February 04, 2015 at 19:59

Hummm...

Could you please post the content of all TIM1 registers, as seen by the entry of each ISR? JW

[oli]

Posted on February 06, 2015 at 16:31 Thanks Jan you were right. I was using the configuration for input capture with PWM for the input capture. So I've got the UEV all the time when an input capture was caught. One more time thanks a lot.