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timer prescaler triggers on first rising edge

Question asked by piet t on Jan 22, 2018
Latest reply on Jan 22, 2018 by waclawek.jan

Hey everyone,

 

I'm using a stm32f722ze

 

I've got a small issue considering the prescaler on the timers. I'm using this to trigger an input capture and DMA request after 8 clock cycles, although the prescaler seems to have a slightly odd issue.

 

The issue:

 

first rising edge -> triggers input capture timer which triggers DMA

every eight rising edges after -> triggers input capture timer which triggers DMA

 

If I've set the prescaler to 8, I ideally would never want it to trigger on the first edge, but definetly on every 8th edge.

 

This completely screws up my timing as it need to only be triggered on every eight edges.

 

Ideally what I'd like is that first edge to never trigger the input capture, but rather every eight edges from the beginning. Is there any way that I can change this so that the first trigger doesn't happen?

 

Thanks in advance for any help. Its really appreciated.

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