PWM input capture tolerance on F334 or F072

Ngai yuk kong · ‎2018-04-22

Posted on April 23, 2018 at 04:22

I would like to ask the tolerance about measuring PWM signal using PWM input capture. I have tried using two Nucleo boards, one is F334 (running at 64MHz, using internal 8MHz RC) and one is F072 (running at 48MHz, using internal 8MHz RC).

With signal generator output at 400kHz, I found that there is always 2 or 3 counts missing in the period measurement.

I tried lower frequency as well, say 40kHz, the 2 to 3 missing counts still exist.

Could anyone tell me what is the expected tolerance for the PWM input capture?

Thank you very much.

Jan Waclawek · ‎2018-04-22

Posted on April 23, 2018 at 08:51

I believe therw is a delay between the moment of capture and reset.

Don't reset, do just capture and calculate the difference.

JW