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danielschramm9
Associate II
November 6, 2018
Question

Timers out of sync 32F746GDISCOVERY ?

  • November 6, 2018
  • 0 replies
  • 739 views

Hello,

i found a strange behavior having 2 timers running.

My initial intention was having 4 input captures on the 32F746GDISCOVERY spread over two timers (no timer with 4 pins connected to the Arduino Header) one running as master and triggering the same start.

I always got phase drift between channels. So I stripped down everything to identify he issue in detail.

Timer 8 on APB2 (200MHz) and Timer 4 running on APB1 (100MHz) are both configured as basic timer with high presclaer. Timer 8 has two times prescaler value than Timer 4.

I would expect both timers showing always the same value (+-1 or 2) since the prescaler is 10000 / 20000 is running the timer very slow compared to the register access.

What I observe is that the timers started at the same time start to drift away from each other.

What is the reason for this difference. Is there a bug in one of the Clock multipliers?

Please find the test configuration attached.

Also a log file is attached.

0690X000006CJz4QAG.png

If instead of TIM8 the TIM3 (on APB1) is used there is no drift compared to TIM4.

Thanks a lot,

Daniel Schramm

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