interrupt latency with 2 two Identical board

[Wleon.1]

Hi, I am using two Identical board, both board installed with a STM32F733ZE, and both have the same program loaded.

The program is very simple where if an interrupt from PG0, will reset the PWM counter of TIM8. provided with the same interrupt source, I am seeing a const 5us delay on the counter reset, given everything are the same I don't understand why am I still getting a 5us delay ?

[Tesla DeLorean]

Does TIM8 have a prescaler?​

[Wleon.1]

yes but I have set it to 0

[TDK]

It's possible the systick interrupt is delaying the interrupt you want from firing. But far more likely is something is different between the two boards, especially if the delay is constant. 5us is quite a long time in terms of cpu cycles.

Cache will also affect execution speed to some degree, though it should be consistent if the two chips are truly running the same code.

[Tesla DeLorean]

Even with crystals the clocks are not identical.

5 us seems like a lot, and not something I can determine specifically.