How fast can I counter using external interrupt?

[Shin KS]

Posted on June 28, 2017 at 13:21

Hi everyone

I'm usging STM32F103VE @72Mhz

I wonder how fast can I counter using external interrupt?

These days I try to count clock signal by EXTI. ( clock signal is 10 Mhz) Is it possible?

If impossible then, what is limit frequence of EXTI?  (using STM32F103VE )

Thanks

[Tesla DeLorean]

Posted on June 28, 2017 at 16:23

>>Is it possible?

No, it is unrealistic.

Likely to saturate the processor beyond a few hundred KHz, depending on how much code is in the IRQ handler, and if running from FLASH vs RAM. The higher the rate, the less useful work the processor can do in the time it has remaining.

For 10 MHz you'd use a TIM where the input pin is used as an External Clock, and then you'd sample the counter every 1ms, as you're limited to 16-bit counters