Doubt on Timer Interrupt

[Killstreet30]

Hi,

So I want to have a timer interrupt of 15 seconds. So I calculated the values of pre scalar and counter accordingly:

Prescalar - 18356

Counter - 65347

I just wanted to ask if I set such values. Will it work? Cause I tried the same using an LED Toggle program but the LED didn't toggle. Also PS I'm using 3 timers and 2 External interrupts so I wonder if all collide and thats's why maybe it doesn't work?

Thanks!

[LCE · Accepted solution]

That depends on your STM32, the timer, and the timer's clock.

Looks like your timer's clock is 80 MHz, so these values are about okay.

But make it a little easier for you, and use other values:

prescaler PSC: take something like 19999 = 20k - 1

-> clock now 4 kHz

auto reload ARR = (15 * 4000) - 1

Then you also need to enable the interrupt, and do something in the ISR.

But because waiting 15 seconds is too boring, start with a LED toggle rate you can see instantly.

[Killstreet30]

Yeah I checked all that still doesn't seem to work even for shorter durations. I tried using another timer channel also but it doesn't work. Any help?

My code is like this

HAL_TIM_Base_Start(&htim1);

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)

{

  if (htim == &htim3) {

   time_up_load = 1 ; // it enables motor to rotate clockwise

  }

}

[JTP1]

Use HAL_TIM_Base_Start_IT and then start correct timer ( now htim1 / htim3).

[Killstreet30]

yeah sorry my bad it was 1 only but still doesn't work and I have enabled global interrupt too.

[LCE]

Is the timer doing anything?

Can you check some registers, be it via debugging or UART output?

[Killstreet30]

I checked it's not performing anything it's just sitting like that. I'm clueless on how to debug further. any ideas?

[waclawek.jan]

As LCE said above, read out and check/post the TIM registers content.

JW

[Killstreet30]

Yeah thank you! it works perfectly fine now.