Doubt on Timer Interrupt

Forum|Forum|3 years ago
March 21, 2023
8 replies
2282 views

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!

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Best answer by LCE

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.

LCEBest answer

Principal II

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.

Killstreet30Author

Associate III

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

}

J

JTP1

Graduate II

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