Changing Timer Capture Compare from Timer ISR

[joshmulder]

I am trying to change the PWM duty cycle of timer3, channel 1 from the period elapsed ISR of timer 6. This seems to cause the chip to crash.

 

I can confirm that:

- timer6 is properly configured and interrupt fires appropriately.

- timer3 is properly configured and is outputting PWM (duty cycle can be changed normally from main loop)

 

Using stm32f103vct6

 

Any ideas?

 

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)

{

         if (htim->Instance == TIM6)

         {   

                 __HAL_TIM_SET_COMPARE(&htim3, TIM_CHANNEL_1, 1800);

         } 

}

[LCE]

What's exactly happening? "The chip crashes" is rather vague... Debugged?

Did you check:

- the reference manual, any prereqs for changing a CCR register on the fly?

- the macro __HAL_TIM_SET_COMPARE ?

- try without the macro, some direct register setting, should be something like "TIM3->CCR1 = 1800;"

- sure that ARR (?) > 1800 ?

The timers are not too hard to handle via direct register settings, maybe check that instead of HAL / MX stuff.

[EXUE.2]

I guess It is because to update the TIM3 configuration too quickly, you can try to control the duration of this setting or add one flag here and move "__HAL_TIM_SET_COMPARE(&htim3, TIM_CHANNEL_1, 1800);" to main(), like below:

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)

{

         if (htim->Instance == TIM6)

         {   

                 MAIN_TIM3_COMPARE_FLAG = 1;

         } 

}

 

void main(void)

{

  if(MAIN_TIM3_COMPARE_FLAG == 1)

  {

      __HAL_TIM_SET_COMPARE(&htim3, TIM_CHANNEL_1, 1800);

      MAIN_TIM3_COMPARE_FLAG = 0;

  }

}