Why __HAL_TIM_CLEAR_IT at start of interrupt?

[Kristoffer Iversen]

Posted on October 15, 2017 at 01:10

Hello

Why does the HAL library call '__HAL_TIM_CLEAR_IT' before calling the 'HAL_TIM_PeriodElapsedCallback' callback, instead of after?

I previously had a bit of code running before the 'HAL_TIM_IRQHandler(...)' in stm32f0xx_it.c for TIM6, which worked well. But when I refactored it to use the callback and then TIM17 stopped working (specifically a different timer all together stops interrupting!?).

After trying to track down the problem it seems that if I clear the interrupt bit for TIM6 before starting my bit of code, that makes TIM17 stop working. However if I run my code first, then clear the interrupt for TIM6, then TIM17 remains unaffected. Also, I can short down the code (so that execution is faster), and then equally TIM17 seems unaffected..

Why does this happen? Why is  __HAL_TIM_CLEAR_IT called by HAL before the Callback is ran?

Thanks for any help!

#interrupt-issue #timer-interrupts #stm32f051r7

[Kristoffer Iversen]

Posted on October 15, 2017 at 01:33

Found the problem: My timer was interrupting quicker than the code of the ISR executed, thus TIM17 which has equal priority never gets to run... TIM6 ISR ran continously always behind.