# STM32 - Timer Interrupts

[TOC]

## References

### [Getting Started with STM32 and Nucleo Part 6: Timers and Timer Interrupts | Digi-Key Electronic](https://youtu.be/VfbW6nfG4kw)

{%youtube VfbW6nfG4kw %}

To avoid busy-checking timestamp to determine if an event should fire, in stead of something like this:

int main()
{
    HAL_TIM_Base_Start_IT(&htim10);
    while (1)
    {
        if (__HAL_TIM_GET_COUNTER(&htim10) - last > THRESHOLD) {
            HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
            last = __HAL_TIM_GET_COUNTER(&htime10);
        }
    }
}

you can implement callbacks for timer-related events listed **TIM Callbacks functions** of **TIM Firmware driver API description** in HAL manuals, and then start timer with interrupt-based APIs like `HAL_TIM_Start_Base_IT`. For example, after setting appropriate timer parameters for `TIM10` and implement a `HAL_TIM_PeriodElapsedCallback`:

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim);

int main()
{
    HAL_TIM_Base_Start_IT(&htim10);
    while (1) {}
}

void HAL_TIM_PeriodElapsedCallback (TIM_HandleTypeDef *htim)
{
  if (htim->Instance == htim10.Instance)
  {
      HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
  }
}

The `HAL_TIM_PeriodElapsedCallback` is triggered whenever its counter period gets reset (e.g. count over the Counter Period). Note that those two examples may require different settings on `TIM10`, so they are not really equivqlent.

### [HAL #10: HowTo Timer with Interrupt](https://youtu.be/YPJlhYm5T8Y)

{%youtube YPJlhYm5T8Y %}