How to call timer interrupt using registers? [NO HAL DRIVERS]

[RShre.2]

Hi, i am trying to call timer interrupt handler using registers and the following is my code, but the problem is that the function is being not called, I see no output in the oscilloscope or live expression. First my DAC value is still 0, the counter is running though. I also tried to use toggle breakpoint to see where the problem lies and I think it's at this point // Clear the interrupt flag

    TIM2->SR &= ~TIM_SR_UIF;

but i am not sure. Could anyone confirm if what i am doing is correct/wrong?

Btw, i am using stm32-g071rb.

int main(){

/* Configure the system clock */

 SystemClock_Config();

 /* USER CODE BEGIN SysInit */

 /* USER CODE END SysInit */

 /* Initialize all configured peripherals */

 MX_GPIO_Init();

 MX_USART2_UART_Init();

 MX_DAC1_Init();

 MX_TIM2_Init();

 /* USER CODE BEGIN 2 */

// TIM2->DIER |= TIM_DIER_UIE;     // Enable the update (overflow) interrupt

 NVIC_SetPriority(TIM2_IRQn, 0);  // Set the interrupt priority (if needed)}

 NVIC_EnableIRQ(TIM2_IRQn);     // Enable the timer interrupt in the NVIC

 TIM2->CR1 |= TIM_CR1_CEN; // Start the timer

}

void TIM2_IRQHandler(void)

{

 /* USER CODE BEGIN TIM2_IRQn 0 */

if (TIM2->SR & TIM_SR_UIF)

  {

    // Timer interrupt flag is set, do something here

    DAC1->DHR12L2 = 1;

    HAL_Delay(100);

//

    // Clear the interrupt flag

    TIM2->SR &= ~TIM_SR_UIF;

  }

 /* USER CODE END TIM2_IRQn 0 */

 HAL_TIM_IRQHandler(&htim2);

 /* USER CODE BEGIN TIM2_IRQn 1 */

 /* USER CODE END TIM2_IRQn 1 */

}

[waclawek.jan]

Read out and check/post TIM2 registers content.

Generic interrupt not fire checklist here.

JW

[Piranha]

And also this:

http://efton.sk/STM32/gotcha/g9.html

[JMala.3]

Your code looks good, Here is my code (for the STM32L010) that works perfectly. Th only comment I have on your code is why did you comment out the line // TIM2->DIER |= TIM_DIER_UIE; This is needed to set the Timer to interrupt. This may have been set already if you checked the interrupt checkbox in the HAL Timeer setup dialog

void SysTick_Init(void)
{
#ifdef BARE_METAL
    SET_AND_WAIT(RCC->APB2ENR, RCC_APB2ENR_TIM21EN);   /* Enable TIM21 Clock */
 
    TIM21->PSC = 3;              /* divide by 4 prescaler */
    TIM21->ARR = 5242;           /* set the countdown value */
#endif
 
    TIM21->DIER |= TIM_DIER_UIE; /* Enable the interrupt */
    TIM21->CR1  |= TIM_CR1_CEN;  /* Enable the timer */
    NVIC_EnableIRQ( TIM21_IRQn );
}
void TIM21_IRQHandler(void)
{
    if (TIM21->SR & TIM_SR_UIF)
    {
       SysTick_Milliseconds += TICK_PERIOD_IN_MS;
    }
    TIM21->SR = 0;  /* Clear all interrupts */
}

[TDK]

You have a race condition here. You should only clear the flag if UIF is set. Otherwise you may clear it without it being handled.

[RShre.2]

Yes, the tim2 is checked mark in the CubeMx as a global interrupt already that's why I commented that part in the code.

 But I see when the timer interrupt is enabled, my CNT is always at 0. Why is that so?

PS: Nevermind, it worked now.

[gbm · Accepted solution]

The first problem is the use of HAL_Delay in the ISR. This call wiiil never return, as it is waiting for a lower priority interrupt to occur while called from a higher priority interrupt. This will not work.

Other problems: you cllear the interrupt flag incorrectly, using &= instead of a simple assignment =. You don't need to call HAL_TIM_IRQHandler() from your routine, it doesn't make sense.

[RShre.2]

I just turned off the interrupt in cubemx and called it manually in the code so now the  HAL_TIM_IRQHandler() is not there anymore. Now, my value is changing. Thanks :)