如何在 stm32 中设置中断处理程序？

Question

void EXTI4_15_IRQHandler()
{
if(EXTI->PR & EXTI_PR_PR8)
    {
    EXTI->PR |= EXTI_PR_PR8;
    // handle interrupt here
    GPIOA->BSRR |= GPIO_BSRR_BS_10;
    Delay(500);
    GPIOA->BSRR |= GPIO_BSRR_BR_10;
    Delay(500);

    }
}

the interrupt init is initialized in the main.c and the setup is correct. Is there anything that i am missing in the handler function?

Answer 1

You have posted only interrupt handler function, which is not a big help on its own. Basically, your MCU either enters it and executes it entirely or not. So if it (the interrupt handler) doesn't run, it means, the interrupt is not triggered. It means, the problem is somewhere else, so I will go over the entire logic of getting EXTI interrupt on STM32, make sure you have all of that done.

In order to get EXTI interrupts working, we need to connect 3 internal peripherals together: GPIO, EXTI and NVIC. You haven't indicated a specific microcontroller, but they all (STM32) do it in the same/similar way, so I will use STM32F746 as an example, since I have it here on my table.

First, you need to set up EXTI. If you want an interrupt on pin GPIOx8, you need to set bits 8 in the appropriate places in the EXTI registers depending on the event you want to trigger an interrupt.

Second of all, you need to connect GPIO port to EXTI. Do you want an interrupt on PA8? Or PB8? Or PC8? EXTI only understands that it's "Pin 8". It doesn't know if it's PA8 or PB8. That you do in SYSCFG peripheral. In the register EXTI->EXTICR3 you need to set port for EXTI8. This is where you decide that it's PB8 and not PA8 that triggers the interrupt, or whatever port you have.

Now, upon the GPIO behavior event defined in EXTI, the EXTI will report an EXTI9_5 event to NVIC. For now, NVIC will set pending bit if EXTI interrupt event occurs, but it will not execute the interrupt, because it's not activated. So we need to configure NVIC and activate EXTI9_5 interrupt there. At this point your interrupt should work.

To recap, the sequence of actions is the following:

1. Configure EXTI with the number of pin, on which you want interrupt. Number of pin, but not a GPIO port. For you, it will be pin 8.
2. Configure SYSCFG to select GPIO port for that EXTI pin. Configure pin 8 to be pin PB8 and not PA8 (or whatever port the interrupt is on).
3. Activate the corresponding NVIC interrupt.

From this also follows, that you can't have interrupts on PA8 and PB8 at the same time.

EDIT: having delays in the ISR is highly inadvisable. Also, make sure your input signal on the interrupt pin is debounced.

EDIT2: I assumed it goes without saying that every peripheral you use requires clock to be supplied to it.