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hlmn7
Associate II
Jan 21, 2025 8:42 AM UTC
Solved

differentiate wake-up reason between two interrupts: RTC & GPIO_EXTI ?

In my system, I initialised two interrupts for wake-up from STOP2 mode, after exiting STOP2 mode, how do I know that the system is waking up by RTC timer or interrupt pin? Is there any variable that I can check after waking up to find the reason why the system is wake?

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Andrew Neil
Andrew NeilBest answer
Super User
Jan 21, 2025 9:20 AM UTC

I mean you create your own flags in your software - the hardware interrupt flags will have been cleared by the handlers.

volatile bool rtc_interrupt_occurred;
volatile bool exti_interrupt_occurred;

Using HAL, you could set them in the callback; eg,

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
 /* Prevent unused argument(s) compilation warning */
 UNUSED(GPIO_Pin);

 exti_interrupt_occurred = true;
}

and then test in your main-line code

 

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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4 replies

Andrew Neil
Andrew Neil
Super User
Jan 21, 2025 8:48 AM UTC

Set flags in your interrupt handlers which indicate which one occurred.

What STM32L4, exactly, are you using?

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
    hlmn7Author
    Associate II
    Jan 21, 2025 9:12 AM UTC

    I am using STM32L476RG, actually I don't get it, I already tried to check flag before and after using this code:

     if (__HAL_RTC_WAKEUPTIMER_GET_FLAG(&hrtc, RTC_FLAG_WUTF) != RESET)
 {
 // Wake-up event detected, clear the flag
 __HAL_RTC_WAKEUPTIMER_CLEAR_FLAG(&hrtc, RTC_FLAG_WUTF);

 // Your code to turn on the LED or perform other actions
 printf("Wake-up event detected, clear the flag\n");
 }
 // Check GPIO 7 interrupt pin Flag
 if(__HAL_GPIO_EXTI_GET_FLAG(GPIO_PIN_7) != RESET)
 {
 // Wake-up event detected, clear the flag
 __HAL_GPIO_EXTI_CLEAR_FLAG(GPIO_PIN_7);

 // Your code to turn on the LED or perform other actions
 printf("Wake-up event detected by interrupt pin, clear the flag\n");
 }

     However, both states are in RESET and the reason not printed out.

    Andrew Neil
    Andrew NeilBest answer
    Super User
    Jan 21, 2025 9:20 AM UTC

    I mean you create your own flags in your software - the hardware interrupt flags will have been cleared by the handlers.

    volatile bool rtc_interrupt_occurred;
volatile bool exti_interrupt_occurred;

    Using HAL, you could set them in the callback; eg,

    void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
 /* Prevent unused argument(s) compilation warning */
 UNUSED(GPIO_Pin);

 exti_interrupt_occurred = true;
}

    and then test in your main-line code

     

    A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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