I was trying baremetal programming for STM32L412T6 controller. I got stuck at RTC wakeup interrupt. My code is jumping to for loop without going to the interrupt handler, Below mentioning my code.

int main(void)

{



    //LedConfig();

    rtc_domain_access();

    rtc_init();



    initialize_rtc_wakeup();

    NVIC_EnableIRQ(RTC_WKUP_IRQn);



    /* Loop forever */

    for(;;)

    {

        flag = 1;

    }

}



void rtc_domain_access(void)

{

    /* Enable Clock for Power interface.*/

    RCC->APB1ENR1 |= (1U<<28);



    /*Disable backup domain write protection*/

    PWR->CR1 |= (1U<<8);

    while((PWR->CR1 & (1U<<8))==0);



    /*Reset the Backup domain*/

    RCC->BDCR |= (1U<<16);

    RCC->BDCR &= ~(1U<<16);



    /*Enable LSE Clock source and wait until LSERDY bit to set*/

    RCC->BDCR |= (1U<<0);

    while ((RCC->BDCR & (1U<<1)) == 0);



    /*Select LSE as RTC Clock*/

    RCC->BDCR |= (1U<<8);

    RCC->BDCR &= ~(1U<<9);



    /*Enable RTC Clock*/

    RCC->BDCR |= (1U<<15);



    /*Disable access to RTC registers*/

    RCC->APB1ENR1 &= ~(1U<<28);



}



void rtc_init(void)

{

     /* Disable the write protection for RTC registers */

    RTC->WPR = 0xCA;

    RTC->WPR = 0x53;



    /* Check if the Initialization mode is set */

    if((RTC->ICSR & (1U<<6))==0)

    {

        /* Set the Initialization mode */

        RTC->ICSR |= (1U<<7);



        /* Wait till RTC is in INIT state*/

        while((RTC->ICSR & (1U<<6))==0);

    }



     /* Clear RTC_CR FMT, OSEL, POL and TAMPOE Bits */

    RTC->CR &= ~(1U<<6);         //FMT

    RTC->CR &= ~(1U<<20);        //POL

    RTC->CR &= ~(1U<<21);        //OSEL

    RTC->CR &= ~(1U<<22);        //OSEL

    RTC->CR &= ~(1U<<26);        //TAMPOE



    /* Set RTC_CR register */

    RTC->CR &= ~(1U<<6);         //FMT bit set as Zero,Hour Format Selected as 24

    RTC->CR &= ~(1U<<20);        //POL bit set as Zero, Output polarity selected as high.

    RTC->CR &= ~(1U<<21);        //OSEL[22:21] set as zero, output selection disabled.

    RTC->CR &= ~(1U<<22);



    /* Configure the RTC PRER */

    RTC->PRER = 0xFF;           // Synchronus value set as 255

    RTC->PRER |= (0x7F<<16);    // Asynchronus value set as 127.



    /* Exit Initialization mode */

    RTC->ICSR &= ~(1U<<7);      // Clear INIT bit.



     /* If CR_BYPSHAD bit = 0, wait for synchro */

    if((RTC->CR & (1U<<5))==0)

    {

        /* Clear RSF flag */

        RTC->ICSR &= ~(1U<<5);



        /* Wait the registers to be synchronised */

        while((RTC->ICSR & (1U<<5))==0);

    }



    /* Clear RTC_CR TAMPALRM_PU, TAMPALRM_TYPE and OUT2EN Bits */

    RTC->CR &= ~(1U<<29);

    RTC->CR &= ~(1U<<30);

    RTC->CR &= ~(1U<<31);



    /*Set Output type as open drain pullup*/

    RTC->CR |= (1U<<30);



    /* Enable the write protection for RTC registers */

    RTC->WPR = 0xFF;



}





void Pwr_Clear_Flag(void)

{

    PWR->SCR = 0x1F;

}



void RTCEx_DeactivateWakeUpTimer(void)

{

    /*Disable Write protection for RTC Registers*/

    RTC->WPR = 0xCA;

    RTC->WPR = 0x53;



    /*Disable the Wakeup Timer*/

    RTC->CR &= ~(1U<<10);



    /*In case of interrupt mode is used, the interrupt source must disabled*/

    RTC->CR &= ~(1U<<14);



    /* Wait till RTC WUTWF flag is set */

    while ((RTC->ICSR & (1U<<2)) == 0);



    /* Enable the write protection for RTC registers */

    RTC->WPR = 0xFF;

}



void RTCEx_SetWakeUpTimer_IT(uint32_t RTC_WAKEUP_TIME_IN_SECONDS,uint32_t WakeUpAutoClr)

{

     /* Disable the write protection for RTC registers */

    RTC->WPR = 0xCA;

    RTC->WPR = 0x53;



     /* Clear WUTE in RTC_CR to disable the wakeup timer */

    RTC->CR &= ~(1U<<10);



     /* Clear flag Wake-Up */

    RTC->SCR = (1U<<2);



     /* Poll WUTWF until it is set in RTC_ICSR to make sure the access to wakeup autoreload

         counter and to WUCKSEL[2:0] bits is allowed. */

    if((RTC->ICSR & (1U<<6))==0)

    {

        while((RTC->ICSR & (1U<<2))==0);

    }





    /* Configure the Wakeup Timer counter and auto clear value */

    RTC->WUTR |= (RTC_WAKEUP_TIME_IN_SECONDS-1);

    RTC->WUTR |= (WakeUpAutoClr<<16);



   /* Configure the clock source */

    RTC->CR &= ~(1U<<0);

    RTC->CR &= ~(1U<<1);

    RTC->CR |= (1U<<2);



     /* RTC WakeUpTimer EXTI Configuration: Interrupt configuration */

    EXTI->IMR1 |= (1U<<20);

    EXTI->RTSR1 |= (1U<<20);



     /* Configure the Interrupt in the RTC_CR register */

    RTC->CR |= (1U<<14);



     /* Enable the Wakeup Timer */

    RTC->CR |= (1U<<10);



     /* Enable the write protection for RTC registers */

    RTC->WPR = 0xFF;

}



void initialize_rtc_wakeup(void)

{

    RTCEx_DeactivateWakeUpTimer();

    Pwr_Clear_Flag();

    RTCEx_SetWakeUpTimer_IT(RTC_WAKEUP_TIME_IN_SECONDS,WakeUpAutoClr);

}



void RTC_WKUP_IRQHandler(void)

{

    EXTI->PR1 = (1U<<20);

    if((RTC->MISR & (1U<<2))!=0)

    {

        //GPIOB->ODR |= 1<<13;

        RTC->SCR |= (1U<<2);

        count++ ;



    }



}

I tried to make a RTC wakeup interrupt in every 3 seconds, when it occurs I tried to increase the value of variable count, instead of that it goes to the infinite loop and changes the flag value.

Review your startup code. Make sure the the interrupt vector table is setup correctly with the RTC_WKUP_IRQn vector is pointing to RTC_WKUP_IRQHandler and not some generic empty handler.

Additionally I would make sure that RTC_WKUP_IRQn is defined to be the correct vector number.

Don't you have to be sleeping to wake up?

 Something like this:

                /* Enter STOP 2 mode */
                HAL_PWREx_EnterSTOP2Mode(PWR_STOPENTRY_WFI);