[STM32] RTC Interrupts Funktionieren nicht

RCC_APB1ENR |= (1<<RCC_APB1ENR_BKPEN) | (1<<RCC_APB1ENR_PWREN);

PWR_CR |= (1<<PWR_CR_DBP);

RCC_BDCR |= (1<<RCC_BDCR_LSEON);  

while(!(RCC_BDCR & (1<<RCC_BDCR_LSERDY)));

RCC_BDCR |= (1<<RCC_BDCR_RTCSEL0);

RCC_BDCR |= (1<<RCC_BDCR_RTCEN);

while(!(RTC_CRL & (1<<RTC_CRL_RTOFF)));

RTC_CRL |= (1<<RTC_CRL_CNF);

RTC_PRLH = 0x0000;

RTC_PRLL = 0x7FFF;

RTC_CNTH = 0;

RTC_CNTL = 0;

RTC_CRH |= (1<<RTC_CRH_SECIE);

RTC_CRL &= ~(1<<RTC_CRL_CNF);

while(!(RTC_CRL & (1<<RTC_CRL_RTOFF)));

if(RTC_CRL & (1<<RTC_CRL_ALRF))

{

  RTC_CRL &= ~(1<<RTC_CRL_SECF);

  if(GPIOB_ODR & GPIO_PIN(5))

    GPIOB_BRR |= GPIO_PIN(5);

  else

    GPIOB_BSRR |= GPIO_PIN(5);

  while(!(RTC_CRL & (1<<RTC_CRL_RSF)));

}