RTC Alarm EventCallback called only 1 time

[Richard Lowe]

Working with the RTC I'm having some issue with the callback only being called a single time.

 

void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc) {
 RTC_AlarmTypeDef sAlarm;
 uint32_t hobb_time;

 __HAL_RTC_ALARM_CLEAR_FLAG(hrtc, RTC_FLAG_ALRAF); // Does not seem to change the ISR register

 hobb_time = HAL_RTCEx_BKUPRead(hrtc, RTC_BKP_DR1);

 // Write the new hobbs incremented value to backup register
 HAL_PWR_EnableBkUpAccess();
 HAL_RTCEx_BKUPWrite(hrtc, RTC_BKP_DR1, ++hobb_time);
 HAL_PWR_DisableBkUpAccess();

 HAL_RTC_GetAlarm(hrtc, &sAlarm, RTC_ALARM_A, FORMAT_BIN);

 if(sAlarm.AlarmTime.Minutes > 58)
 {
 sAlarm.AlarmTime.Minutes = 0;
 }
 else
 {
 sAlarm.AlarmTime.Minutes = sAlarm.AlarmTime.Minutes + 1;
 }

 while(HAL_RTC_SetAlarm_IT(hrtc, &sAlarm, RTC_FORMAT_BIN) != HAL_OK){}
}

 

I have the alarm being triggered every 1 minute. I can see the alarmA flag and try to clear it with this macro: 

__HAL_RTC_ALARM_CLEAR_FLAG(hrtc, RTC_FLAG_ALRAF);

But the ISR register is unaffected. 

I've masked the DAYS, SECONDS, etc.

sAlarm.AlarmMask = RTC_ALARMMASK_DATEWEEKDAY|RTC_ALARMMASK_HOURS
 |RTC_ALARMMASK_SECONDS;
sAlarm.AlarmSubSecondMask = RTC_ALARMSUBSECONDMASK_ALL;

Anybody working with alarm events that only trigger a single time?

[Richard Lowe]

I still have nothing. Seems like the HAL functions to perform all the actions called for in the datasheet. 

• Clear the interrupt on the Alarm
• Clear EXTI interrupt
• Write to protection registers
• Re-enable the interrupt

ISR Flag does not clear:

 

Still can only get a single interrupt. Single alarm handler, that's it..... Please advise.

[Richard Lowe]

This is in HAL_RTC_SetAlarm_IT. Seems to include everything in the Reference Manual.

/* Disable the write protection for RTC registers */
__HAL_RTC_WRITEPROTECTION_DISABLE(hrtc);

/* Configure the Alarm register */
if(sAlarm->Alarm == RTC_ALARM_A)
{
 /* Disable the Alarm A interrupt */
 __HAL_RTC_ALARMA_DISABLE(hrtc);

 /* Clear flag alarm A */
 __HAL_RTC_ALARM_CLEAR_FLAG(hrtc, RTC_FLAG_ALRAF);

 tickstart = HAL_GetTick();
 /* Wait till RTC ALRAWF flag is set and if timeout is reached exit */
#if defined(TAMP)
 while (READ_BIT(hrtc->Instance->ICSR, RTC_FLAG_ALRAWF) == 0U)
#else
 while (__HAL_RTC_ALARM_GET_FLAG(hrtc, RTC_FLAG_ALRAWF) == 0U)
#endif /* TAMP */
 {
 if((HAL_GetTick() - tickstart) > RTC_TIMEOUT_VALUE)
 {
 /* Enable the write protection for RTC registers */
 __HAL_RTC_WRITEPROTECTION_ENABLE(hrtc);

 hrtc->State = HAL_RTC_STATE_TIMEOUT;

 /* Process Unlocked */
 __HAL_UNLOCK(hrtc);

 return HAL_TIMEOUT;
 }
 }

 hrtc->Instance->ALRMAR = (uint32_t)tmpreg;
 /* Configure the Alarm A Sub Second register */
 hrtc->Instance->ALRMASSR = subsecondtmpreg;
 /* Configure the Alarm state: Enable Alarm */
 __HAL_RTC_ALARMA_ENABLE(hrtc);
 /* Configure the Alarm interrupt */
 __HAL_RTC_ALARM_ENABLE_IT(hrtc, RTC_IT_ALRA);

 

[Richard Lowe]

The following lines will disable the RTC and cause all my issues:

HAL_PWR_EnableBkUpAccess();
HAL_RTCEx_BKUPWrite(hrtc, RTC_BKP_DR1, ++hobb_time);
HAL_PWR_DisableBkUpAccess();

The first line is already called in the RTC_Init() function, but the the last line, HAL_PWR_DisableBkUpAccess() will disable the RTC..... So that is why it was only called once.