STM32L4, can't wake up with RTC Alarm A after Stop 2 mode (WFE)

[AFahr.1]

Hi all,

As stated above, I can't seem to wake up the controller from STOP2 mode using WFE with the ALARM A. Here's my alarm and EXTI settings:

if(EXTI->PR1 & EXTI_PR1_PIF18)
{
	EXTI->PR1 |= EXTI_PR1_PIF18;	///< Clear pending interrupt if necessary
}
EXTI->EMR1 |= EXTI_EMR1_EM18; ///< RTC Alarm Mask
EXTI->RTSR1 |= EXTI_RTSR1_RT18; ///< Rising trigger
 
 
/* Set the alarm values with the config values */
 
HAL_PWREx_EnableInternalWakeUpLine();
__HAL_RTC_ALARMA_ENABLE(&hrtc);
__HAL_RTC_ALARM_CLEAR_FLAG(&hrtc, RTC_FLAG_ALRAF);
 
alarm_Time.Hours = storage_config.wup_time.Hours;
alarm_Time.Minutes = storage_config.wup_time.Minutes;
alarm_Time.Seconds = storage_config.wup_time.Seconds;
alarm_Time.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
 
alrm_a.Alarm = RTC_ALARM_A;
alrm_a.AlarmMask = RTC_ALRMAR_MSK4;
alrm_a.AlarmDateWeekDay = RTC_WEEKDAY_MONDAY;
alrm_a.AlarmTime = alarm_Time;
alrm_a.AlarmSubSecondMask = RTC_ALARMSUBSECONDMASK_ALL;
 
HAL_RTC_DeactivateAlarm(&hrtc, RTC_ALARM_A);
if (HAL_RTC_SetAlarm(&hrtc, &alrm_a, RTC_FORMAT_BIN) != HAL_OK)
{
 log_msg(LOG_ERR, "dg_system.c: Error setting alarm Line: %u", __LINE__);
}
 
log_msg(LOG_INF

To send the unit to sleep (I'm using FreeRTOS):

/* Send system to sleep */
vTaskSuspendAll();
vPortRaiseBASEPRI();
 
HAL_PWREx_EnterSTOP2Mode(PWR_STOPENTRY_WFE);

I know that the code above works, because I can wake up the micro using a push button:

GPIO_InitStruct.Pin = GPIO_PIN_9;
GPIO_InitStruct.Mode = GPIO_MODE_EVT_RISING;
GPIO_InitStruct.Pull = GPIO_PULLDOWN;
HAL_GPIO_Init(USB_Det_GPIO_Port, &GPIO_InitStruct);

But either I'm not configuring the Alarm correctly or there is some incorrect setting in the EXTI. I cannot really use an interrupt, as the OS would then trigger it...

Any ideas or pointers are welcome.

Cheers,

Alberto

[AFahr.1]

I seem to again have found my own solution... I had to enable the RTC interrupt even though I'm only using the event.... I get confused by that still.

if(EXTI->PR1 & EXTI_PR1_PIF18)
{
	EXTI->PR1 |= EXTI_PR1_PIF18;	///< Clear pending interrupt if necessary
}
EXTI->EMR1 |= EXTI_EMR1_EM18; ///< RTC Alarm Mask
EXTI->RTSR1 |= EXTI_RTSR1_RT18; ///< Rising trigger
 
 
/* Set the alarm values with the config values */
 
HAL_PWREx_EnableInternalWakeUpLine();
__HAL_RTC_ALARMA_ENABLE(&hrtc);
__HAL_RTC_ALARM_CLEAR_FLAG(&hrtc, RTC_FLAG_ALRAF);
 
alarm_Time.Hours = storage_config.wup_time.Hours;
alarm_Time.Minutes = storage_config.wup_time.Minutes;
alarm_Time.Seconds = storage_config.wup_time.Seconds;
alarm_Time.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
 
alrm_a.Alarm = RTC_ALARM_A;
alrm_a.AlarmMask = RTC_ALRMAR_MSK4;
alrm_a.AlarmDateWeekDay = RTC_WEEKDAY_MONDAY;
alrm_a.AlarmTime = alarm_Time;
alrm_a.AlarmSubSecondMask = RTC_ALARMSUBSECONDMASK_ALL;
 
HAL_NVIC_SetPriority(RTC_Alarm_IRQn, 7, 0);			///< Set the interrupt priority and enable
HAL_NVIC_EnableIRQ(RTC_Alarm_IRQn);
 
HAL_RTC_DeactivateAlarm(&hrtc, RTC_ALARM_A);
if (HAL_RTC_SetAlarm_IT(&hrtc, &alrm_a, RTC_FORMAT_BIN) != HAL_OK)
{
 log_msg(LOG_ERR, "dg_system.c: Error setting alarm Line: %u", __LINE__);
}
 
log_msg(LOG_INFO, "Setting alarm: %02d:%02d:%02d", alrm_a.AlarmTime.Hours, alrm_a.AlarmTime.Minutes, alrm_a.AlarmTime.Seconds);

This worked when I turned it off at 11 PM and it woke up at 6 AM again.

Cheers,

Alberto

[waclawek.jan]

Which STM32?

I believe you don't need to enable the interrupt in NVIC and it would suffice to set ALRAIE/ALRBIE in RTC.

JW

[AFahr.1]

Thanks Jan,

I will give that a try.

It's an STM32L496

Cheers,

Alberto

[AFahr.1]

@Community member​ Hi, you were right, enabling the ALRAIE bit did the trick, no need to enable the interrupt!

Cheers,

Alberto

[Mohamed Aymen HZAMI]

Hello @Community member​,

In order to help other users found quickly the solution please mark waclawek.jan's answer as Best.

Thanks,

Mohamed Aymen.