2020-10-02 07:12 AM
Hi,
I have a STM32L071 on a custom board
The code was generated with CubeMx for TrueSTUDIO.
I have an alarm set on the RTC to wake up the chip from standby mode everyday at 2 AM.
I tested it and the system does wake up ! good.
My problem is that I need to differentiate the origin of the wake up between RTC alarm and WKUP pin 1.
I check for PWR_FLAG_WU which does not give much information to differentiate the two.
My understanding from the reference manual (RM0377 DocID025942 Rev 8 p559) is that the bit ALRAF in the RTC initialization and status register (RTC_ISR) is the one that might be useful for me.
But even tho the system wakes up from RTC, the ALRAF flag is not set
same with RTC_IT_ALRA and RTC_FLAG_WUTF
Is there a way to know if the origin of wake up is the WKUP pin ?
regards,
Benjamin GREFFE.
code used to check the flags :
if(__HAL_RTC_ALARM_GET_IT(&hrtc, RTC_IT_ALRA))
{
lbWakedUpByRTC_IT = true;
}
if (__HAL_RTC_ALARM_GET_FLAG(&hrtc, RTC_FLAG_ALRAF))
{
lbWakedUpByRTC_ALRAF = true;
}
if (__HAL_RTC_WAKEUPTIMER_GET_FLAG(&hrtc, RTC_FLAG_WUTF))
{
lbWakedUpByRTC_WUTF = true;
}
code to initialize the rtc
static void MX_RTC_Init(void)
{
RTC_AlarmTypeDef sAlarm = {0};
/** Initialize RTC Only
*/
hrtc.Instance = RTC;
hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
hrtc.Init.AsynchPrediv = 125;
hrtc.Init.SynchPrediv = 296;
hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
hrtc.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
if (HAL_RTC_Init(&hrtc) != HAL_OK)
{
Error_Handler();
}
/** Enable the Alarm A
*/
sAlarm.AlarmTime.Hours = 0x2;
sAlarm.AlarmTime.Minutes = 0x0;
sAlarm.AlarmTime.Seconds = 0x0;
sAlarm.AlarmTime.SubSeconds = 0x0;
sAlarm.AlarmTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
sAlarm.AlarmTime.StoreOperation = RTC_STOREOPERATION_RESET;
sAlarm.AlarmMask = RTC_ALARMMASK_DATEWEEKDAY;
sAlarm.AlarmSubSecondMask = RTC_ALARMSUBSECONDMASK_ALL;
sAlarm.AlarmDateWeekDaySel = RTC_ALARMDATEWEEKDAYSEL_DATE;
sAlarm.AlarmDateWeekDay = 0x1;
sAlarm.Alarm = RTC_ALARM_A;
if (HAL_RTC_SetAlarm_IT(&hrtc, &sAlarm, RTC_FORMAT_BCD) != HAL_OK)
{
Error_Handler();
}
}
code to go to sleep
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1);
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);
HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN1);
HAL_PWR_EnterSTANDBYMode();
while (1)
{
NVIC_SystemReset();
}
2021-03-05 12:37 AM
Hi, I have the same or similar problem. ALRAF is not set when returning from standby. I am on a different MCU, STM32F100.
For me all works according to the datasheets when I run in the debugger (ST-Link). However when I run outside the debugger the ALRAF bit never reads as 1. The MCU is returning (reset) perfectly from standby on RTC but I am not able to read a correct value on ALRAF.
Did you find a solution somewhere?
/Mats
2022-09-12 04:28 AM
Any one found a solution for this?
2022-09-12 05:37 AM
I have found a workaround to differentiate source of wakeup
after the SystemClock_Config(); i clear all wakeup flags.
/* Check and handle if the system was resumed from StandBy mode */
if(__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET)
{
/* Clear Standby flag */
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
}
/* Disable all used wakeup sources: PWR_WAKEUP_PIN1 */
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1);
/* Clear all related wakeup flags*/
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);
then i compare current RTC date with expected Calendar alarm
/**** check alarm wakeup ****/
/* read programmed alarm */
uint32_t tmpregalarm = (uint32_t) RTC->ALRMAR;
int alr_hour = bcd2int((uint8_t)((tmpregalarm & (RTC_ALRMAR_HT | RTC_ALRMAR_HU )) >> 16));
int alr_min = bcd2int((uint8_t)((tmpregalarm & (RTC_ALRMAR_MNT | RTC_ALRMAR_MNU)) >> 8 ));
int alr_sec = bcd2int((uint8_t) (tmpregalarm & (RTC_ALRMAR_ST | RTC_ALRMAR_SU )) );
/* read current RTC */
uint32_t tmpregrtc = (uint32_t) RTC->TR;
int rtc_hour = bcd2int((uint8_t)((tmpregrtc & (RTC_TR_HT | RTC_TR_HU )) >> 16));
int rtc_min = bcd2int((uint8_t)((tmpregrtc & (RTC_TR_MNT | RTC_TR_MNU)) >> 8 ));
int rtc_sec = bcd2int((uint8_t) (tmpregrtc & (RTC_TR_ST | RTC_TR_SU )) );
/* if current date= alarm -> alarm wakeup */
if(alr_hour==rtc_hour && alr_min==rtc_min && alr_sec==rtc_sec){lbSystemWakedUpByRtcAlarm = true ;}
else {lbSystemWakedUpByRtcAlarm = false;}
if true, the source of wakeup was the alarm. If false, the source of wakeup was from another source( WKUP PIN or RST in my case)
2022-09-12 06:00 AM
Many thanks. Really appreciated. I also asked this question from ST if I get any different reply I will share it here for everyone to use.
2022-10-05 03:45 PM
2023-10-20 12:39 PM
I don't know if it is the same case for the STM32L071 as the STM32F103, but after many attempts and tests, I have opened a ticket with ST, and I've got this answer:
"It turns out that the ALRF flag (and indeed the whole register) is not kept through system reset - which occurs at wake up. Although this is not explicitly documented. The only similar flag that is kept is WUF in PWR_CSR register but this is combines wakeup from button and RTC alarm so not helpful in your case.
The solution is then the one you already applied - compare the current time to a predefined one from Flash/backup registers."
Check the following post if you have not solved this topic yet: