RTC alarm A cannot wake up MCU from Stop mode 2

[BLS_Karo]

Post Edited by ST moderator to apply source code formatting

Hi ST Community,
I am using STm32U575VGTX. I configure RTC as default, enable RTC non-secure interrupt, activate alarm A trigger each 10 seconds as below:

*******************************************
static void MX_RTC_Init(void)

{



/* USER CODE BEGIN RTC_Init 0 */



/* USER CODE END RTC_Init 0 */



RTC_PrivilegeStateTypeDef privilegeState = {0};

RTC_TimeTypeDef sTime = {0};

RTC_DateTypeDef sDate = {0};

RTC_AlarmTypeDef sAlarm = {0};



/* USER CODE BEGIN RTC_Init 1 */



/* USER CODE END RTC_Init 1 */



/** Initialize RTC Only

*/

hrtc.Instance = RTC;

hrtc.Init.HourFormat = RTC_HOURFORMAT_24;

hrtc.Init.AsynchPrediv = 127;

hrtc.Init.SynchPrediv = 255;

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;

hrtc.Init.OutPutPullUp = RTC_OUTPUT_PULLUP_NONE;

hrtc.Init.BinMode = RTC_BINARY_NONE;

if (HAL_RTC_Init(&hrtc) != HAL_OK)

{

Error_Handler();

}

privilegeState.rtcPrivilegeFull = RTC_PRIVILEGE_FULL_NO;

privilegeState.backupRegisterPrivZone = RTC_PRIVILEGE_BKUP_ZONE_NONE;

privilegeState.backupRegisterStartZone2 = RTC_BKP_DR0;

privilegeState.backupRegisterStartZone3 = RTC_BKP_DR0;

if (HAL_RTCEx_PrivilegeModeSet(&hrtc, &privilegeState) != HAL_OK)

{

Error_Handler();

}



/* USER CODE BEGIN Check_RTC_BKUP */



/* USER CODE END Check_RTC_BKUP */



/** Initialize RTC and set the Time and Date

*/

sTime.Hours = 0x0;

sTime.Minutes = 0x0;

sTime.Seconds = 0x0;

sTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;

sTime.StoreOperation = RTC_STOREOPERATION_RESET;

if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK)

{

Error_Handler();

}

sDate.WeekDay = RTC_WEEKDAY_MONDAY;

sDate.Month = RTC_MONTH_JANUARY;

sDate.Date = 0x1;

sDate.Year = 0x0;



if (HAL_RTC_SetDate(&hrtc, &sDate, RTC_FORMAT_BCD) != HAL_OK)

{

Error_Handler();

}



/** Enable the Alarm A

*/

sAlarm.AlarmTime.Hours = 0x0;

sAlarm.AlarmTime.Minutes = 0x0;

sAlarm.AlarmTime.Seconds = 0x0;

sAlarm.AlarmTime.SubSeconds = 0x0;

sAlarm.AlarmMask = RTC_ALARMMASK_NONE;

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();

}

/* USER CODE BEGIN RTC_Init 2 */

__HAL_RTC_ALARM_ENABLE_IT(&hrtc, RTC_IT_ALRA);

/* USER CODE END RTC_Init 2 */

}

********************************

I add IWDG period 20 seconds and refresh in alarm call back function:
********************************

void SetRTCAlarm(void)

{

RTC_AlarmTypeDef sAlarm = {0};

RTC_TimeTypeDef sTime = {0};

RTC_DateTypeDef sDate = {0};



__HAL_RTC_ALARM_CLEAR_FLAG(&hrtc, RTC_FLAG_ALRAF);



/* Get current time */

HAL_RTC_GetTime(&hrtc, &sTime, RTC_FORMAT_BIN);

HAL_RTC_GetDate(&hrtc, &sDate, RTC_FORMAT_BIN);



/* Set alarm for every 10 seconds */

sAlarm.AlarmTime.Hours = sTime.Hours;

sAlarm.AlarmTime.Minutes = sTime.Minutes;

sAlarm.AlarmTime.Seconds = (sTime.Seconds + 10) % 60;



/* Handle minute rollover (not hour directly) */

if (sAlarm.AlarmTime.Seconds < sTime.Seconds) { // wrap happened

sAlarm.AlarmTime.Minutes = (sTime.Minutes + 1) % 60;

if (sAlarm.AlarmTime.Minutes == 0) { // minute wrapped → hour

sAlarm.AlarmTime.Hours = (sTime.Hours + 1) % 24;

} else {

sAlarm.AlarmTime.Hours = sTime.Hours;

}

} else {

sAlarm.AlarmTime.Minutes = sTime.Minutes;

sAlarm.AlarmTime.Hours = sTime.Hours;

}

/* Configure alarm settings */

sAlarm.AlarmMask = RTC_ALARMMASK_DATEWEEKDAY;

sAlarm.AlarmSubSecondMask = RTC_ALARMSUBSECONDMASK_ALL;

sAlarm.AlarmDateWeekDaySel = RTC_ALARMDATEWEEKDAYSEL_DATE;

sAlarm.AlarmDateWeekDay = 1;

sAlarm.Alarm = RTC_ALARM_A;



/* Set and enable the alarm */

HAL_RTC_DeactivateAlarm(&hrtc, RTC_ALARM_A);

HAL_RTC_SetAlarm_IT(&hrtc, &sAlarm, RTC_FORMAT_BIN);

}



void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc)

{

HAL_IWDG_Refresh(&hiwdg);

/* Set next alarm */

SetRTCAlarm();

}

********************************

I init peripherals:

********************************

int main(void)

{



/* USER CODE BEGIN 1 */



/* USER CODE END 1 */



/* MCU Configuration--------------------------------------------------------*/



/* Reset of all peripherals, Initializes the Flash interface and the Systick. */

HAL_Init();



/* USER CODE BEGIN Init */



/* USER CODE END Init */



/* Configure the system clock */

SystemClock_Config();



/* USER CODE BEGIN SysInit */



/* USER CODE END SysInit */



/* Initialize all configured peripherals */

MX_GPIO_Init();

MX_GPDMA1_Init();

MX_ADC1_Init();

MX_LPTIM1_Init();

MX_RTC_Init();

MX_IWDG_Init();

********************************

Errata said I must disable WUTF because I use GDMA1. STM32U575xx and STM32U585xx device errata - Errata sheet

********************************

void RTC_IRQHandler(void)

{

/* USER CODE BEGIN RTC_IRQn 0 */

SET_BIT(RTC->CR, RTC_CR_WUTE);

SET_BIT(RTC->SCR, RTC_SCR_CWUTF); // See https://www.st.com/resource/en/errata_sheet/es0499-stm32u575xx-and-stm32u585xx-device-errata-stmicroelectronics.pdf (Section 2.2.4)

/* USER CODE END RTC_IRQn 0 */

HAL_RTC_AlarmIRQHandler(&hrtc);

/* USER CODE BEGIN RTC_IRQn 1 */



/* USER CODE END RTC_IRQn 1 */

}

********************************

Until now, everything is good. Alarm trigger and watchdog is refreshed. Then I want MCU goes to stop mode 2 and will be waken up by Alarm A

********************************

static void BMS_EnterStopMode(void)

{

HAL_SuspendTick();

__HAL_RCC_PWR_CLK_ENABLE();

HAL_PWREx_EnterSTOP2Mode(PWR_STOPENTRY_WFI);



SystemClock_Config();

HAL_ResumeTick();



// Led on to check wake up

}

********************************

Surprisingly, after entering stop mode 2, no wake up happen. WD reset MCU and then hard fault occur due to I access WD (in alarm irq) without init WD first.
Am I wrong somewhere? Sorry I cannot attach project here. Thank you all.