STANDBY and SLEEP Modes using RTC

[AnanyaRavi29]

Hello,
I am trying to use the SLEEP and STANDBY modes with the RTC. I want the device to go to sleep/standby mode for 10 seconds and wake up after the 10 seconds are done. I have tried it with an interrupt using UART and Button and both the modes are working fine.But with RTC I am facing an issue.
Can anyone pls help with this query of mine?

Thanking you.

[Sarra.S]

Hello @AnanyaRavi29, 

See STM32CubeL1/Projects/NUCLEO-L152RE/Examples/PWR/PWR_STANDBY_RTC at master · STMicroelectronics/STM32CubeL1 · GitHub

[AnanyaRavi29]

Its working for STANDBY Mode.But for SLEEP Mode I am unable to get the core to wake up pls.

HAL_RTC_GetTime(&hrtc, &sTime, RTC_FORMAT_BIN);
	      HAL_RTC_GetDate(&hrtc, &sDate, RTC_FORMAT_BIN);
	      sprintf(date, "Date: %02d.%02d.%02d\t", sDate.Date, sDate.Month, sDate.Year);
	      sprintf(time, "Time: %02d:%02d:%02d\r\n", sTime.Hours, sTime.Minutes, sTime.Seconds);
	      HAL_UART_Transmit(&huart2, (uint8_t *)date, strlen(date), HAL_MAX_DELAY);
	      HAL_UART_Transmit(&huart2, (uint8_t *)time, strlen(time), HAL_MAX_DELAY);

	      // Configure RTC alarm to trigger after 10 seconds
	      RTC_AlarmTypeDef sAlarm;
	      sAlarm.AlarmTime.Hours = 0;
	      sAlarm.AlarmTime.Minutes = 0;
	      sAlarm.AlarmTime.Seconds = 10;
	      sAlarm.Alarm = RTC_ALARM_A;
	      if (HAL_RTC_SetAlarm_IT(&hrtc, &sAlarm, RTC_FORMAT_BIN) != HAL_OK)
	      {
	        Error_Handler();
	      }

	      // Enter Sleep mode
	      HAL_UART_Transmit(&huart2, (uint8_t *)"MCU is going to sleep...\r\n", strlen("MCU is going to sleep...\r\n"), HAL_MAX_DELAY);
	      HAL_SuspendTick(); // Suspend HAL tick
	      HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFE);

	      // MCU wakes up here

	      // Resume operations after wake-up
	      //SystemClock_Config(); // Restore system clock settings
	      HAL_ResumeTick();     // Resume HAL tick

	      HAL_UART_Transmit(&huart2, (uint8_t *)"MCU woke up from sleep mode\r\n", strlen("MCU woke up from sleep mode\r\n"), HAL_MAX_DELAY);

	      // Delay to avoid immediate sleep cycle
	      HAL_Delay(1000);

...

void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc) {
HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);

	  // Print current time and date after wake-up
	  HAL_RTC_GetTime(hrtc, &sTime, RTC_FORMAT_BIN);
	  HAL_RTC_GetDate(hrtc, &sDate, RTC_FORMAT_BIN);
	  sprintf(date, "Date: %02d.%02d.%02d\t", sDate.Date, sDate.Month, sDate.Year);
	  sprintf(time, "Time: %02d:%02d:%02d\r\n", sTime.Hours, sTime.Minutes, sTime.Seconds);
	  HAL_UART_Transmit(&huart2, (uint8_t *)date, strlen(date), HAL_MAX_DELAY);
	  HAL_UART_Transmit(&huart2, (uint8_t *)time, strlen(time), HAL_MAX_DELAY);
}

This is the code I wrote.Can you pls tell where I went wrong?
 

[Sarra.S]

Hello @AnanyaRavi29 

In Sleep mode, only certain interrupts can wake up the microcontroller, make sure that the RTC wakeup interrupt is enabled

[AnanyaRavi29]

So instead of Alarm I have to use Wakeup Interrupt pls?

[Sarra.S]

try HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFI);

Use WFI instead of WFE if you are not using an actual interrupt handler

[AnanyaRavi29]

I have tried that pls.

Its still not working.

while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
	  // Print current time and date
	      HAL_RTC_GetTime(&hrtc, &sTime, RTC_FORMAT_BIN);
	      HAL_RTC_GetDate(&hrtc, &sDate, RTC_FORMAT_BIN);
	      sprintf(date, "Date: %02d.%02d.%02d\t", sDate.Date, sDate.Month, sDate.Year);
	      sprintf(time, "Time: %02d:%02d:%02d\r\n", sTime.Hours, sTime.Minutes, sTime.Seconds);
	      HAL_UART_Transmit(&huart2, (uint8_t *)date, strlen(date), HAL_MAX_DELAY);
	      HAL_UART_Transmit(&huart2, (uint8_t *)time, strlen(time), HAL_MAX_DELAY);

	      // Configure RTC Wakeup Timer to trigger after 10 seconds
	      HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0x5F86 , RTC_WAKEUPCLOCK_RTCCLK_DIV16);

	      // Enter Sleep mode using WFE
	      HAL_UART_Transmit(&huart2, (uint8_t *)"MCU is going to sleep...\r\n", strlen("MCU is going to sleep...\r\n"), HAL_MAX_DELAY);
	      HAL_SuspendTick(); // Suspend HAL tick
	      HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFI);

	      // MCU wakes up here

	      // Resume operations after wake-up
	      SystemClock_Config(); // Restore system clock settings
	      HAL_ResumeTick();     // Resume HAL tick

	      HAL_UART_Transmit(&huart2, (uint8_t *)"MCU woke up from sleep mode\r\n", strlen("MCU woke up from sleep mode\r\n"), HAL_MAX_DELAY);

	      // Delay to avoid immediate sleep cycle
	      HAL_Delay(1000);


  }



void HAL_RTCEx_WakeUpTimerEventCallback(RTC_HandleTypeDef *hrtc)
{
    // Handle RTC Wakeup event
    // Example: Toggle an LED to indicate wake-up
    HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);

    // Print current time and date after wake-up (optional)
    RTC_DateTypeDef sDate;
    RTC_TimeTypeDef sTime;
    HAL_RTC_GetTime(hrtc, &sTime, RTC_FORMAT_BIN);
    HAL_RTC_GetDate(hrtc, &sDate, RTC_FORMAT_BIN);
    char time[20];
    sprintf(time, "%02d:%02d:%02d\r\n", sTime.Hours, sTime.Minutes, sTime.Seconds);
    HAL_UART_Transmit(&huart2, (uint8_t *)time, strlen(time), HAL_MAX_DELAY);
}


static void MX_RTC_Init(void)
{

  /* USER CODE BEGIN RTC_Init 0 */

  /* USER CODE END RTC_Init 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.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
  hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
  if (HAL_RTC_Init(&hrtc) != 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 = 0x5;
  sTime.Minutes = 0x50;
  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_THURSDAY;
  sDate.Month = RTC_MONTH_JUNE;
  sDate.Date = 0x20;
  sDate.Year = 0x24;

  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 = 0x10;
  sAlarm.AlarmTime.SubSeconds = 0x0;
  sAlarm.AlarmTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
  sAlarm.AlarmTime.StoreOperation = RTC_STOREOPERATION_RESET;
  sAlarm.AlarmMask = RTC_ALARMMASK_DATEWEEKDAY|RTC_ALARMMASK_HOURS
                              |RTC_ALARMMASK_MINUTES;
  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();
  }

  /** Enable the WakeUp
  */
  if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0, RTC_WAKEUPCLOCK_RTCCLK_DIV16) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN RTC_Init 2 */

  /* USER CODE END RTC_Init 2 */

}