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