STM32L476RC RTC run, wakeup and standby mode problems

[SLesh.1]

Hi here,

I have made a prototype with STM32L476RG on Nucleo-board - MCU are doing some task and go to standby mode with wakeup from RTC (1 Hz counter). The code was migrated into my own board with STM32L476RC - RTC doesn't work correctly - MCU goes to Standby, but never wakeup.

I have made the simplest one project for test - only RTC and UART3 for debuging. It works very strange. Source was generated by CubeMX 1.4.0.

HAL_RTC_GetTime(&hrtc, &currentTime, RTC_FORMAT_BCD) returns the same time. But if I do hard reset (f.e. flash new firmware) it gets new time (I'm not set time in the app) - RTC runs! But wakeup doesn't work. RTC works in both case from LSI.

static void MX_RTC_Init(void)
{
 
  /* USER CODE BEGIN RTC_Init 0 */
 
  /* USER CODE END RTC_Init 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;
  if (HAL_RTC_Init(&hrtc) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN RTC_Init 2 */
 
  /* USER CODE END RTC_Init 2 */
 
}
 
 
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_RTC_Init();
  MX_USART3_UART_Init();
  /* USER CODE BEGIN 2 */
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
		RTC_TimeTypeDef currentTime;
 
		char message[22];
		if (HAL_RTC_GetTime(&hrtc, &currentTime, RTC_FORMAT_BCD) == HAL_OK) {
 
			sprintf(message,"%.2x:%.2x:%.2x", currentTime.Hours, currentTime.Minutes, currentTime.Seconds );
			debug_print_message(message);
		}
		else
			debug_error();
 
		HAL_Delay(2000);
 
		if (HAL_RTC_GetTime(&hrtc, &currentTime, RTC_FORMAT_BCD) == HAL_OK) {
 
			sprintf(message,"%.2x:%.2x:%.2x", currentTime.Hours, currentTime.Minutes, currentTime.Seconds );
			debug_print_message(message);
		}
		else
				debug_error();
 
		HAL_Delay(2000);
 
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

UART output:

12:21:52

12:21:52

After re-flash:

12:25:09

12:25:09

The original code with wakeUp that works on STM32L476RG Nucleo board:

/**
/* Battery saving mode
*/
void sleepMode(uint32_t timeout) { // timeout in seconds
 
	HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1); //
	HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN2); //
	HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN3); //
	HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN4); //
	HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN5); // Disable all used wake up sources
 
	HAL_RTCEx_DeactivateWakeUpTimer(&hrtc); // disable wake up RTC interrupt
 
	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU); //
	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUFI); // clear wake up flags
 
	// check timeout
	if (timeout < 0x10001) { // less 18 hours
 
		if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, timeout - 1, RTC_WAKEUPCLOCK_CK_SPRE_16BITS) != HAL_OK) {
 
			Error_Handler();
		}
	}
	else if ((timeout >= 0x10001 ) & (timeout <= 0x1FFFF )) { // more then 18 hours
 
		if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, timeout - 1, RTC_WAKEUPCLOCK_CK_SPRE_17BITS) != HAL_OK) {
 
			Error_Handler();
		}
	}
	else { // invalid value - set maximum - 36 hours
 
		if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0x1FFFF, RTC_WAKEUPCLOCK_CK_SPRE_17BITS) != HAL_OK) {
 
			Error_Handler();
		}
	}
 
	HAL_PWR_EnterSTANDBYMode(); // go to standby mode
}

Init the system when it runs:

void system_init(void) {
 
	__HAL_RCC_PWR_CLK_ENABLE();
 
	if(__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET) { // check wake up
 
		__HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB); // clear standby flag
 
#if DEBUG
		HAL_UART_Transmit(&huart3, "wakeup\r\n", 8, 100);
#endif
 
	}
	else { // the first start
		RTC_AlarmConfig(); // set default RTC settings // TODO ...
 
#if DEBUG
		HAL_UART_Transmit(&huart3, "run\r\n", 5, 100);
#endif
 
	}
 
	HAL_RTCEx_DeactivateWakeUpTimer(&hrtc); // disable wake up interrupts
 
	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU); // clear wake up flags
	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUFI); // clear wake up flags\
 
 
#if DEBUG
	RTC_TimeTypeDef currentTime;
	char message[22];
	if (HAL_RTC_GetTime(&hrtc, &currentTime, RTC_FORMAT_BCD) == HAL_OK) {
 
		sprintf(message,"%.2x:%.2x:%.2x", currentTime.Hours, currentTime.Minutes, currentTime.Seconds );
		debug_print_message(message);
	}
	else
		debug_error();
 
	HAL_Delay(2000);
 
	if (HAL_RTC_GetTime(&hrtc, &currentTime, RTC_FORMAT_BCD) == HAL_OK) {
 
		sprintf(message,"%.2x:%.2x:%.2x", currentTime.Hours, currentTime.Minutes, currentTime.Seconds );
		debug_print_message(message);
	}
	else
			debug_error();
#endif
 
}

[waclawek.jan]

> HAL_RTC_GetTime(&hrtc, &currentTime, RTC_FORMAT_BCD) returns the same time.

You need to read date, too.

JW

[SLesh.1]

Ok, thank you! That is clear.

But wakeup doesn't work. It looks that wakeup counter don't run. The code:

	if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 5, RTC_WAKEUPCLOCK_CK_SPRE_16BITS) != HAL_OK) {
 
		Error_Handler();
	}
 
	uint32_t wkp = HAL_RTCEx_GetWakeUpTimer(&hrtc);
	sprintf(message,"wkp: %d", wkp );
	debug_print_message(message);
 
	HAL_Delay(2000);
 
	wkp = HAL_RTCEx_GetWakeUpTimer(&hrtc);
	sprintf(message,"wkp: %d", wkp );
	debug_print_message(message);
 
	HAL_PWR_EnterSTANDBYMode(); // go to standby mode

UART output:

wakeup

08:56:32

08:56:33

wkp: 5

wkp: 5

Have I to read something else or is it stopped?

[waclawek.jan · Accepted solution]

The wake-up *timer* itself is not visible to the user. What you write and read is the register holding the autoreload value, (RTC_WUTR).

I don't use and don't understand Cube. For the problem with the wake-up you may want to read the relevant portions of RTC, EXTI and PWR chapters. Maybe start with checking the wake-up timer settings by reading out the RTC registers content, and check if the wakeup flag gets set periodically while the processor is still running.

JW

[SLesh.1]

@Community member​ thank you! wakeup interrupts works. I replace

HAL_PWR_EnterSTANDBYMode();

by

HAL_Delay(10000);

and add

void HAL_RTCEx_WakeUpTimerEventCallback(RTC_HandleTypeDef *hrtc)
{
  /* Prevent unused argument(s) compilation warning */
	HAL_UART_Transmit(&huart3, "rtc wkp\r\n", 9, 100);
 
  /* NOTE : This function should not be modified, when the callback is needed,
            the HAL_RTCEx_WakeUpTimerEventCallback could be implemented in the user file
   */
}

It is happening.

But flag

if (__HAL_RTC_WAKEUPTIMER_GET_IT_SOURCE(&hrtc, RTC_IT_WUT) == 1U) {
 
	debug_print_message("WKP IT = 1U");
}
else {
 
	debug_print_message("WKP IT = 0U");
}

After-

HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 5, RTC_WAKEUPCLOCK_CK_SPRE_16BITS);

is 1U.

It is enabled. But it doesn't work

[SLesh.1]

Solved.

I'm stupid... Sorry, guys. Difference is in boot0 pin. I'm thinking that is has internal pulldown. But no.