STM32F042 RTC wont start

[lmill.1]

I seem to be unable to get the RTC to start. I can set the time, and read from it, but it doesn't increment.

I have tried using the external and internal oscillator, neither have been successful.

Everything has been set up with CubeMx, and I have used the RTC before on an STM32L0 micro with no issue, comparing it to my old code I cant see what I am doing differently.

I have attached the relevant parts of the code, if you know what I am missing please let me know.

Thanks,

Luke

static void MX_RTC_Init(void)
{
 
  RTC_TimeTypeDef sTime;
  RTC_DateTypeDef sDate;
 
    /**Initialize RTC Only 
    */
  hrtc.Instance = RTC;
if(HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) != 0x32F2){
  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(__FILE__, __LINE__);
  }
 
    /**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(__FILE__, __LINE__);
  }
 
  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(__FILE__, __LINE__);
  }
 
    HAL_RTCEx_BKUPWrite(&hrtc,RTC_BKP_DR0,0x32F2);
  }
 
}
/* USER CODE BEGIN PV */
RTC_TimeTypeDef sTimeGet;
RTC_TimeTypeDef sTimeSet;
 
/* Private variables ---------------------------------------------------------*/
 
/* USER CODE END PV */
 
void updateTime(void){
	//RTC_TimeTypeDef sTimeGet;
	//RTC_TimeTypeDef sTimeSet;
	HAL_RTC_GetTime(&hrtc, &sTimeGet, RTC_FORMAT_BIN);
	seconds = sTimeGet.Seconds;
	minutes = sTimeGet.Minutes;
	hours = sTimeGet.Hours;
 
	if(hours>12){
		hours = 0;
		sTimeSet.Hours = hours;
		HAL_RTC_SetTime(&hrtc, &sTimeSet, RTC_FORMAT_BIN);
	}
}

[waclawek.jan]

Do you read date after reading time?

JW

[lmill.1]

No I haven't tried. I likely wont end up using that function.

[KnarfB]

Call HAL_RTC_GetDate() afterwards even if you don't use it. There is a note about that in the source code. The topic pops up here frequently.

[waclawek.jan · Accepted solution]

Have you visited the link I provided above?

Btw. this one is documented even in Cube/HAL.

JW

[lmill.1]

No I had completely missed it. I checked it out now.

I tried both, together and independently and I am got the same result.

I currently am reading the date after the time. Strangely if i step my way through the time and date my time variables update, but if i run through like normal they don't, do you have any thoughts on this?

void updateTime(void){
	//RTC_TimeTypeDef sTimeGet;
	//RTC_TimeTypeDef sTimeSet;
	RTC_DateTypeDef sDateGet;
	HAL_RTC_GetTime(&hrtc, &sTimeGet, RTC_FORMAT_BIN);
	HAL_RTC_GetDate(&hrtc, &sDateGet, RTC_FORMAT_BIN);
	seconds = sTimeGet.Seconds;
	minutes = sTimeGet.Minutes;
	hours = sTimeGet.Hours;
 
	if(hours>12){
		hours = 0;
		sTimeSet.Hours = hours;
		HAL_RTC_SetTime(&hrtc, &sTimeSet, RTC_FORMAT_BIN);
	}
}

[lmill.1]

I currently am reading the date after the time. Strangely if i step my way through the time and date my time variables update, but if i run through like normal they don't, do you have any thoughts on this?

void updateTime(void){
	//RTC_TimeTypeDef sTimeGet;
	//RTC_TimeTypeDef sTimeSet;
	RTC_DateTypeDef sDateGet;
	HAL_RTC_GetTime(&hrtc, &sTimeGet, RTC_FORMAT_BIN);
	HAL_RTC_GetDate(&hrtc, &sDateGet, RTC_FORMAT_BIN);
	seconds = sTimeGet.Seconds;
	minutes = sTimeGet.Minutes;
	hours = sTimeGet.Hours;
 
	if(hours>12){
		hours = 0;
		sTimeSet.Hours = hours;
		HAL_RTC_SetTime(&hrtc, &sTimeSet, RTC_FORMAT_BIN);
	}
}

[KnarfB]

You may use STM32CubeIDE to generate default code for init. Mine looks like (STM32L4, RTC running on LSI clock):

/**
  * @brief RTC Initialization Function
  * @param None
  * @retval None
  */
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};
 
  /* USER CODE BEGIN RTC_Init 1 */
 
  /* USER CODE END RTC_Init 1 */
  /** Initialize RTC Only
  */
  hrtc.Instance = RTC;
  hrtc.Init.HourFormat = RTC_HOURFORMAT_12;
  hrtc.Init.AsynchPrediv = 127;
  hrtc.Init.SynchPrediv = 249;
  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 Check_RTC_BKUP */
 
  /* USER CODE END Check_RTC_BKUP */
 
  /** Initialize RTC and set the Time and Date
  */
  sTime.Hours = 1;
  sTime.Minutes = 0;
  sTime.Seconds = 0;
  sTime.TimeFormat = RTC_HOURFORMAT12_AM;
  sTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
  sTime.StoreOperation = RTC_STOREOPERATION_RESET;
  if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BIN) != HAL_OK)
  {
    Error_Handler();
  }
  sDate.WeekDay = RTC_WEEKDAY_MONDAY;
  sDate.Month = RTC_MONTH_JANUARY;
  sDate.Date = 1;
  sDate.Year = 0;
 
  if (HAL_RTC_SetDate(&hrtc, &sDate, RTC_FORMAT_BIN) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN RTC_Init 2 */
 
  /* USER CODE END RTC_Init 2 */
 
}

and reading

HAL_RTC_GetTime(&hrtc, &sTime, RTC_FORMAT_BIN);
HAL_RTC_GetDate(&hrtc, &sDate, RTC_FORMAT_BIN);

in a loop is sufficient. The RTC can handle AM/PM if configured so.

hth

KnarfB

[lmill.1]

Sorry but I dont understand how this is much different than the init code I already have. What would this do differently?

I am calling my updateTime() function, which contains the getTime getDate, with a timer interrupt and it is being called regularly.

[KnarfB]

My code is only for your reference, there must be differences, othewise your code would work. Your code snippet does not define sTimeSet, must be defined elsewhere,...