Q: Why Cubemx use 0x32F2 as an indicator for the RTC configuration? I've created a program with activated RTC peripheral by cubemx. After analyzing the code and searching in the internet, I found out that the reason of writing 0x32F2 in RTC_BKP_DR1 is for checking weather the RTC was configured before or not.  
Why it uses 0x32F2 as an indicator and not another number?
Is there any reason?
static void MX_RTC_Init(void)
{
     RTC_TimeTypeDef sTime;
     RTC_DateTypeDef DateToUpdate;
     /**Initialize RTC Only */
     hrtc.Instance = RTC;
     hrtc.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
     hrtc.Init.OutPut = RTC_OUTPUTSOURCE_CALIBCLOCK; 

     if (HAL_RTC_Init(&hrtc) != HAL_OK)
     {
        _Error_Handler(__FILE__, __LINE__);
     }

     /**Initialize RTC and set the Time and Date*/
     if(HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR1) != 0x32F2){
         sTime.Hours = 1;
         sTime.Minutes = 0;
         sTime.Seconds = 0;

         if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BIN) != HAL_OK)
         {
            _Error_Handler(__FILE__, __LINE__);
         }

         DateToUpdate.WeekDay = RTC_WEEKDAY_MONDAY;
         DateToUpdate.Month = RTC_MONTH_JANUARY;
         DateToUpdate.Date = 1;
         DateToUpdate.Year = 15;

         if (HAL_RTC_SetDate(&hrtc, &DateToUpdate, RTC_FORMAT_BIN) != HAL_OK)
         {
            _Error_Handler(__FILE__, __LINE__);
         }

         HAL_RTCEx_BKUPWrite(&hrtc,RTC_BKP_DR1,0x32F2);
     }
}


A: I don't think there is any reason, just the programmers choice for a constant. You can use any constant there that is not the power on default ( 0xFFFFFFFF probably).

A: The backup registers are for user application data. The bits in these registers do not configure any kind of functionality. Thus the value in question is indeed just a random choice.
These registers are special because:

The BKP_DRx registers are not reset by a  System reset or Power reset
  or when the  device wakes up from Standby mode. They are reset by a
  Backup Domain reset or by a TAMPER pin event (if the TAMPER  pin
  function is activated).

And it seems that STM32 HAL writers dedicated one of these registers to the RTC and use it as a simple isConfiguredFlag.
