请问为什么每次重启开发板后时间都是恢复成我设置的时间 而不是纽扣电池供电呢 F103MINI开发板
void MX_RTC_Init(void)
{
  RTC_TimeTypeDef sTime;
  RTC_DateTypeDef DateToUpdate;

    /**Initialize RTC and set the Time and Date
    */
  hrtc.Instance = RTC;
  hrtc.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
  hrtc.Init.OutPut = RTC_OUTPUTSOURCE_NONE;
  HAL_RTC_Init(&hrtc);

  sTime.Hours = 13;
  sTime.Minutes = 36;
  sTime.Seconds = 0;

  HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BIN);

  DateToUpdate.WeekDay = RTC_WEEKDAY_WEDNESDAY;
  DateToUpdate.Month = RTC_MONTH_JULY;
  DateToUpdate.Date = 8;
  DateToUpdate.Year = 17;

  HAL_RTC_SetDate(&hrtc, &DateToUpdate, RTC_FORMAT_BIN);

}


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

  /* USER CODE BEGIN 3 */
                /* Get the RTC current Time ,must get time first*/
                HAL_RTC_GetTime(&hrtc, &stimestructure, RTC_FORMAT_BIN);
                /* Get the RTC current Date */
                HAL_RTC_GetDate(&hrtc, &sdatestructure, RTC_FORMAT_BIN);

                /* Display date Format : yy/mm/dd */
                printf("%02d/%02d/%02d ",2000 + sdatestructure.Year, sdatestructure.Month, sdatestructure.Date);
                /* Display time Format : hh:mm:ss */
                printf("%02d:%02d:%02d ",stimestructure.Hours, stimestructure.Minutes, stimestructure.Seconds);

                printf(" ");       
                HAL_Delay(1000);
  }