STM32F0303C8T6 在使用RTC的过程中发现，概率性RTC初始化失败；但是LSE 是成功起振；
最终的原因是ISR寄存器的INTF 标志位写失败；



我用的是F0 V1.5的库函数；
发现 枚举类型RTC_Init；返回值是ERROR

/**
  * @brief  Initializes the RTC registers according to the specified parameters
  *         in RTC_InitStruct.
  * @param  RTC_InitStruct: pointer to a RTC_InitTypeDef structure that contains
  *         the configuration information for the RTC peripheral.
  * @note   The RTC Prescaler register is write protected and can be written in
  *         initialization mode only.  
  * @retval An ErrorStatus enumeration value:
  *          - SUCCESS: RTC registers are initialized
  *          - ERROR: RTC registers are not initialized  
  */
ErrorStatus RTC_Init(RTC_InitTypeDef* RTC_InitStruct)
{
  ErrorStatus status = ERROR;
  /* Check the parameters */
  assert_param(IS_RTC_HOUR_FORMAT(RTC_InitStruct->RTC_HourFormat));
  assert_param(IS_RTC_ASYNCH_PREDIV(RTC_InitStruct->RTC_AsynchPrediv));
  assert_param(IS_RTC_SYNCH_PREDIV(RTC_InitStruct->RTC_SynchPrediv));
  /* Disable the write protection for RTC registers */
  RTC->WPR = 0xCA;
  RTC->WPR = 0x53;
  /* Set Initialization mode */
  if (RTC_EnterInitMode() == ERROR)
  {
    status = ERROR;
  }
  else
  {
    /* Clear RTC CR FMT Bit */
    RTC->CR &= ((uint32_t)~(RTC_CR_FMT));
    /* Set RTC_CR register */
    RTC->CR |=  ((uint32_t)(RTC_InitStruct->RTC_HourFormat));
  
    /* Configure the RTC PRER */
    RTC->PRER = (uint32_t)(RTC_InitStruct->RTC_SynchPrediv);
    RTC->PRER |= (uint32_t)(RTC_InitStruct->RTC_AsynchPrediv << 16);
    /* Exit Initialization mode */
    RTC_ExitInitMode();
    status = SUCCESS;
  }
  /* Enable the write protection for RTC registers */
  RTC->WPR = 0xFF;
  return status;
}


最后附上 整个RTC初始化的代码；
RTC_InitTypeDef  RTC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR,DISABLE);
PWR_BackupAccessCmd(DISABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR,ENABLE);

/* Allow access to RTC */
PWR_BackupAccessCmd(ENABLE);
// RTC->WPR = 0x000000CA;
// RTC->WPR = 0x00000053;//取消写保护

RCC_LSEConfig(RCC_LSE_ON);
while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == 0)
{
  //printf(" LSE Error!");
}
RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);

RTC_DeInit();
  /* Calendar Configuration */
RTC_InitStructure.RTC_AsynchPrediv = 0x7f;//127
RTC_InitStructure.RTC_SynchPrediv = 0xFF;//255
RTC_InitStructure.RTC_HourFormat = RTC_HourFormat_24;
RTC_Init(&RTC_InitStructure);//进入初始化模式，

//RTC->ISR |= RTC_ISR_INIT; //进入初始化模式
  //while (!(RTC->ISR | RTC_ISR_INITF));


RTC_DateInitStructure.RTC_Year = 17;
RTC_DateInitStructure.RTC_Month = 1;
RTC_DateInitStructure.RTC_Date = 1;
RTC_DateInitStructure.RTC_WeekDay = 5;
RTC_SetDate(RTC_Format_BIN,&RTC_DateInitStructure);

RTC_TimeInitStructure.RTC_H12 = RTC_H12_AM;
RTC_TimeInitStructure.RTC_Hours = 0;
RTC_TimeInitStructure.RTC_Minutes = 0;
RTC_TimeInitStructure.RTC_Seconds = 0;
RTC_SetTime(RTC_Format_BIN,&RTC_TimeInitStructure);//
RCC_RTCCLKCmd(ENABLE);//使能RTC

RTC_WaitForSynchro();//等待时钟同步


其实，关键我在想为什么是概率性的；
对其他方面也没什么影响，就是初始化的时间没写进去；
INTF标志位写入失败，到底是什么原因导致的