RTC设备调用HAL_RTCEx_BKUPWrite()失败

//在rtc_sample.c中，粗体是在原来的基础上增加的代码
static int rtc_sample(int argc, char *argv[])
{
    rt_err_t ret = RT_EOK;
    time_t now;
    /* 设置日期 */
    ret = set_date(2020, 8, 15);
    if (ret != RT_EOK)
    {
        rt_kprintf("set RTC date failed\n");
        return ret;
    }
    /* 设置时间 */
    ret = set_time(16, 55, 0);
    if (ret != RT_EOK)
    {
        rt_kprintf("set RTC time failed\n");
        return ret;
    }
    **HAL_PWR_EnableBkUpAccess();//取消备份区域写保护**
    **HAL_RTCEx_BKUPWrite(&RTC_Handler,RTC_BKP_DR1,BKUP_REG_DATA);//标记已经初始化过了**
    /* 延时3秒 */
    rt_thread_mdelay(3000);
    /* 获取时间 */
    now = time(RT_NULL);
    rt_kprintf("%s\n", ctime(&now));
    return ret;
}

//在rtc.c中，粗体是在原来的基础上增加的代码
static void date(uint8_t argc, char **argv)
{
    if (argc == 1)
    {
        time_t now;
        /* output current time */
        now = time(RT_NULL);
        rt_kprintf("%.*s", 25, ctime(&now));
    }
    else if (argc >= 7)
    {
        /* set time and date */
        uint16_t year;
        uint8_t month, day, hour, min, sec;
        year = atoi(argv[1]);
        month = atoi(argv[2]);
        day = atoi(argv[3]);
        hour = atoi(argv[4]);
        min = atoi(argv[5]);
        sec = atoi(argv[6]);
        if (year > 2099 || year < 2000)
        {
            rt_kprintf("year is out of range [2000-2099]\n");
            return;
        }
        if (month == 0 || month > 12)
        {
            rt_kprintf("month is out of range [1-12]\n");
            return;
        }
        if (day == 0 || day > 31)
        {
            rt_kprintf("day is out of range [1-31]\n");
            return;
        }
        if (hour > 23)
        {
            rt_kprintf("hour is out of range [0-23]\n");
            return;
        }
        if (min > 59)
        {
            rt_kprintf("minute is out of range [0-59]\n");
            return;
        }
        if (sec > 59)
        {
            rt_kprintf("second is out of range [0-59]\n");
            return;
        }
        set_time(hour, min, sec);
        set_date(year, month, day);
        **HAL_PWR_EnableBkUpAccess();//取消备份区域写保护**
        **HAL_RTCEx_BKUPWrite(&RTC_Handler, RTC_BKP_DR1, BKUP_REG_DATA);//标记已经初始化过了**
    }
    else
    {
        rt_kprintf("please input: date [year month day hour min sec] or date\n");
        rt_kprintf("e.g: date 2018 01 01 23 59 59 or date\n");
    }
}

//在drv_rtc.c中，粗体是在原来的基础上增加的代码
static rt_err_t rt_rtc_config(struct rt_device *dev)
{
    RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
    HAL_PWR_EnableBkUpAccess();
    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
//#ifdef BSP_RTC_USING_LSI
    //PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSI;
//#else
    PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
//#endif
    HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);
    /* Enable RTC Clock */
    __HAL_RCC_RTC_ENABLE();
    RTC_Handler.Instance = RTC;
    if (HAL_RTCEx_BKUPRead(&RTC_Handler, RTC_BKP_DR1) != BKUP_REG_DATA)
    {
        LOG_I("RTC hasn't been configured, please use <date> command to config.");
//#if defined(SOC_SERIES_STM32F1)
        //RTC_Handler.Init.OutPut = RTC_OUTPUTSOURCE_NONE;
        //RTC_Handler.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
//#elif defined(SOC_SERIES_STM32F0)
        /* set the frequency division */
//#ifdef BSP_RTC_USING_LSI
        //RTC_Handler.Init.AsynchPrediv = 0XA0;
        //RTC_Handler.Init.SynchPrediv = 0xFA;
//#else
        //RTC_Handler.Init.AsynchPrediv = 0X7F;
        //RTC_Handler.Init.SynchPrediv = 0x0130;
//#endif /* BSP_RTC_USING_LSI */
        //RTC_Handler.Init.HourFormat = RTC_HOURFORMAT_24;
        //RTC_Handler.Init.OutPut = RTC_OUTPUT_DISABLE;
        //RTC_Handler.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
        //RTC_Handler.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
//#elif defined(SOC_SERIES_STM32F2) || defined(SOC_SERIES_STM32F4) || defined(SOC_SERIES_STM32F7) || defined(SOC_SERIES_STM32L4) || defined(SOC_SERIES_STM32H7)
        /* set the frequency division */
//#ifdef BSP_RTC_USING_LSI
        //RTC_Handler.Init.AsynchPrediv = 0X7D;
//#else
        RTC_Handler.Init.AsynchPrediv = 0X7F;
//#endif /* BSP_RTC_USING_LSI */
        RTC_Handler.Init.SynchPrediv = 0XFF;
        RTC_Handler.Init.HourFormat = RTC_HOURFORMAT_24;
        RTC_Handler.Init.OutPut = RTC_OUTPUT_DISABLE;
        RTC_Handler.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
        RTC_Handler.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
//#endif
        if (HAL_RTC_Init(&RTC_Handler) != HAL_OK)
        {
            return -RT_ERROR;
        }
        **set_time(16, 55, 0);**
        **set_date(2020, 8, 15);**
        **HAL_PWR_EnableBkUpAccess();//取消备份区域写保护**
        **HAL_RTCEx_BKUPWrite(&RTC_Handler, RTC_BKP_DR1, BKUP_REG_DATA);//标记已经初始化过了**
    }
    return RT_EOK;
}