基于CH32V307EVT板的RTC测试

何谓RTC？RTC(Real Time Clock)：实时时钟， CH32V307EVT的RTC外设，实质是一个掉电后还继续运行的定时器。RTC是个独立的BCD定时器/计数器。提供一个日历时钟，两个可编程闹钟中断，以及一个具有中断功能的周期性可编程唤醒标志。RTC还包含用于管理低功耗模式的自动唤醒单元。
两个32位寄存器包含二进码十进制格式(BCD)的秒，分钟，小时（12或24小时制），星期几，日期，月份和年份。此外还可以提供二进制的亚秒值。系统可以自动将月份的天数补偿为28，29（闰年），30，31天。并且还可以进行夏令时补偿。
官方给出了关于RTC的参考例程，这里就简单的验证其精准性。原理图中有涉及RTC部分电路。

部分参考代码：

#include "debug.h"

typedef struct
{
    vu8 hour;
    vu8 min;
    vu8 sec;

    vu16 w_year;
    vu8  w_month;
    vu8  w_date;
    vu8  week;
} _calendar_obj;

_calendar_obj calendar;

u8 const table_week[12] = {0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5};
const u8 mon_table[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

/* Exported_Functions */
u8 RTC_Init(void);
u8 Is_Leap_Year(u16 year);
u8 RTC_Alarm_Set(u16 syear, u8 smon, u8 sday, u8 hour, u8 min, u8 sec);
u8 RTC_Get(void);
u8 RTC_Get_Week(u16 year, u8 month, u8 day);
u8 RTC_Set(u16 syear, u8 smon, u8 sday, u8 hour, u8 min, u8 sec);

/*********************************************************************
 * @fn      RTC_NVIC_Config
 *
 * [url=home.php?mod=space&uid=2666770]@Brief[/url]   Initializes RTC Int.
 *
 * [url=home.php?mod=space&uid=1141835]@Return[/url]  none
 */
static void RTC_NVIC_Config(void)
{
    NVIC_InitTypeDef NVIC_InitStructure = {0};
    NVIC_InitStructure.NVIC_IRQChannel = RTC_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

/*********************************************************************
 * @fn      RTC_Init
 *
 * @brief   Initializes RTC collection.
 *
 * @return  1 - Init Fail
 *          0 - Init Success
 */
u8 RTC_Init(void)
{
    u8 temp = 0;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);
    PWR_BackupAccessCmd(ENABLE);

    /* Is it the first configuration */

    BKP_DeInit();
    RCC_LSEConfig(RCC_LSE_ON);
    while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET && temp < 250)
    {
        temp++;
        Delay_Ms(20);
    }
    if(temp >= 250)
        return 1;
    RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);
    RCC_RTCCLKCmd(ENABLE);
    RTC_WaitForLastTask();
    RTC_WaitForSynchro();
    RTC_ITConfig(RTC_IT_SEC, ENABLE);
    RTC_WaitForLastTask();
    RTC_EnterConfigMode();
    RTC_SetPrescaler(32767);
    RTC_WaitForLastTask();
    RTC_Set(2023, 06, 13, 14, 50, 25); /* Setup Time */
    RTC_ExitConfigMode();
    BKP_WriteBackupRegister(BKP_DR1, 0XA1A1);

    RTC_NVIC_Config();
    RTC_Get();

    return 0;
}

/*********************************************************************
 * @fn      Is_Leap_Year
 *
 * @brief   Judging whether it is a leap year.
 *
 * [url=home.php?mod=space&uid=3142012]@param[/url]   year
 *
 * @return  1 - Yes
 *          0 - No
 */
u8 Is_Leap_Year(u16 year)
{
    if(year % 4 == 0)
    {
        if(year % 100 == 0)
        {
            if(year % 400 == 0)
                return 1;
            else
                return 0;
        }
        else
            return 1;
    }
    else
        return 0;
}

/*********************************************************************
 * @fn      RTC_Set
 *
 * @brief   Set Time.
 *
 * @param   Struct of _calendar_obj
 *
 * @return  1 - error
 *          0 - success
 */
u8 RTC_Set(u16 syear, u8 smon, u8 sday, u8 hour, u8 min, u8 sec)
{
    u16 t;
    u32 seccount = 0;
    if(syear < 1970 || syear > 2099)
        return 1;
    for(t = 1970; t < syear; t++)
    {
        if(Is_Leap_Year(t))
            seccount += 31622400;
        else
            seccount += 31536000;
    }
    smon -= 1;
    for(t = 0; t < smon; t++)
    {
        seccount += (u32)mon_table[t] * 86400;
        if(Is_Leap_Year(syear) && t == 1)
            seccount += 86400;
    }
    seccount += (u32)(sday - 1) * 86400;
    seccount += (u32)hour * 3600;
    seccount += (u32)min * 60;
    seccount += sec;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);
    PWR_BackupAccessCmd(ENABLE);
    RTC_SetCounter(seccount);
    RTC_WaitForLastTask();
    return 0;
}

/*********************************************************************
 * @fn      RTC_Alarm_Set
 *
 * @brief   Set Alarm Time.
 *
 * @param   Struct of _calendar_obj
 *
 * @return  1 - error
 *          0 - success
 */
u8 RTC_Alarm_Set(u16 syear, u8 smon, u8 sday, u8 hour, u8 min, u8 sec)
{
    u16 t;
    u32 seccount = 0;
    if(syear < 1970 || syear > 2099)
        return 1;
    for(t = 1970; t < syear; t++)
    {
        if(Is_Leap_Year(t))
            seccount += 31622400;
        else
            seccount += 31536000;
    }
    smon -= 1;
    for(t = 0; t < smon; t++)
    {
        seccount += (u32)mon_table[t] * 86400;
        if(Is_Leap_Year(syear) && t == 1)
            seccount += 86400;
    }
    seccount += (u32)(sday - 1) * 86400;
    seccount += (u32)hour * 3600;
    seccount += (u32)min * 60;
    seccount += sec;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);
    PWR_BackupAccessCmd(ENABLE);
    RTC_SetAlarm(seccount);
    RTC_WaitForLastTask();

    return 0;
}

/*********************************************************************
 * @fn      RTC_Get
 *
 * @brief   Get current time.
 *
 * @return  1 - error
 *          0 - success
 */
u8 RTC_Get(void)
{
    static u16 daycnt = 0;
    u32        timecount = 0;
    u32        temp = 0;
    u16        temp1 = 0;
    timecount = RTC_GetCounter();
    temp = timecount / 86400;
    if(daycnt != temp)
    {
        daycnt = temp;
        temp1 = 1970;
        while(temp >= 365)
        {
            if(Is_Leap_Year(temp1))
            {
                if(temp >= 366)
                    temp -= 366;
                else
                {
                    temp1++;
                    break;
                }
            }
            else
                temp -= 365;
            temp1++;
        }
        calendar.w_year = temp1;
        temp1 = 0;
        while(temp >= 28)
        {
            if(Is_Leap_Year(calendar.w_year) && temp1 == 1)
            {
                if(temp >= 29)
                    temp -= 29;
                else
                    break;
            }
            else
            {
                if(temp >= mon_table[temp1])
                    temp -= mon_table[temp1];
                else
                    break;
            }
            temp1++;
        }
        calendar.w_month = temp1 + 1;
        calendar.w_date = temp + 1;
    }
    temp = timecount % 86400;
    calendar.hour = temp / 3600;
    calendar.min = (temp % 3600) / 60;
    calendar.sec = (temp % 3600) % 60;
    calendar.week = RTC_Get_Week(calendar.w_year, calendar.w_month, calendar.w_date);
    return 0;
}

/*********************************************************************
 * @fn      RTC_Get_Week
 *
 * @brief   Get the current day of the week.
 *
 * @param   year/month/day
 *
 * @return  week
 */
u8 RTC_Get_Week(u16 year, u8 month, u8 day)
{
    u16 temp2;
    u8  yearH, yearL;

    yearH = year / 100;
    yearL = year % 100;
    if(yearH > 19)
        yearL += 100;
    temp2 = yearL + yearL / 4;
    temp2 = temp2 % 7;
    temp2 = temp2 + day + table_week[month - 1];
    if(yearL % 4 == 0 && month < 3)
        temp2--;
    return (temp2 % 7);
}

/*********************************************************************
 * @fn      main
 *
 * @brief   Main program.
 *
 * @return  none
 */
int main(void)
{
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    SystemCoreClockUpdate();
    Delay_Init();
    USART_Printf_Init(115200);	
    printf("SystemClk:%d\r\n", SystemCoreClock);
    printf( "ChipID:%08x\r\n", DBGMCU_GetCHIPID() );
    printf("RTC Test\r\n");
    RTC_Init();

    while(1)
    {
        Delay_Ms(1000);
        printf("year-month-day | week | hour-min-sec:\r\n");
        printf("%d-%d-%d | %d | %02d:%02d:%02d\r\n", calendar.w_year, calendar.w_month, calendar.w_date,
               calendar.week, calendar.hour, calendar.min, calendar.sec);
    }
}

使用“MounRiver Studio”编译，下载，运行后对比电脑端的实时时钟，呈现的效果如下视频，走时非常同步。