灵动微课堂 (第154讲) | MM32F013x——RTC闹钟定时唤醒

MM32F013x有22个外部中断源，其中EXti 17对应的是RTC闹钟事件，所以结合RTC闹钟的功能，本文将重点介绍如何在MM32F013x上通过内部RTC模块的闹钟事件来唤醒处于停机模式下的MCU。

01
实现功能
通过内部RTC模块的闹钟事件（对应的是外部中断EXTI 17）来唤醒处于停机模式下的MCU。系统在进入停机模式时拉高GPIO端口，在恢复到正常运行状态时拉低GPIO端口。

02
配置顺序
1）使能PWR和BKP时钟：
RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);

2）使能后备寄存器访问：
PWR_BackupAccessCmd(ENABLE);
3）配置RTC时钟源，使能RTC时钟，如果使用LSE，要打开LSE：
RCC_LSEConfig(RCC_LSE_ON);
while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET);
RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);
RCC_RTCCLKCmd(ENABLE);
4）设置RTC预分频系数：
RTC_SetPrescaler();

5）开启相关中断：
RTC_ITConfig(RTC_IT_ALR, ENABLE);

6）配置外部中断线：
EXTI_StructInit(&EXTI_InitStructure);
EXTI_InitStructure.EXTI_Line    = EXTI_Line17;
EXTI_InitStructure.EXTI_Mode    = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);

7）配置中断服务函数：
NVIC_InitStructure.NVIC_IRQChannel  = RTC_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

8）部分操作要等待写操作完成和同步。


03
参考代码
3.1  RTC初始化配置：使用外部32.768kHz的晶振源

void RTC_Configure(void)
{
    uint16_t BKP_Value = 0x5A5A;
    EXTI_InitTypeDef EXTI_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    /* Enable PWR Clock */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);

    /* Enable Access To The RTC & Backup Registers */
    PWR_BackupAccessCmd(ENABLE);

    if(BKP_ReadBackupRegister(BKP_DR1) != BKP_Value)
    {
        BKP_DeInit();

        /* Enable LSE Clock Source */
        RCC_LSEConfig(RCC_LSE_ON);

        /* Wait LSI Clock Source Ready */
        while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET);

        /* Config RTC Clock Source : LSE */
        RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);

        /* Enable RTC Clock */
        RCC_RTCCLKCmd(ENABLE);

        /* Wait For Synchronization */
        RTC_WaitForSynchro();
        /* Wait Until Last Write Operation On RTC REG Has Finished */
        RTC_WaitForLastTask();

        /* Set The RTC Prescaler Value */
        RTC_SetPrescaler(32767);
        /* Wait Until Last Write Operation On RTC REG Has Finished */
        RTC_WaitForLastTask();
        /* Enable RTC AlARM Interrupt */
        RTC_ITConfig(RTC_IT_ALR, ENABLE);
        /* Wait Until Last Write Operation On RTC REG Has Finished */
        RTC_WaitForLastTask();
        /* Exit From The RTC Configuration Mode */
        RTC_ExitConfigMode();
        BKP_WriteBackupRegister(BKP_DR1, BKP_Value);
        /* Wait Until Last Write Operation On RTC REG Has Finished */
        RTC_WaitForLastTask();
    }
    else
    {
        /* Wait For Synchronization */
        RTC_WaitForSynchro();
        /* Enable RTC Alarm Interrupt */
        RTC_ITConfig(RTC_IT_ALR, ENABLE);
        /* Wait Until Last Write Operation On RTC REG Has Finished */
        RTC_WaitForLastTask();
    }
    /* Clear EXTI Line17 Flag */
    EXTI_ClearITPendingBit(EXTI_Line17);

   /* Configure EXTI Line17(RTC Alarm) To Generate An Interrupt On Rising Edge */
    EXTI_StructInit(&EXTI_InitStructure);
    EXTI_InitStructure.EXTI_Line    = EXTI_Line17;
    EXTI_InitStructure.EXTI_Mode    = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);

    /* Config RTC NVIC */
    NVIC_InitStructure.NVIC_IRQChannel  = RTC_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

3.2   RTC闹钟中断函数

void RTC_BKP_IRQHandler(void)
{
    if(RTC_GetITStatus(RTC_IT_ALR) != RESET)
    {
        GPIO_WriteBit(LED_GPIO, LED_PIN, Bit_RESET);

        /* Clear EXTI Line17 Flag */
        EXTI_ClearITPendingBit(EXTI_Line17);

        /* Check If The Wake-Up Flag Is Set */
        if(PWR_GetFlagStatus(PWR_FLAG_WU) != RESET)
        {
            /* Clear Wake Up Flag */
            PWR_ClearFlag(PWR_FLAG_WU);
        }
        /* Clear Alarm Flag */
        RTC_ClearITPendingBit(RTC_IT_ALR);

        /* Wait Until Last Write Operation On RTC REG Has Finished */
        RTC_WaitForLastTask();
    }
}

3.3  设置RTC闹钟时间，系统进入STOP模式

void RTC_EntryStopMode(void)
{
    /* Wait till RTC Second event occurs */
    RTC_ClearFlag(RTC_FLAG_SEC);
    while(RTC_GetFlagStatus(RTC_FLAG_SEC) == RESET);

    /* Set The RTC Alarm Value */
    RTC_SetAlarm(RTC_GetCounter() + 3);

    /* Wait Until Last Write Operation On RTC REG Has Finished */
    RTC_WaitForLastTask();

    GPIO_WriteBit(LED_GPIO, LED_PIN, Bit_SET);

    /* Enter Stop Mode */
    PWR_EnterSTOPMode(PWR_Regulator_ON, PWR_STOPEntry_WFI);
}


04
运行结果
编译软件工程无误后下载代码，调用RTC_EntryStopMode()函数使系统进入到停机模式，等待RTC闹钟事件3S后唤醒停机模式下的MCU，唤醒后继续执行程序，通过观察GPIO的电平状态来查看运行结果：