STM32L151C8 periodically wakes up from standby mode (RTC Wakeup Timer)

#include "stm32l1xx.h"

#include "system_stm32l1xx.h"

#include "OLED.h"

#include "delay.h"

void RtcWakeUpConfig(void);

u8 RtcInit(void);

u8 RtcConfig(void);

int main()

{

    DelayInit(); //Delay initialization

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE); //Enable PWR clock

    if(PWR_GetFlagStatus(PWR_FLAG_SB)) //Wake up from standby mode 

    {

        PWR_ClearFlag(PWR_FLAG_SB);

        PWR_ClearFlag(PWR_FLAG_WU);

    }

    OLED_Init();

    RtcInit();

    while(1)    

    {

        OLED_8x16StrP(0,0,"Runing..."); //LCD prompts that it is running

        DelayS(2); //Delay 2 seconds

        RtcWakeUpConfig(); //RTC wakeup configuration: automatic wakeup every 500ms

// PWR_WakeUpPinCmd(PWR_WakeUpPin_1,ENABLE); //Periodic auto-wakeup does not require an external wake-up pin, so this sentence is not needed

        PWR_EnterSTANDBYMode(); //Enter standby mode     

    }

}

void RtcWakeUpConfig(void)

{

    RTC_WakeUpCmd(DISABLE);

    RTC_ClearFlag(RTC_FLAG_WUTF);

    RTC_WakeUpClockConfig(RTC_WakeUpClock_RTCCLK_Div8); //Select the clock as external 32.768KHz 8-division

    RTC_SetWakeUpCounter(2047); //500ms interval

    RTC_ClearITPendingBit(RTC_IT_WUT);

    RTC_ITConfig(RTC_IT_WUT,ENABLE); //Need to enable interrupt, no interrupt function is needed

    RTC_WakeUpCmd(ENABLE);

}

u8 RtcInit(void)

{

    // Check if it is the first time to configure the clock

    u8 flag = 0;

    if (RTC_ReadBackupRegister(RTC_BKP_DR0) != 0x32F2) //Read data from the specified backup register: The data read does not match the specified data written.

    {

        /* RTC configuration  */

        flag = RtcConfig();

        if(flag == 0)

        {

            RTC_WriteBackupRegister(RTC_BKP_DR0, 0x32F2);

        }

        else

            return flag;

    }

    else

    {

        /* Enable the PWR clock */

        RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);

        /* Allow access to RTC */

        PWR_RTCAccessCmd(ENABLE);

        /* Wait for RTC APB registers synchronisation */

        RTC_WaitForSynchro();

    }

    return 0; //ok

}   

/**

  * @brief  Configure the RTC peripheral by selecting the clock source.

  * @param  None

  * @retval None

  */

u8 RtcConfig(void)

{

    /* Enable the PWR clock */

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);

    /* Allow access to RTC */

    PWR_RTCAccessCmd(ENABLE);

    /* Enable the LSE OSC */

    RCC_LSEConfig(RCC_LSE_ON);

    /* Wait till LSE is ready */ 

    u32 temp = 0;

    while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET)

    {

        temp++;

        delay_ms(10);

        if(temp >= 250) return 1; //Failed to initialize the clock, the crystal oscillator has a problem, the 32768 crystal oscillator start-up limit time is 1-5S 

    }

    /* Select the RTC Clock Source */

    RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);

    /* Enable the RTC Clock */

    RCC_RTCCLKCmd(ENABLE);

    /* Wait for RTC APB registers synchronisation */

    RTC_WaitForSynchro();

    /* Configure the RTC data register and RTC prescaler */

    RTC_InitTypeDef RTC_InitStructure;

    RTC_InitStructure.RTC_AsynchPrediv = 0x7F;

    RTC_InitStructure.RTC_SynchPrediv = 0xFF;

    RTC_InitStructure.RTC_HourFormat = RTC_HourFormat_24;

    RTC_Init(&RTC_InitStructure);

    return 0;

}

Non-standby mode, RTC Wakeup timer interrupt configuration and interrupt processing

void RTC_IRQConfig(void)

{

    NVIC_InitTypeDef NVIC_InitStructure; 

    EXTI_InitTypeDef EXTI_InitStructure;

    /* EXIT configuration ************************************************** *********/

    EXTI_ClearITPendingBit(EXTI_Line20);

    EXTI_InitStructure.EXTI_Line = EXTI_Line20;

    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;

    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;

    EXTI_InitStructure.EXTI_LineCmd = ENABLE;

    EXTI_Init(&EXTI_InitStructure);

    /* Enable the RTC Wakeup Interrupt */

    NVIC_InitStructure.NVIC_IRQChannel = RTC_WKUP_IRQn;

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

    NVIC_Init(&NVIC_InitStructure);  

}

void RTC_WKUP_IRQHandler(void)

{

    if(RTC_GetITStatus(RTC_IT_WUT) != RESET) 

    {

        EXTI_ClearITPendingBit(EXTI_Line20); 

        PWR_RTCAccessCmd(ENABLE); //If it was disabled before, reopen it

        RTC_ClearITPendingBit(RTC_IT_WUT);

        PWR_RTCAccessCmd(DISABLE); //Can be turned off again

        GPIO_ToggleBits( GPIOB, GPIO_Pin_4 );

    }

}