stm32休眠 以及休眠中如何喂狗

在STM32开发中经常会用到独立看门狗（IWDG）和低功耗模式，看门狗是为了检测和解决由软件错误引起的故障，低功耗模式是为了在CPU不需要继续运行时进入到休眠模式用以节省电能。其中独立看门狗的时钟由独立的RC振荡器（STM32F10x一般为40kHz）提供，即使在主时钟出现故障时，也仍然有效，因此可以在停止和待机模式下工作。而且独立看门狗一旦启动，除了系统复位，它不能再被停止。但这样引发的一个问题是当MCU进入到低功耗模式后由于CPU停止运行无法喂狗，会导致系统频繁复位。那如何解决这个问题呢，难道独立看门狗和低功耗模式没法同时使用？

一个很好的方式是在休眠模式下通过RTC定时唤醒来喂狗，喂完够在进入继续进入到休眠模式。比如看门狗复位的时间间隔为10s。那么在进入休眠模式前设置RTC闹钟中断时间为5s。这样每隔5s唤醒一次喂一次狗。便可以很好的解决这个问题。

while(1)  {    // 执行任务Task1();Task2();// ..// 喂狗dev_iwdg_feed();// 进入待机模式开关if(m_bEnterStandByMode){    // 使能外部中断，GPIOB3，用以MCU从待机模式唤醒    dev_exti_enable(TRUE);ENTERSTOPMODE:// 设置RTC闹钟，5秒钟产生一次RTC闹钟中断*/dev_rtc_setAlarm(5);// 进入停止模式（低功耗），直至外部中断触发时被唤醒PWR_EnterSTOPMode(PWR_Regulator_LowPower, PWR_STOPEntry_WFI);// 是否是RTC闹钟中断唤醒if(dev_rtc_isAlarm()){// 喂狗dev_iwdg_feed();// 喂完狗继续进入停止模式goto ENTERSTOPMODE;}// 禁止外部中断 dev_exti_enable(FALSE);// 从停止模式唤醒后恢复系统时钟dev_clk_restore();}        }

以下是完整的代码：

//**********************************************************************************************     //  STM32F10x StopMode RTC Feed Dog //  compiler: Keil UV3     //  2013-01-04 , By friehood     //**********************************************************************************************  #include "stm32f10x_lib.h"#include "platform_config.h"static Boolean g_bRTCAlarm = FALSE;/******************************************************************************** Function Name  : RCC_Configuration* Description    : Configures the different system clocks.* Input          : None* Output         : None* Return         : None*******************************************************************************/void RCC_Configuration(void){/* RCC system reset(for debug purpose) */RCC_DeInit();/* Enable HSE */RCC_HSEConfig(RCC_HSE_ON);/* Wait till HSE is ready */if(RCC_WaitForHSEStartUp() == SUCCESS){/* Enable Prefetch Buffer */FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);//FLASH时序控制         //推荐值：SYSCLK = 0~24MHz   Latency=0         //        SYSCLK = 24~48MHz  Latency=1         //        SYSCLK = 48~72MHz  Latency=2//FLASH_SetLatency(FLASH_Latency_1);   //警告:修改为1会对DMA值有影响（如ADC采集值会错位）FLASH_SetLatency(FLASH_Latency_2);/* HCLK = SYSCLK */RCC_HCLKConfig(RCC_SYSCLK_Div1); /* PCLK2 = HCLK */RCC_PCLK2Config(RCC_HCLK_Div1); /* PCLK1 = HCLK/2 */RCC_PCLK1Config(RCC_HCLK_Div2);/* PLLCLK = 12MHz * 3 = 36 MHz */RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_3);/* Enable PLL */ RCC_PLLCmd(ENABLE);/* Wait till PLL is ready */while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET){}/* Select PLL as system clock source */RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);/* Wait till PLL is used as system clock source */while(RCC_GetSYSCLKSource() != 0x08){}}/* Enable PWR and BKP clock */RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE);/* Enable AFIO clock */RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);}/******************************************************************************** Function Name  : NVIC_Configuration* Description    : Configures the nested vectored interrupt controller.* Input          : None* Output         : None* Return         : None*******************************************************************************/void NVIC_Configuration(void){  NVIC_InitTypeDef NVIC_InitStructure;#ifdef  VECT_TAB_RAM  /* Set the Vector Table base location at 0x20000000 */  NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0);#else  /* VECT_TAB_FLASH  */  /* Set the Vector Table base location at 0x08000000 */  NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);#endif  /* Configure one bit for preemption priority */  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);}/******************************************************************************** Function Name  : SysTick_Configuration* Description    : Configures the SysTick to generate an interrupt each 1 millisecond.* Input          : None* Output         : None* Return         : None*******************************************************************************/void SysTick_Configuration(void){  /* Select AHB clock(HCLK) as SysTick clock source */  SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK);  /* Set SysTick Priority to 3 */  NVIC_SystemHandlerPriorityConfig(SystemHandler_SysTick, 3, 0);     /* SysTick interrupt each 1ms with HCLK equal to 72MHz */  SysTick_SetReload(72000);  /* Enable the SysTick Interrupt */  SysTick_ITConfig(ENABLE);}/******************************************************************************** Function Name  : Delay* Description    : Inserts a delay time.* Input          : nTime: specifies the delay time length, in milliseconds.* Output         : None* Return         : None*******************************************************************************/void Delay(u32 nTime){  /* Enable the SysTick Counter */  SysTick_CounterCmd(SysTick_Counter_Enable);    TimingDelay = nTime;  while(TimingDelay != 0);  /* Disable the SysTick Counter */  SysTick_CounterCmd(SysTick_Counter_Disable);  /* Clear the SysTick Counter */  SysTick_CounterCmd(SysTick_Counter_Clear);}/******************************************************************************** Function Name  : RTC_Configuration* Description    : Configures RTC clock source and prescaler.* Input          : None* Output         : None* Return         : None*******************************************************************************/void RTC_Configuration(void){EXTI_InitTypeDef EXTI_InitStructure;NVIC_InitTypeDef NVIC_InitStructure;/* RTC clock source configuration ------------------------------------------*//* Allow access to BKP Domain */PWR_BackupAccessCmd(ENABLE);/* Reset Backup Domain */BKP_DeInit();/* Enable the LSI OSC */RCC_LSICmd(ENABLE);/* Wait till LSI is ready */while (RCC_GetFlagStatus(RCC_FLAG_LSIRDY) == RESET){}/* Select the RTC Clock Source */RCC_RTCCLKConfig(RCC_RTCCLKSource_LSI);/* Enable the RTC Clock */RCC_RTCCLKCmd(ENABLE);/* RTC configuration -------------------------------------------------------*//* Wait for RTC APB registers synchronisation */RTC_WaitForSynchro();/* Set RTC prescaler: set RTC period to 1sec */RTC_SetPrescaler(40000);/* Wait until last write operation on RTC registers has finished */RTC_WaitForLastTask();/* Enable the RTC Alarm interrupt */RTC_ITConfig(RTC_IT_ALR, ENABLE);/* Wait until last write operation on RTC registers has finished */RTC_WaitForLastTask();/* Configure EXTI Line17(RTC Alarm) to generate an interrupt on rising edge */    EXTI_ClearITPendingBit(EXTI_Line17);    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);/* Enable the RTC Interrupt */NVIC_InitStructure.NVIC_IRQChannel = RTCAlarm_IRQChannel;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);}/******************************************************************************** Function Name  : RTCAlarm_IRQHandler* Description    : This function handles RTC Alarm interrupt request.* Input          : None* Output         : None* Return         : None*******************************************************************************/void RTCAlarm_IRQHandler(void){if(RTC_GetITStatus(RTC_IT_ALR) != RESET){    /* Set the RTC alarm flag */    g_bRTCAlarm = TRUE;/* Clear EXTI line17 pending bit */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);} /* Wait until last write operation on RTC registers has finished */RTC_WaitForLastTask();   /* Clear RTC Alarm interrupt pending bit */RTC_ClearITPendingBit(RTC_IT_ALR);/* Wait until last write operation on RTC registers has finished */RTC_WaitForLastTask();}}/******************************************************************************** Function Name  : dev_rtc_setAlarm* Description    : 设置RTC闹钟.* Input          : 闹钟时间* Output         : None* Return         : None*******************************************************************************/void dev_rtc_setAlarm(u32 AlarmValue){/* Clear the RTC SEC flag */RTC_ClearFlag(RTC_FLAG_SEC);/* Wait clear RTC flag sccess */    while(RTC_GetFlagStatus(RTC_FLAG_SEC) == RESET);   /* Wait until last write operation on RTC registers has finished */RTC_WaitForLastTask(); /* Sets the RTC alarm value */    RTC_SetAlarm(RTC_GetCounter() + AlarmValue);/* Wait until last write operation on RTC registers has finished */RTC_WaitForLastTask(); }/******************************************************************************** Function Name  : dev_rtc_isAlarm* Description    : RTC闹钟是否触发* Input          : None* Output         : None* Return         : TRUE:已触发，FALSE，未触发*******************************************************************************/Boolean dev_rtc_isAlarm(void){if(g_bRTCAlarm){    /* Clear the RTC alarm flag */g_bRTCAlarm = FALSE;return TRUE;}return FALSE;}void dev_iwdg_init(void){/* Enable write access to IWDG_PR and IWDG_RLR registers */IWDG_WriteAccessCmd(IWDG_WriteAccess_Enable);/* IWDG counter clock: 40KHz(LSI) / 256 = 0.15625 KHz */    IWDG_SetPrescaler(IWDG_Prescaler_256);/* Set counter reload value to 1562 */IWDG_SetReload(1562);// 10s/* Reload IWDG counter */IWDG_ReloadCounter();/* Enable IWDG (the LSI oscillator will be enabled by hardware) */IWDG_Enable();}void dev_iwdg_feed(void){IWDG_ReloadCounter();}/******************************************************************************** Function Name  : dev_clk_restore* Description    : Restore system clock after wake-up from STOP: enable HSE, PLL*                  and select PLL as system clock source.* Input          : None* Output         : None* Return         : None*******************************************************************************/void dev_clk_restore(void){  /* Enable HSE */  RCC_HSEConfig(RCC_HSE_ON);  /* Wait till HSE is ready */  HSEStartUpStatus = RCC_WaitForHSEStartUp();  if(HSEStartUpStatus == SUCCESS)  {    /* Enable PLL */     RCC_PLLCmd(ENABLE);    /* Wait till PLL is ready */    while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)    {    }    /* Select PLL as system clock source */    RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);    /* Wait till PLL is used as system clock source */    while(RCC_GetSYSCLKSource() != 0x08)    {    }  }}/******************************************************************************** Function Name  : EXTI_Configuration* Description    : Configures EXTI Line3.* Input          : None* Output         : None* Return         : None*******************************************************************************/void EXIT_Configuration(void){EXTI_InitTypeDef EXTI_InitStructure;GPIO_EXTILineConfig(GPIO_PortSourceGPIOB,GPIO_PinSource3);EXTI_ClearITPendingBit(EXTI_Line3);EXTI_InitStructure.EXTI_Line = EXTI_Line3;EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;  EXTI_InitStructure.EXTI_Trigger= EXTI_Trigger_Falling;EXTI_InitStructure.EXTI_LineCmd = ENABLE;EXTI_Init(&EXTI_InitStructure);}void dev_exti_enable(Boolean bEnable){NVIC_InitTypeDef NVIC_InitStructure;/* Clear the Key Button EXTI line pending bit */EXTI_ClearITPendingBit(EXTI_Line3);NVIC_ClearIRQChannelPendingBit(EXTI3_IRQChannel);NVIC_InitStructure.NVIC_IRQChannel = EXTI3_IRQChannel;  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;NVIC_InitStructure.NVIC_IRQChannelCmd = bEnable ? ENABLE : DISABLE;NVIC_Init(&NVIC_InitStructure);}/******************************************************************************** Function Name  : main* Description    : Main program.* Input          : None* Output         : None* Return         : None*******************************************************************************/int main(void){  /* System Clocks Configuration */  RCC_Configuration();  /* NVIC configuration */  NVIC_Configuration();  /* Configure RTC clock source and prescaler */  RTC_Configuration();  /* Configure the SysTick to generate an interrupt each 1 millisecond */  SysTick_Configuration();  /* Configures EXTI Line3 */  EXIT_Configuration();  /* IWDG initialize*/  dev_iwdg_init();  while(1)  {    // 执行任务Task1();Task2();// ..// 喂狗dev_iwdg_feed();// 进入待机模式开关if(m_bEnterStandByMode){    // 使能外部中断，GPIOB3，用以MCU从待机模式唤醒    dev_exti_enable(TRUE);ENTERSTOPMODE:// 设置RTC闹钟，5秒钟产生一次RTC闹钟中断*/dev_rtc_setAlarm(5);// 进入停止模式（低功耗），直至外部中断触发时被唤醒PWR_EnterSTOPMode(PWR_Regulator_LowPower, PWR_STOPEntry_WFI);// 是否是RTC闹钟中断唤醒if(dev_rtc_isAlarm()){// 喂狗dev_iwdg_feed();// 喂完狗继续进入停止模式goto ENTERSTOPMODE;}// 禁止外部中断 dev_exti_enable(FALSE);// 从停止模式唤醒后恢复系统时钟dev_clk_restore();}        }}