窗口看门狗 WWDG

一，窗口看门狗

二，喂狗注意事项

三，程序设计

1.检查复位状态，有助于观察当前工作的可靠性

 /* Check if the system has resumed from WWDG reset ，检查是否窗口看门狗导致的复位，如果发现由窗口看门狗导致的复位，输出打印信息*/
         if (RCC_GetFlagStatus(RCC_FLAG_WWDGRST) != RESET)
         {
                   /* WWDGRST flag set */
                   printf("wwdg reset cpu\r\n");

                   /* Clear reset flags */
                   RCC_ClearFlag();
         }
         else
         {
                   /* WWDGRST flag is not set */
                   printf("normal reset cpu\r\n");
         }

         delay_ms();delay_ms();

2.     看门狗的初始化

      /* WWDG configuration ，窗口看门狗的配置*/
         /* Enable WWDG clock ，使能看门狗的时钟*/
         RCC_APB1PeriphClockCmd(RCC_APB1Periph_WWDG, ENABLE);

         /* 窗口看门狗的时钟 = (PCLK1 (42MHz)/4096)/8 = 1281 Hz (~780 us)  */
         WWDG_SetPrescaler(WWDG_Prescaler_8);

         /* Set Window value to 80; WWDG counter should be refreshed only when the counter
           is below 80 (and greater than 0x40) otherwise a reset will be generated
         设置窗口的上限值为80
         */
         WWDG_SetWindowValue();

         /* 设置计数值的初值为127，则窗口看门狗的超时时间 = 780 us * 64 = 49.92 ms
                   这个时候窗口刷新时间如下
        ~780 * (127-80) = 36.6ms < refresh window < ~780 * 64 = 49.9ms

         */
         WWDG_Enable();

         //WWDG NVIC 配置
         NVIC_InitStructure.NVIC_IRQChannel = WWDG_IRQn;                        //窗口看门狗中断通道
         NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=;               //抢占优先级0
         NVIC_InitStructure.NVIC_IRQChannelSubPriority =;                    //子优先级0
         NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                     //IRQ通道使能
         NVIC_Init(&NVIC_InitStructure);                                   //根据指定的参数初始化VIC寄存器         

         //清空提前唤醒中断标志位
         WWDG_ClearFlag();

         //使能提前唤醒中断
         WWDG_EnableIT();

3.     看门狗中断服务函数

void WWDG_IRQHandler(void)
{
         if(WWDG_GetFlagStatus()==SET)
         {
                   //进行喂狗
                   WWDG_SetCounter();

                   //清空提前唤醒中断标志位
                   WWDG_ClearFlag();         

         }
}

#include "stm32f4xx.h"
#include "stm32f4xx_gpio.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx_usart.h"
#include "stdio.h"
#include "sys.h"

static GPIO_InitTypeDef      GPIO_InitStructure;
static USART_InitTypeDef     USART_InitStructure;
static NVIC_InitTypeDef     NVIC_InitStructure;        

//重定义fputc函数
int fputc(int ch, FILE *f)
{
    USART_SendData(USART1,ch);
    while(USART_GetFlagStatus(USART1,USART_FLAG_TXE)==RESET);  

    return ch;
}   

void delay_us(uint32_t nus)
{
    uint32_t temp;
    SysTick->LOAD =SystemCoreClock//*nus;     //时间加载
    SysTick->VAL  =0x00;                            //清空计数器
    SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ;         //使能滴答定时器开始倒数
    do
    {
        temp=SysTick->CTRL;
    }while((temp&0x01)&&!(temp&(<<)));            //等待时间到达
    SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk;         //关闭计数器
    SysTick->VAL =0X00;                               //清空计数器
}

void delay_ms(uint16_t nms)
{
    uint32_t temp;
    SysTick->LOAD=SystemCoreClock//*nms;        //时间加载(SysTick->LOAD为24bit)
    SysTick->VAL =0x00;                               //清空计数器
    SysTick->CTRL|=SysTick_CTRL_ENABLE_Msk ;        //能滴答定时器开始倒数
    do
    {
        temp=SysTick->CTRL;
    }while((temp&0x01)&&!(temp&(<<)));            //等待时间到达
    SysTick->CTRL&=~SysTick_CTRL_ENABLE_Msk;        //关闭计数器
    SysTick->VAL =0X00;                               //清空计数器
} 

void LED_Init(void)
{         

    //使能GPIOE，GPIOF时钟
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE | RCC_AHB1Periph_GPIOF, ENABLE);            

    //GPIOF9,F10初始化设置
    GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_9 | GPIO_Pin_10;        //LED0和LED1对应IO口
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_OUT;                    //普通输出模式，
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;                    //推挽输出，驱动LED需要电流驱动
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;                //100MHz
    GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;                    //上拉
    GPIO_Init(GPIOF, &GPIO_InitStructure);                            //初始化GPIOF，把配置的数据写入寄存器                        

    //GPIOE13,PE14初始化设置
    GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_13 | GPIO_Pin_14;        //LED2和LED3对应IO口
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_OUT;                    //普通输出模式
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;                    //推挽输出
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;                //100MHz
    GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;                    //上拉
    GPIO_Init(GPIOE, &GPIO_InitStructure);                            //初始化GPIOE，把配置的数据写入寄存器

    GPIO_SetBits(GPIOF,GPIO_Pin_9  | GPIO_Pin_10);                    //GPIOF9,PF10设置高，灯灭
    GPIO_SetBits(GPIOE,GPIO_Pin_13 | GPIO_Pin_14);
}

void USART1_Init(uint32_t baud)
{
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE);                             //使能GPIOA时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);                            //使能USART1时钟

    //串口1对应引脚复用映射
    GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1);                         //GPIOA9复用为USART1
    GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1);                         //GPIOA10复用为USART1

    //USART1端口配置
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;                         //GPIOA9与GPIOA10
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;                                    //复用功能
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;                                //速度50MHz
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;                                     //推挽复用输出
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;                                     //上拉
    GPIO_Init(GPIOA,&GPIO_InitStructure);                                             //初始化PA9，PA10

    //USART1 初始化设置
    USART_InitStructure.USART_BaudRate = baud;                                        //波特率设置
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;                        //字长为8位数据格式
    USART_InitStructure.USART_StopBits = USART_StopBits_1;                            //一个停止位
    USART_InitStructure.USART_Parity = USART_Parity_No;                                //无奇偶校验位
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;    //无硬件数据流控制
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;                    //收发模式
    USART_Init(USART1, &USART_InitStructure);                                         //初始化串口1

    USART_Cmd(USART1, ENABLE);                                                      //使能串口1 

    USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);                                    //开启相关中断

    //Usart1 NVIC 配置
    NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;                                //串口1中断通道
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=;                            //抢占优先级3
    NVIC_InitStructure.NVIC_IRQChannelSubPriority =;                                //子优先级3
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                                    //IRQ通道使能
    NVIC_Init(&NVIC_InitStructure);                                                    //根据指定的参数初始化VIC寄存器
}

int main(void)
{ 

    LED_Init();        

    //系统定时器初始化，时钟源来自HCLK，且进行8分频，
    //系统定时器时钟频率=168MHz/8=21MHz
    SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8); 

    //设置中断优先级分组2
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

    //串口1,波特率115200bps,开启接收中断
    USART1_Init();

    /* Check if the system has resumed from WWDG reset ，检查是否窗口看门狗导致的复位，如果发现由窗口看门狗导致的复位，输出打印信息*/
    if (RCC_GetFlagStatus(RCC_FLAG_WWDGRST) != RESET)
    {
        /* WWDGRST flag set */
        printf("wwdg reset cpu\r\n");

        /* Clear reset flags */
        RCC_ClearFlag();
    }
    else
    {
        /* WWDGRST flag is not set */
        printf("normal reset cpu\r\n");
    }

    delay_ms();delay_ms();

    /* WWDG configuration ，窗口看门狗的配置*/
    /* Enable WWDG clock ，使能看门狗的时钟*/
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_WWDG, ENABLE);

    /* 窗口看门狗的时钟 = (PCLK1 (42MHz)/4096)/8 = 1281 Hz (~780 us)  */
    WWDG_SetPrescaler(WWDG_Prescaler_8);

    /* Set Window value to 80; WWDG counter should be refreshed only when the counter
      is below 80 (and greater than 0x40) otherwise a reset will be generated
    设置窗口的上限值为80
    */
    WWDG_SetWindowValue();

    /* 设置计数值的初值为127，则窗口看门狗的超时时间 = 780 us * 64 = 49.92 ms
        这个时候窗口刷新时间如下
        ~780 * (127-80) = 36.6ms < refresh window < ~780 * 64 = 49.9ms

    */
    WWDG_Enable();

    //WWDG NVIC 配置
    NVIC_InitStructure.NVIC_IRQChannel = WWDG_IRQn;                            //窗口看门狗中断通道
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=;                    //抢占优先级0
    NVIC_InitStructure.NVIC_IRQChannelSubPriority =;                        //子优先级0
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                            //IRQ通道使能
    NVIC_Init(&NVIC_InitStructure);                                            //根据指定的参数初始化VIC寄存器    

    //清空提前唤醒中断标志位
    WWDG_ClearFlag();

    //使能提前唤醒中断
    WWDG_EnableIT();

    while()
    {
#if 0
        //进行喂狗
        WWDG_SetCounter();

        //清空提前唤醒中断标志位
        WWDG_ClearFlag();
#endif

    }
}

void WWDG_IRQHandler(void)
{
    if(WWDG_GetFlagStatus()==SET)
    {
        //进行喂狗
        WWDG_SetCounter();

        //清空提前唤醒中断标志位
        WWDG_ClearFlag();    

    }
}

void USART1_IRQHandler(void)                                //串口1中断服务程序
{
    uint8_t d;

    if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)      //接收中断
    {

    }
} 

wwdg.c