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 "); /* Clear reset flags */ RCC_ClearFlag(); } else { /* WWDGRST flag is not set */ printf("normal reset cpu "); } delay_ms(500);delay_ms(500);
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(80); /* 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(127); //WWDG NVIC 配置 NVIC_InitStructure.NVIC_IRQChannel = WWDG_IRQn; //窗口看门狗中断通道 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0; //抢占优先级0 NVIC_InitStructure.NVIC_IRQChannelSubPriority =0; //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(127); //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/8/1000000*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&(1<<16))); //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/8/1000*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&(1<<16))); //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=3; //抢占优先级3 NVIC_InitStructure.NVIC_IRQChannelSubPriority =3; //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(115200); /* 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 "); /* Clear reset flags */ RCC_ClearFlag(); } else { /* WWDGRST flag is not set */ printf("normal reset cpu "); } delay_ms(500);delay_ms(500); /* 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(80); /* 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(127); //WWDG NVIC 配置 NVIC_InitStructure.NVIC_IRQChannel = WWDG_IRQn; //窗口看门狗中断通道 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0; //抢占优先级0 NVIC_InitStructure.NVIC_IRQChannelSubPriority =0; //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(1) { #if 0 //进行喂狗 WWDG_SetCounter(127); //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(127); //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 { } }