#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;                //100MHzGPIO_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;                //100MHzGPIO_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USART1GPIO_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GPIOA10GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;                                    //复用功能GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;                                //速度50MHzGPIO_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3NVIC_InitStructure.NVIC_IRQChannelSubPriority =3;                                //子优先级3NVIC_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\r\n");/* Clear reset flags */RCC_ClearFlag();}else{/* WWDGRST flag is not set */printf("normal reset cpu\r\n");}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 counteris 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0NVIC_InitStructure.NVIC_IRQChannelSubPriority =0;                        //子优先级0NVIC_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
    {}
}