void init_usart(void)

//RCC初始化

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO,，ENABLE);//使能GPIOA时钟

RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2,ENABLE);

//nvic

NVIC_ InitTypeDef NVIC_InitStructure;#ifdef VECT_TAB_RAM

NVIC_SetVectorTable(NVIC_VectTab_RAM,Ox0);#else

NVIC_SetVectorTable(NVIC_VectTab_FLASH,Ox0);#endif

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;NVIC_InitStructure.NVIC_IRQChannelSubPriority = o;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_lnitStructure);

//GPIO初始化

GPIO_IlnitTypeDef GPIO_InitStructure;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;GPIO_IlnitStructure.GPIO_Speed = GPIO_Speed_5OMHz;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;

GPIO_Init(GPIOA,&GPIO_InitStructure);

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_5OMHz;GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;

GPIO_Init(GPIOA,&GPIO_InitStructure);

//USART初始

//USART_DeInit(USART2);

USART_InitTypeDef USART_InitStructure;

//串口设置恢复默认参数

USART_ClockInitTypeDef USART_ClocklnitStructure;

USART_InitStructure.USART_BaudRate = 9600;

//波特率9600

USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长8位USART_InitStructure.USART_StopBits = USART_StopBits_1;

//1位停止字节

USART_InitStructure.USART_Parity = USART_Parity_No;

川/无奇偶校验

USART_IlnitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无流控制

USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;//打开Rx接收和Tx发送功能

USART_ClockInitStructure.USART_Clock =USART_Clock_Disable;USART_ClockInitStructure.USART_CPOL =USART_CPOL_High;USART_ClockInitStructure.USART_CPHA =USART_CPHA_2Edge;USART_ClocklnitStructure.USART_LastBit =USART_LastBit_Disable;USART_Clocklnit(USART2,&USART_ClockInitStructure);

USART_Init(USART2,&USART_InitStructure);

//初始化

USART_ITConfig(USART2,USART_IT_RXNE,ENABLE);//开启接收中断,这个必须在打开串口之前设置USART_Cmd(USART2,ENABLE);

/启动串口

void USART2_IRQHandler(void)

//接收中断

if(USART_GetlTStatus(USART2,USART_IT_RXNE)==SET)(

USART_ClearlTPendingBit(USART2,USART_IT_RXNE);usart_rx=USART_ReceiveData(USART2);

usart_rx_flag=1;

}

//溢出-如果发生溢出需要先读SR,再读DR寄存器则可清除不断入中断的问题[牛人说要这样]if(USART_GetFlagStatus(USART2,USART_FLAG_ORE)==SET)

USART_ClearFlag(USART2,USART_FLAG_ORE);//读SR其实就是清除标志USART_ReceiveData(USART2);//读DR

}

}