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//波特率
  uint32_t USART_BaudRate;            /*!< This member configures the USART communication baud rate.
                                           The baud rate is computed using the following formula:
                                            - IntegerDivider = ((PCLKx) / (16 * (USART_InitStruct->USART_BaudRate)))
                                            - FractionalDivider = ((IntegerDivider - ((u32) IntegerDivider)) * 16) + 0.5 */

//字节长度，我们一般选8字节
  uint16_t USART_WordLength;          /*!< Specifies the number of data bits transmitted or received in a frame.
                                           This parameter can be a value of @ref USART_Word_Length */

//停止位，一般选一位停止位
  uint16_t USART_StopBits;            /*!< Specifies the number of stop bits transmitted.
                                           This parameter can be a value of @ref USART_Stop_Bits */

//校验位，一般我们不选
  uint16_t USART_Parity;              /*!< Specifies the parity mode.
                                           This parameter can be a value of @ref USART_Parity
                                           @note When parity is enabled, the computed parity is inserted
                                                 at the MSB position of the transmitted data (9th bit when
                                                 the word length is set to 9 data bits; 8th bit when the
                                                 word length is set to 8 data bits). */
 
 //串口模式，一般接收和发送都打开
  uint16_t USART_Mode;                /*!< Specifies wether the Receive or Transmit mode is enabled or disabled.
                                           This parameter can be a value of @ref USART_Mode */

//是否硬件流控制，当然不啊
  uint16_t USART_HardwareFlowControl; /*!< Specifies wether the hardware flow control mode is enabled
                                           or disabled.
                                           This parameter can be a value of @ref USART_Hardware_Flow_Control */

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  USART_InitStructure.USART_BaudRate = 9600;//也可以写一个形参
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;//八位数据位
  USART_InitStructure.USART_StopBits = USART_StopBits_1;//一位停止位
  USART_InitStructure.USART_Parity = USART_Parity_No;//无校验位
  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;//使能发送接收
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//不使能硬件流控制

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void Usart2_Init(void){
  USART_InitTypeDef USART_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
	
	//使能时钟
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
	
	//串口2初始化
  USART_InitStructure.USART_BaudRate = 9600;
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;//八位数据位
  USART_InitStructure.USART_StopBits = USART_StopBits_1;//一位停止位
  USART_InitStructure.USART_Parity = USART_Parity_No;//无校验位
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//不使能硬件流控制
  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;//使能发送接收
  USART_Init(USART2, &USART_InitStructure);
  USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);//使能接收中断
  USART_Cmd(USART2, ENABLE);//使能串口2
	
	
	
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOA, &GPIO_InitStructure);//PA3为接收引脚，配置为浮空输入
  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);//PA2为发送引脚，设置为复用推挽输出 
	
	  
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
  
  /* Enable the USARTy Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;//开启串口2中断
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;//优先级最高
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;//使能中断
  NVIC_Init(&NVIC_InitStructure);
}

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void USART2_IRQHandler(void)
{
  if(USART_GetITStatus(USART2, USART_IT_RXNE) != RESET)
  {
    RxBuffer1[RxCounter1++] = USART_ReceiveData(USART2);

    if(RxCounter1 == NbrOfDataToRead1)
    {
      /* Disable the USARTy Receive interrupt */
      USART_ITConfig(USARTy, USART_IT_RXNE, DISABLE);
    }
  }
  
}

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unsigned char RXBUF[20];
unsigned char RXOVER = 0;
unsigned char RXCUNT = 0;

void USART2_IRQHandler(void)
{
	unsigned char temp;
	if(USART_GetFlagStatus(USART2, USART_IT_RXNE) == SET){//检查指定的 USART 中断发生与否
		USART_ClearITPendingBit(USART2,USART_IT_RXNE);//清除中断标志位
		temp = USART_ReceiveData(USART2);//接收数据
		if(temp == 'e'){//发送e之前的数据
			RXCUNT = 0;
			RXOVER = 1;
			USART_ITConfig(USART2, USART_IT_RXNE, DISABLE);//关闭中断
		}
		else{
			RXBUF[RXCUNT] = temp;
			RXCUNT ++;
		}
	}
  
}

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unsigned char Usart2_SendChar(uint8_t ucChar){
	while(!USART_GetFlagStatus(USART2,USART_FLAG_TXE));
	USART_SendData(USART2,ucChar);
  return ucChar;
}

void Usart2_SendString(uint8_t * pucStr){
	while(*pucStr != '')
		Usart2_SendChar(USART2,*pucStr ++);
	while(!USART_GetFlagStatus(USART2,USART_FLAG_TC));//注意这一步，不然可能导致数据丢失
}

void Usart2_disp(void){
	int i;
	if(RXOVER){
		LCD_ClearLine(Line4);
		LCD_DisplayStringLine(Line4,RXBUF);
		Usart2_SendString(USART2,RXBUF);
		for(i = 0;i < 20;i ++){
			RXBUF[i] = 0;
		}//其实也可以用memset函数,注意加 string.h 头文件
		//memset( RXBUF, 0 , ( 20 * sizeof(uint8_t) ) );//清零RXBUF数组
		USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
		RXOVER = 0;
	}
}