STM32F103C8T6 三串口同时收发消息

测试使用的是最小核心开发板，代码如下：

void My_USART1_Init(void)
{
	GPIO_InitTypeDef GPIO_InitStrue;
	USART_InitTypeDef USART_InitStrue;
	NVIC_InitTypeDef NVIC_InitStrue;
	
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);    //GPIO端口使能
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);   //串口使能
	
	GPIO_InitStrue.GPIO_Mode=GPIO_Mode_AF_PP;               //推挽输出
	GPIO_InitStrue.GPIO_Pin=GPIO_Pin_9;                     //PA9
	GPIO_InitStrue.GPIO_Speed=GPIO_Speed_10MHz;             //翻转速度
  GPIO_Init(GPIOA,&GPIO_InitStrue);                       //GPIO端口初始化
	
	GPIO_InitStrue.GPIO_Mode=GPIO_Mode_IN_FLOATING;         //浮空输入
	GPIO_InitStrue.GPIO_Pin=GPIO_Pin_10;                    //PA10
	GPIO_InitStrue.GPIO_Speed=GPIO_Speed_10MHz;             //翻转速度
  GPIO_Init(GPIOA,&GPIO_InitStrue);                       //GPIO端口初始化
	
	USART_InitStrue.USART_BaudRate = 115200  ;                                     //波特率
	USART_InitStrue.USART_HardwareFlowControl=USART_HardwareFlowControl_None;      //无流控制
	USART_InitStrue.USART_Mode=USART_Mode_Tx|USART_Mode_Rx;                        //输入输出模式
	USART_InitStrue.USART_Parity=USART_Parity_No;                                  //无校验
	USART_InitStrue.USART_StopBits=USART_StopBits_1;                               //停止位
	USART_InitStrue.USART_WordLength=USART_WordLength_8b;                          //数据位	
	USART_Init(USART1,&USART_InitStrue);                                           //串口参数初始化
	
	USART_Cmd(USART1,ENABLE);                            //使能串口1	
	USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);         //开启接收中断
	
	NVIC_InitStrue.NVIC_IRQChannel=USART1_IRQn;          //指定IRQ通道
	NVIC_InitStrue.NVIC_IRQChannelCmd=ENABLE;            //中断使能
	NVIC_InitStrue.NVIC_IRQChannelPreemptionPriority=1;  //指定优先级
	NVIC_InitStrue.NVIC_IRQChannelSubPriority=1;         //
	NVIC_Init(&NVIC_InitStrue);                          //中断初始化                              
	
	
}



void My_USART2_Init(void)
{
	  GPIO_InitTypeDef GPIO_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    
    /* Enable the USART2 Pins Software Remapping */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA|RCC_APB2Periph_AFIO, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2|RCC_APB2Periph_AFIO, ENABLE); 
    
    /* Configure USART2 Rx (PA.03) as input floating */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;    
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    
    /* Configure USART2 Tx (PA.02) as alternate function push-pull */
    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);
    
    /* Enable the USART2 Interrupt */
    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);    
    
    USART_InitStructure.USART_BaudRate = 115200;                
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;     
    USART_InitStructure.USART_Parity = USART_Parity_No;        
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;      
    
    USART_Init(USART2, &USART_InitStructure);
    USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
    /* Enable USART2 */
    USART_Cmd(USART2, ENABLE);
}




void My_USART3_Init(void)
{
	  GPIO_InitTypeDef GPIO_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    
    /* Enable the USART3 Pins Software Remapping */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE); 
    
    /* Configure USART3 Rx (PB.11) as input floating */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;    
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
    
    /* Configure USART3 Tx (PB.10) as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
    
    /* Enable the USART3 Interrupt */
    NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);    
    
    USART_InitStructure.USART_BaudRate = 115200;                
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;     
    USART_InitStructure.USART_Parity = USART_Parity_No;        
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;      
    
    USART_Init(USART3, &USART_InitStructure);
    USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
    /* Enable USART3 */
    USART_Cmd(USART3, ENABLE);
}



void USART1_IRQHandler(void)
{
	u8 res;
	 if(USART_GetITStatus(USART1,USART_IT_RXNE))
 {
     res= USART_ReceiveData(USART1); 
     USART_SendData(USART1,res);   
  }
}
 
void USART2_IRQHandler(void)
{
	u8 res;
	 if(USART_GetITStatus(USART2,USART_IT_RXNE))
 {
     res= USART_ReceiveData(USART2); 
     USART_SendData(USART2,res);   
  }
}


void USART3_IRQHandler(void)
{
	u8 res;
	 if(USART_GetITStatus(USART3,USART_IT_RXNE))
 {
     res= USART_ReceiveData(USART3); 
     USART_SendData(USART3,res);   
  }
}

 int main(void)
 {	
	 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
	 
	My_USART1_Init();
	 
	My_USART2_Init();
	 
	My_USART3_Init();
	 

	 
	while(1)
	{
	}
 }