回复【7楼】正点原子:
---------------------------------
原子哥 程序如下：
#if 1
#pragma import(__use_no_semihosting)                   
struct __FILE 
{ 
int handle; 

}; 

FILE __stdout;       
 
_sys_exit(int x) 
{ 
x = x; 
} 
int fputc(int ch, FILE *f)
{      
while((USART2->SR&0X40)==0);
            USART2->DR = (u8) ch;      
return ch;
}
#endif 

void uart_init(u32 bound)
{
        GPIO_InitTypeDef GPIO_InitStructure;
        USART_InitTypeDef USART_InitStructure;
        NVIC_InitTypeDef NVIC_InitStructure;
 
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1|RCC_APB2Periph_GPIOA|RCC_APB2Periph_AFIO, ENABLE);
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
       //USART1_TX   A.2
       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);
   
       //USART1_RX   A.3
       GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
       GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
       GPIO_Init(GPIOA, &GPIO_InitStructure);  


       NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
       NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;
       NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
       NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
       NVIC_Init(&NVIC_InitStructure); //  
   
       USART_InitStructure.USART_BaudRate = bound;
       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);
       USART_Cmd(USART2, ENABLE);                  
}


void USART2_IRQHandler(void)                
{
u8 Res;
if(USART_GetITStatus(USART2, USART_IT_RXNE) != RESET)  // {
Res =USART_ReceiveData(USART2);//(USART1->DR); //
if((USART_RX_STA&0x80)==0)//???????ê??
{
      if(USART_RX_STA&0x40)//????????0x0d
{
if(Res!=0x0a)USART_RX_STA=0;//
                                               else      USART_RX_STA|=0x80; //
}
else //????????0X0D
{
if(Res==0x0d)USART_RX_STA|=0x40;
else
{
USART_RX_BUF[USART_RX_STA&0X3F]=Res ;
USART_RX_STA++;
if(USART_RX_STA>63)USART_RX_STA=0;//   
}  
}
}     
     } 
} 


main里面是这样的
while(1)
{
USART_RX_BUF[0] = 0x67;
for(t=0;t<1;t++)
  {
 USART2->DR=USART_RX_BUF[t];
 while((USART2->SR&0X40)==0);//   }
}