GPIO_InitTypeDef GPIO_InitStructure;
 USART_InitTypeDef USART_InitStructure;
 
 GPIO_PinRemapConfig(GPIO_Remap_USART2,ENABLE);
 /* Enable USART2 clock  */
   RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
 /* USART2 remap to PD5 PD6 */
 /* Configure the GPIO ports( USART2 Transmit and Receive Lines) */
   /* Configure the USART2_Tx as Alternate function Push-Pull */
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
   GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_5;
   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   GPIO_Init(GPIOD, &GPIO_InitStructure);
   /* Configure the USART2_Rx as input floating */
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 ;
   GPIO_Init(GPIOD, &GPIO_InitStructure);

   /* USART2 configuration ------------------------------------------------------*/
   /* USART2 configured as follow:
        - BaudRate = 4800 baud 
        - Word Length = 8 Bits
        - One Stop Bit
        - No parity
        - Hardware flow control disabled (RTS and CTS signals)
        - Receive and transmit enabled
   */
   USART_InitStructure.USART_BaudRate = 4800;
   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;
   /* Configure the USART2 */
   USART_Init(USART2, &USART_InitStructure);
 
 /* Configure the USART2 RX interrupt */
 USART_ITConfig(USART2,USART_IT_RXNE,ENABLE);
   /* Enable the USART2 */
   USART_Cmd(USART2, ENABLE);
 
 
 收发均不工作,没有Remap试过TX可以,RX没试(电路板不好试).
 

你有没有打开 AFIO 的时钟呢

正是,回头去看别人的例程发现了这个问题.谢谢!