STM32发送数据可以，接受不对？

问题： STM32给PC机发送数据可以，但是接受PC机发送的数据时感觉进不了中断是什么问题？
程序如下：
void uart_init(void)
{
  USART_InitTypeDef USART_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

  GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_USART1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource9,  GPIO_AF_USART1);

  /* Configure USART Tx and Rx as alternate function push-pull */
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
  GPIO_Init(GPIOA, &GPIO_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(USART1, &USART_InitStructure);

  /* NVIC configuration */
  /* Configure the Priority Group to 2 bits */
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

  /* Enable the USARTx Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

  /* Enable USART */
  USART_Cmd(USART1, ENABLE);
  USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
}
int fputc(int ch, FILE *f)
{
        USART_SendData(USART1, (unsigned char) ch);
        while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET);
        return (ch);
}


void USART1_IRQHandler(void)
{
        unsigned char ch;
        if(USART_GetITStatus(USART3, USART_IT_RXNE) != RESET)
         {
           /* Read one byte from the receive data register */
           ch = (USART_ReceiveData(USART3));
       
           printf("in[%c].rn",ch);
         }   
}
int main (void)
{
        uart_init();
        while(1)
        {
                printf("%3x",0x01);
                delay(10000000);
        }

}