最近编写了STM32F407 USART1的串口，在进入USART1接收中断的时候没有反应。后用keil调试的时候发现，卡在了  B  这个位置，入下图所示：
串口1的配置代码如下：
void uart1_init()
{
        GPIO_InitTypeDef GPIO_InitStructure;
        USART_InitTypeDef USART_InitStructure;
        NVIC_InitTypeDef NVIC_InitStructure_USART1;
       
        RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE); //ê1ÄüGPIOAê±Öó
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);//ê1ÄüUSART1ê±Öó
       
        GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1); //GPIOA9¸′óÃÎaUSART1
        GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1); //GPIOA10¸′óÃÎaUSART1
       
        //USART1¶Ë¿úÅäÖÃ
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10; //GPIOA9óëGPIOA10
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;//¸′óÃ1|Äü
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;        //Ëù¶è50MHz
        GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //íÆíì¸′óÃêä3ö
        GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; //éÏà-
        GPIO_Init(GPIOA,&GPIO_InitStructure); //3õê¼»ˉPA9￡&#172A10
       
        //USART1 3õê¼»ˉéèÖÃ
        USART_InitStructure.USART_BaudRate = 115200;//2¨ìØÂêéèÖÃ
        USART_InitStructure.USART_WordLength = USART_WordLength_8b;//×Ö3¤Îa8λêy¾Y¸ñê½
        USART_InitStructure.USART_StopBits = USART_StopBits_1;//ò»¸öí￡Ö1λ
        USART_InitStructure.USART_Parity = USART_Parity_No;//ÎTÆæżD￡Ñéλ
        USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//ÎTó2¼têy¾Yá÷¿ØÖÆ
        USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;        //êÕ·￠Ä￡ê½
  USART_Init(USART1, &USART_InitStructure); //3õê¼»ˉ′®¿ú1
       
        USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);//¿aÆôÏà1ØÖD¶Ï
        USART_Cmd(USART1, ENABLE);  //ê1Äü′®¿ú1       
       
        while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) != SET)
    ;
       
        NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
        //Usart1 NVIC ÅäÖÃ
  NVIC_InitStructure_USART1.NVIC_IRQChannel = USART1_IRQn;//′®¿ú1ÖD¶Ïí¨μà
        NVIC_InitStructure_USART1.NVIC_IRQChannelPreemptionPriority=0x03;//ÇàÕ¼óÅÏ輶2
        NVIC_InitStructure_USART1.NVIC_IRQChannelSubPriority =0x02;                //×óóÅÏ輶3
        NVIC_InitStructure_USART1.NVIC_IRQChannelCmd = ENABLE;                        //IRQí¨μàê1Äü
        NVIC_Init(&NVIC_InitStructure_USART1);        //¸ù¾YÖ¸¶¨μÄ2Îêy3õê¼»ˉVIC¼Ä′æÆ÷
}

void USART1_IRQHandler(void)                        //′®¿ú1ÖD¶Ï·tÎñ3ìDò
{
        u8 Res;

        if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)  //½óêÕÖD¶Ï
        {
                Res =USART_ReceiveData(USART1);//(USART1->DR);        //¶á衽óêÕμ½μÄêy¾Y
                USART_SendData(USART1,Res);
  }
}



除了串口1之外，我也配置了串口2和串口3，代码如下：
void
USART2_Gpio_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

  GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_2 | GPIO_Pin_3;
  GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2); // tx
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2); // rx
}

void
USART3_Gpio_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);

  GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_10 | GPIO_Pin_11;
  GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

  GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_USART3); // tx
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource11, GPIO_AF_USART3); // rx
}

/*
* USART2 is used for receiving commands from PC and
* printing debug information to PC
*/
void
USART2_Config(void)
{
  USART2_Gpio_Config();

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
  USART_InitTypeDef USART_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);

  USART_Cmd(USART2, ENABLE);

  while (USART_GetFlagStatus(USART2, USART_FLAG_TXE) != SET)
    ;
}

/*
* USART3 is used for communicating with the DJI flight controller
* The Baud rate needs to match the Baud rate used by the flight controller
*/
void
USART3_Config(void)
{
  USART3_Gpio_Config();

  USART_InitTypeDef USART_InitStructure;
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);

  USART_InitStructure.USART_BaudRate   = 230400;
  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);

  USART_Cmd(USART3, ENABLE);
  while (USART_GetFlagStatus(USART3, USART_FLAG_TXE) != SET)
    ;
}

void
USARTxNVIC_Config()
{
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

  NVIC_InitTypeDef NVIC_InitStructure_USART3;
  NVIC_InitStructure_USART3.NVIC_IRQChannelPreemptionPriority = 0x04;
  NVIC_InitStructure_USART3.NVIC_IRQChannelSubPriority        = 0x03;
  NVIC_InitStructure_USART3.NVIC_IRQChannel                   = USART3_IRQn;
  NVIC_InitStructure_USART3.NVIC_IRQChannelCmd                = ENABLE;
  NVIC_Init(&NVIC_InitStructure_USART3);

  NVIC_InitTypeDef NVIC_InitStructure_USART2;
  NVIC_InitStructure_USART2.NVIC_IRQChannelPreemptionPriority = 0x03;
  NVIC_InitStructure_USART2.NVIC_IRQChannelSubPriority        = 0x02;
  NVIC_InitStructure_USART2.NVIC_IRQChannel                   = USART2_IRQn;
  NVIC_InitStructure_USART2.NVIC_IRQChannelCmd                = ENABLE;
  NVIC_Init(&NVIC_InitStructure_USART2);
       
                //Usart1 NVIC ÅäÖÃ
        NVIC_InitTypeDef NVIC_InitStructure_USART1;
  NVIC_InitStructure_USART1.NVIC_IRQChannel = USART1_IRQn;//′®¿ú1ÖD¶Ïí¨μà
        NVIC_InitStructure_USART1.NVIC_IRQChannelPreemptionPriority=0x03;//ÇàÕ¼óÅÏ輶2
        NVIC_InitStructure_USART1.NVIC_IRQChannelSubPriority =0x02;                //×óóÅÏ輶3
        NVIC_InitStructure_USART1.NVIC_IRQChannelCmd = ENABLE;                        //IRQí¨μàê1Äü
        NVIC_Init(&NVIC_InitStructure_USART1);        //¸ù¾YÖ¸¶¨μÄ2Îêy3õê¼»ˉVIC¼Ä′æÆ÷

}



每次执行代码都无法进入串口1的接收中断，希望有大神可以帮我解答一下！！！
十分感谢！！！