STM32 接收中断可以接收数据，但进入中断后RXNE标识位是0

void RCC_Configuration(void)

{

  /* RCC system reset(for debug purpose) */

  RCC_DeInit();                                                                                         //将外设RCC寄存器重设为缺省值



  /* Enable HSE */

  RCC_HSEConfig(RCC_HSE_ON);                                                        //设置外部高速晶振（HSE ） 



  /* Wait till HSE is ready */

  HSEStartUpStatus = RCC_WaitForHSEStartUp();                        //等待HSE 起振



  if(HSEStartUpStatus == SUCCESS)

  {

    /* Enable Prefetch Buffer */

    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);



    /* Flash 2 wait state */

    FLASH_SetLatency(FLASH_Latency_2);    

        /* HCLK = SYSCLK */

    RCC_HCLKConfig(RCC_SYSCLK_Div1);                                         //设置AHB时钟（HCLK）

  

    /* PCLK2 = HCLK/2 */

    RCC_PCLK2Config(RCC_HCLK_Div2);                                         //设置高速AHB时钟（PCLK2） 



    /* PCLK1 = HCLK/2 */

    RCC_PCLK1Config(RCC_HCLK_Div2);                                                //设置低速AHB时钟（PCLK1） 

 

   /* PLLCLK = 8MHz * 9 = 72 MHz */

    RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_6);         //设置PLL 时钟源及倍频系数



    /* Enable PLL */ 

    RCC_PLLCmd(ENABLE);                                                                        //使能PLL



    /* Wait till PLL is ready */

    while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)

    {

    }



    /* Select PLL as system clock source */

    RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);



    /* Wait till PLL is used as system clock source */

    while(RCC_GetSYSCLKSource() != 0x08)

    {

    }

  }



  /* Enable peripheral clocks --------------------------------------------------*/

  /* GPIOA,GPIOB,GPIOC,SPI1 and USART1 clock enable */

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_GPIOC |

                         RCC_APB2Periph_USART1 |RCC_APB2Periph_SPI1, ENABLE);



  /* USART2,USART3,UART4 Periph clock enable */

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2 | RCC_APB1Periph_USART3 |

                                                   RCC_APB1Periph_UART4, ENABLE);                                //USART2,USART3,UART4在APB1总线上

}

        GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_10;

        GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_IN_FLOATING;

        GPIO_Init(GPIOA, &GPIO_InitStructure);

        

        /* Configure USART1 Tx (PA9) as alternate function push-pull                */

        GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_9;

        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

        GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF_PP;

        GPIO_Init(GPIOA, &GPIO_InitStructure);

  NVIC_InitTypeDef   NVIC_InitStructure;

  /* Configure one bit for preemption priority */

  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);



  /* Enable the SPI1 Interrupt */

//  NVIC_InitStructure.NVIC_IRQChannel = SPI1_IRQChannel ;

//  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;

//  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

//  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

//  NVIC_Init(&NVIC_InitStructure);



  NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQChannel;                                         //选择串口1中断

  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;                                         //抢占式中断优先级设置为0

  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;                                                 //响应式中断优先级设置为0

  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                                                         //使能中断          

  NVIC_Init(&NVIC_InitStructure);

        USART_InitStructure.USART_BaudRate = 1200;

        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_ClockInitStructure.USART_Clock = USART_Clock_Disable;

        USART_ClockInitStructure.USART_CPOL = USART_CPOL_Low;

        USART_ClockInitStructure.USART_CPHA = USART_CPHA_2Edge;

        USART_ClockInitStructure.USART_LastBit = USART_LastBit_Disable;

        USART_Init(USART1, &USART_InitStructure);

        USART_ClockInit(USART1, &USART_ClockInitStructure);

        USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);

        USART_Cmd(USART1, ENABLE);