在对USART初始化后，每次上电发送的第一个数据总没有，后续的数据全部正常，是否还需要对哪个标志位进行配置呢？
初始化代码  
 /* USART5 mode config */
 USART_InitStructure.USART_BaudRate = 9600;  //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(UART5, &USART_InitStructure); 
 USART_Cmd(UART5, ENABLE);
发送 代码    
USART_SendData(UART5 , shuju);
      while( USART_GetFlagStatus(UART5, USART_FLAG_TC) == RESET );