void USART_SendData(USART_TypeDef* USARTx, u16 Data)
{
  /* Check the parameters */
  assert_param(IS_USART_ALL_PERIPH(USARTx));
  assert_param(IS_USART_DATA(Data));

  /* Transmit Data */
  USARTx->DR = (Data & (u16)0x01FF);
}

/*******************************************************************************
* Function Name  : USART_ReceiveData
* Description    : Returns the most recent received data by the USARTx peripheral.
* Input          : - USARTx: Select the USART or the UART peripheral.
*                    This parameter can be one of the following values:
*                     - USART1, USART2, USART3, UART4 or UART5.
* Output         : None
* Return         : The received data.
*******************************************************************************/
u16 USART_ReceiveData(USART_TypeDef* USARTx)
{
  /* Check the parameters */
  assert_param(IS_USART_ALL_PERIPH(USARTx));

  /* Receive Data */
  return (u16)(USARTx->DR & (u16)0x01FF);
}
这是代码