请教：USART3能接收到数据，不能发送数据，是什么原因？

只看该作者 · 2009-11-15 22:40

我的配置程序如下：
void UART_Config(void)
{
USART_InitTypeDef USART_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
/* Configure USART1 Tx(PA.09) as alternate function open-drain */
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Pin = RS485_TXD1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Configure USART3 Tx(PC.10) as alternate function open-drain */
GPIO_InitStructure.GPIO_Pin = RS232_TXD4;
  GPIO_Init(GPIOC, &GPIO_InitStructure);
/* Configure USART3 Tx(PB.10) as alternate function open-drain */
GPIO_InitStructure.GPIO_Pin = ALARM_TXD3;
  GPIO_Init(GPIOB, &GPIO_InitStructure);
/* Configure USART1_Rx(PA.10) as input floating */
  GPIO_InitStructure.GPIO_Pin = RS485_RXD1;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Configure USART1_Rx(PC.11) as input floating */
GPIO_InitStructure.GPIO_Pin = RS232_RXD4;
  GPIO_Init(GPIOC, &GPIO_InitStructure);
/* Configure USART1_Rx(PB.11) as input floating */
GPIO_InitStructure.GPIO_Pin = ALARM_RXD3;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

/* USARTx configuration ------------------------------------------------------*/
  /* USARTx configured as follow:
      - BaudRate = 115200 baud
      - Word Length = 8 Bits
      - One Stop Bit
      - No parity
      - Hardware flow control disabled (RTS and CTS signals)
      - Receive and transmit enabled
  */

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;
/* Configure the USARTx */
  USART_Init(UART4, &USART_InitStructure);
  /* Enable USART1 Receive and Transmit interrupts */
  USART_ITConfig(UART4, USART_IT_RXNE, ENABLE);
  /* Enable the USARTx */
  USART_Cmd(UART4, ENABLE);
/* Configure the USARTx */
  USART_Init(USART3, &USART_InitStructure);
  /* Enable USART1 Receive and Transmit interrupts */
  USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
  /* Enable the USARTx */
  USART_Cmd(USART3, ENABLE);

}
UART4能收能接，USART3却是不能发送数据，只能接受

只看该作者 · 2009-11-16 08:54

把你发送数据的代码贴出来看看[url][/url]

只看该作者 · 2009-11-16 09:14

void UART3_SendByte(unsigned char Data)
{

/* Loop until USART1 DR register is empty */
while(USART_GetFlagStatus(USART3, USART_FLAG_TXE) == RESET)
{
}

USART_SendData(USART3, Data);

}