串口发送数据为什么要用延时呢

小五子一号 · 发表于 2014-5-10 16:40:33

USART_SendData(USART1,kahao[0]);
delay_ms(500);
USART_SendData(USART1,kahao[1]);
delay_ms(500);
   USART_SendData(USART1,kahao[2])
   delay_ms(500);
   USART_SendData(USART1,kahao[3])
   delay_ms(500);

之前没有加延时在串口上总是显示最后   USART_SendData(USART1,kahao[3])的数据，这是什么原因呢？是有发送完成的标志吗

小五子一号 · 发表于 2014-5-10 16:40:34

回复【4楼】jermy_z:
---------------------------------
  找到了谢谢

/**
  * @brief  Checks whether the specified USART flag is set or not.
  * @param  USARTx: Select the USART or the UART peripheral.
  *   This parameter can be one of the following values:
  *   USART1, USART2, USART3, UART4 or UART5.
  * @param  USART_FLAG: specifies the flag to check.
  *   This parameter can be one of the following values:
  *     @arg USART_FLAG_CTS:  CTS Change flag (not available for UART4 and UART5)
  *     @arg USART_FLAG_LBD:  LIN Break detection flag
  *     @arg USART_FLAG_TXE:  Transmit data register empty flag
  *     @arg USART_FLAG_TC:   Transmission Complete flag
  *     @arg USART_FLAG_RXNE: Receive data register not empty flag
  *     @arg USART_FLAG_IDLE: Idle Line detection flag
  *     @arg USART_FLAG_ORE:  OverRun Error flag
  *     @arg USART_FLAG_NE:   Noise Error flag
  *     @arg USART_FLAG_FE:   Framing Error flag
  *     @arg USART_FLAG_PE:

arity Error flag
  * @retval The new state of USART_FLAG (SET or RESET).
  */
FlagStatus USART_GetFlagStatus(USART_TypeDef* USARTx, uint16_t USART_FLAG)
{
  FlagStatus bitstatus = RESET;
  /* Check the parameters */
  assert_param(IS_USART_ALL_PERIPH(USARTx));
  assert_param(IS_USART_FLAG(USART_FLAG));
  /* The CTS flag is not available for UART4 and UART5 */
  if (USART_FLAG == USART_FLAG_CTS)
  {
    assert_param(IS_USART_123_PERIPH(USARTx));
  }

  if ((USARTx->SR & USART_FLAG) != (uint16_t)RESET)
  {
    bitstatus = SET;
  }
  else
  {
    bitstatus = RESET;
  }
  return bitstatus;
}

/**
  * @brief  Clears the USARTx's pending flags.
  * @param  USARTx: Select the USART or the UART peripheral.
  *   This parameter can be one of the following values:
  *   USART1, USART2, USART3, UART4 or UART5.
  * @param  USART_FLAG: specifies the flag to clear.
  *   This parameter can be any combination of the following values:
  *     @arg USART_FLAG_CTS:  CTS Change flag (not available for UART4 and UART5).
  *     @arg USART_FLAG_LBD:  LIN Break detection flag.
  *     @arg USART_FLAG_TC:   Transmission Complete flag.
  *     @arg USART_FLAG_RXNE: Receive data register not empty flag.
  *
  * @note
  *   -

E (Parity error), FE (Framing error), NE (Noise error), ORE (OverRun
  *     error) and IDLE (Idle line detected) flags are cleared by software
  *     sequence: a read operation to USART_SR register (USART_GetFlagStatus())
  *     followed by a read operation to USART_DR register (USART_ReceiveData()).
  *   - RXNE flag can be also cleared by a read to the USART_DR register
  *     (USART_ReceiveData()).
  *   - TC flag can be also cleared by software sequence: a read operation to
  *     USART_SR register (USART_GetFlagStatus()) followed by a write operation
  *     to USART_DR register (USART_SendData()).
  *   - TXE flag is cleared only by a write to the USART_DR register
  *     (USART_SendData()).
  * @retval None
  */
void USART_ClearFlag(USART_TypeDef* USARTx, uint16_t USART_FLAG)
{
  /* Check the parameters */
  assert_param(IS_USART_ALL_PERIPH(USARTx));
  assert_param(IS_USART_CLEAR_FLAG(USART_FLAG));
  /* The CTS flag is not available for UART4 and UART5 */
  if ((USART_FLAG & USART_FLAG_CTS) == USART_FLAG_CTS)
  {
    assert_param(IS_USART_123_PERIPH(USARTx));
  }

  USARTx->SR = (uint16_t)~USART_FLAG;
}

/**
  * @brief  Checks whether the specified USART interrupt has occurred or not.
  * @param  USARTx: Select the USART or the UART peripheral.
  *   This parameter can be one of the following values:
  *   USART1, USART2, USART3, UART4 or UART5.
  * @param  USART_IT: specifies the USART interrupt source to check.
  *   This parameter can be one of the following values:
  *     @arg USART_IT_CTS:  CTS change interrupt (not available for UART4 and UART5)
  *     @arg USART_IT_LBD:  LIN Break detection interrupt
  *     @arg USART_IT_TXE:  Tansmit Data Register empty interrupt
  *     @arg USART_IT_TC:   Transmission complete interrupt
  *     @arg USART_IT_RXNE: Receive Data register not empty interrupt
  *     @arg USART_IT_IDLE: Idle line detection interrupt
  *     @arg USART_IT_ORE:  OverRun Error interrupt
  *     @arg USART_IT_NE:   Noise Error interrupt
  *     @arg USART_IT_FE:   Framing Error interrupt
  *     @arg USART_IT_PE:

arity Error interrupt
  * @retval The new state of USART_IT (SET or RESET).
  */
ITStatus USART_GetITStatus(USART_TypeDef* USARTx, uint16_t USART_IT)
{
  uint32_t bitpos = 0x00, itmask = 0x00, usartreg = 0x00;
  ITStatus bitstatus = RESET;
  /* Check the parameters */
  assert_param(IS_USART_ALL_PERIPH(USARTx));
  assert_param(IS_USART_GET_IT(USART_IT));
  /* The CTS interrupt is not available for UART4 and UART5 */
  if (USART_IT == USART_IT_CTS)
  {
    assert_param(IS_USART_123_PERIPH(USARTx));
  }

  /* Get the USART register index */
  usartreg = (((uint8_t)USART_IT) >> 0x05);
  /* Get the interrupt position */
  itmask = USART_IT & IT_Mask;
  itmask = (uint32_t)0x01 << itmask;

  if (usartreg == 0x01) /* The IT  is in CR1 register */
  {
    itmask &= USARTx->CR1;
  }
  else if (usartreg == 0x02) /* The IT  is in CR2 register */
  {
    itmask &= USARTx->CR2;
  }
  else /* The IT  is in CR3 register */
  {
    itmask &= USARTx->CR3;
  }

  bitpos = USART_IT >> 0x08;
  bitpos = (uint32_t)0x01 << bitpos;
  bitpos &= USARTx->SR;
  if ((itmask != (uint16_t)RESET)&&(bitpos != (uint16_t)RESET))
  {
    bitstatus = SET;
  }
  else
  {
    bitstatus = RESET;
  }

  return bitstatus;
}