SPI协议程序(SPI Protocol Procedure)

 嘿，我正在将ADS1292用于我自己的项目，而我自己也对SPI协议感到困惑。 
 
 我在互联网上找到了一些代码，我发现它一次发送和接收。 
 
 例如，我想向从设备发送0xFF。 
 
 然后它首先发送数据并等待接收。 
 
 当接收数据时，它发送一个虚拟字节然后接收。 
 
 有人请解释他们为什么这样做？ 
 
uint8_t sEE_ReadByte(void)
{
  return (sEE_SendByte(sEE_DUMMY_BYTE));
}

uint8_t sEE_SendByte(uint8_t byte)
{
  /*!< Loop while DR register in not empty */
  while (SPI_I2S_GetFlagStatus(sEE_SPI, SPI_I2S_FLAG_TXE) == RESET);

  /*!< Send byte through the SPI peripheral */
  SPI_SendData(sEE_SPI, byte);

  /*!< Wait to receive a byte => I do not understand this point*/
  while (SPI_I2S_GetFlagStatus(sEE_SPI, SPI_I2S_FLAG_RXNE) == RESET);

  /*!< Return the byte read from the SPI bus */
  return (uint8_t)SPI_ReceiveData(sEE_SPI);
}

hey i am using ADS1292 for my own project, and myself is confused with SPI protocol.
 
i found some code on the internet and i found it sends and receive at one time.
 
for example, i want to send 0xFF to slave device.
 
then it sends the data first and wait for a receive.
 
And when receiving data, it sends a dummy byte and then receive.
 
Anyone please explain why they do this?
 
uint8_t sEE_ReadByte(void)
{
  return (sEE_SendByte(sEE_DUMMY_BYTE));
}

uint8_t sEE_SendByte(uint8_t byte)
{
  /*!< Loop while DR register in not empty */
  while (SPI_I2S_GetFlagStatus(sEE_SPI, SPI_I2S_FLAG_TXE) == RESET);

  /*!< Send byte through the SPI peripheral */
  SPI_SendData(sEE_SPI, byte);

  /*!< Wait to receive a byte => I do not understand this point*/
  while (SPI_I2S_GetFlagStatus(sEE_SPI, SPI_I2S_FLAG_RXNE) == RESET);

  /*!< Return the byte read from the SPI bus */
  return (uint8_t)SPI_ReceiveData(sEE_SPI);
}

原文：https://stackoverflow.com/questions/36492711