stm32 SPI 读取和写入的问题

unsigned char SPI1_ReadWrite(unsigned char writedat)

{

/* Loop while DR register in not emplty */

while(SPI_I2S_GetFlagStatus(SPI1,SPI_I2S_FLAG_TXE) == RESET);

/* Send byte through the SPI1 peripheral */

SPI_I2S_SendData(SPI1, writedat);

/* Wait to receive a byte */

while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);

/* Return the byte read from the SPI bus */

return SPI_I2S_ReceiveData(SPI1);

}