stm32 flash spi

hwh123

u16 SPI_Flash_ReadID(void)
{
u16 Temp = 0;  
SPI_FLASH_CS_LOW;//SPI_FLASH_CS=0;    
SPI2_ReadWriteByte(0x90);//·???????ID?ü??    
SPI2_ReadWriteByte(0x00);    
SPI2_ReadWriteByte(0x00);    
SPI2_ReadWriteByte(0x00);   
// Temp|=SPI2_ReadWriteByte(0x00)<<8;  
// Temp|=SPI2_ReadWriteByte(0x00);
SPI2_ReadWriteByte(0x00);
Temp|=SPI2_ReadWriteByte(0xFF)<<8;  
Temp|=SPI2_ReadWriteByte(0xFF);  
SPI_FLASH_CS_HIGH;//SPI_FLASH_CS=1;    
return Temp;
}
stm32F0 需要多发送一个SPI2_ReadWriteByte(0x00);  才能读取到0xEF14.是什么原因导致的啊，求助啊？？

正点原子

看看波形吧。