AT45DB161D_Flash 读取不了ID号？？

有人用过AT45DB161D的Flash片子没？   我读取的ID号是全FF  正确的应该是0x1F260000  求助啊   纠结好久了~~~
FlashID = SPI_FLASH_ReadID();
u32 SPI_FLASH_ReadID(void)
{
  u32 Temp = 0, Temp0 = 0, Temp1 = 0, Temp2 = 0, Temp3 = 0;

  /* Select the FLASH: Chip Select low */
  SPI_FLASH_CS_LOW();

  /* Send "RDID " instruction */
  SPI_FLASH_SendByte(0x9F);                //Manufacturer and Device Read   Datasheet P44

  /* Read a byte from the FLASH */
  Temp0 = SPI_FLASH_SendByte(Dummy_Byte);
        //printf("Temp0 =0x%X\n",Temp0);

  /* Read a byte from the FLASH */
  Temp1 = SPI_FLASH_SendByte(Dummy_Byte);
//        printf("Temp1 =0x%X\n",Temp1);
  /* Read a byte from the FLASH */
  Temp2 = SPI_FLASH_SendByte(Dummy_Byte);
//        printf("Temp2 =0x%X\n",Temp2);
  /* Read a byte from the FLASH */
  Temp3 = SPI_FLASH_SendByte(Dummy_Byte);
// printf("Temp3 =0x%X\n",Temp3);
  /* Deselect the FLASH: Chip Select high */
  SPI_FLASH_CS_HIGH();

  Temp = (Temp0 << 24) | (Temp1 << 16) | (Temp2<<8) | Temp3;

  return Temp;
}