基于C8051F340的SD卡读写，移植了FATFS的文件系统。可以实现文件的读写。本人验证通过，可对有文件系统的SD进行读写。-Based on C8051F340' s SD card reader, transplant FATFS the file system. File read and write can be achieved. I verified by, a file system can read and write SD.