详细介绍了SD的接口规范，对于SD卡的开发有很好的指导意义-SD detailed interface specifications for the development of SD cards have a very good guide

SD卡初始化，及读写流程，以及SD卡上文件系统介绍，及51MCU FAT32文件系统程序(The SD card initialization, and the reading and writing process, as well as the file system introduction on the SD card, and the 51MCU FAT32 file system program)