开机检测SD卡是否存在，然后初始化FAT文件系统，在这之后开始查找根目录下的PICTURE文件夹，如果找到则显示该文件夹下面的图片，循环显示，通过按KEY0和KEY1可以快速浏览下一张和上一张。如果未找到图片文件夹/图片，则提示错误。同样我们也是用LED0来指示程序正在运行。-Boot to detect the existence of SD card and then initialize the FAT file system, after it begins searching for the root directory of the PICTURE folder, if find the image below shows this folder, cycle, by pressing the KEY0 and KEY1 can quickly browse the next and on one piece. If the pictures folder/picture is not found, then the errors. We also use same LED0 to indicate that the application is running.