附上网上找的usb资料链接，讲的很全面也和通俗易懂！墙裂推荐！
https://www.crifan.com/files/doc/docbook/usb_disk_driver/release/htmls/index.html
点击打开链接
https://www.crifan.com/files/doc/docbook/usb_basic/release/html/usb_basic.html
