usb协议层知识，能够帮助你更好理解usb规范-This chapter presents a bottom-up view of the USB protocol, starting with field and packet definitions

对串行总线及其协议作了总结，然后在此基础上对USB协议进行了深 入的分析，并针对协议的要求，对字段、包、数据传输事务、数据切换同步以及错误 检测等的实现进行了详细设计 -On the serial bus and protocol are summarized, and then on the basis of the USB protocol conducted in-depth analysis, and the requirement for agreement on the

该文档里面详细说明了USB设备标准请求的格式及各类请求的编号,同时详细解释了所有的标准请求,还包含了常用的描述符的格式及各字段详细说明,额外增加了HID描述符等(The document details the format of the USB device standard request and the number of various requests, and explains all the standard requests in detail. It also includes

51单片机通过CH372（内置固件模式程序）传输数据给PC机(USB is the English acronym for Universal Serial BUS, Chinese meaning is "Universal Serial Bus." It is not a new bus standard, but in the PC field of application interface technology.)