usb 枚举过程实例，是翻译的老外的资料，讲的非常简单易懂-usb enumeration process instances, the information is translated foreigners, in a very simple and easy to understand

Ｃ语言的数据类型、运算符、表达式相关的意义，适用条件，相当于简单的教科书-C language data types, operators, expressions of related meaning, the applicable conditions, equivalent to a simple textbook