这个是我学习STM32 USB编程时的总结，其中的部分内容是英文文档直接复制过来的，不影响我的阅读，并且我有时也觉得不能准确表达原文的意思，所以我就没有翻译。-This is a summary of when I learned the STM32 USB programming, elements of which are directly copied from the English document, does not affect my reading, and I sometimes think you can not accurately express the original meaning, so I did not have the translation.