说明：  本文介绍了在基于ARM7的嵌入式系统上开发 USB接口的详细内容。项目使用 ARM7 （MCU处理器）和PDIUSBD12（USB芯片）完成了U 盘的开发。主要内容涉及 USB 接口 的 U 盘开发过程中所涉及的技术内容；重点介绍项目调试方法与步骤；并附上了自己在开 发此项目过程中的一些心得与体会
(In this paper, ARM7-based embedded systems developed on the details of USB interface. Projects using ARM7 (MCU processor) and PDIUSBD12 (USB chip) completed the development of U disk. Mainly related to the U disk USB interface development process involved in the technical content focuses on project debugging methods and steps with its own process in the development of this project some of the ideas and experience)