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和PDIUSBD12完成U盘的开发。主要内容涉及USB接口开发，重点介绍项目调试方法和步骤。
(In this paper, ARM7-based embedded systems development of USB interface on the details of projects completed arm7 and U disk PDIUSBD12 development. USB interface related to the main content development, the project focuses on testing methods and steps.)