介绍了CYPRESS公司生产的主／从双工作模式USB接口芯片SL811HS的性能与内部结构,给出了SL811HS芯片在单片机系统中扩展ＵＳＢ接口的硬件电路,同时给出了该系统的USB驱动程序及实现Ｕ盘读写功能的应用程序。 -CYPRESS company introduced the master/slave USB interface chip dual-mode performance and internal structure SL811HS given SL811HS chip microcomputer system expansion hardware USB interface, and gives the driver the system and achieve USB U disk read and write capabilities of the application.