Design Of The Embedded USB Host Interface

USB interface has the characteristics of convenient-use,high-speed and supporting hot-plugging in PC. The development of USB devices is difficult because of the complex protocol. That how to apply USB to embedded system and realize communication of point-to-point become hot in the field of USB research now.The simplified USB system includes two subsystems: USB host system and USB slave system. The development of USB slave system and technology of USB host system based on PC have been already mature, however, implement of USB host system based on embedded system encountered many difficulties because of limited resources compared with the abundant resources on the PC. According to the design requestments, firstly, the USB1.1 specification is analyzed, in which, the USB system architecture,data communication model,data packet format and USB standard descriptor have become the key point.Secondly, the logical communication model between host and device is established on the basis of analyzing the USB device Mass Storage Class specification. Thirdly, that the Embedded USB Host system selects W78E58B and SL811HS to act as the CPU and USB Host interface chip separately constructs the Host system.The project of the system possesses the virtues of low costs, low power and high speed, etc. And from the point of the software, the system integrates USB Driver, USB host controller driver, and user software.The paper makes analysises and conclusions on the design of the embeded Host system.According to the method introduced in this paper, we established the Embedded USB Host system successfully ,which has the general significance to the development of embeded Host system and the usage of USB devided from PC. The prospects of the development in USB protocol has been made in the end of the article.