The Research And Application On USB Communication Based On Embedded System

With the development of PC peripherals and digital products, the interface andconnection between any two of them has become a difficult problem. USB has been extensicely adoped as a bus interface technology in PCs today. People hope to use USB devices in some embeded systems, but the kernel of USB topology is PC and USB deviceds cannot use without PC. In order to overcome the llimitation,this article analyzed the structure of USB ptotocol and its commumication process,decided the software and condition that an embedded USB host must prosess,and gave the design outline.With the background of the USB interface design in stored program control switching system forZY-T6. in which the design and implementation of the hardware and software on both host and device sides are demonstrated based usb protocol in details. According to the design request, the USB 1.1 specification isanalyzed in this thesis, in which, put the emphasis on the USB system architecture, data communication model, data packet format, USB standard descriptor. Secondly, on the basis of analyzing the USB device Mass Storage Class speciation, the logical communication model between host and device is established.While designing the hardware, we use AT9140800 (32-bit embeded MCU) as processor, SL811HS(USB host controller) as host controller.By analyzing the architecture of the chips, the founction of the pins and the read/write timing, the USB host controller interface circuit is accomplished. Depending on it, AT9140800 can operate and control SL811HS.Device driver is anobstacle in peripheral development. Thus the kernels in the design of device driver and client application are elaborated after the analysis of the software architecture of USB host and Linux driver model. This article introduces device management in embedded uCLinux system, frame of driver and an approach of adding driver.Moreover, the latest evolution of USB specif-ication and its future application are introduced due to the trend that the technology of computer, communication and consumer electronics is running into amalgamation.The design scheme and theoretical analysis form a base for further research, and provide reference for other embedded USB systems.