USB Interface Development And Function Implement

USB is universal serial bus, which has some advantages. It can automatically identify equipments, automatically install drivers, and support the synchronous and asynchronous transmission modes with different rates, support hot-plug and plug-and-play. Therefore, USB has become the mainstream interface which connects with PC and external communication device. Since these advantages of USB, the application of the USB technology in embedded systems will bring great convenience.This paper introducts the USB basic knowledge and the USB interface structure. The platform is embedded PNX6718 and the operating system is RTK real-time operating system. The C programming is used to design and exploit the USB wireless network card interface. Because each USB device can map out multiple interfaces, the various interface functions are also studied.Not only the software development of the USB wireless network card interface is implemented, but also the automatical installation and loading scheme of the host-side driver is designed. So that the USB interface can be automatically configured and the normal communication also can be realized.Since each interface in USB device is represented by one function, this paper achieves a variety of applications in USB interface.This paper, through abstract control model (ACM) and Ethernet Control Model (ECM) in Communication Device Class (CDC), respectively achieves the virtual modem interface and the virtual Ethernet interface. Then, the scheme which let the device and the host can know each other is designed based on the requirements and notifications. Like the serial port or Ethernet interface, the host can communicate normally.Secondly, the standard data bulk transmission is achieved by the USB interface. The file system module, storage device interface module and storage protocol module are studied in the paper. These modules conbined with USB interface module realize data transmission.