Based On USB2.0 Camera-free Drive Firmware Design

With the development the times and advances of informational technology, although traditional cameras has a lot to improve on the transmission data rate as the development of the technology with the bus. But there are still many shortcomings. For a camera, users must install the corresponding driver. When changing the camera, users need change the driver or upgrade the operating system to use normally. There is a great deal of inconvenience for users. This time, more and more cameras appear in people's vision. Compared with the traditional camera, camera-free drive can achieve a compatible operating system, can achieve truly plug and play. For this free driver web camera, this article design a way to drive firmware design, which focuses on the process of their ways and treatment with certain problems.First, this paper introductions the history of the camera-free drive, and introduces the basic knowledge of the firmware design, including the USB2.0 protocol, USB bus transfer characteristics, USB data transfer methods. On the basis of analyzing UVC protocol, the structure of Camera chip-free drive and related registers are described. At the same time, the data structure used in firmware design are described. In chapters of firmware design, for firmware, interrupt message handling mechanism used, facile program structure and streamline processing function designed, treat various command state timely to save the space of the RAM running and reduce costs of design and ensure the normal high-speed operation of equipment. In work of design, it uses compilation tools KeilC51, bases on USB2.0 and UVC agreement, prepares underlying firmware of camera-free drive; With UVC agreement, it designs options of a multi-bandwidth, saves bus resources; Using visual programming tool VC++6.0 (Microsoft Visual C++ 6.0),it prepares the head-tier application software of camera, it achieved the isplaying screen image on the host sides and capturing of video image; It designs a way to download the firmware, designs a new way to save the EEPROM data, facilitates updates in the variables and constants of firmware; Combination with manual controller, It complete the software of messaging mechanism of the firmware in the section of device. Finally, the paper shows part of the process and results of simulation methods.In particular that, this paper focus on the avoid flooding design of camera. This paper shows the way of firmware design of camera-free drive in the market, including the design of USB communication, the design of screen interface and standard control class interface design to support the request.