基于USB2.0的图像采集卡的设计与实现

【作者】 成志强；

【导师】 叶玉堂；

【作者基本信息】 电子科技大学 ， 光学工程， 2007， 硕士

【摘要】 随着多媒体技术发展，数字图像的采集和处理已经成为许多应用系统的核心和基础。本文阐述了基于USB(Universal Serial Bus)接口的图像采集卡的设计、制作及软件的编写过程。本卡将用于在基于红外热图像分析的电路板检测系统中，采集红外热像仪输出的图像数据。现在市面上的数字图像采集卡价格昂贵，且大多使用PCI(Peripheral Component Interconnect)接口，使用不方便。本文研制的图像采集卡使用了较新且较普遍的USB接口，具有极强的易用性和便携性，且能够实现与红外热像仪的良好匹配。将USB接口的图像采集卡与红外热像仪集成为一体在国内还未见报道。论文从图像采集的意义和本课题的应用背景出发，阐述了图像采集系统的组成，分析了各部分的性能需要，比较了现有的计算机总线技术及可编程逻辑技术，提出了一种基于计算机USB2.0总线接口，应用FPGA进行逻辑控制的方案。USB2.0接口有很多突出的优点：即插即用，连接方便，传输速度快，兼容性强。它已经在诸多设备中得到了非常广泛的应用。FPGA的使用大大简化了逻辑控制电路的设计，并且由于体积小、速度快及可编程性强等诸多优点，它已经渐渐成为数字逻辑设计的首选。论文从硬件系统设计和软件设计两大方面详细阐述了其开发方法和实现过程。在硬件电路设计方面，本论文分模块介绍了各部分电路的时钟电源设计、接口设计，说明了FPGA(Field Programmable Gate Array)的启动配置模式和重要信号引脚的连接设计，分析并选择了Slave FIFO模式为USB芯片和FPGA之间的接口模式。系统软件设计分为三个大部分进行：固件程序、驱动程序和上层应用程序。固件程序部分重点介绍了软件流程和USB芯片的中断系统。Windows下WDM(Win32 Driver Model)驱动程序是功能的提供者，操作系统才是过程的管理者。因此驱动程序部分在介绍了WDM的层次结构基础上，分析了驱动程序被调用流程，及关键函数的设计方法。应用设计主要关注了图像数据的格式转换及显示方式。经过设计、制作和调试，本图像采集卡已经开发完成，完全满足预定目标。该卡的研制成功，为基于红外图像分析的电路板检测系统的小型化、实用化奠定了坚实的技术基础。更多还原

【Abstract】 With the development of multimedia technology, the digital image acquisition and processing have become the core and foundation of a lot of application system. In this paper, the design, fabrication and software programming of an image acquisition card which is based on USB2.0 interface are presented. This card will be used for acquiring image data exported by infrared camera in PCB diagnosis system which is based on thermal images processing.The commercially available digital image acquisition cards are expensive, and usually connected through PCI interface, which is not convenient to use. The card we develop can be connected through USB interface providing great convenience to use and take around, and can make a good match with our infrared camera. Interiorly it hasn’t been reported to integrate image acquisition card which is based on USB interface with infrared camera.In this dissertation, beginning from the significance of image acquisition and the application background, the modules of the image acquisition system are presented, the capability requiring of every module is analyzed, the existing computer bus technology and programmable logic technology are compared, a scheme is brought forward which uses USB2.0 as the bus interface and uses FPGA to control the logic.The USB2.0 interface has a lot of advantages, including Plug and Play, connecting convenience, high-speed transportation and strong compatibility. It has been widely used in many devices. By using FPGA, the design of logic-control circuit has been significantly simplified, and because of the advantages such as small size, high speed and programmability, FPGA has become the top option in digital logic design.In this dissertation, the method and implementation process of both hardware system and software design are presented. In aspect of hardware circuit, the design of the clock, power and interface is introduced; the start-up configuration modes and the significant signal pins connections are explained; the Slave FIFO interface mode between USB chip and FPGA chip is chosen after analyzing. System software design is composed of three parts: firmware, driver and application. In the part of firmware, software flow and the interrupt system are put emphasis on. Under Windows, the WDM (Win32 Driver Model) driver is the provider of functions, and the operating system is in charge of the process. So after the hierarchy of WDM is introduced, the sequence of function calls and the design method of key functions are analyzed. In Application design, the format conversion and the display usage are focused on.After design, fabrication and debugging, the image acquisition card has been completed, and the anticipated goal has been achieved. It has provided a firm technical basis for miniaturization and practicality of the PCB diagnosis system which is based on thermal image processing.更多还原