车载测试数据传输系统免驱USB主从机设计

摘要

基于USB的车载测试数据传输系统原有设计方案存在着跨操作系统平台应用不便、无法实现与计算机及外部USB存储设备的双向通信、驱动安装偶发性故障等问题;针对上述问题,提出了一种车载测试数据传输系统免驱USB主从机设计方法;该方法以USB接口芯片CH378为核心进行USB主从机传输系统设计,通过专门的USB主从机状态电路实现USB主从模式的自动切换,通过嵌套USB2.0协议、USB Mass Storage协议、FAT32文件系统协议实现免驱动获取测试数据的功能;重点介绍了新型车载测试数据传输系统的总体设计方案、CH378硬件接口电路、USB主从机状态电路以及USB从机模式下免驱功能的实现要点;通过实验验证,该设计可以实现车载测试数据传输系统免驱USB主从机功能,给车载测试数据传输系统的应用与维护带来了便利.%There have some application problems about traditional design of vehicle test data transmission system,such as inconvenient for cross application operating system platform,unable to realize two-way communication with the computer and the external USB storage device,sporadic failure of driver installation,and so on.Aiming at these issues,a free drive design of USB Host & Device for vehicle test da ta transmission system is proposed.The design uses USB interface chip CH378 as the core of transmission system,and realizes automatic switching between USB host and USB device by USB Host & Device state circuit.Moreover,it achieves free drive design through the nested USB2.0 protocol,the USB Mass Storage protocol and FAT32 file system protocol.Some aspects are discussed emphatically,such as the overall design plan,CH378 hardware interface circuit,USB Host & Device state circuit and free drive functions.Through experimental verifi cation,the design can realize free drive of USB Host & Device and provide convenience to the application and maintenance of vehicle test data transmission system.