【摘要】 由于即插即用的USB设备给工业仪表的使用带来很大便利,文中介绍了一种具有USB接口的接地电阻测量仪的设计方案。在分析接地电阻测量仪的设计原理基础上,提出采用镜像电流源的形式设计了恒流源电路,采用双积分式A/D转换器进行接地数据采集并给出了具体的硬件原理图。针对USB传输接口的标准和USB1.1协议。给出了USB硬件接口设计和端口的软件控制方法。接地电阻系统具有数据传输速率高、使用方便的特点,满足了工程的实际需要。更多还原

【Abstract】 Introduced a kind of ground resistance measurement instrument with USB interface.Bastd on the analysis of ground resistance measurement device’s design principle, carries out the method of designing constant-current source circuit as measurement circuit and using dual integration A/D convert as data collection.Aiming at USB transfer interface standard and USB 1 1 protocol, it also gives the method of USB interface circus design and program.The system meets the engineering practical requirement with character of highspeed in data-transfer and convenience to use.更多还原