西华大学课程设计说明书
基于单片机的小电阻测试仪
摘 要：本文提出了基于单片机的小电阻测量的设计方案，该测试仪通过检测小
电阻两端的电压差，经过高精度的电压放大过后，该电压信号经A/D转换器后将模拟信号转化为数字信号。最后将数字信号送入AT89C51单片机，经过软件滤波和误差处理，在LCD上显示输出相应的电阻值。该仪器的特点是电路设计简单、测温精度高、实用性强。
关键词：测试仪，小电阻，A/D，AT89C51，LCD
Abstract: The text proposed revivification of the resistance of designs, the dosimeters through detecting the electrical resistance equal to voltage with high precision, the enlargement of the signal, the voltage converter by a d the analog signals into digital signal. the figures at89c51 monolithic integrated circuits after the signal is sent, filter software and error, the LCD display the output of resistance. the instrument is a circuit design simple, temperature and practicality. high precision。
Keywords: IC Temperature Sensor, Temperature Measurement, A/ D, AT89C51, LED
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西华大学课程设计说明书
目录
1 前言 ....................................................................................................................................................................... 3 2 整体方案设计 ....................................................................................................................................................... 4
2.1 方案论证 ................................................................................................................................................... 4 2.2 方案比较 ................................................................................................................................................... 5 3 单元模块设计 ....................................................................................................................................................... 6
3.1 电阻检测模块 ........................................................................................................................................... 6
3.2 测量信号转换模块 ........................................................................................................................... 7 3.2.1 测量信号转换模块原理 ................................................................................................................. 7 3.2.2 ICL7135介绍 .............................................................................................................................. 8
4 软件设计 ............................................................................................................................................................. 12 5 系统调试 ............................................................................................................................................................. 13
5.1 硬件调试 ................................................................................................................................................. 13
5.1.1 恒流源调试 ................................................................................................................................... 13 5.1.2 弱信号放大器调试 ....................................................................................................................... 13 5.2 软件调试 ................................................................................................................................................. 14 6 系统功能和指标参数 ......................................................................................................................................... 16 7 总结 ..................................................................................................................................................................... 17
7.1 设计小结 ................................................................................................................................................. 17 7.2 设计收获 ................................................................................................................................................. 17 7.3 设计改进 ................................................................................................................................................. 17 8 参考文献 ............................................................................................................................................................. 18 附录1：电路总图 .................................................................................................................................................. 19 附录2：软件代码 .................................................................................................................................................. 20
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西华大学课程设计说明书
1 前言
在电路测试过程中常常会碰到由于忽略某些小电阻的影响引起实验数据与理论值之间存在较大误差，从而影响测试效果。例如电感器、变压器中往往存在铜电阻，地铁铁轨的电阻；由于其数值较小，一般的指针万用表无法测量出来；通常实验室里会用电桥进行测量，但电桥操作手续较烦，又不能直接读出被测电阻阻值。鉴于此，我们采用了单片机，利用单片机的优势设计了该测量仪。该测量仪可直接从LCD显示屏上读出所测得的电阻值，测量范围为1mΩ～1Ω。该测试仪的测量精度高达±0.1%，并采用四端测量法，电阻值不受引线长短及接触电阻的影响。不仅测量简便，读数直观，且测量精度、分辨率也高于一般电桥。可用于实验室、研究所，尤其适用于工作现场。
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