微电阻测量系统
学生：XX 指导老师：XX
内容摘要：本设计根据题目要求制作一台简易自动电阻测试仪，能够测量100Ω、1kΩ、10k
Ω、10MΩ四档不同的量程，并实现其中前三档的自动量程转换功能，同时自动显示小数点和单位。基于这些要求，经过讨论，决定利用555多谐振荡电路将电阻参数转化为频率，频率f是单片机很容易处理的数字量，一方面测量精度高，另一方面便于使仪表实现自动化，而且单片机构成的应用系统有较大的可靠性。通过输入单片机AT89C51控制继电器控制被测RC振荡电路频率的自动选择，输入输出控制采用键盘输入控制电路、LCD12864显示系统和报警控制电路组成，能很好的实现各个要求。单片机具有可编程性，硬件的功能描述可完全在软件上实现，另一方面便于使仪表实现自动化，设计时间短，成本低，可靠性高。
关键字：AT89C51单片机 555多谐振荡电路 继电器 自动量程转换
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The resistance measurement system
Abstract：The design on the basis of the subject demand produced a simple automatic
resistance tester, capable of measuring 100 Omega Omega, 1K, 10K, 10M Omega Omega four profile at different range, and realizes the automatic conversion range before the third, while automatically display a decimal point and unit. Based on these requirements, after discussion, decided to use the 555 multivibrator circuit resistance parameters are transformed into frequency, frequency of F SCM is easily handled the digital quantity, a high measuring precision, on the other hand, so easy to realize automation of instrumentation, and chip microprocessor application system has higher reliability. Through the input of single-chip AT89C51 control relay to control the tested RC oscillating circuit frequency automatic selection, input / output control using the keyboard input control circuit, LCD12864 display system and an alarm control circuit, can achieve a very good all. Microcontroller having programmable, hardware description of the function can be completely realized in software, on the other hand, so easy to realize automation of instrumentation, short design time, low cost, high reliability.
Keywords: single chip AT89C51 555 multivibrator circuit relay automatic
range switching
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目 录
前言................................................................................................................................. 1 1 基本原理 .................................................................................................................... 2 2 设计思路 .................................................................................................................... 3
2.1 总体方案组成和说明 ......................................................................................... 3 2.2 组成部分及说明 ................................................................................................ 3 3 设计实现 .................................................................................................................... 6
3.1 测量电路设计 ................................................................................................... 6 3.2 通道选择电路设计 .............................................................................................. 6 3.3 控制电路设计 ................................................................................................... 7 4 测试及结果分析 ....................................................................................................... 10
4.1 测试方法及使用的仪器 ................................................................................... 10 5 结束语 .................................................................................................................... 11 参考文献 ....................................................................................................................... 13 附录............................................................................................................................... 13
附录1: 主要元器件清单 .......................................................................................... 13 附录2：程序清单.................................................................................................... 14 附录3：实物图 ....................................................................................................... 24
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