简易自动电阻测试仪学院______自动化及其电气学院_______专业班级__________自动化092____________成员_____余华杰、陈沈杰、温昌省_____指导老师___________项新建_______________2011年12月15日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、10kΩ、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AbstractThedesignonthebasisofthesubjectdemandproducedasimpleautomaticresistancetester,capableofmeasuring100OmegaOmega,1K,10K,10MOmegaOmegafourprofileatdifferentrange,andrealizestheautomaticconversionrangebeforethethird,whileautomaticallydisplayadecimalpointandunit.Basedontheserequirements,afterdiscussion,decidedtousethe555multivibratorcircuitresistanceparametersaretransformedintofrequency,frequencyofFSCMiseasilyhandledthedigitalquantity,ahighmeasuringprecision,ontheotherhand,soeasytorealizeautomationofinstrumentation,andchipmicroprocessorapplicationsystemhashigherreliability.Throughtheinputofsingle-chipAT89C51controlrelaytocontrolthetestedRCoscillatingcircuitfrequencyautomaticselection,input/outputcontrolusingthekeyboardinputcontrolcircuit,LCD12864displaysystemandanalarmcontrolcircuit,canachieveaverygoodall.Microcontrollerhavingprogrammable,hardwaredescriptionofthefunctioncanbecompletelyrealizedinsoftware,ontheotherhand,soeasytorealizeautomationofinstrumentation,shortdesigntime,lowcost,highreliability.Keywords:singlechipAT89C51555multivibratorcircuitrelayautomaticrangeswitching目录一、选题背景..................................................................................-1-二、方案论证..................................................................................-1-2.1方案论证与比较........................................................................-1-2.2设计思路..............................................................................-2-2.2.1总体方案组成和说明..................................................................-2-2.2.2组成部分及说明......................................................................-2-三、设计实现..................................................................................-5-3.1测量电路设计.........................................................................-5-3.2通道选择电路设计.....................................................................-5-3.3控制电路设计.........................................................................-6-3.4显示电路.............................................................................-8-3.5软件设计.............................................................................-8-四、测试及结果分析............................................................................-9-4.1测试方法及使用的仪器.................................................................-9-4.2指标测试和测试结果......................................................
