毕业论文--基于单片机的电子秤设计

基于单片机系统的电子秤设计1基于单片机的电子秤设计摘要:本设计以51系列单片机STC89C52RC为控制核心，实现电子秤的基本控制功能。在设计系统时，为了更好地采用模块化设计法，分步的设计各个单元功能模块，系统的硬件部分可以分为最小系统、数据采集、人机交互界面(键盘以及显示)和系统电源四大部分。最小系统部分为STC89C52RC系统；数据采集部分由压力传感器、信号的前级处理和A/D转换部分组成，包括运算放大器OP07和A/D转换器ADC0809；人机交互界面为键盘输入和数码管显示，主要使用5X5键盘、CH423数码管控制芯片及13位数码管显示，可以方便的输入数据并直观的显示重量、单价和总价。系统电源是以LM7805、LM7812为核心设计电路以提供系统正常工作电源。软件部分应用单片机C51语言进行编程，实现了该设计的基本控制功能。该电子秤可以实现基本的称重功能（称重范围为0～10Kg，重量误差不大于±0.02Kg）,重量、单价、总价的计量可以精确到两位小数，键盘设置有数字键（‘0’～‘9’、‘.’）、储存键、单价1～单价8调用单价键、清除键、去皮键等；发挥部分有8种不同物品的单价记忆功能、99种消费商品价格累计功能、；待发挥部分为讲电子秤与打印机连接，能打印消费记录（小票），超量程和欠量程的报警功能。本系统结构简单，使用方便，功能齐全，精度高，具有一定的开发价值。关键词：单片机采样电路A/D转换器CH423数码管驱动芯片数码管显示工作电源基于单片机系统的电子秤设计2thedesignofelectronicscalesbasedonSingle-chipMicrocomputerABSTRACT:Thedesignforthecontrolof51computersSTC89C52RCthecore,toachievethebasiccontrolfunctionsofelectronicscales.Indesigningthesystem,inordertobettermodulardesign,thedesignofeachunitstepfunctionmodules,thesystemcanbedividedintotheminimumhardwaresystem,dataacquisition,man-machineinterface(keypadanddisplay)andthesystempower4most.MinimumsystempartlySTC89C52RCsystem;datacollectioninpartbythepressuresensor,signalprocessingandthefirstclassA/Dconversioncomponents,includingtheoperationalamplifierOP07andtheA/DconverterADC0809;man-machineinterfaceforthekeyboardanddigitaldisplayThemainuseof5X5keypad,CH423digitalcontrolchipand13digitaldisplay,caneasilyenterdataandvisualdisplayweight,unitpriceandtotalprice.SystempowerisbasedonLM7805,LM7812asthecoredesignofthecircuittoprovidenormalpowersupplysystem.SoftwarepartoftheapplicationMCUC51languageprogramming,thedesignofthebasiccontrolfunctions.Theelectronicweighingscalescanrealizethebasicfunctions(weighingrangeof0~10Kg,theweightoftheerrorisnotgreaterthan±0.02Kg),weight,unitprice,totalmeasurementisaccuratetotwodecimalplaces,thekeyboardsettingsarethenumberkeys('0'~'9','.'),storagekey,Unit1toUnit8Unitcallkey,clearkey,peeledkeys,etc.;playapartin8differentitemspricedmemory,99kindsofconsumergoodspricescumulativefunction;playaparttobeaboutelectronicscalesandprintersconnectedtoprintconsumptionrecords(smallnotes),overrangeandunder-rangealarm.Thesystemissimple,easytouse,fullyfunctional,highprecision,hassomevaluefordevelopment.Keywords：microcontrollersamplingcircuitA/DconverterCH423digitaltubedriverchipdigitaldisplayPowerSupply基于单片机系统的电子秤设计3目录第一章绪论11.1引言.....................................................................................................11.2选题背景与意义................................................................................1第二章系统方案的设计.............................................................................22.1电子秤的设计要求..........................................................................22.1.1基本要求....................................................................................22.1.2特色与创新................................................................................22.2实验原理及设计基本思路.................................................................22.2.1系统工作原理...............................................................................22.2.2系统设计基本思路......................................................................22.3系统总体设计方案比较与论证......................................................32.4单片机的选型.....................................................................................42.5数据采集部分的方案确定..............................................................42.5.1传感器..........................................................................................42.5.2前级放大器部分..........................................................................72.5.3A/D转换器...............................................................................92.6人机交互部分...................................................................................112.6.1键盘输入....................................................................................112.6.2输出显示....................................................................................112.7系统电源...........................................................................................122.8具体实施方案简介..........................................................................13第三章系统硬件设计...............................................................................153.1基于STC89C52RC的主控电路.....................................................153.1.1芯片介绍.....................................................................................153.2系统电源........................................................................................183.2.1芯片介绍..................................................................................183.2.2电源电路..................................................................................19第四章软件流程.....................................................................................204.1主程序流程图................................................................................20基于单片机系统的电子秤设计44.2键盘扫描流程图............................................................................21第五章结论.................................................................