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本科生毕业设计（论文）I摘要超声波液位测量是一种非接触式的测量方式,它是利用超声波在同种介质中传播速度相对恒定以及碰到障碍物能反射的原理研制而成的。与其它方法相比(如电磁的或光学的方法),它不受光线、被测对象颜色的影响，对于被测物处于黑暗、有灰尘、烟雾、电磁干扰、有毒等恶劣的环境下有一定的适应能力。因此，研究超声波在高精度测距系统中的应用具有重要的现实意义。本设计基于单片机的超声波液位测量系统主要由硬件与软件两部分组成，硬件是基于AT89C51芯片为核心的超声波液位测量，采用AT89C51单片机进行控制及数据处理，给出了超声波发射和接收电路，通过盲区的消除以及环境温度的采样，提高了测距的精确度。利用超声波传输中距离与时间的关系，设计出了能精确测量两点间距离的超声波液位检测系统。此系统具有易控制、工作可靠、测量精度高的优点，可实时检测液位。并有超声波处理模块CX20106A、CD4069组成的超声波发射电路、超声波接收电路、单片机复位电路、LED显示电路、报警电路等。软件部分由主程序、预置子程序、发射子程序、接收子程序、显示子程序组成。各探头的信号经单片机综合分析处理。最后通过实物的调试，各项参数及功能符合设计要求，能达到预期的目的。关键词：单片机;超声波;温度控制;高精度测距本科生毕业设计（论文）IIAbstractTheultrasonicliquidlevelmeasurementisanon-contactmeasurementmethod,realizedbytheprincipleofultrasonicwaveinthesamemediumwithrelativelyconstantpropagationvelocityandbeingreflectedwhenitapproachesanobstacle.Comparedwithothermethods(suchaselectromagneticoropticalmethod),ithasacertainofadaptabilitywhenobjectstobemeasuredareundersuchharshenvironmentasdarkness,dust,smoke,electromagneticinterference,toxicity,unaffectedbythelightorthecoloroftheobjecttobemeasured.Therefore,itbearsimportantpracticalsignificancetoconductresearchontheapplicationofultrasonicwaveinhighprecisionrangingsystem.Inthisproject,SCM-basedultrasonicliquidlevelmeasuringsystemismainlycomposedoftwocomponents,namelythehardwareandthesoftware.ThehardwareisultrasonicliquidlevelmeasurementbasedonAT89C51chipasthecore;itadoptsAT89C51singlechipmicrocomputerforcontrolanddataprocessing,providestheultrasonictransmittingandreceivingcircuit,andimprovesrangingaccuracythrougheliminationofblindspotandsamplingofambienttemperature,.Bytakingadvantageoftherelationshipbetweendistanceandtimeinultrasonictransmission,anultrasonicliquidleveldetectingsystemwhichcanaccuratelymeasurethedistancebetweentwopointsisdesigned.Thissystemhastheseadvantageslikeeasycontrol,reliableoperation,highmeasurementprecision,andreal-timedetectionofliquidlevel.Andithasultrasonictransmittingandreceivingcircuit,resetcircuitsofSCM,LEDdisplaycircuit,alarmcircuitcomposedofultrasonicprocessingmoduleCX20106AandCD4069.Thesoftwarepartconsistsofmainprogram,presetsubroutine,transmittingandreceivingsubroutine,anddisplaysubroutine.TheprobesignalisprocessedbySCMthroughcomprehensiveanalysis.Finallythroughdebuggingofrealobjects,variousparametersandfunctionscanmeettheprojectrequirementstoachievethedesiredobjective.Keywords:singlechipmicrocomputer(SCM);ultrasonicwave;temperaturecontrol;highprecisionranging本科生毕业设计（论文）III目录第一章绪论................................................................................................................11.1课题研究的背景及意义................................................................................11.2国内外发展的现状........................................................................................31.3液位计的类型................................................................................................31.4本文的主要工作............................................................................................5第2章系统的总体方案设计......................................................................................72.1系统设计内容和功能....................................................................................72.2课题设计的任务和要求：............................................................................72.3系统方案选择................................................................................................82.4系统总体方案的设计....................................................................................82.5超声波和超声波传感器................................................................................92.6超声波传感器的主要应用..........................................................................102.7超声波传感器测距原理..............................................................................102.8超声波测距原理..........................................................................................122.9超声波发生器选择......................................................................................122.10盲区处理....................................................................................................14第3章各单元硬件电路设计....................................................................................163.1单片机最小系统电路..................................................................................163.2温度补偿电路设计......................................................................................183.3超声波发射电路设计..................................................................................193.4超声波接收电路设计..................................................................................203.5显示电路设计..............................................................................................223.6电源电路设计..............................................................................................223.7LED显示系统设计.......................................................................................233.8报警电路设计..............................................................................................24第4章系统软件的设计..............................................................................