外文翻译--基于AT89C2051 的智能型汽车防撞报警器的设计.doc

AnAT89C2051BasedIntelligentProximityWarningIndicatorforAutomobileItintroducesthefunctionandcharacteristicsofmicrocontrollerAT89C2051Basedonit.Alowcosthigh-accuracymicrominiaturizationanddigitaldisplayproximitywarningindicatorforautomobileisdesigned.Theindicatormeasuresthedistanceandspeedoftheautomobile,withultrasonicwaveandintegratedHallunitandcontrolsthesystembythereal-timecontrolandData-processingofthemicrocontrollerMoreover.itscircuitryprincipleisintroducedindetailaswellasitssoftwaredesign.Alongwithmodernrhythmoflifespeedingup,thefrequencywhichthetrafficaccidentoccurredisincreasing,forenhancesthesecurityofautomobilemovement.Thisarticleintroducedonekindofalarmsystembasedonmonolithicintegratedcircuitcontrolstheautomobileguardsagainsthitting.Thisequipmentthemonolithicintegratedcircuitreal-timecontrolandthedataprocessingfunction,withtheultrasonicwaverangefindertechnology,thesensortechnologyunifies,mayexamineintheautomobilemovementrearareatheobstacleandtheautomobiledistanceandtheautomobilevehiclespeed,revealstheinstallmentdemonstrationdistancethroughthenumber,andisawayfromfarandnearthesituationbythesoundproductionelectriccircuitbasistosendoutthewarningsound.Theultrasonicrangingprincipleis,afterunceasinglyexaminestheultrasonicwavelaunchtomeettheechowhichtheobstaclereflects,thusdeterminesthelaunchultrasonicwaveandreceivestheechothetimedifference.ThenextractsisawayfromS=C×T/2,Cistheultrasonicwavewavevelocity,underthenormaltemperaturetakesis344m/s.Aftersonicspeeddetermination,solongasobtainstheultrasonicwaveround-tripthetime,thenobtainsthedistance.TheautomobilevehiclespeedsurveyisintegratesthesensorthroughHalltorealize.Namely,isloadedwiththepermanentmagnettheturntableinputaxisandthewheelrevolutionaxisisconnected,whenthewheelrotates,theturntablealongwithitrotation,thistime,ontheturntablepermanentmagnetcanintegratethesensorafterHall,thusintegratesthesensorinHalltheinputendtoobtainamagnetismsignal,iftheturntabledoesnotstoptherotation,Hallintegratesthesensorthentobeabletooutputtherotationalspeedsignal.Itcanbesaidthat,totheautomobilevehiclespeedsurveyessenceintotherotationalspeedsignalfrequencysurvey.AT89C2051isalowpowerloss,thehighperformance8CMOSmicroprocessor,iscompatiblewiththeMCS-51seriesinstructioncollectionandthepin,hasfollowingcharacteristic:128bytesinternalRAM,2KbytesEPROM,fifteenI/Oline,twosixteen-fixedtimecounters,fivetwo-levelofinterruptsources,oneentireduplexserialport,internalpreciselysimulatesthecomparatorandinternalswingming,thelowpowerlossleavesunusedandfallstheelectricitypattern.Theworkingvoltagescope4.255.5V,theoperatingfrequencytakes12MHz.InAT89C2051,twosixteen-fixedtime/countersregistersisT0andT1,makefixedtime/counters,maycountthemachinecycle,countsthefrequencyfortheoscilationfrequency1/12；Whenmakesthecounter,mayappearstoonexteriorinputpinP3.4/T0andP3.5/T1from1to0changeswhenincrease1,countsthefrequencyfortheoscilationfrequency1/24.Thisalarmapparatusismadeupofthecontrolsystem,theultrasonicwavetransmissioncircuit,theacceptingcircuit,measuredthefastelectriccircuit,thealarmcircuit,theLEDdisplaycircuitetc.TheultrasonicwavelaunchelectricityrouteCC7555timebasecircuitandtheultrasonicwavelaunchpokesheadintocompose.ThemonolithicintegratedcircuitAT89C2051pincontrolstheP1.7pintocontroltheCC7555timebasecircuittoproducethe40kHzfrequencycodefortheultrasonicgenerator,pokesheadintheultrasonicwaveLaunchobstaclebytheultrasonicwavewhichlaunches.Hasthecharacteristicbelowusingtheultrasonicranging:highsurveysensitivity,strongpenetratingpower,quicksurveyspeed,thebigsurveyangleis,inthecorrelationwiderangeobjectcarriesontheexamination.Thesupersonicreceptionelectriccircuitiscomposedofpokesheadin,theamplifierbandtheshapercircuit.Theultrasonicwavereflectswhichbytheobstaclepokesheadinafterthereceive,totransformfortheelectricitypulsesignal,againaftertheamplifier,theshaperenlargementandthereshapingsendsintheP3.2pin.ofAT89C2051.Theamplifiersuitablyselectshastheenoughgainandthelowernoisewidebandamplifier,maintainsthepulsesignalfrontnottohavethedistortioninparticular,enhancestherangefindertheprecision.Measuredthefastelectriccircuitiscomposedofthesensor,thepulseamplifier,theshaper,theCC7555timebasesignalcircuit,thegate.Hallintegratesthesensortoturnthewheelrotationalspeedsignalthepulsesignaloutput,aftertheenlargement,thereshapingelectriccircuitsendsinthegate,producesunittimebasesignalcontrolgateopeningbytheCC7555timebasecircuitswithtoshut,controlstherotationalspeedsignalintheunittimethroughthegate,sendsinmonolithicintegratedcircuittheP3.5pinofAT89C2051,controlledtheT1countertocount,hasrealizedinunittimecounting.ThealarmcircuitiscomposedoftheCC7555electriccircuitsandthespeaker.TheP1.6pinofAT89C2051controlstheCC7555electriccircuitbasismeasurementresult,producesthecertainfrequencysignalactuationspeakertosendoutreportstothepolicethesound.Sendsoutwhenthespeakerreportstothepolicethesound,timebasecircuitCC7555isintemporarilythestablestate,thistimepowersourcetoelectriccapacitycharge,thuscausesCC7555toendtemporarilythestablestatetoreplythesteadystate,outputsthelowlevel,causesthespeakertostopsendingoutreportstothepolicethesound,producesnewlyuntilthenextrangefinderconclusionreportstothepolicethesound.TheLEDdisplaycircuitiscomposedofthedigitaltubeandtheactuationelectriccircuit.Withtwodigitaltubesdemonstrationdistance,thedigitaltubeusesthestaticstatetodemonstratethat,bythechipMCS14495actuationsdemonstrations,P1.4,P1.5separatelysavesthesignalastheactuationchipMCS14495locks,usesinBCDwhichcontrolsproduces(BinarCodeDecimal),thebinarycodeexpressiontensdigitisdemonstratesthetopdigitorthelowposition.TheAT89C2051mainlycompletestheproceduretheexecution,dataprocessingandtoexteriorelectriccircuitreal-timecontrol.InternaltimerT0workinfixedtimeway,whenultrasonicwavelaunchstartstocount,afterpinP3.2receivestheecho,stopscounting,T0timesnamelyfortheultrasonicwaveround-triptransmissiontime,themonolithicintegratedcircuitcarriesonprocessingtothisdata,thendeterminesthedistance.TheinternaltimerT1workiscountingtheway,countsbyP3.5pininputpulsesignalcontrolT1,countsthevaluebyT1todeterminetheautomobiletherotationalspeed.Themonolithicintegratedcircuitbasismeasuredisawayfromandthevehiclespeedcarriesonthecomparison,judgeswhetheractuatesthealarmcircuittoreporttothepolice,likehypothesis:Whenthevehiclespeedissmallerorequalto30km/s,thesafedistanceshouldbebiggerthanisequalto1m；Whenthevehiclespeedissmallerorequalto80km/s,thesafedistanceshouldbebiggerthanisequalto2m；Whenthevehiclespeedisbiggerthan80km/s,thesafedistanceshouldbebiggerthanisequalto5m.Thisinstallmentcontrolsoftwaremustcompletethesysteminitialization,thecontroltriggerpulsesignallaunchandthereceive,accordingtofixedtimethecount-downobstacledistance,accordingtocountsthefrequencycomputationautomobilevehiclespeed,judgesmeasuredisawayfromwhetherinthemarginforsafetywhichthevehiclespeedcorresponds,andaccordingtocalculateshastheBCDcodeandthecorrespondingfrequencypulsesignalwiththejudgementresult,actuatesthedisplaycircuitandthesoundproductionelectriccircuit基于AT89C2051的智能型汽车防撞报警器的设计本文介绍了AT89C2051单片机的性能及特点，及以其为核心的一种低成本、高精度、微型化、数字显示的汽车防撞报警器。该防撞报警器利用超声波及集成霍尔元件实现对汽车的测距和测速，利用单片机的实时控制和数据处理功能，完成系统的控制。文章给出了报警器的硬件电路原理及软件设计。随着现代生活节奏的加快，交通事故发生的频率也在增加，为提高汽车运行的安全性，本文介绍一种单片机控制的汽车防撞报警系统。该装置将单片机的实时控制及数据处理功能，与超声波的测距技术、传感器技术相结合，可检测汽车运行中后方障碍物与汽车的距离及汽车车速，通过数显装置显示距离，并由发声电路根据距离远近情况发出警告声。超声波测距的原理是，通过不断检测超声波发射后遇到障碍物所反射的回波，从而测出发射超声波和接收到回波的时间差，然后求出距离S=C×T/2，其中，C为超声波波速，常温下取为344m/s。声速确定后，只要测得超声波往返的时间，即可求得距离。汽车车速的测量是通过霍尔集成传感器来实现的。即，装有永久磁铁的转盘的输入轴与车轮的转轴相连，当车轮转动时，转盘随之转动，此时，转盘上的永久磁铁会经过霍尔集成传感器，从而在霍尔集成传感器的输入端得到一个磁信号，如果转盘不停转动，霍尔集成传感器便会输出转速信号。可以说，对汽车车速的测量实质上是对转速信号的频率的测量。AT89C2051是一个低功耗、高性能的8位CMOS微处理器，与MCS-51系列指令集和引脚兼容，具有以下特点：128bytes内部RAM，2KbytesEPROM，15根I/O线，2个16位定时计数器，5个两级中断源，1个全双工串行口，一个片内精密模拟比较器和片内荡器，低功耗的闲置和掉电模式。工作电压范围4.255.5V，工作频率取12MHz。AT89C2051中的两个16位定时/计数器寄存器T0和T1，作定时/计数器时，可计数机器周期，计数频率为振荡频率的1/12；作计数器时，可对外部输入引脚P3.4/T0和P3.5/T1上出现从1至0的变化时增1，计数频率为振荡频率的1/24。该报警器由控制系统、超声波发射电路、接收电路、测速电路、报警电路、LED显示电路组成。超声波发射电路由CC7555时基电路和超声波发射探头组成。单片机AT89C2051的引脚控制P1.7引脚控制CC7555时基电路产生40kHz的频率信号给超声波发生器，由超声波探头发射的超声波射向障碍物。利用超声波测距具有以下特点：测量灵敏度高，穿透力强，测量速度快，测量角度大，可对较大范围内的物体进行检测。超声波接收电路由超声波接收探头、放大器和整形器组成。由障碍物反射回来的超声波经接收探头，变换为电脉冲信号，再由放大器、整形器放大和整形后送入到AT89C2051的P3.2引脚。放大器宜选用有足够增益和较低噪声的宽带放大器，以保持脉冲信号尤其是前沿不发生畸变，提高测距的精度。测速电路由传感器、脉冲放大器、整形器、CC7555时基信号电路、选通门组成。霍尔集成传感器将车轮转速信号变成脉冲信号输出，经放大、整形电路后送入选通门，由CC7555时基电路产生的单位时基信号控制选通门的开与闭，以控制转速信号在单位时间内通过选通门，送入单片机AT89C2051的P3.5引脚，控制T1计数器计数，实现了在单位时间内的计数。