搜索
第1页原文Title：VISIONSYSTEMBASEDONASINGLE-CHIPMICROCOMPUTERVisionsensorswhichusedynamicRAMarecheaperandeasiertointerfacethantheiralternatives--videconorCCD.AndrewRusselldescribesaDRAM-based'intelligent'visionsysteminwhichallinterfacingandimageprocessingfunctionsareprovidedbyan8751single-chipmicrocomputerThepaperdescribesacompactandinexpensivebinaryvisionsysteminwhichallinterfacinganddataprocessingfunctionsareperformedbyanIntel8751single-chipmicrocomputer.Thevisionsensorisa64kbitdynamicRAMchipwhichiscapableofprovidingapictureresolutionofupto256X128pixels.Pictureprocessingalgorithmsareimplementedwithinthevisionsystemandobjectstatisticsaretransferredtothehostcomputeroveraserialinterface.Theresultingsystemisimplementedusingonlyfourintegratedcircuitsandiseminentlysuitableforcomponentidentificationandinspectioninaflexiblemanufacturingsystemenvironment.MicrosystemscomputervisionDRAMopticalsensors8751Computervisionsystemsarebeingusedinincreasingnumbersforavarietyofindustrialinspection,partidentificationandcontroltasks.Dynamicrandom-accessmemory(DRAM)circuitshavebeendevelopedasbinaryopticalsensorsfortheseapplications1'2.DRAM-basedvisionsystemsareverylowincostandhavedirectcompatibilitywithdigitalelectronics.Theseadvantagesarenotsharedbythealternativetypesofsystemavailable-'videcon'orCCD(chargecoupleddevice)visionsensors--whicharerelativelyexpensive,wereoriginallydesignedforcompatibilitywithtelevisiondisplaysandthereforedonotprovideanoutputwhichcanbereadilyaccessedbyacomputer.FormanyinspectionandidentificationtasksthehigherresolutionofvideconorCCDsensorsisnotrequired,andinsuchapplicationsaDRAM-basedsystemcanbeamorecosteffectivesolution.Thispaperdescribesan'intelligent'visionsensorinwhichallinterfacingandimageprocessingfunctionsareperformedbyanIntel8751single-chipmicrocomputer.The8751containsacomplete8-bitmicroprocessoraswellasEPROM,RAM,twotimers,afullduplexI/OportandparallelI/Olinesg.Theseresourceswithinthe8751areusedto:•directlycontroltheDRAMopticalsensor,anIS32OpticRAMmanufacturedby第2页MicronTechnologyInc.•performaddress'descramble'andinterpolationfunctionsonthedataintheDRAM•eithertransmittheimagetoahostcomputerincompressedformorperformimageprocessingalgorithmsandtransmittheresultingstatisticstoahostcomputer.The8751-basedvisionsystemimplementedcontainsonlyfourintegratedcircuitsincludingtheOpticRAM.ThelargequantityofinterfacingelectronicsrequiredbysimilarDRAMvisionsystemsiseliminated.Inaddition,atruly'intelligent'sensoriscreatedbyincorporatingvisionprocessingfunctionswithinthe8751.UsingadramasavisionsensorADRAMstoresinformationinanarrayofmemorycells,eachconsistingofacapacitorandatransistor4.Figure1showsthememorycelllayout.Dataisreadfromorwrittentoamemorycellbythefollowingoperations.•An8-bitrowaddressisestablishedontheDRAMaddresslines.•Ro~s.addressstrobe(RAS)isasserted,causingtherowaddressdecodertoselectoneof256rowlines.The256transistorsQconnectedtotheselectedrowlineare'switchedon'andtransferchargefromtheassociatedcapacitorCtoacolumnline.•Chargefromthememorycellisregenerativelyamplifiedandfedbackontothecolumnlinestore-establishtheoriginalchargeonthecapacitors.•An8-bitcolumnaddressispresentedontheDRAMaddresslines.•Columnaddressstrobe(CAS)isasserted,initiatingtheselectionofoneoutof256columnsenseamplifiersanddirectingitsoutputtothedataout(DOUT)pin,theDRAM.Ifamemorywriteoperationisrequireddatafromthedatain(DIN)pinwouldberoutedtothe,selectedsenseamplifierandhencetotheappropriatememorycell.Chargeonthememorycellcapacitorstendstoleakaway.Ifdataistoberetainedthechargemustbesensedbeforeithasdecayedawaycompletely,andrestoreditsoriginallevel.Theoperationofrestoringmemorychargeiscalled'refresh'andoccurswhenareadorwrit~cycleisperformedonthesamerowasthecell.Iflightincidentonthecapacitorstheirrateofchargedecayincreased.Thusifallcapacitorsarechargedandasuitablelengthoftinqeisallowedtoelapsebeforereadingthememorycellsitwillbefoundthatsomeofthebitshaw,beencorrupted.Thosebitswhicharecorruptedwillcomefromcapacitorssubjectedtoahigherlevelofilluminationthanthosewhicharenotcorrupted.Ifthephysicallayoutofthe.第3页memorycellscanbedetermineditwillbepossibletolocatethoseareasofthecircuitwherethelightintensity,isaboveacertainthresholdandthustoproduceaimageoftheincidentillumination.The65536memorycellsintheIS32integratedcircuitsaregroupedintotworegionswithanareacontainsenseamplifiersbetweenthem.Formostapplicationsalargegapinthevisualfieldwillbeunacceptable.CamerasystemADRAMopticalsensormaybeinterfacedtoamicro-computerbydirectconnectiontotheprocessoraddressbusorindirectlyviaanI/Oport.ConnectionthroughanI/Oportisslowerandrequiresamorecomplicatedcontrolprogram.Thesedrawbacksarebalancedbyaconsiderablereductionincircuitcomplexity.Theaimofthisprojectwastoproduceasimple,inexpensivevisionsystemandthereforetheDRAMwasconnectedthroughanI/Oport.MemoryrefreshThisprocessrestoresthechargelevelonmemoryceilcapacitorsandisonlystoppedduringimageacquisitiontomakethememorycellssensitivetolight.Timingfortherefreshoperationiscontrolledbyoneofthe8751,internal16-bitcounters.Count