VHDL语言设计数字系统的外文翻译教学内容.docx
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VHDL语言设计数字系统的外文翻译教学内容.docx
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VHDL语言设计数字系统的外文翻译教学内容
DesigningaDigitalsystemwithVHDL
ValentinaStoyanovaKukenska
Abstract:
InthispaperadigitalsystemdesigningwithVHDLispresented.Hereareexposedsequentiallyallthephasesoftheverydigitalsystem'sdesigning.Themainmethodsarealsoonshowhere.Theprojectdescriptions’typesarepresented.ThestressisputontheuseofVHDLforsynthesisofstructuralandbehavioralmodels.
ForcreatingtheprojectofthechosendigitalsystemanintegratedsystemWebPackwasused,aswellasModelSImXEIIforthemodel'ssimulation.
Keywords:
Design,VHDL,digitalsystems,model,WebPack
1.INTRODUCTION
Thedigitalsystemsarecomplexones,consistingoflotsofcomponents.Asfarastheautomateddesignofsuchsystemsisconcerned,methodsfordesigningtimereducingandlimitingthecomplexityofthetaskaresoughtoutandapplied.Amethodofthekindisconnectedwiththedecompositionandhierarchyprinciples.Thedecompositionofthesystemsisrealizedinaway,whichdifferentiatesfunctionallyindependentmodules.
Adigitalsystemcanbedescribedasamodulewithinputsand/oroutputs.Theelectricalvaluesontheoutputsaresomefunctionofthevaluesontheinputs.
Onewayofdescribingthefunctionofamoduleistodescribehowitiscomposedofsub-modules.Eachofthesub-modulesisaninstanceofsomeentity,andtheportsoftheinstancesareconnectedusingsignals.Thiskindofdescriptioniscalledastructuraldescription.
Inmanycases,itisnotappropriatetodescribeamodulestructurally.Onesuchcaseisamodule,whichisatthebottomofthehierarchyofsomeotherstructuraldescription.Forexample,ifyouaredesigningasystemusingICpackagesboughtfromanICshop,youdonotneedtodescribetheinternalstructureofanIC.Insuchcases,adescriptionofthefunctionperformedbythemoduleisrequired,withoutreferencetoitsactualinternalstructure.Suchadescriptioniscalledafunctionalorbehavioraldescription.
Usually,forstructuralandbehavioraldescription,eitherVerilogorVHDLisused.InthispaperadesigningwithVHDLispresented.Hereareexposedsequentiallyallthephasesoftheverydigitalsystem'sdesigning.Themainmethodsarealsoonshowhere.Theprojectdescriptions’typesarepresented.ThestressisputontheuseofVHDLforsynthesisofstructuralandbehavioralmodels.HerearepresentedseveralVHDLmodelsofcomputersystems’components.
2.Methodsandstagesindigitalsystems’design
Indigitalsystems’design,aswellasdesignofcomplexsystems,acoupleofmethodsareinuse:
∙∙ top-downdesigning;
∙∙ up-downdesigning.
Intop-downdesigningthebuildingupofthesystemisusuallystartedfrombelowinuprightdirectionthroughelaboratingtheelementblocks’schemes,assembledlatertoformthewholeproduct.
Anadvantageofthismethodistheuseofrepresentationonfunctionalblocklevelandthelower,thestructurallevel,isaddressedonlyduringtheerrorchecksimulationswithintheproject.
Theup-downdesigningstartswithaspecificationonthehighestlevel.Afterthat,theprojectisbeingdecomposedintofunctionalblocksandtherequirementsfortheincomeandoutcometimeproportionsarespecified.Thefunctionalmodelsaredescribedthroughbehavioralmodelsorbymodelsonregisterlevelsandaresubsequentlysimulated.
Someoftheadvantagesofthemethodsare:
∙∙ аneasierexecutionofthetask’sspecifications;
∙∙ иtallowsaprojects’checkonsystemlevel,withouttacklingthestructuraldetails;
∙∙ Theproject’scheckisdone,withnoregardtothetechnologyofitsrealization.Thatallowsthatthechoiceoftechnologybemadeonalaterstageofthedesigningproject.
Themosteffectiveup-downdesigningmethodistheuseofanabstractdescriptionoftheschemeandthesequentialdetailsspecifyingofthedifferenthierarchylevels’description.
Thedigitalsystems’designgoesthroughthenextstages:
∙∙ Specification;
∙∙ Functional(electrical)designing;
∙∙ Physicaldesigning;
∙∙ Manufacturing;
∙∙ Testing.
Throughspecificationtheproductparameters,necessaryforitsproperdestination,aredetermined.
Throughthefunctional(electrical)designing,theelectricalscheme,responsibleforthefunctionsandparametersoftheproduct,intermsofthespecification,iselaborated.
Thebehavioralstageservesasadescriptionfortheschemeasasystem,anditsentriesandexitsaremarkedout.Inmostofthecases,VHDLmodelsareused.
TheFunctional(electrical)designingdealswithmainfunctionalblocks’elaboration.UsuallyadetailedVHDLdescriptionofthefunctionalblockismadeandbeingcheckedbyaVHDLsimulation.
Withtheincreasingcomplexityoftheprojects,fortheelaborationonstructurallevel,thetechniqueofsynthesisisapplied.ItallowsthattheschemewithlogicalelementsbesynthesizedfromaVHDLdescription.Throughlogicaldescriptiondetailssuchascharging,elements’delay,arespecifiedandcrucialmethodsandproblemswithtimescatteringofsignalsaredefined.
ThePhysicaldesigningstagesstronglydependontechnology.Thecommontaskisconcernedwiththedeployingofthelogicalelementsanddefining(tracing)theirinterrelations.
ProvidedthatfortheproductrealizationPLD,CPLDorFPGAchipsareused,thentheresultofthephysicaldesigningrepresentsaconfigurationfilefordesigningthechosendevice’sresources.
Thetestingoftheprojectrepresentsanumberofprocedures,usedbydesigners,toprovide:
∙adequacybetweenprojectandspecification;
∙theexecutionoftheprojectintermsofthechosentechnology.
Thedesigningprocessisusuallyiterative,includingpre-designingofgivenparts,untiltheintendedindicatorsareobtained.
Forthetasksoftestinginelectricaldesigning(thefunctionalityoftheproductanditselectricalparameters),simulationsareused.
Thesimulationonbehavioralleveldefineshowtheproductwillrun,beforeitsactualcompoundingblocksarechosen.Forworkingoutofthebehavioralmodels,thehardwaredescriptionlanguagesareused(VHDL,Verilogandothers).
Throughsimulation,onalogicalprimitiveslevel,theschemesarebuiltupwithbasiclogicalelements“AND-NO”,“OR-NO”,invertorsandtriggersandarebeingsimulatedinordertofindoutirrelevanceswiththeirexpectedacting.
Infunctionaltesting,thedelaysarenotconcernedortheyaresupposedsimilarforalllogicalelements.
Erroridentificationafterthephysicaldesign
Aftertopology’sfinalelaborationaremadethenextprocedures:
∙∙ checkoutofthetechnormsthroughoutmanufacturing;
∙∙ checkoutfortheproject’sauthenticity.
Thetechnormsformanufacturingarespecificforeachtechnologicalprocess.
Theauthenticityverificationoftheprojectaimstoguaranteetheproduct’sproperworking.Itincludes:
∙∙ findingouttheinterconnectionofthescheme;
∙∙ findingouttheparasitecomponentsofthetopology.
3.Typesofdesigndescriptions
Throughthedesigningprocess,threetypesofdesigndescriptionareinuse:
∙∙ behavioral;
∙∙ structural;
∙∙ physical.
Thebehavioraldescriptiontacklesthesystemasifitwereakindof“blackbox”withitsentrancesandexits,withnoregardtoitsstructure.Theaimistoignoretheredundantdetailsandtoconcentrateonthespecificationofthenecessaryforthefunctions,whicharetobedonebytheproduct.Onthisstage,languagesfortheapparatuspartareusedHDL(HardwareDescriptionLanguages)-VHDL,Verilogandothers.
Thestructuraldescriptiondefinesthewaythatthesystemistobebuiltup.Here,thesystem’sstructure,madeofblocksandtheirinterrelations,istackled.Thesubsystems,whicharetoprovideitsfunctionalexecution,aswellastheirdetaileddescriptionforanalysisoftheoperationalspeed,chargingandsoon,aredefined.Thestructuraldescriptioncanbepresentedbylanguagesforthedescriptionofthehardware,aswellasbyelectricalschemes.
Thedesignprocessisconnectedwiththetransformationsofthesystems’descriptionsandtheirsequentialdetailsspecification.Decompositionfrombehavioraltostructuraldescriptioncanberealizedonanumberoflevelsinahierarchy.Fromthehighesttothelowest,theselevelscanbeoutlinedasitfollows:
∙∙ systemlevel;
∙∙ functionallevel;
∙∙ logicallevel;
∙∙ schemelevel.
Onthehighestsystemlevel,thesystem’sbehaviorisrepresentedbyalgorithmsthatdescribeitsfunctions.Inorderthatthesefunctionsbeexecuted,thearchitectureofthesystemisworkedout,includingmicroprocessors,memories,mainboardsandotherstructuralcomponents.
Onthelowerlevel,thesystem’sbehaviorisdescribedbyBoliviaequations.Fortheirexecution,logicalelementsandtriggersareused.
4.UseofVHDLforsynthesisofstructuralandbehavioralmodels
VHDLisaHardwareDescriptionLanguagefordescribingdigitalsystem[2].
VHDLisdesignedtofullanumberofneedsinthedesignprocess.
VHDLcontainsanumberoffacilitiesformodifyingthestateofobjectsandcontrollingtheflowofexecutionofmodules.
InVHDL,anentityissuchamodulewhichmaybeusedasacomponentinadesign,orwhichmaybethetop-levelmoduleofthedesign.Theentitydeclarativepartmaybeusedtodeclareitems,whicharetobeusedintheimplementationoftheentity.
Onceanentityhashaditsinterfacespecifiedinanentitydeclaration,oneormoreimplementationsoftheentitycanbedescribedinarchitecturebodies.Eacharchitecturebodycandescribeadifferentviewoftheentity.
Thedeclarationsinthearchit
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