中英文对照外文翻译
(文档含英文原文和中文翻译
DESIGNINGADIGITALSYSTEMWITHVHDL
Abstract:InthispaperadigitalsystemdesigningwithVHDLispresented.Hereare
exposedsequentiallyallthephasesoftheverydigitalsystem'sdesigning.Themainmethodsarealsoonshowhere.Theprojectdescriptions’typesarepresented.ThestressisputontheuseofVHDLforsynthesisofstructuralandbehavioralmodels.
ForcreatingtheprojectofthechosendigitalsystemanintegratedsystemWebPackwas
used,aswellasModelSImXEIIforthemodel'ssimulation.
Keywords:Design,VHDL,digitalsystems,model,WebPack
1.INTRODUCTION
Thedigitalsystemsarecomplexones,consistingoflotsofcomponents.Asfarasthe
automateddesignofsuchsystemsisconcerned,methodsfordesigningtimereducingandlimitingthecomplexityofthetaskaresoughtoutandapplied.Amethodofthekindisconnectedwiththedecompositionandhierarchyprinciples.Thedecompositionofthesystemsisrealizedinaway,whichdifferentiatesfunctionallyindependentmodules.
Adigitalsystemcanbedescribedasamodulewithinputsand/oroutputs.Theelectrical
valuesontheoutputsaresomefunctionofthevaluesontheinputs.
Onewayofdescribingthefunctionofamoduleistodescribehowitiscomposedof
sub-modules.Eachofthesub-modulesisaninstanceofsomeentity,andtheportsoftheinstancesareconnectedusingsignals.Thiskindofdescriptioniscalledastructuraldescription.
Inmanycases,itisnotappropriatetodescribeamodulestructurally.Onesuchcaseisa
module,whichisatthebottomofthehierarchyofsomeotherstructuraldescription.Forexample,ifyouaredesigningasystemusingICpackagesboughtfromanICshop,youdonotneedtodescribetheinternalstructureofanIC.Insuchcases,adescriptionofthefunctionperformedbythemoduleisrequired,withoutreferencetoitsactualinternalstructure.Suchadescriptioniscalledafunctionalorbehavioraldescription.
Usually,forstructuralandbehavioraldescription,eitherVerilogorVHDLisused.Inthis
paperadesigningwithVHDLispresented.Hereareexposedsequentiallyallthephasesoftheverydigitalsystem'sdesigning.Themainmethodsarealsoonshowhere.Theprojectdescriptions’typesarepresented.ThestressisputontheuseofVHDLforsynthesisofstructuralandbehavioralmodels.HerearepresentedseveralVHDLmodelsofcomputersystems’components.
2.METHODSANDSTAGESINDIGITALSYSTEMS’DESIGN
Indigitalsystems’design,aswellasdesignofcomplexsystems,acoupleofmethodsarein
use:
top-downdesigning;up-downdesigning.
Intop-downdesigningthebuildingupofthesystemisusuallystartedfrombelowin
uprightdirectionthroughelaboratingtheelementblocks’schemes,assembledlatertoformthewholeproduct.
Anadvantageofthismethodistheuseofrepresentationonfunctionalblocklevelandthe
lower,thestructurallevel,isaddressedonlyduringtheerrorchecksimulationswithintheproject.
Theup-downdesigningstartswithaspecificationonthehighestlevel.Afterthat,the
projectisbeingdecomposedintofunctionalblocksandtherequirementsfortheincomeandoutcometimeproportionsarespecified.Thefunctionalmodelsaredescribedthroughbehavioralmodelsorbymodelsonregisterlevelsandaresubsequentlysimulated.
Someoftheadvantagesofthemethodsare:
аneasierexecutionofthetask’sspecifications;
иtallowsaprojects’checkonsystemlevel,withouttacklingthestructural
details;
Theproject’scheckisdone,withnoregardtothetechnologyofitsrealization.
Thatallowsthatthechoiceoftechnologybemadeonalaterstageofthedesigningproject.
Themosteffectiveup-downdesigningmethodistheuseofanabstractdescriptionofthe
schemeandthesequentialdetailsspecifyingofthedifferenthierarchylevels’description.
Thedigitalsystems’designgoesthroughthenextstages:
