Fundamentals of Digital logic

864 Pages·2013·5.64 MB·English

December31,2012 09:16 vra80547_title Sheetnumber1 Pagenumberi magentablack
Fundamentals
of
Digital Logic with Verilog Design
THIRD EDITION
Stephen Brown and Zvonko Vranesic
DepartmentofElectricalandComputerEngineering
UniversityofToronto
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FUNDAMENTALSOFDIGITALLOGICWITHVERILOGDESIGN,THIRDEDITION
PublishedbyMcGraw-Hill,abusinessunitofTheMcGraw-HillCompanies,Inc.,1221AvenueoftheAmericas,
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1234567890DOC/DOC109876543
ISBN978–0–07–338054–4
MHID0–07–338054–7
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LibraryofCongressCataloging-in-PublicationData
Brown,Stephen.
FundamentalsofdigitallogicwithVerilogdesign/StephenBrownandZvonkoVranesic.—Thirdedition.
pagescm
ISBN978–0–07–338054–4(alk.paper)
1.Logiccircuits—Designandconstruction—Dataprocessing. 2.Verilog(Computerhardware
descriptionlanguage).3.Computer-aideddesign. I.Vranesic,ZvonkoG. II.Title.
TK7868.L6B76 2014
621.39(cid:2)2–dc23 2012042163
www.mhhe.com
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ToSusanandAnne
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About the Authors
StephenBrownreceivedhisB.A.Sc.degreeinElectricalEngineeringfromtheUniversity
ofNewBrunswick,Canada,andtheM.A.Sc.andPh.D.degreesinElectricalEngineering
fromtheUniversityofToronto. HejoinedtheUniversityofTorontofacultyin1992,where
heisnowaProfessorintheDepartmentofElectrical&ComputerEngineering. Heisalso
theDirectoroftheworldwideUniversityProgramatAlteraCorporation.
Hisresearchinterestsincludefield-programmableVLSItechnologyandcomputerar-
chitecture. He won the Canadian Natural Sciences and Engineering Research Council’s
1992DoctoralPrizeforthebestPh.D.thesisinCanadaandhaspublishedmorethan100
scientificresearchpapers.
He has won five awards for excellence in teaching electrical engineering, computer
engineering,andcomputersciencecourses. Heisacoauthoroftwootherbooks: Funda-
mentalsofDigitalLogicwithVHDLDesign,3rded.andField-ProgrammableGateArrays.
ZvonkoVranesicreceivedhisB.A.Sc.,M.A.Sc.,andPh.D.degrees,allinElectricalEngi-
neering,fromtheUniversityofToronto. From1963–1965heworkedasadesignengineer
with the Northern Electric Co. Ltd. in Bramalea, Ontario. In 1968 he joined the Univer-
sityofToronto,whereheisnowaProfessorEmeritusintheDepartmentsofElectrical&
ComputerEngineeringandComputerScience. Duringthe1978–1979academicyear,he
wasaSeniorVisitorattheUniversityofCambridge, England, andduring1984–1985he
was at the University of Paris, 6. From 1995 to 2000 he served as Chair of the Division
ofEngineeringScienceattheUniversityofToronto. Heisalsoinvolvedinresearchand
developmentattheAlteraTorontoTechnologyCenter.
His current research interests include computer architecture and field-programmable
VLSItechnology.
Heisacoauthoroffourotherbooks: ComputerOrganizationandEmbeddedSystems,
6thed.;FundamentalsofDigitalLogicwithVHDLDesign,3rded.;MicrocomputerStruc-
tures;andField-ProgrammableGateArrays. In1990,hereceivedtheWightonFellowship
for“innovativeanddistinctivecontributionstoundergraduatelaboratoryinstruction.” In
2004, he received the Faculty TeachingAward from the Faculty ofApplied Science and
EngineeringattheUniversityofToronto.
He has represented Canada in numerous chess competitions. He holds the title of
InternationalMaster.
v
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Preface
This book is intended for an introductory course in digital logic design, which is a basic
course in most electrical and computer engineering programs. Asuccessful designer of
digitallogiccircuitsneedsagoodunderstandingofbasicconceptsandafirmgraspofthe
moderndesignapproachthatreliesoncomputer-aideddesign(CAD)tools.
The main goals of the book are (1) to teach students the fundamental concepts in
classical manual digital design and (2) illustrate clearly the way in which digital circuits
aredesignedtoday,usingCADtools. Eventhoughmoderndesignersnolongerusemanual
techniques, except in rare circumstances, our motivation for teaching such techniques is
to give students an intuitive feeling for how digital circuits operate. Also, the manual
techniquesprovideanillustrationofthetypesofmanipulationsperformedbyCADtools,
givingstudentsanappreciationofthebenefitsprovidedbydesignautomation. Throughout
the book, basic concepts are introduced by way of examples that involve simple circuit
designs, which we perform using both manual techniques and modern CAD-tool-based
methods. Havingestablishedthebasicconcepts,morecomplexexamplesarethenprovided,
using the CAD tools. Thus our emphasis is on modern design methodology to illustrate
howdigitaldesigniscarriedoutinpracticetoday.
Technology
Thebookdiscussesmoderndigitalcircuitimplementationtechnologies. Theemphasisison
programmablelogicdevices(PLDs),whichisthemostappropriatetechnologyforuseina
textbookfortworeasons. First,PLDsarewidelyusedinpracticeandaresuitableforalmost
alltypesofdigitalcircuitdesigns. Infact,studentsaremorelikelytobeinvolvedinPLD-
baseddesignsatsomepointintheircareersthaninanyothertechnology. Second,circuits
areimplementedinPLDsbyend-userprogramming. Therefore,studentscanbeprovided
with an opportunity, in a laboratory setting, to implement the book’s design examples in
actualchips. Studentscanalsosimulatethebehavioroftheirdesignedcircuitsontheirown
computers. WeusethetwomostpopulartypesofPLDsfortargetingofdesigns: complex
programmablelogicdevices(CPLDs)andfield-programmablegatearrays(FPGAs).
Weemphasizetheuseofahardwaredescriptionlanguageinspecifyingthelogiccir-
cuits,becausetheHDL-basedapproachisthemostefficientdesignmethodtouseinpractice.
We describe in detail the IEEE StandardVerilog HDLlanguage and use it extensively in
examples.
vi
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Preface vii
ScopeoftheBook
Thiseditionofthebookhasbeenextensivelyrestructured. Allofthematerialthatshould
becoveredinaone-semestercourseisnowincludedinChapters1to6. Moreadvanced
materialispresentedinChapters7to11.
Chapter1providesageneralintroductiontotheprocessofdesigningdigitalsystems.
ItdiscussesthekeystepsinthedesignprocessandexplainshowCADtoolscanbeused
to automate many of the required tasks. It also introduces the representation of digital
information.
Chapter 2 introduces the logic circuits. It shows how Boolean algebra is used to
representsuchcircuits. Itintroducestheconceptsoflogiccircuitsynthesisandoptimization,
andshowshowlogicgatesareusedtoimplementsimplecircuits. Italsogivesthereader
a first glimpse atVerilog, as an example of a hardware description language that may be
usedtospecifythelogiccircuits.
Chapter3concentratesoncircuitsthatperformarithmeticoperations. Itdiscussesnum-
bersandshowshowtheycanbemanipulatedusinglogiccircuits. Thischapterillustrates
howVerilogcanbeusedtospecifythedesiredfunctionalityandhowCADtoolsprovidea
mechanismfordevelopingtherequiredcircuits.
Chapter4presentscombinationalcircuitsthatareusedasbuildingblocks. Itincludes
the encoder, decoder, and multiplexer circuits. These circuits are very convenient for
illustratingtheapplicationofmanyVerilogconstructs,givingthereaderanopportunityto
discovermoreadvancedfeaturesofVerilog.
StorageelementsareintroducedinChapter5. Theuseofflip-flopstorealizeregular
structures, suchasshiftregistersandcounters, isdiscussed. Verilog-specifieddesignsof
thesestructuresareincluded.
Chapter6givesadetailedpresentationofsynchronoussequentialcircuits(finitestate
machines). It explains the behavior of these circuits and develops practical design tech-
niquesforbothmanualandautomateddesign.
Chapter7isadiscussionofanumberofpracticalissuesthatariseinthedesignofreal
systems. Ithighlightsproblemsoftenencounteredinpracticeandindicateshowtheycan
be overcome. Examples of larger circuits illustrate a hierarchical approach in designing
digitalsystems. CompleteVerilogcodeforthesecircuitsispresented.
Chapter8dealswithmoreadvancedtechniquesforoptimizedimplementationoflogic
functions. Itpresentsalgorithmictechniquesforoptimization. Italsoexplainshowlogic
functionscanbespecifiedusingacubicalrepresentationaswellasusingbinarydecision
diagrams.
AsynchronoussequentialcircuitsarediscussedinChapter9. Whilethistreatmentis
not exhaustive, it provides a good indication of the main characteristics of such circuits.
Even though the asynchronous circuits are not used extensively in practice, they provide
anexcellentvehicleforgainingadeeperunderstandingoftheoperationofdigitalcircuits
ingeneral. Theyillustratetheconsequencesofpropagationdelaysandraceconditionsthat
maybeinherentinthestructureofacircuit.
Chapter10presentsacompleteCADflowthatthedesignerexperienceswhendesign-
ing,implementing,andtestingadigitalcircuit.
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viii Preface
Chapter11introducesthetopicoftesting. Adesigneroflogiccircuitshastobeaware
oftheneedtotestcircuitsandshouldbeconversantwithatleastthemostbasicaspectsof
testing.
AppendixAprovidesacompletesummaryofVerilogfeatures.AlthoughuseofVerilog
is integrated throughout the book, this appendix provides a convenient reference that the
readercanconsultfromtimetotimewhenwritingVerilogcode.
TheelectronicaspectsofdigitalcircuitsarepresentedinAppendixB.Thisappendix
showshowthebasicgatesarebuiltusingtransistorsandpresentsvariousfactorsthataffect
circuitperformance. Theemphasisisonthelatesttechnologies, withparticularfocuson
CMOStechnologyandprogrammablelogicdevices.
WhatCanBeCoveredinaCourse
Muchofthematerialinthebookcanbecoveredin2one-quartercourses.Agoodcoverage
of the most important material can be achieved in a single one-semester, or even a one-
quartercourse. Thisispossibleonlyiftheinstructordoesnotspendtoomuchtimeteaching
the intricacies ofVerilog and CAD tools. To make this approach possible, we organized
theVerilogmaterialinamodularstylethatisconducivetoself-study. Ourexperiencein
teachingdifferentclassesofstudentsattheUniversityofTorontoshowsthattheinstructor
mayspendonlythreetofourlecturehoursonVerilog,describinghowthecodeshouldbe
structured,includingtheuseofdesignhierarchy,usingscalarandvectorvariables,andon
thestyleofcodeneededtospecifysequentialcircuits. TheVerilogexamplesgiveninthe
bookarelargelyself-explanatory,andstudentscanunderstandthemeasily.
Thebookisalsosuitableforacourseinlogicdesignthatdoesnotincludeexposureto
Verilog. However, someknowledgeofVerilog, evenatarudimentarylevel, isbeneficial
tothestudents,anditisagreatpreparationforajobasadesignengineer.
One-SemesterCourse
Thefollowingmaterialshouldbecoveredinlectures:
• Chapter1—allsections.
• Chapter2—allsections.
• Chapter3—Sections3.1to3.5.
• Chapter4—allsections.
• Chapter5—allsections.
• Chapter6—allsections.
One-QuarterCourse
Inaone-quartercoursethefollowingmaterialcanbecovered:
• Chapter1—allsections.
• Chapter2—allsections.
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Preface ix
• Chapter3—Sections3.1to3.3andSection3.5.
• Chapter4—allsections.
• Chapter5—allsections.
• Chapter6—Sections6.1to6.4.
Verilog
Verilogisacomplexlanguage,whichsomeinstructorsfeelistoohardforbeginningstudents
tograsp. Wefullyappreciatethisissueandhaveattemptedtosolveit. Itisnotnecessary
to introduce the entire Verilog language. In the book we present the important Verilog
constructsthatareusefulforthedesignandsynthesisoflogiccircuits. Manyotherlanguage
constructs,suchasthosethathavemeaningonlywhenusingthelanguageforsimulation
purposes,areomitted. TheVerilogmaterialisintroducedgradually,withmoreadvanced
featuresbeingpresentedonlyatpointswheretheirusecanbedemonstratedinthedesign
ofrelevantcircuits.
Thebookincludesmorethan120examplesofVerilogcode. Theseexamplesillustrate
howVerilogisusedtodescribeawiderangeoflogiccircuits,fromthosethatcontainonly
afewgatestothosethatrepresentdigitalsystemssuchasasimpleprocessor.
AlloftheexamplesofVerilogcodepresentedinthebookareprovidedontheAuthors’
websiteat
www.eecg.toronto.edu/∼brown/Verilog_3e
SolvedProblems
The chapters include examples of solved problems. They show how typical homework
problemsmaybesolved.
HomeworkProblems
Morethan400homeworkproblemsareprovidedinthebook.Answerstoselectedproblems
aregivenatthebackofthebook. Solutionstoallproblemsareavailabletoinstructorsin
theSolutionsManualthataccompaniesthebook.
PowerPointSlidesandSolutionsManual
PowerPointslidesthatcontainallofthefiguresinthebookareavailableontheAuthors’
website. Instructors can request access to these slides, as well as access to the Solutions
Manualforthebook,at:
www.mhhe.com/brownvranesic