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Design_0

    Design

29卷第3

    ;20083

    ;仪器仪表学报

    ;ChineseJournalofScientificInstrument

    ;Vo1.29No.3

    ;Mar.2008

    ;DesignandrealizationofdigitalaudioequalizerbasedonMCUandFPAA ;ZhouPing,LiuZhuo,XiaLiang

    ;fJGuilinUniversityofElectronicTechnology,Guilin541004,China) ;2DeUniversityofTechnology,Holand)

    ;Abstract:Inana1ogaudioequalizer,thefiltersareconstructedbyopamplifi

    ersanddiscretecomponents.Beingin

    ;fluencedbvitsdiscretecapabilities,audioequalizerhasmanydisadvantages.Meanwhile,puredigitalaudioequaliz

    ;erhasgotbetterperformaneeandstability,butitscostandpricearetoohigh.Sodigitalaudioequalizeronlyhasits

    ;applicationinupscaledomain.Anewdesignmethodforaudioequalizerisproposed,whichattemptstodesignand

    ;realizeahighprecisionandhighSNR(signalnoiseratio)digitalaudioequalize

rsystembasedonfieldprogrammable

    ;ana1oga1Tav(FPAA)andmicrocontrollerunit.Thisdesignconfirmsthatdesignspeedandperformancewillbe

    ;greatlyenhancedwhenFPAAtechnologyisappliedtoanalogdesigndomain.

    ;Keywords:FPAA;MCU;audioequalizer

    ;1Introduction

    ;Beinganimportantaudioadjustmentfacility,audioequal

    ;izerperformsapivotalfunctioninmusicstyleadjustment. ;Withfastdevelopmentofmediatechnology,audioequalizer ;designsuffersanunprecedentedpressuretofurtherimprove ;itsperformanceandpracticability.

    ;Inprimaryapplication,theaudioequalizerwithlessthan ;10segmentsisthemostuniversalchoice.Theaudioequaliz

    ;erwithmorethan31segmentshasabetterimpactonthe ;soundtuningup.Butitsapplicationislimitedinprofession

    ;aldomain,becauseofitshighercost,higherpriceanddiffi

    ;cuhyintuningupproperly.Inthefiltersofcurrentaudioe

    ;qualizer,theanaloginductanceisconstructedbyoperational ;amplifier,resistorsandcapacitors.Filterperformanceis ;closelyrelatedtotheaccuracyandtemperaturevariabilityof ;thediscretecomponents.Whendesigningahighperform

    ;anceaudioequalizer,agreatdealofnonstandardandhigh

    ;precisiondiscretecomponentsarerequired,therefore,the ;productioncostsincrease.Meanwhile,thefiltersystemof ;audioequalizerisconstructedbyoperationalamplifierand ;discretecomponents,whichneedmuchlargerPCBareaand ;takemuchroomintheaudioequalizerfacility.especiallyin ;realizingaudioequalizerwithmorethan31segments. ;Anewdesignideaofaudioequalizerisproposedbasedon ;thecombiningmicrocontrollerunit(MCU)andfieldpro

    ;grammableanalogarray(FPAA);thenewaudioequalizer ;willmakethequalityfactor(Q)andcenterfrequency(fc) ;dynamicallyeonfignrable.Furthermore,FPAAisanad

    ;vancedanalogprogrammabletechnologybasedonhighpreci

    ;sionswitchcapacitancetechnology.Itsperformanceisrela

    ;tivelystableduringchangesoftemperatureandvoltage.With ;thereconfigurablecharacteristic.FPAAsupportsdynamic ;andstaticprogramming,soastoimprovetheaudiosignal ;processingprecisionandeffect.WhenFPAAisusedtode

    ;signthefiltersystemoftheaudioequalizer,highdegreeof ;systemintegrationisachieved,resultinginasmallPCBarea ;andhighreliability.Moreover,intheaudioequalizerwith ;31ormoresegments,thesystempowerconsumptionwillbe ;cutdowntoitsminimum.

;BasedonAtmel89S51,AtmelAT17seriesEEPROM

    ;AT17C128andAnadigmFPAAICAN221E04,anewaudio ;equalizerwasdesigned.Itfeatureshighprecision,highreli

    ;abilityandlowpowerconsumptioncharacteristics.Especial

    ;ly,itrealizesfilterparameterstaticanddynamiccontro1. ;2Designconcepts

    ;Filtersystemisthemostpivotalpartoftheaudioequaliz

    ;er;itsprecisionandeffectinfluencethewholeaudioequaliz

    ;erperformance.WhenusingFPAAICAN221E04,devel

    ;ReceivedDate:2007-01收稿日期:200712

    ;$Foundationitem:SupposedbytheGuangxiNaturalScienceFund(0640173) ;

    ;484仪器仪表学报第29

    ;opedbyAnadigm,toconstructthefilters,amplifiersand ;signalintegrationsystemoftheaudioequalizer,highintegra

    ;tion,highfilterprecision,goodanti-jammingcapability, ;goodsystemstabilityandlowpowerconsumptionarea

    ;chieved.Gettingridoftheinfluencesofdiscretefilterdesign ;onprecisionandtemperaturecharacteristicandreducingthe ;quantityofhighprecisionnonstandarddiscretecomponents, ;FPAAtechnologyenhancesthefiltersystemperformanceand ;reducesthecosts.

    ;FPAAICAN221E04hastheprogrammablecharacteristic ;inanalogsignalprocessingequivalenttoFPGA(fieldpro

    ;grammablegatearrays)ICindigitalsignalprocessing. ;AN221E04isthemainchipemployedinthisinnovativede

    ;signconcept.Foureonfigurableanalogblocks(CAB)are ;embeddedinanAN221E04chip,thefunctionandstructure ;ofCABissimilartothatoftheeonfigurablelogicblock ;(CLB)inFPGA.Fig.1showstheCABinnerstructure. ;C0n?DlIShadowSRAM

    ;LogicIConfiguralnSRAM

    ;AnalogyClocksLook-UPTablcSARClock

    ;Fig.1CABinnerstructure

    ;Anewdesignconceptinaudiofilterdesignisconceived ;basedonhardwareplatformofFPAA,anddevelopedbyAna

    ;digmspecialEDAsoftwareAD2(AnadigmDesigner2),in

    ;cludingvariousreadyeonfigurableanalogmodules(CAM) ;inAD2,whichrealizetheprimaryanalogfunctions.Each ;CABcanbeusedtodesignfiltersfrom2to8-orders,which ;includesButterworth,Chebyshev,EllipticandBesselfil

    ;ters.Forinstance,a6-orderButterworthswitchcapacitance ;bandpassfilterisdesignedbasedonAD2.Thedesign ;schemeusingAD2isshowninfig.2.

;1kHzBPF

    ;Fig.26-orderButterworthbandpassfilterdesign ;Thefrequencyresponseofthe6-orderButterworthband ;passfilterisshowninfig.3.

    ;Frepuencyresponse/

    ;Fig.36-orderButterworthbandpassfilter~equeneyresponse ;ForAN221E04towork,itneedstobeprogrammed.The ;configurationdatashouldbewrittenintoadatafile.andthen ;aprogrammerisusedtoburnthedataintoanEEPROM. ;Meanwhile,audioequalizerrequiresatleast5musiceffect ;options,SO5moreconfigurationdatafilesareneeded,which ;areNormal,Pop,Rock,JazzandClassic.Afterallthedata ;areburnedintotheEEPROM.MCU89S51wil1contro1the ;configurationprocedure.

    ;3Realizationandsimulation

    ;Butterworth,Chebyshev,EllipticandBesseltype8-order ;lowpassfiltersweredesignedrespectively,andthepass ;bandinnerrippleofthefiltersis1dB,thefrequencyre

    ;sponsecurvesforeachtypefilterareshowninfig.4. ;?譬旨已如目0F,三岢苫

    ;

    ;3

ZhuoPingetal:Designandrealizationofdigitalaudioequ~izerbased0nMCUa

    ndFPAA485

    ;Fig.48-orderlowpassfilterfrequencyresponsecomparison ;Throughcomparison,wechoseButterworthfilterandE1

    ;lipticfiltertodesignthefiltersystemoftheaudioequalizer, ;andchosethemostsuitablefiltertypetostartthesystem ;hardwaredesign.

    ;Theaudioequalizerwith7-segmentsand1--octavewasde-- ;signed.Thecenterfrequencyofthebandpassfilterisselect

    ;edas125Hz,250Hz,500Hz,1kHz,2kHz,4kHzand

    ;8kHz.Thepassbandgainsofeachbandpassfilterindif- ;ferentmusicstylesareshownintable1.

    ;Table1Passbandgainsetting

    ;Accordingtotable1,theAD2specialfilterdesigntool ;AnadigmFilterisusedtodesignButterworthandElliptic ;bandpassfiltersystemindifferentsoundstyles.Theaudio ;equalizerfrequencyresponsesoftheButterworthfiltersystem ;areshowninfig.5.

    ;Freguencymsponse/Hz

    ;Fig.5Butterworthfilterequalizer~equencyresponses ;TheEllipticfiltersystemfrequencyresponsesof5kindsof ;soundstylesareshowninFig.6

    ;ThroughcomparingFig.5andFig.6,thetransitionband ;snloothnessofthefrequencyresponsecurveintheButter

    ;Worthfiheraudioeuualizerisveryclosetothatofthefre

    ;quencyresponsecurveoftheidealsoundstyles. ;Therefore,weselectButterworthfiltertodesignthenew ;filtersystemoftheaudioequalizer.

    ;Freguencyresponse/Hz

    ;Fig.6Ellipticfilterequalizerfrequencyresponses ;4Systemsimulationresults

    ;Somemusicsectionsweretakenastheoriginalaudiosig

    ;nalinput,andeachmusicstylewasinputtedintoFPAAar

    ;raycircuit.TheresponsesofNonnalstylesimulationand ;Rockstylesimulationareshowninfig.7andfig.8. ;Rock......——

    ;originalaudiosignalinput

    ;Time/ms

    ;Fig.7Normalstylesimulations

    ;Rock......——

    ;originalaudiosignalinput

    ;Time/ms

    ;Fig.8Rockstylesimulations

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    ;486仪器仪表学报第29

    ;5Systemrealization

    ;InAnadigmDesigner2,themaximumallowednumberof ;FPAAICsis20inoneanalogcircuit.Thisdesignuses10 ;FPAAICsAN221E04.including1for20kHzlowpassfil. ;ter.7for1octavebandpassfilterand2forbandpassfilter. ;ThefirstAN221E04issettoMODE1.theothersin ;M0DE0.Withdifferentmusicstyles.FPAAcircuitdata ;filesarenamedasNormal,Pop,Rock,JazzandClassic, ;andtheyarewrittenintodifferentEEPROMsusingEEPROM ;programmer.MCUisusedtocontrolFPAAarrayprimary ;configurationandmusicstyleswitch.Thesystemhardware ;platformdesignoftheaudioequalizerisshowninfig.9. ;Fig.9Systemhardwareplatformdesign

    ;Systemcircuitworkingprocedure:

    ;(1)Systempowerup.Twoexternalcrystalsareused, ;oneis16MHzactivecrystal,whichprovidesclockfor ;MODElAN221E04chip,andtheotheris11.592MHzpas- ;sivecrystal,whichprovidesclockformicro-controllerAtmel ;89S51.FPAAarraywillloadNormalsoundstyledatatoper- ;formprimaryconfigurationwithoutanyexternalcontrolsig- ;na1.

    ;(2)Whenanothersoundstyleneedstobetransferred, ;justpressthekeycorrespondingtothemusicstyleID,and ;thentheMCUwillresponsethecontrolsignalandloadthe ;configurationdatafromcorrespondingEEPROMtoFPAAar- ;ray.Afterthereconfigurationiscompleted,thesystemwill ;workintheupdatedstructureandnewcircuitparameters. ;(3)Audiosignalinput/outputmodule.Theinput/output ;audiosignalwillbepre-amplified,andthende.noises.Dur- ;ingtheprimaryconfigurationanddynamicreconfiguration, ;thepreviousstyleaudiowillbepausedforabout30ms, ;how.

    ;everitwillbeneglectedbyhumanhearing.

    ;6Conclusion

    ;ThePFAAarrayfiltersystemdemonstratesagoodperform- ;anceintheaudioequalizer.Thenewconceptoftheaudioe-

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