单片机信号发生器中英文对照外文翻译文献.docx

单片机信号发生器中英文对照外文翻译文献.docx

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单片机信号发生器中英文对照外文翻译文献

中英文资料翻译

DesignofDigitalControlledSignalGeneratorBasedonDDSandMCU

Keywords:

DDS;MCU;Signalgenerator;PhaseAccumulator;DAC

Abstract.ItsadvantagetouseDDSchipisoutputsignalfrequencybigger,andprecisionhigher,Butuserscan'tchangetheoutputsignalwaveforms.TheMCUcanproducetherequiredarbitrary

waveforms,butitsprogramexecutionoftheorderlimitthespeed.SoweusetheirSynergytodesignthedigitalcontrolledsignalgenerator.TheSystemhastheadvantageofoutputgoodqualitywaveform,frequencyofprecisionandstability,andhighfrequency,empty,amplitudeandphaseistostepintotheneed.

Introduction

Thedigitallysynthesizedsinewaveform（DirectDigitalSynthesis,DDS）isawell-knownmethodandhasbeenappliedtomanyembeddedapplications[1].Thistechniquecanbeusedtocreateapositivedigitalsinewaveform.Comparedtootherfrequencycomposingmethod,DirectDigitalFrequencySynthesis（DDS）hasbeenthemostpopulartrendinmodernfrequencysynthetictechniqueforitsexcellentcharacteristics.ThesignalsourcethattheDDStechnologyrealizescancarryoutaccuratecontrollingonDDSfrequency,extent,phaseexportingwaveform'setc.bynumericalcontrolcircuit,thesystemmakinguseofthismethodhasmanymeritssuchasstability,reliablyandaccuracy.

ThecommercialDDSchipcanonlyexportasinewaveforthedataintheROMformalreadyhasbeensolidified.Ifneedingtocomeintobeinganywaveform,itmaycometruebythewaythatFPGAadoptsDDSIPcoreorhardwaredescribelanguageetc,however,thecostofThiswaycostishigh;ontheotherhand,anywaveformcanbeachievedbymakinguseofmicrocontrollerunit（MCU）tocarryoutfigurefrequencycombiningandDAconverting.TheexperimentandapplyingtestinghaveshownthatthenumericalcontrolsignalsourcecomposedofSTM32microcontrollerandDDSchipcanworkwell.

DDSandwaveformprogrammingpattern

ThecoreofDDSsystemisphaseaccumulatorcarriage,anditiscomposedofaADRandoneunitphaseregister.Whenanyclockcomes,thephaseregisterincreasesbywiththesteplength,phaseregisteroutputandphasecontrolwordaddtogether,andthentheoutputisimportedtosineinquiryformaddress.

Thesineinquiringformincludesthenumeralextentinformationofone-periodsinewave,each

addresscorrespondstothephasedotof0~360degreesofthesinewave.ThemappingdigitalsignaldrivesDACandoutputsanalogvalue.Theoutputsinecircleandfrequencyare

Thephaseregisterwillreturntotheoriginalstatewhenthe2N/Mfcclockisfinished.Accordingly,theDDSsystemoutputasinewavewhenthesineinquiringformfinishacircle.TheoutputsinecircleandfrequencyisTO--outputsinewavecircle,unit:

s;TC--externalreferencedclockcircle,unit:

s;M--accumulatedsteplengthofphaseregister,constant;fout--outputsinewavefrequency,unit:

Hz;fc--externalreferencedclockfrequency,unit:

Hz;N--phaseaccumulatordigit,constant.

Therelationshipamongthefrequencycontrolword,andtheoutputsignalfrequencyandthe

referencedclockfrequencyare:

Frequencycontrolwordisdirectlyproportionaltotheoutputsignalfrequency.Inordertodescribeclearly,thesinewaveformisasonevectorturnsaroundphasecircle,thephasecirclematchesalongwithacyclesinewave.Everysamplingpotsinwaveformcorrespondstoaphasedotofthephasecircle.

Tosynthesistherequiredfrequencysignal,itneedstoaccomplishthefollowingsteps

1.Controllingeverysamplingincrementofphaseandaccumulatingthem（frequencycontrolwordK）,output2picumulatedphase（usingphaseaccumulator）.

2.Converting2piaccumulatingphaseintothecorrespondingsineamplitude,useROMtostorethecorrespondingphase-extentformofsinefunctioningeneral.

3.UseDACtochangeextentcodeintothesignalsimulatingvoltage.

4.ThevoltagesignalthatDACexportsisladderwaveform,therequiredsimulationvoltageoutisachievedafterLPFsmoothing.

NumericalcontrolDDSsignalsourcesystemdesignsanalysis

SystemusestheSTM32ascontrolcoreandtheAD9850asgenerator.STM32is32-bitARM-basedmicrocontrollerwith128Kbyteflashmemory.

ThetwosignaloutputofSTM32canbeachievedbycontrollingAD9850andDAC0832outputsimultaneously.ThesystemdesignsblockdiagramisshowninFig.1.Onesignaloutputcangenerate30MHzsinewaveandrectangularwavebycontrollingAD9850,theotheroutputgenerateanywaveformwithitsfrequencylessthan10KHzbynumericalfrequencymixtureofDAC0832.

Fig.1Systemdesignsblockdiagram

Hardwaredesign

AD9850module

AD9850containstheDDSsystemandhigh-speedcomparator.TheAD9850canrealizetheentirenumericalfrequencycombining.ThecoreoftheprogrammableDDSisthephaseaccumulator,itiscomposedofaADRandaNbitphaseregister,Nisfor24~32.

Afterconnectingtotheaccurateclocksourceandwritingthefrequencyphasecontrolword,

AD9850cangeneratethefrequency-programmableandphase-programmableoutputofanalogsinewave,whichcanbeusedasthedirectfrequencysignalsourceorbetransferredintorectangularwavethroughhigh-speedcomparator.

Withthe125MHzclock,32-bitfrequencycontrolwordcancarryouttheoutputfrequency

resolutionratioofAD9850with0.0291Hz[4].

DAC0832module

ThecircuitexportsthephasedatasheettoDAC0832fromSTM32andgetscorrespondingwaveformbyDAconverting.Thestep-by-stepadjustingphaseamountscancreatearbitraryfrequency,thePWMsignalfromtheSTM32transfersintothecorrespondingvoltagebylow-passfilter,therefore,thereferencedvoltageofDAC0832iscontrolled,furthermore,theoutputwaveformextentistunedappropriately.ThedigitaltoanalogconversioncircuitisshowninFig.2

Fig.2DACcircuit

PWMconvertingDAcircuit

Thelow-passfilteredPWMsignalfromSTM32isthenstableusingthevoltagefollower,whichwillyieldastableoutputvoltage;thevoltagecanbeadjustedbytuningthePWMdutyfactor.ThesystemoutputthreePWMsignals,whichcontrolsAD9850outputextent,dutyfactorandtheoutputextentofDAC0832,respectively,.Fig.3showsthePWMcontrolsDAtransferringcircuit.

Fig.3PWMcontrolledDAconvertingcircuit

Fig.4Exportamplificationandthewavefilteringcircuit.（a）amplificationcircuit;（b）filtering

circuit

Amplificationandwavefilteringcircuit

Theamplificationcircuitwillexportamplifiedwaveformandmodifythefactorofamplification.Anexcellentsmoothoutputwaveformcanbeachievedbyusingthelow-passactivepowerfiltering.TheamplificationcircuitandthefilteringcircuitisshowedinFig.4.

Softwaredesign

AndthesystemsoftwaremainlyincludeAD9850drivingmodule,DAC0832drivingmodule,thestep-by-stepautomationmodule,PWM-converting-DAmoduleanduC/GUIfiguresupporting

systemimplantedinprocedure.Theoperationinterfaceisfullofhumanizationforthemulti-windowpatternisadopted.ThedesignprocessofthesystemsoftwareisshowninFig.5.

ImplanteduC/GUI

ThenumericalcontrolsignalsourcehasusedtheuC/GUIsoftwaresufficientlytoestablishmanywindowsandcontrolbuttons.Bymeansofinvokingthecorrespondingwindowsandcontrolwiththefeedbackinformation,theperipheralequipmentoperatedunderthecontrolofthesystem.

Theexternalequipmentismainlyseparatedintotwodrivers,thedrivebeinganAD9850moduleandDAC0832moduledrive,respectively.Thetwomodulescanbecontrolledbymeansoftheoutsideinterruptionandtiminginterruption.

AD9850Drive

AD9850has40controlwords,amongthem,32-bitisusedforfrequencycontrol,5-bitisusedforthephasecontrol,1-bitisusedforthepowersourcedormancycontrol,2-bitisusedtochooseoperationpattern.

Fig.5Systematicprocedureflowchart

This40controlwordsmayarriveatAD9850byconcurrencewayorserialway,intheconcurrenceway,8datahighwaygeneralscantransferthedatatoaregister.

Afterrepeating5times,the40-bitdataisloadedintothefrequency/phasedataregister（forrefreshingDDSoutputfrequencyandphase）attheFQ-UDrisingedge,meanwhile,theaddresspointerisresettothefirstinputregister

Thenthe8-bitdataisloadedattheW-CLKrisingedge,andthepointerissettothenextinputregister.Afterrepeating5timesofW-CLKrisingedge,theW-CLKrisingedgewillworknolongeruntiltheresetsignalcomesortheaddresspointerisresettothefirstinputregisterbytheFQ-UDrisingedge.

TheprocedureoperateAD9850modulethroughthebottomfunction,as

voidad9850（

doublefrequency,//frequency

unsignedcharphase,//phase

unsignedcharmode,//pattern

unsignedcharpower//source

）

TheDAC0832drivenmodule

Inthedesignofthenumericalcontrolsignalsource,DAC0832isdefinedassinglebuffered

pattern,whenthe8bitParalleldataD0~D7isinput,theDAwilltransferdataintheCS.

ThebottomfunctionofvoidDA0832（u8value）caninvokeOut_To_DDS0832（double

Frequency,u8type）functionandcontrolthedefinedwaveformandfrequency.

Thisfunctionisbasedonfigurefrequencycomposesprinciple,ittransferstheinputfrequencyintocorrespondingcontrolword,andthencombingphasestep-by-stepexpect,outputwaveformdatasheetinmemory.

TheextentanddutyfactorcanbetunedthroughinvokingAdjust_Vpp（）andAdjustDuty（）

Step-by-stepautomationprocedure

Astep-by-stepautomationprocedurebrickisaddedtothedesigntodefinethefrequencyrange,step-by-steprate,step-by-stepamounts,ascendingorlapse,cyclingpattern.

Thestep-by-stepautomationfunctioncanberealizedthroughinvokingAutoStep（AutoStepStr*AS）andpassingmemorystructuretypetoafunction.

Testtheexperimentanddataan