Understanding Stratix IIIProgrammable IO Delay Settingsin the Quartus II Software了解Stratix IIIProgrammable I_O延迟设置 在Quartus II软件中

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1、UnderstandingStratixIIIProgrammableI/ODelaySettingsintheQuartusIISoftwareNovember2007,ver.1.0ApplicationNote474IntroductionAltera®Stratix®IIIseriesdeviceshaveaveryversatileI/Oarchitecture.IncludedinthevariousfeaturesoftheStratixIIII/Oareoptionsforskewmanagementinyoursystems.The

2、StratixIIII/Ohasvariousphysicalprogrammabledelayelementsinitsarchitecture.Usingtheoptiontoprogramthesedelayelementswithdifferentsettingsprovidesamethodforskewmanagement.Skewmanagementisanadvancedtechniquethatcanbeusedinsomecasestomitigatetimingproblemsinyoursystem.Totakeadvanta

3、geofthistechnique,youmustunderstandhowprogrammabledelayelementsinStratixIIII/OdevicesarepresentedandassignedintheQuartus®IIsoftware.Thisdocumentdescribestheprogrammabledelayelementsettings,themethodstoconfigurethem,andsomeapplicationsinwhichtheprogrammabledelayelementsarereprog

4、rammedtoovercomeatimingproblem.StratixIIII/Oprogrammabledelayelementsareconstructedandstaggeredtoprovideyouwithversatilesolutionsforcoarseandfinetuningofdelays.Whenyoutunedelays,youaremanagingtheskewbetweenvarioussignalsinyoursystem.Circumstancesinwhichyoucanuseskewmanagementwi

5、thprogrammabledelayelementsinclude:■Toskewordeskewdatasignalstoorfromabusofpinstocompensateforprocessvariationsinthedie,package,circuitboard,andexternalinterfacingdevices.■Toskewsimultaneousswitchingoutput(SSO)signalstomitigateanysimultaneousswitchingnoise(SSN)problems■Toskewor

6、deskewdatasignalsonDDRinterfacestomitigateanyDDRreadandwriteproblems■Toskewordeskewinputdatasignalstothedevicetomeettimingperformance■Toincreaseordecreasesetuptimes(tSU)withinthecore■Toincreaseordecreaseclock-to-output(tCO)timeswithinthecoretimingThisdocumentincludesthefollowin

7、gtopics:■“DelayElementsOverview”onpage2■“SkewManagementintheDesignCycle”onpage4■“DelayElementsReport”onpage7■“ChangingtheProgrammableDelaySettings”onpage7■“Example:ManagingSkewatOutputs”onpage15AlteraCorporation1AN-474-1.0PreliminaryUnderstandingStratixIIIProgrammableI/ODelaySe

8、ttingsintheQuartusIISoftwareDelayElementsOneoftheprima