LPC1700之用DMA方式将内存数据传送到DAC的应用示例.pdf

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1、AN10917MemorytoDACdatatransfersusingtheLPC1700'sDMARev.01—8March2010ApplicationnoteDocumentinformationInfoContentKeywordsLPC1700,DMA,DAC,ADC,Timer0,Memory-to-PeripheralAbstractThisapplicationnotecoversapplicationdetailsonperformingmemory-to-DACDMAtransfers.Theapplication

2、examplesgeneratesineandtriangularwaveformsontotheDAC.NXPSemiconductorsAN10917MemorytoDACDMAtransfersRevisionhistoryRevDateDescription0120100308Initialversion.ContactinformationForadditionalinformation,pleasevisit:http://www.nxp.comForsalesofficeaddresses,pleasesendanemai

3、lto:salesaddresses@nxp.comAN10917_1Allinformationprovidedinthisdocumentissubjecttolegaldisclaimers.©NXPB.V.2010.Allrightsreserved.ApplicationnoteRev.01—8March20102of23NXPSemiconductorsAN10917MemorytoDACDMAtransfers1.IntroductionThisapplicationnoteservesasaquickintroducti

4、ontotheLPC1700’smemory-to-DACDMAtransfersfunctionality.ItwillprovideasimpledescriptiononhowtheDMAcanbeusedtogenerateanoutputontotheDACwithoututilizingtheCPU.AdetailedfeaturedescriptionoftheperipheralslistedbelowcanbefoundintheLPC1700usermanual.1.1DMADatatransferscanrequi

5、realotofCPUtimeperformingloadandstoreinstructions.WhenusingaDirectMemoryAccess(DMA)controller,theCPUisfreeduptoexecuteotherinstructions.TheDMAcontrollerintheLPC1700supportsmemory-to-memory,memory-to-peripheral,peripheral-to-peripheral,andperipheral-to-memorytransfers.Wit

6、htheuseoflinkedlists,italsosupportsscatterorgathermodes.Thesemodesenabledatatransfersfromnon-contiguousareasofmemory.Sincetheclockisfunctioningduringsleepmode,itcanalsoperformDMAtransfersto/fromAHBSRAMblocks.1.2Timer0TheLPC1700featuresfourconfigurable32-bittimer/counters

7、.1.3ADCAnAnalog-to-DigitalConverter(ADC)capturesanexternalvoltageandrepresentsitasadigitalvalue.TheLPC1700containsan8-channelmultiplexed12-bitsuccessiveapproximationADC.1.4DACTheDigital-to-AnalogConverter(DAC)createsanoutputvoltagefromacorrespondingdigitalinputvalue.TheL

8、PC1700featuresadoublebuffered10-bitDACthatcangeneraterepetitiveDMArequestsusinganinternalcountdowncount