Atmel Studio & ASF开发入门

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1、2015爱特梅尔中国大学技术巡回讲座（一）APPLICATIONNOTEAtmelAN-6397:SAMD21DMACTrainingASFPROJECTDOCUMENTATIONIntroductionThedatatransferbetweenmemoriesandperipheralsisanessentialpartofmicrocontrollerbaseddesigns.Normally,theCPUofthemicrocontrollermanagesthedatatransferbetweenvariousperipheralsandmemory.Thedrawbackin

2、thiscaseisthattheCPUwillhavetouseconsiderableamountofprocessingtimetomanagethisdatatransfer.WiththeintroductionofDirectMemoryAccessController(DMAC),thememoriesandperipheralscantransferdatadirectlywithoutCPUintervention.ThiswillreducetheCPUusagefordatatransfer.ThenCPUcanbeutilisedtodootherprocessin

3、g.TheCPUcanbeinlowpowermodeforlongertimetosavemorepower.ItalsoenableshighdatatransferratesasthereisnoCPUoverhead.Thishands-ontrainingmaterialwilldemonstratetheuseofDMACforthedatatransferbetweenperipheralandmemory.TheanalogvoltagemeasuredusingADCwillbetransferredtothedatabufferininternalSRAM.Thecod

4、edevelopedforthistrainingwillusetheADCininputscanmodethatwillscanmultipleADCchannels.WithoutDMA,theCPUreadsADCresultfromADCregisterandthenCPUwritesthatdatatointernalSRAM.ButwithDMAC,theADCreadingswillbetransferreddirectlytomultipledatabuffersinSRAM,withoutCPUintervention.6397-MCU-05/2014TableofCon

5、tentsIntroduction.........................................................................................11.PrerequisitesandIconkeyIdentifiers..........................................31.1.Prerequisites..............................................................................31.2.IconKeyIdent

6、ifiers.....................................................................32.SAMD21DMAC..........................................................................42.1.SAMD21DMACFeatures............................................................42.2.DMABasics.......................................

7、........................................42.3.DMATransferFormatsintheSAMD21..........................................52.3.1.Beat.............................................................................52.3.2.B