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ID:5316506
大小:539.50 KB
页数:27页
时间:2017-12-08
《005 - resets & interrupts》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、Resets&Interrupts•Power-OnReset•ExternalHardwareReset•CrystalMonitor•ComputerOperatingProperlyRealtimeinterruptPowerOnReset•InitiatedbypositivetransitiononVDD.8192Eclockdelayisbuiltintoallowoscillatortostabilize.VDDCPUCLKDATABUS/ADDRESSBUSIRESET8192ECLKCyclesInternalResetis
2、heldlowbyMCUForabout8192Eclocks•InGeneral:Subsystemsandcontrolbitsareinitializedtohaveleasteffectonsystem(I.e.interruptsmasked,portsreadonly,serialcommunicationdisabled,...)VFPPPV-VECTORFETCHF-FREECYCLEP-PROGRAMFETCHFFFEFFFE1stOpcode2ndOpcode3rdOpcode128ECLKCycles64ECLKCycles
3、External&InternalResets•RESETpinassertedfor>2Eclocks.•RESETpinmustnegatebeforeresetservicecanbegin.•Nodelaytostabilizeoscillator.64ECLKCYCLES32ECLKCYCLESCPUCLKDATABUS/ADDRESSBUSRESETIRESET96EClocksSAMPLEPINFFFEFFFE1stOpcode2ndOpcode3ndOpcodeCrystalMonitor(1of2)Usefulfor:1.Au
4、tomaticResetfromasloworstoppedclock.2.Improvesfaulttoleranceofsystem.Description:IftheEclockdropsbelowafrequencyof10KHZ*andtheCrystalMonitorfunctionhasbeenenabled,then:1.systemresetisassertedontheexternalresetpin.2.CrystalMonitorvectorisfetched.ElseEnterSelfClockModeifEnabled
5、*IFECLOCKFREQUENCY>10KHzand<500KHz,THENACLOCKMONITORRESETMAYOCCUR.(NOTGUARANTEED)Note:CrystalMonitorTime-outrange2usec-150usec.CrystalMonitor(2of2)CrystalMonitorfunctioncanbeenabled/disabledatanytime.PINS:1.RESET–Assertedfor64Eclocks.AddressOffset$0006PLLCTL-CRGPLLControlRegi
6、sterCME-CrystalMonitorEnable1=Monitorisenabled0=MonitorisdisabledWhentheCrystalMonitorisenabled,asloworstoppedclocks,(includingtheStopinstruction)causesacrystalfailureto:1.ResettheMCU(FetchCMVectorfrom$FFFC-$FFFD)or2.Enterself-clockmodeCrystalLoss/Stop&ResetRecoverySequenceCM
7、E=1&SCME=0?MCUResetsInterrupt?CME=1&SCME=0?StopModeCount8192OSCLKSCME=1?Clock?WaitforClockClocksReleasedClock?MCUResetsCount8192OSCLKClock?AssertSCM&SCMIFMCUEntersSelfCMCount8192OSCLKClock?NegateSCMClocksresumeNormalOperationResumeNormalOperationClockFailedStopInstructionPowe
8、r-OnYesYesNoNoYesYesYesYesYesYesNoNoNoNoNoNoNote1:CrystalMonitorTime
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