飞思卡尔后背资料2.ppt

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1、Resets&Interrupts•Power-OnReset•ExternalHardwareReset•CrystalMonitor•ComputerOperatingProperlyRealtimeinterruptPowerOnReset•InitiatedbypositivetransitiononVDD.8192Eclockdelayisbuiltintoallowoscillatortostabilize.VDDCPUCLKDATABUS/ADDRESSBUSIRESET8192ECLKCyclesInternalResetisheldl

2、owbyMCUForabout8192Eclocks•InGeneral:Subsystemsandcontrolbitsareinitializedtohaveleasteffectonsystem(I.e.interruptsmasked,portsreadonly,serialcommunicationdisabled,...)VFPPPV-VECTORFETCHF-FREECYCLEP-PROGRAMFETCHFFFEFFFE1stOpcode2ndOpcode3rdOpcode128ECLKCycles64ECLKCyclesExternal&I

3、nternalResets•RESETpinassertedfor>2Eclocks.•RESETpinmustnegatebeforeresetservicecanbegin.•Nodelaytostabilizeoscillator.64ECLKCYCLES32ECLKCYCLESCPUCLKDATABUS/ADDRESSBUSRESETIRESET96EClocksSAMPLEPINFFFEFFFE1stOpcode2ndOpcode3ndOpcodeCrystalMonitor(1of2)Usefulfor:1.AutomaticResetfro

4、masloworstoppedclock.2.Improvesfaulttoleranceofsystem.Description:IftheEclockdropsbelowafrequencyof10KHZ*andtheCrystalMonitorfunctionhasbeenenabled,then:1.systemresetisassertedontheexternalresetpin.2.CrystalMonitorvectorisfetched.ElseEnterSelfClockModeifEnabled*IFECLOCKFREQUENCY>1

5、0KHzand<500KHz,THENACLOCKMONITORRESETMAYOCCUR.(NOTGUARANTEED)Note:CrystalMonitorTime-outrange2usec-150usec.CrystalMonitor(2of2)CrystalMonitorfunctioncanbeenabled/disabledatanytime.PINS:1.RESET–Assertedfor64Eclocks.AddressOffset$0006PLLCTL-CRGPLLControlRegisterCME-CrystalMonitorEna

6、ble1=Monitorisenabled0=MonitorisdisabledWhentheCrystalMonitorisenabled,asloworstoppedclocks,(includingtheStopinstruction)causesacrystalfailureto:1.ResettheMCU(FetchCMVectorfrom$FFFC-$FFFD)or2.Enterself-clockmodeCrystalLoss/Stop&ResetRecoverySequenceCME=1&SCME=0?MCUResetsInterrupt?

7、CME=1&SCME=0?StopModeCount8192OSCLKSCME=1?Clock?WaitforClockClocksReleasedClock?MCUResetsCount8192OSCLKClock?AssertSCM&SCMIFMCUEntersSelfCMCount8192OSCLKClock?NegateSCMClocksresumeNormalOperationResumeNormalOperationClockFailedStopInstructionPower-OnYesYesNoNoYesYesYesYesYesYesNoN

8、oNoNoNoNoNote1:CrystalMonitorTime