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поискавой системы для электроныых деталей |
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поискавой системы для электроныых деталей |
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HT45F4N датащи(PDF) 39 Page - Holtek Semiconductor Inc |
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HT45F4N датащи(HTML) 39 Page - Holtek Semiconductor Inc |
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39 / 170 page  Rev. 1.30 38 De�e��e� 1�� �01� Rev. 1.30 39 De�e��e� 1�� �01� HT45F4N/HT45FH4N Power Bank Flash MCU HT45F4N/HT45FH4N Power Bank Flash MCU Reading Data from the EEPROM ToreaddatafromtheEEPROM,thereadenablebit,RDEN,intheEECregistermustfirstbeset hightoenablethereadfunction.TheEEPROMaddressofthedatatobereadmustthenbeplaced intheEEAregister.IftheRDbitintheEECregisterisnowsethigh,areadcyclewillbeinitiated. SettingtheRDbithighwillnotinitiateareadoperationiftheRDENbithasnotbeenset.When thereadcycleterminates,theRDbitwillbeautomaticallyclearedtozero,afterwhichthedatacan bereadfromtheEEDregister.ThedatawillremainintheEEDregisteruntilanotherreadorwrite operationisexecuted.TheapplicationprogramcanpolltheRDbittodeterminewhenthedatais validforreading. Writing Data to the EEPROM TheEEPROMaddressofthedatatobewrittenmustfirstbeplacedintheEEAregisterandthedata placedintheEEDregister.TowritedatatotheEEPROM,thewriteenablebit,WREN,intheEEC registermustfirstbesethightoenablethewritefunction.Afterthis,theWRbitintheEECregister mustbeimmediatelysethightoinitiateawritecycle.Thesetwoinstructionsmustbeexecuted consecutively.TheglobalinterruptbitEMIshouldalsofirstbeclearedbeforeimplementingany writeoperations,andthensetagainafterthewritecyclehasstarted.NotethatsettingtheWRbit highwillnotinitiateawritecycleiftheWRENbithasnotbeenset.AstheEEPROMwritecycleis controlledusinganinternaltimerwhoseoperationisasynchronoustomicrocontrollersystemclock, acertaintimewillelapsebeforethedatawillhavebeenwrittenintotheEEPROM.Detectingwhen thewritecyclehasfinishedcanbeimplementedeitherbypollingtheWRbitintheEECregisteror byusingtheEEPROMinterrupt.Whenthewritecycleterminates,theWRbitwillbeautomatically clearedtozerobythemicrocontroller,informingtheuserthatthedatahasbeenwrittentothe EEPROM.TheapplicationprogramcanthereforepolltheWRbittodeterminewhenthewritecycle hasended. Write Protection Protectionagainstinadvertentwriteoperationisprovidedinseveralways.Afterthedeviceis powered-ontheWriteEnablebitinthecontrolregisterwillbeclearedpreventinganywrite operations.Alsoatpower-ontheBankPointer,BP,willberesettozero,whichmeansthatData MemoryBank0willbeselected.AstheEEPROMcontrolregisterislocatedinBank1,thisaddsa furthermeasureofprotectionagainstspuriouswriteoperations.Duringnormalprogramoperation, ensuringthattheWriteEnablebitinthecontrolregisterisclearedwillsafeguardagainstincorrect writeoperations. EEPROM Interrupt TheEEPROMwriteinterruptisgeneratedwhenanEEPROMwritecyclehasended.TheEEPROM interruptmustfirstbeenabledbysettingtheDEEbitintherelevantinterruptregister.Howeveras theEEPROMiscontainedwithinaMulti-functionInterrupt,theassociatedmulti-functioninterrupt enablebitmustalsobeset.WhenanEEPROMwritecycleends,theDEFrequestflagandits associatedmulti-functioninterruptrequestflagwillbothbeset.Iftheglobal,EEPROMandMulti- functioninterruptsareenabledandthestackisnotfull,ajumptotheassociatedMulti-function Interruptvectorwilltakeplace.WhentheinterruptisservicedonlytheMulti-functioninterruptflag willbeautomaticallyreset,theEEPROMinterruptflagmustbemanuallyresetbytheapplication program.MoredetailscanbeobtainedintheInterruptsection. |
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