HT66F0187 datasheet(37/192 Pages) HOLTEK

37 / 192 page

Rev. 1.20

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Rev. 1.20

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HT66F0187

A/D Flash MCU with EEPROM

HT66F0187

A/D Flash MCU with EEPROM

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

TowritedatatotheEEPROM,theEEPROMaddressofthedatatobewrittenmustfirstbeplaced

intheEEAregisterandthedataplacedintheEEDregister.Thenthewriteenablebit,WREN,

intheEECregistermustfirstbesethightoenablethewritefunction.Afterthis,theWRbitin

theEECregistermustbeimmediatelysethightoinitiateawritecycle.Thesetwoinstructions

mustbeexecutedconsecutively.TheglobalinterruptbitEMIshouldalsofirstbeclearedbefore

implementinganywriteoperations,andthensetagainafterthewritecyclehasstarted.Notethat

settingtheWRbithighwillnotinitiateawritecycleiftheWRENbithasnotbeenset.Asthe

EEPROMwritecycleiscontrolledusinganinternaltimerwhoseoperationisasynchronousto

microcontrollersystemclock,acertaintimewillelapsebeforethedatawillhavebeenwritteninto

theEEPROM.Detectingwhenthewritecyclehasfinishedcanbeimplementedeitherbypollingthe

WRbitintheEECregisterorbyusingtheEEPROMinterrupt.Whenthewritecycleterminates,

theWRbitwillbeautomaticallyclearedtozerobythemicrocontroller,informingtheuserthatthe

datahasbeenwrittentotheEEPROM.TheapplicationprogramcanthereforepolltheWRbitto

determinewhenthewritecyclehasended.

Write Protection

Protectionagainstinadvertentwriteoperationisprovidedinseveralways.Afterthedeviceis

poweredon,theWriteEnablebitinthecontrolregisterwillbeclearedpreventinganywrite

operations.Alsoatpower-ontheMemoryPointerhighbyteregisters,MP1HandMP2H,willbe

resettozero,whichmeansthatDataMemorySector0willbeselected.AstheEEPROMcontrol

registerislocatedinSector1,thisaddsafurthermeasureofprotectionagainstspuriouswrite

operations.Duringnormalprogramoperation,ensuringthattheWriteEnablebitinthecontrol

registerisclearedwillsafeguardagainstincorrectwriteoperations.

EEPROM Interrupt

TheEEPROMwriteinterruptisgeneratedwhenanEEPROMwritecyclehasended.TheEEPROM

interruptmustfirstbeenabledbysettingtheDEEbitintherelevantinterruptregister.However,as

theEEPROMiscontainedwithinaMulti-functionInterrupt,theassociatedmulti-functioninterrupt

enablebitmustalsobeset.WhenanEEPROMwritecycleends,theDEFrequestflagandits

associatedmulti-functioninterruptrequestflagwillbothbeset.Iftheglobal,EEPROMandMulti-

functioninterruptsareenabledandthestackisnotfull,ajumptotheassociatedMulti-function

Interruptvectorwilltakeplace.WhentheinterruptisservicedonlytheMulti-functioninterruptflag

willbeautomaticallyreset,theEEPROMinterruptflagmustbemanuallyresetbytheapplication

program.

HT66F0187 Datasheet(PDF) 37 Page - Holtek Semiconductor Inc

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