HT66FV240 datasheet(41/203 Pages) HOLTEK

41 / 203 page

Rev. 1.40

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Rev. 1.40

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HT66FV240

Wireless Voice Flash MCU

HT66FV240

Wireless Voice Flash MCU

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-ontheMemoryPointerhighbyteregister,MP1H,willberesettozero,

whichmeansthatDataMemorysector0willbeselected.AstheEEPROMcontrolregisterislocated

insector1,thisaddsafurthermeasureofprotectionagainstspuriouswriteoperations.During

normalprogramoperation,ensuringthattheWriteEnablebitinthecontrolregisterisclearedwill

safeguardagainstincorrectwriteoperations.

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.

HT66FV240 Datasheet(PDF) 41 Page - Holtek Semiconductor Inc