HT45F75 datasheet(40/190 Pages) HOLTEK

40 / 190 page

Rev. 1.10

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Rev. 1.10

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HT45F75

Body Fat Scale Flash MCU

HT45F75

Body Fat Scale 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-ontheMemoryPointerhighbyteregister,MP1HorMP2H,willbereset

tozero,whichmeansthatDataMemorySector0willbeselected.AstheEEPROMcontrolregister

islocatedinSector1,thisaddsafurthermeasureofprotectionagainstspuriouswriteoperations.

Duringnormalprogramoperation,ensuringthattheWriteEnablebitinthecontrolregisteris

clearedwillsafeguardagainstincorrectwriteoperations.

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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