HT66F0042 datasheet(39/178 Pages) HOLTEK

39 / 178 page

Rev. 1.30

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Rev. 1.30

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HT66F0042/HT66F0082

A/D Flash MCU with EEPROM

HT66F0042/HT66F0082

A/D Flash MCU with EEPROM

Programming Considerations

CaremustbetakenthatdataisnotinadvertentlywrittentotheEEPROM.ProtectioncanbePeriodic

byensuringthattheWriteEnablebitisnormallyclearedtozerowhennotwriting.AlsotheBank

PointercouldbenormallyclearedtozeroasthiswouldinhibitaccesstoBank1wheretheEEPROM

controlregisterexist.Althoughcertainlynotnecessary,considerationmightbegiveninthe

applicationprogramtothecheckingofthevalidityofnewwritedatabyasimplereadbackprocess.

WhenwritingdatatheWRbitmustbesethighimmediatelyaftertheWRENbithasbeensethigh,

toensurethewritecycleexecutescorrectly.TheglobalinterruptbitEMIshouldalsobecleared

beforeawritecycleisexecutedandthenre-enabledafterthewritecyclestarts.Notethatthedevices

shouldnotentertheIDLEorSLEEPmodeuntiltheEEPROMreadorwriteoperationistotally

complete.Otherwise,theEEPROMreadorwriteoperationwillfail.

Programming Examples

Reading data from the EEPROM – polling method

MOV A,EEPROM_ADRES ;userdefinedaddress

MOV EEA,A

MOV A,040H;setupmemorypointerMP1

MOV MP1,A ;MP1pointstoEECregister

MOV A,01H;setupBankPointer

MOV BP,A

SET IAR1.1 ;setRDENbit,enablereadoperations

SET IAR1.0 ;startReadCycle-setRDbit

BACK:

SZ IAR1.0 ;checkforreadcycleend

JMP BACK

CLR IAR1;disableEEPROMwrite

CLR BP

MOV A,EED ;movereaddatatoregister

MOV READ_DATA,A

Writing Data to the EEPROM – polling method

MOV A,EEPROM_ADRES ;userdefinedaddress

MOV EEA,A

MOV A,EEPROM_DATA ;userdefineddata

MOV EED,A

MOV A,040H;setupmemorypointerMP1

MOV MP1,A ;MP1pointstoEECregister

MOV A,01H;setupBankPointer

MOV BP,A

CLR EMI

SET IAR1.3 ;setWRENbit,enablewriteoperations

SET IAR1.2 ;startWriteCycle-setWRbit–executedimmediately

;aftersetWRENbit

SET EMI

BACK:

SZ IAR1.2 ;checkforwritecycleend

JMP BACK

CLR IAR1;disableEEPROMwrite

CLR BP

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