HT67F488 datasheet(36/171 Pages) HOLTEK

36 / 171 page

Rev. 1.60

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HT67F488/HT67F489

TinyPowerTM A/D Flash MCU with LCD & EEPROM

Programming Considerations

CaremustbetakenthatdataisnotinadvertentlywrittentotheEEPROM.Protectioncanbe

enhancedbyensuringthattheWriteEnablebitisnormallyclearedtozerowhennotwriting.

AlsotheMemoryPointerhighbyte,MP1HorMP2H,couldbenormallyclearedtozeroasthis

wouldinhibitaccesstoSector1wheretheEEPROMcontrolregisterexist.Althoughcertainlynot

necessary,considerationmightbegivenintheapplicationprogramtothecheckingofthevalidity

ofnewwritedatabyasimplereadbackprocess.WhenwritingdatatheWRbitmustbesethigh

immediatelyaftertheWRENbithasbeensethigh,toensurethewritecycleexecutescorrectly.The

globalinterruptbitEMIshouldalsobeclearedbeforeawritecycleisexecutedandthenre-enabled

afterthewritecyclestarts.NotethatthedeviceshouldnotentertheIDLEorSLEEPmodeuntil

theEEPROMreadorwriteoperationistotallycomplete.Otherwise,theEEPROMreadorwrite

operationwillfail.

Programming Examples

Reading data from the EEPROM - polling method

MOV A,EEPROM_ADRES;userdefinedaddress

MOV EEA,A

MOV A,040H;setupmemorypointerMP1L

MOV MP1L,A;MP1pointstoEECregister

MOV A,01H;setupmemorypointerMP1H

MOV MP1H,A

SET IAR1.1;setRDENbit,enablereadoperations

SET IAR1.0;startReadCycle-setRDbit

BACK:

SZ IAR1.0;checkforreadcycleend

JMP BACK

CLR IAR1 ;disableEEPROMread/write

CLR MP1H

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;setupmemorypointerMP1L

MOV MP1L,A;MP1pointstoEECregister

MOV A,01H;setupmemorypointerMP1H

MOV MP1H,A

CLR EMI

SET IAR1.3;setWRENbit,enablewriteoperations

SET IAR1.2;startWriteCycle-setWRbit–executedimmediatelyafter

set WRENbit

SET EMI

BACK:

SZ IAR1.2;checkforwritecycleend

JMP BACK

CLR IAR1 ;disableEEPROMread/write

CLR MP1H

HT67F488 데이터시트(PDF) 36 Page - Holtek Semiconductor Inc

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