HT69F240 datasheet(31/172 Pages) HOLTEK

31 / 172 page

Rev. 1.20

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Rev. 1.20

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HT69F240

I/O 8-Bit Flash MCU with LED/LCD Driver

HT69F240

I/O 8-Bit Flash MCU with LED/LCD Driver

Programming Considerations

CaremustbetakenthatdataisnotinadvertentlywrittentotheEEPROM.Protectioncanbe

enhancedbyensuringthattheWriteEnablebitisnormallyclearedtozerowhennotwriting.Also

theBankPointercouldbenormallyclearedtozeroasthiswouldinhibitaccesstoBank1wherethe

EEPROMcontrolregisterexist.Althoughcertainlynotnecessary,considerationmightbegiveninthe

applicationprogramtothecheckingofthevalidityofnewwritedatabyasimplereadbackprocess.

WhenwritingdatatheWRbitmustbesethighimmediatelyaftertheWRENbithasbeensethigh,

toensurethewritecycleexecutescorrectly.TheglobalinterruptbitEMIshouldalsobecleared

beforeawritecycleisexecutedandthenre-enabledafterthewritecyclestarts.

Programming Examples

Reading Data from the EEPROM – Polling Mothod

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;disableEEPROMread/write

CLR BP

MOV A,EED ;movereaddatatoregister

MOV READ_DATA,A

Writing Data to the EEPROM – Polling Mothod

CLR EMI

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

SET IAR1.3 ;setWRENbit,enablewriteoperations

SET IAR1.2 ;StartWriteCycle-setWRbit-executedimmediately

;aftersetWRENbit

SET EMI

BACK:

SZ IAR1.2 ;checkforwritecycleend

JMP BACK

CLR IAR1;disableEEPROMread/write

CLR BP

HT69F240 Datasheet(PDF) 31 Page - Holtek Semiconductor Inc

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