HT66F317 datasheet(39/198 Pages) HOLTEK

39 / 198 page

Rev. 1.20

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Rev. 1.20

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HT66F317/HT66F318

Enhanced A/D MCU with LCD Driver

HT66F317/HT66F318

Enhanced A/D MCU with LCD Driver

Programming Considerations

CaremustbetakenthatdataisnotinadvertentlywrittentotheEEPROM.Protectioncanbe

enhancedbyensuringthattheWriteEnablebitisnormallyclearedtozerowhennotwriting.Also

theBankPointercouldbenormallyclearedtozeroasthiswouldinhibitaccesstoBank1where

theEEPROMcontrolregisterexist.Althoughcertainlynotnecessary,considerationmightbegiven

intheapplicationprogramtothecheckingofthevalidityofnewwritedatabyasimplereadback

process.WhenwritingdatatheWRbitmustbesethighimmediatelyaftertheWRENbithasbeen

sethigh,toensurethewritecycleexecutescorrectly.TheglobalinterruptbitEMIshouldalsobe

clearedbeforeawritecycleisexecutedandthenre-enabledafterthewritecyclestarts.Notethat

thedeviceshouldnotentertheIDLEorSLEEPmodeuntiltheEEPROMreadorwriteoperationis

totallycomplete.Otherwise,theEEPROMreadorwriteoperationwillfail.

Programming Examples

Reading data from the EEPROM – polling method

MOV A, EEPROM_ADRES

; user defined address

MOV EEA, A

MOV A, 040H

; setup memory pointer MP1

MOV MP1, A

; MP1 points to EEC register

MOV A, 01H

; setup Bank Pointer

MOV BP, A

SET IAR1.1

; set RDEN bit, enable read operations

SET IAR1.0

; start Read Cycle - set RD bit

BACK:

SZ IAR1.0

; check for read cycle end

JMP BACK

CLR IAR1

; disable EEPROM read/write

CLR BP

MOV A, EED

; move read data to register

MOV READ_DATA, A

Writing Data to the EEPROM – polling method

MOV A, EEPROM_ADRES

; user defined address

MOV EEA, A

MOV A, EEPROM_DATA

; user defined data

MOV EED, A

MOV A, 040H

; setup memory pointer MP1

MOV MP1, A

; MP1 points to EEC register

MOV A, 01H

; setup Bank Pointer

MOV BP, A

CLR EMI

SET IAR1.3

; set WREN bit, enable write operations

SET IAR1.2

; start Write Cycle - set WR bit

SET EMI

BACK:

SZ IAR1.2

; check for write cycle end

JMP BACK

CLR IAR1

; disable EEPROM read/write

CLR BP

HT66F317 Datasheet(PDF) 39 Page - Holtek Semiconductor Inc

HT66F317 Datasheet(HTML) 39 Page - Holtek Semiconductor Inc

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