HT45F3W datasheet(44/167 Pages) HOLTEK

44 / 167 page

Rev. 1.50

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Rev. 1.50

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HT45F3W

R-Type Blood Pressure Meter Flash MCU

HT45F3W

R-Type Blood Pressure Meter Flash MCU

Programming Considerations

CaremustbetakenthatdataisnotinadvertentlywrittentotheEEPROM.Protectioncanbe

enhancedbyensuringthattheWriteEnablebitisnormallyclearedtozerowhennotwriting.Also

theBankPointercouldbenormallyclearedtozeroasthiswouldinhibitaccesstoBank1where

theEEPROMcontrolregisterexist.Althoughcertainlynotnecessary,considerationmightbegiven

intheapplicationprogramtothecheckingofthevalidityofnewwritedatabyasimplereadback

process.

WhenwritingdatatheWRbitmustbesethighimmediatelyaftertheWRENbithasbeensethigh,

toensurethewritecycleexecutescorrectly.TheglobalinterruptbitEMIshouldalsobecleared

beforeawritecycleisexecutedandthenre-enabledafterthewritecyclestarts.Notethatthedevice

shouldnotentertheIDLEorSLEEPmodeuntiltheEEPROMreadorwriteoperationistotally

complete.Otherwise,theEEPROMreadorwriteoperationwillfail.

• Programming Examples

♦

ReadingdatafromtheEEPROM-pollingmethod

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

♦

WritingDatatotheEEPROM–pollingmethod

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

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