HT45F65 datasheet(211/231 Pages) HOLTEK

211 / 231 page

Rev. 1.60

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Rev. 1.60

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HT45F65/HT45F66/HT45F67

Glucose Meter 8-Bit Flash MCU

Programming Considerations

CertainprecautionsmustbetakenwhenprogrammingtheLCD.Oneoftheseistoensurethat

theLCDMemoryisproperlyinitialisedafterthemicrocontrollerispoweredon.LiketheGeneral

PurposeDataMemory,thecontentsoftheLCDMemoryareinanunknownconditionafterpower-

on.AsthecontentsoftheLCDMemorywillbemappedintotheactualdisplay,itisimportantto

initialisethismemoryareaintoaknownconditionsoonafterapplyingpowertoobtainaproper

displaypattern.

ConsiderationmustalsobegiventothecapacitiveloadoftheactualLCDusedintheapplication.

AstheloadpresentedtothemicrocontrollerbyLCDpixelscanbegenerallymodeledasmainly

capacitiveinnature,itisimportantthatthisisnotexcessive,apointthatisparticularlytrueinthe

caseoftheCOMlineswhichmaybeconnectedtomanyLCDpixels.Theaccompanyingdiagram

depictstheequivalentcircuitoftheLCD.

One additional consideration that must be taken into account is what happens when the

microcontrollerenterstheIdleorSlowMode.TheLCDENcontrolbitintheLCDCregisterpermits

thedisplaytobepoweredofftoreducepowerconsumption.Ifthisbitiszero,thedrivingsignals

tothedisplaywillcease,producingablankdisplaypatternbutreducinganypowerconsumption

associatedwiththeLCD.

AfterPower-on,notethatastheLCDENbitwillbeclearedtozero,thedisplayfunctionwillbe

disabled.

CO M0

CO M1

CO M2

CO Mn

SE G0

SE G1

SE G2

SE Gn

LCD Panel Equivalent Circuit

HT45F65 Datasheet(PDF) 211 Page - Holtek Semiconductor Inc