HT16L21 datasheet(16/36 Pages) HOLTEK

16 / 36 page

Rev. 1.00

November 16, 2011

HT16L21

Segment Driver Outputs

TheLCDdrivesectionincludes32segmentoutputsSEG0~SEG31or24segmentoutputsSEG0~SEG23which

shouldbeconnecteddirectlytotheLCDpanel.Thesegmentoutputsignalsaregeneratedinaccordancewiththe

multiplexedLEDsignalsandwiththedataresidentinthedisplaylatch.Theunusedsegmentoutputsshouldbeleft

open-circuitwhenlessthan32or24segmentoutputsarerequired.

Column Driver Outputs

TheLCDdrivesectionincludes4columnoutputsCOM0~COM3whichshouldbeconnecteddirectlytotheLCD

panel.ThecolumnoutputsignalsaregeneratedinaccordancewiththeselectedLCDdrivemode.Theunused

columnoutputsshouldbeleftopen-circuitiflessthan4columnoutputsarerequired.

Address Pointer

TheaddressingmechanismforthedisplayRAMisimplementedusingtheaddresspointer.Thisallowstheloading

ofanindividualdisplaydatabyte,oraseriesofdisplaydatabytes,intoanylocationofthedisplayRAM.The

sequencecommenceswiththeinitializationoftheaddresspointerbytheDisplayDataInputcommand.

Blinking Function

Thedevicecontainsversatileblinkingcapabilities.Thewholedisplaycanbeblinkedatfrequenciesselectedby

theBlinkingFrequencycommand.Theblinkingfrequencyisasubdividedratioofthesystemfrequency.The

ratiobetweenthesystemoscillatorandblinkingfrequenciesdependsontheblinkingmodeinwhichthedeviceis

operating,asshowninthefollowingtable:

Blinking Mode

Blinking Frequency (Hz)

Blink off

0.5

Frame Frequency

ThedeviceprovidesfourframefrequenciesselectedwithFrameFrequencycommandknownas64Hz,85.3Hz,

128Hzand170.6Hzrespectively.

LED Function

TheLEDpinsareNMOS-structuredoutputpins.TheDatafortheLEDoutputiscontainedintheLEDoutput

settingcommand,startingfromthemostsignificantbit.WhenawrittendatabitforaLEDpinissetto1,the

correspondingdrivingLEDlightsupwhiletheLEDisswitchedoffwhenthewrittendatabitis0.TheLEDpins

arepin-sharedwiththeLCDsegmentpinsandcanbeselectedusingtheSP1andSP0bitsintheDriveMode

command.

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