Holtek BS82B12A-3 - LCD Bias Cont�Ol

Rev. 1.20 144 January 23, 2015 Rev. 1.20 145 January 23, 2015
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
AcyclicLCDwaveformincludestwoframes,knownasFrame0andFrame1forwhichthe
followingoffersafunctionalexplanation.
In Frame 0
ToselectFrame0cleartheFRAMEbitto0.
Inframe0,theCOMsignaloutputcanhaveavalueofV
DD
,orhaveaV
bias
valueof(1/3)V
DD
.The
SEGsignalcanhaveavalueofV
SS
,orhaveaV
bias
valueof(2/3)V
DD
.
In Frame 1
Inframe1,theCOMsignaloutputcanhaveavalueofV
SS
,orhaveaV
bias
valueof(2/3)V
DD
.The
SEGsignalcanhaveavalueofV
DD
haveaVbiasvalueof(1/3)V
DD
.
TheCOM0~COMnwaveformiscontrolledbytheapplicationprogramusingtheFRAMEbit,andthe
correspondingI/OdataregisterfortherespectiveCOMpintodeterminewhethertheCOM0~COMn
outputhasavalueofeitherV
DD
,V
SS
orV
bias
.TheSEG0~SEGmwaveformiscontrolledinasimilar
wayusingtheFRAMEbitandthecorrespondingI/OdataregisterfortherespectiveSEGpinto
determinewhethertheSEG0~SEGnoutputhasavalueofeitherV
DD
,V
SS
orV
bias
.
LCD Bias Control
TheLCDCOMandSEGdriverenablearangeofselectionstobeprovidedtosuittherequirement
oftheLCDpanelwhicharebeingused.ThebiasresistorchoiceisimplementedusingtheISEL1
andISEL0bitsintheSLCDC0register.
SLCDC0 Register
Bit 7 6 5 4 3 2 1 0
Name FRAME ISEL1 ISEL0 LCDEN
COM3EN COM2EN COM1EN COM0EN
R/W R/W R/W R/W R/W R/W R/W R/W R/W
POR 0 0 0 0 0 0 0 0
Bit7 FRAME:Fram0orFrame1outputselection
0:Frame0
1:Frame1
Bit6~5 ISEL1~ISEL0:SCOMandSSEGoperatingcurrentselection(V
DD
=5V)
00:8.3μA
0
1:16.7μA
10:50μA
11:100μA
Bit4 LCDEN:SCOMandSSEGmoduleon/offcontrol
0:Disable
1:Enable
TheSCOMnandSSEGmlinescanbeenabledusingCOMnENandSEGmENif
LCDEN=1.WhenLCDEN=0,thentheSCOMnandSSEGmoutputswillbexedata
V
SS
level.
Bit3 COM3EN:SCOM3orotherfunctionselection
0:Otherfunction
1:SCOM3
Bit2 COM2EN:SCOM2orotherfunctionselection
0:Otherfunction
1:SCOM2
Bit1 COM1EN:SCOM1orotherfunctionselection
0:Otherfunction
1:SCOM1
Bit0 COM0EN:SCOM0orotherfunctionselection
0:Otherfunction
1:SCOM0