Holtek HT66F20 - SCOM Function for LCD; LCD Operation

Rev. 2.50 228 June 22, 2017 Rev. 2.50 229 June 22, 2017
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
SCOM Function for LCD
ThedeviceshavethecapabilityofdrivingexternalLCDpanels.ThecommonpinsforLCDdriving,
SCOM0~SCOM3,arepinsharedwithcertainpinonthePC0~PC3orPC0~PC1,PC6~PC7port.
TheLCDsignals(COMandSEG)aregeneratedusingtheapplicationprogram.
LCD Operation
AnexternalLCDpanelcanbedrivenusingthisdevicebyconguringthePC0~PC3orPC0~PC1,
PC6~PC7pinsascommonpinsandusingotheroutputportslinesassegmentpins.TheLCDdriver
functioniscontrolledusingtheSCOMCregisterwhichinadditiontocontrollingtheoverallon/off
functionalsocontrolsthebiasvoltagesetupfunction.ThisenablestheLCDCOMdrivertogenerate
thenecessaryV
DD
/2voltagelevelsforLCD1/2biasoperation.
TheSCOMENbitintheSCOMCregisteristheoverallmastercontrolfortheLCDdriver,however
thisbitisusedinconjunctionwiththeCOMnENbitstoselectwhichPortCpinsareusedforLCD
driving.NotethatthePortControlregisterdoesnotneedtorstsetupthepinsasoutputstoenable
theLCDdriveroperation.









    
LCD COM Bias
SCOMEN COMnEN Pin Function O/P Level
0 X I/O
0 or 1
1 0 I/O 0 or 1
1 1 SCOMn V
DD
/2
Output Control