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TOUCH PANEL CIRCUIT
Four electrodes are installed in top and bottom right and left of panel, and the touch panel recognizes the
coordinate which was pushed with a pen on panel by detecting change volume of current which flowed through
panel by pushing panel.
X1
Y2
Y1
TOUCH PANEL
X2
TC74HC4066
Circuit Operation
TXL and TYU of drive signals are sent through LS240 from CPU by X1,Y1 of touch panel when turn on power
supply. And, TXR,TYD signals are output through LS240 from touch panel to AIN terminal of A/D converter
TC35093, and convert the analog value into digital value, and TC35093 outputs digital data DB0~DB7 of 8 bits
to CPU.
TC35093 changes TXR of X axis signal, TYD of Y axis signal in alternating by analog switch 4066 by ADCH
signal from CPU to output digital data, and input analog data into AIN terminal of TC35093.
Synchronize analog data input from AIN terminal in clock signal of 1 pin, and TC35093 outputs digital data
DB0~DB7 to CPU when OE and STC signal input become H.
TC74LCX240
TYU
1Y
TXR
1G-
TYD
1A
TXL
VDD
IC82
— 9 —
2A
2G-
2Y
TC35093
KO7(TABYG)
KO8(TABXG)
KO6(TABLUB)
KO5(TABRDB)
CS8B
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
CPU
HD62119A03
ADCH
ADSTOB
ADSTBY
OCLK
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