Document No. DER-S0137A
3
Rev 1.1 ©2016 DMC Co., Ltd.
TSC-54/RU-F User
’s Guide
1-3. Peripheral Composition Overview
A resistive touch screen is operated by resistance sensitive system between two layers such as film or
glass. Two pieces of transparent materials with conductive coating are placed in the same direction as
two electrodes face each other. The touch screen is activated when these transparent conductive layers
are pressed to contact each other with a finger or a pen. The one of these conductive layers functions as
an X-coordinates electric circuits and the other as a Y-coordinates circuits. To measure the X-coordinates
TSC-54/RU-F supplies voltage, Vcc to the one of X-coordinates electrodes with GND to the other. When
the touch screen is pressed under this environment the voltage of the X-coordinates resistance is detected
by the Y-coordinates electrode (A_in) at the input point (x1), where the X-Y coordinate resistance layers
make contact. The detected voltage in supply side is higher than the GND side, which means
‘A_in’=Vcc
at the point
‘E’ and ‘A_in’=0(*1) at the point ‘A’. TSC-54/RU-F calculates coordinates data starting from
A/D conversion of the
‘A_in’ voltage. The Y-coordinates is measured in the same way. By repeating this
process alternately, coordinate value at the input point is determined.
(*1) Excluding the loss in the controller circuits and touch screen. Actual detected voltage should be lower
than
‘Vcc - GND’ because of loss happened in the circuitry.
xl
A_in
Output Data
A
0V
0000h (Min.)
B
1.25V
00FFh
C
2.5V
01FFh
D
3.75V
02FFh
E
5V
03FFh (Max.)
Vcc
= 5.0V
xl
A_in
X-resistive-layer
Y-resistive-layer
Touch
Vcc
(TSC-50/IC)
E
D
C
B
A
(Touch Screen)
(TSC-54/RU-F)
(RS
-232C
/USB
)
To host
Y-resistive-layer
X-resistive-layer (reverse side)
xl
X electrode
(reverse side)
Y electrode
Vcc
A_in
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