Datasheet

935
SAM9X35 [DATASHEET]
11055E–ATARM–10-Mar-2014
Figure 42-7. Pressure Measurement
42.7.5 5-wire Resistive Touchscreen Principles
To make a 5-wire touchscreen, a resistive layer with a contact point at each corner and a conductive layer are used.
The 5-wire touchscreen differs from the 4-wire type mainly in that the voltage gradient is applied only to one layer, the
resistive layer, while the other layer is the sense layer for both measurements.
The measurement of the X position is obtained by biasing the upper left corner and lower left corner to V
DDANA and the
upper right corner and lower right to ground.
To measure along the Y axis, bias the upper left corner and upper right corner to V
DDANA and bias the lower left corner
and lower right corner to ground.
X
P
X
M
VDDANA
GND
Switch
Resistor
Switch
Resistor
XPos Measure(Yp)
Y
P
Y
M
Open
circuit
Rp
X
P
X
M
VDDANA
GND
Switch
Resistor
Switch
Resistor
Z1 Measure(Xp)
Y
P
Y
M
Open
circuit
Rp
X
P
X
M
VDDANA
GND
Switch
Resistor
Switch
Resistor
Z2 Measure(Xp)
Y
P
Y
M
Open
circuit
Rp