Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Data Sheet

 899

SAM9M10 [DATASHEET]

6355F–ATARM–12-Mar-13

Touch Screen Switches Implementation

The method to measure the pressure (Rp) applied to the touch screen is based on the knowledge of the X-Panel
resistance (Rxp).

Three conversions (Xpos,Z1,Z2) are necessary to determine the value of Rp (Zaxis resistance).

Rp = Rxp*(Xpos/1024)*[(Z2/Z1)-1]

X

P

X

M

Y

M

VDDANA

Y

P

VDDANA

GND

GND

To the ADC

X

P

X

M

Y

P

VDDANA

GND

Switch 

Resistor

Switch 

Resistor

Y

P

Y

M

X

P

VDDANA

GND

Switch 

Resistor

Switch 

Resistor

Horizontal Position Detection

Vertical Position Detection