A resistive touch screen sensor panel (often referred to as the touch glass)
consists of two conductive layers separated with insulating spacers. Each
layer has a xed resistance dened during fabrication and in the ideal case
the resistance between the two layers is innite. When pressure is applied
to one of the layers the two layers connect and by measuring the resistance
between the two layers the coordinate of were the touch panel is pressed can
be calculated. This is done by applying a known voltage over one of the layers
and then measure the voltage over the second layer. The voltage dierence
corresponds to the coordinate where the touch panel has been pressed in one
dimension. When in its idle state the voltage measured over one layer is zero.