Overview
Two of the four touch screen interface wires are
for the X-axis and two are for the Y-axis. The pairs are operated on
independently (e.g. the other pair is tristated by the
microcontroller). The operation performed by the microcontroller on each
pair is to apply Vcc to one wire and apply Gnd to the other. The wire to which
Gnd is applied is also connected to an ADC input on the microcontroller, and
the voltage read is proportional to the position being touched along that axis.
4 Wire Resistive Touch Screen Driver:
