App note: Interfacing 4/5/8 wire resisitve touch screens

Resistive touch screens are pretty cheap, and make it easy to interface with device without placing a lot of buttons. This app note describes how to interface with 4, 5, and 8 wire resistive touch screens on your next project.

All analog touch screens consist of a ridged layer and a flexible layer with a separation layer between them. The flexible layer is exposed to the outside, towards the user. The inside surfaces of the ridged and flexible layers are coated with a resistive coating, usually ITO (indium tin oxide). When the flexible layer is pushed its conductive surface will make contact with the conductive surface of the ridged layer making an electrical connection between the two layers at the point of contact. Measurements are then made to determine the point of contact.