Simple Touch Screen Interface

           Touch screen or touch activated technology has been around for a few decades now, but only recently have prices dropped and the technology been (somewhat) perfected. As an input device touch screens offer a more natural interaction that humans are used to, which offers a great advantage for businesses selling to the general public over traditional keyboards and mouses.
           This article will look at how to interface to a 4-wire resistive touch screen and find out the X and Y coordinates of the current point being touched. A minimal number of parts will be used to simplify the system hardware, and to focus more on the theory of how it works.

Simple Touch Screen Interface - Demonstration

Simple Touch Screen Interface - Setup

Purpose & Overview of this project
           The goal for this system is to use a 4-wire resistive touch screen as an input device, and to output the current X and Y coordinate being touched to an LCD output device. A microcontroller will be used to control the outputs to the touch screen and to understanding the inputs from it as well. Similarly, the microcontroller will drive the LCD with the current X/Y outputs sensed from the touch screen.
           The output LCD we will use will be a 16x2 character segment LCD. It uses the HD44780 interface so the LCD module is completely self-contained. The touch screen we will use is a generic 4-wire resistive touch screen that I found at an electronics surplus store. These types of touch screens are very common now and also very cheap. A PIC 18F452 microcontroller will be used for driving the output and understanding the input.