1 Introduction

Resistive touch screens are widely adopted in industrial, medical, and consumer applications due to their robustness, cost-effectiveness, and ability to function with any input medium (including gloved fingers). Unlike capacitive touch screens, resistive implementations do not require specialized conductive materials and offer superior performance in harsh environments.

The MSPM0L1306 microcontroller provides the necessary analog and digital interfaces to implement a complete resistive touch screen controller. This application note presents practical firmware implementations for touch detection and analysis using GPIO pins to drive the resistive layers and the integrated ADC to acquire coordinate measurements. Two example projects are provided: a basic touch detection system, and an advanced system capable of distinguishing between click events and drag/long-touch gestures through a timing based measurement using the Timer G peripheral.

A resistive touch screen works by applying a voltage across a resistor network and measuring the change in resistance at a given point on the matrix where a screen is touched by an input stylus, pen, or finger. This device consists of two transparent resistive layers made by ITO (Indium Tim Oxide) and separated by a thin air gap. When a user applies pressure with a stylus, pen, or finger, the top layer contacts the bottom layer, creating a closed circuit at that specific location. This method is used by the microcontroller to get the location of the touch.

The related software can be accessed at MSPM0L1306-RESISTIVE-TOUCH-APPSW.