Universal controller for resistive touch screens

Abstract

This report describes the development of a universal touch screen controller to be used with a 8-wire resistive touch panels and function as input device for the overlaying system. The controller is imple- mented in a microcontroller and designed to function with resistive touch screens of different sizes and from different vendors. The con- troller enables the determination of the touch status of the screen as well as the touchpoints X-Y position. The controller is designed to function in equipments used in rugged environments. Connection to the overlaying host system is provided through a USB connection. It is adapted to the HID protocol which gives the benefit that the drivers needed are provided in most major operating systems. Because it is common for touch screen sensor panels to be misaligned and suffer from problems with linearity, a calibration software for Windows that communicates with the controller has been developed. The resulting prototype is a 8-wire touch controller that utilizes a robust measuring technique in order to provide accurate and calibrated coordinates even in harsh environments.