Interface to Four-Wire Resistive Touchscreen | Cypress Semiconductor
Interface to Four-Wire Resistive Touchscreen
AN2376 shows how PSoC 1 can be used to control a resistive touchscreen, and read (x,y) positions of single touches as well as touch pressure. It describes the essential mathematics in detail, and includes a method for calibrating a touchscreen to a display. A project is included that passes touchscreen readings to a PC through a USB HID interface.
Touchscreen interfaces are effective in many information appliances, in personal digital assistants (PDAs), and as generic pointing devices for instrumentation and control applications. This application note describes resistive types of touchscreens. Their construction is simple, their cost is low, and their operation is well understood by users. The only concern is that the resistive layers can be damaged by very sharp objects. This document considers the basic principles of how resistive touchscreens work and how to best convert these analog inputs into usable digital data using a PSoC.