Touch-4Wire Library
This is the 4-wire resistive touch screen firmware for Arduino - and Spark Core.
For Arduino
Works with all Arduinos and the Mega
To install, click DOWNLOAD SOURCE in the top right corner, and rename the uncompressed folder "TouchScreen". See our tutorial at http://www.ladyada.net/library/arduino/libraries.html on Arduino Library installation
For Spark Core (ported by ScruffR - Nov. 2014)
To download go to https://github.com/ScruffR/touch_4wire