touchscreen calibration

Question

Is there an easy way, without using higher math, to calibrate a touchscreen?

I have written my own LCD library and my own touchpad library, both do work great, but of course I need to calibrate the touchpad before it gets usable results. The only thing I found is this, and that's to much math for me. Also I don't need a very very accurate result. Just beeing able to get +- 10 pixels.

I use a TFT 3.2" LCD 320x240 module with SSD1289 controller, and ADS7843 touchpad controller.

http://www.eetimes.com/design/embedded/4023968/How-To-Calibrate-Touch-Screens

Thanks for your help.

Answer 1

I worked out a simple solution. It uses simple linear algebra. This works only accurate, when the TouchPad foil is sticked parallel and not in a slight angle to the screen (which is correct in most cases).

calibration source code