The touch screen really has a central place in this project. Therefore predictable behavior with high level of precision is of paramount importance.

We spent (or wasted) considerable amount of time guessing what going wrong with touch screen control. Possibly we just discover hot water by finding that working with touch screen is not straight forward. Maybe the problem laying in unfortunate match of resistive sensor and touch controller (XPT2046). At the beginning a Utouch library is taken for granted as "the solution" for small displays and comes with Arduino support that we need.

But, after some time my colleague realized that Utouch missed many things and that simply blaming hardware is not fair. Actually it's possible to completely change situation from frustrating and completely unusable to precise and predicable solution. He started with tweaking existing utouch, and finally gave up completely from it and in addition deploy tactics that David Beer presented here (thank you very much David!).

I prepared two short demos, first one with simple filtering and second one with new approach: