ringing and overshoot on data lines for screen.

You are seeing ringing on the lines because they are acting as poorly terminated transmission lines. A correct termination will make this much better.

As a start, try 100 ohms in series at the source end. A (worse) alternative is 100 ohms in series with 50 pf at the destination.

PN2222a

Thanks for the information. The lines coming out of the microcontroller are not floating and go directly to the screen. Doesn't the screen terminate the signal?

The screen will look like a capacitor. Transmission lines are terminated by a resistive load roughly equal to their characteristic impedance, which tends to be in the range from 50R to 75R depending on the width of track, the spacing to the underlying ground plane and the dielectric constant of the spacing material(s).

-- Bill Sloman, Nijmegen

The thought is that the ringing and the overshoot is caused by reflections coming back from the screen? When I remove the screen completely I am still seeing the overshoot and the ringing on the data lines!! Do you guys still think this still is a reflection problem?

Thank you!

-Mike