3.2" TFT Sainsmart (UTFT-tiny) Flickering Problem

Using the demo code 'portrait/lanscape' it works fine when I'll just use the computer's USB port at a power source. The problem arises if I make it a stand-alone and power the mega ADK using a 12v power supply, the images distorts every time it loads up. You can still see the images refresh but there's a huge amount of distortion.

Has anyone encountered this problem? Thanks.

It sounds like your power supply is not good enough. Maybe it has too much ripple? Or maybe you are missing the ground off something that connects accidentally through the USB / computer.

Other than that you don't give much information so we can't be too specific. One thing it is not is the software so no need to post the code but a schematic would be good.

Thanks for the reply.

Right now I am using a Sainsmart TFT shield. By then, could we say that it’s not a connection/grounding problem?

Please see the video link attached. It works when using 5v adapter, and does not when powered by 12v.

With regards to the power, I am using a regulated 12v power supply…

photo.JPG

I am using a 2gb microSD card plugged into an SD adapter. Would that matter? Thanks..

The problem arises if I make it a stand-alone and power the mega ADK using a 12v power supply, the images distorts every time it loads up. You can still see the images refresh but there's a huge amount of distortion.

That is not what was shown on the video. It looked like there was some sort of error message being printed out. What did it say?

That is not what was shown on the video. It looked like there was some sort of error message being printed out. What did it say?

Uhm. The distortion occurred when we were not using a TFT shield (just plain jumper wires following this connection http://www.geeetech.com/wiki/index.php/3.2TFT_LCD#Application_Ideas). I thought that it's better to use a shield since it has resistors in it (current limiting purposes i believe) rather than jumper wires. The error message says "FILE NOT FOUND" followed by the file name. The file names were read though when powered by USB. Weird.. Somehow it does not read them when using an external 12v.

Thanks for the reply. Appreciate it pretty much.

The error message says "FILE NOT FOUND" followed by the file name.

So you have to look at the sketch and see why that should be if there is no serial connection. Is it reading something from the serial port to act as a file name or is it amending something unprintable to the file name in the absence of the serial connector?

The distortion occurred when we were not using a TFT shield

It is most likely that the shield contains some extra decoupling capacitors that are needed to smooth out the supply. Try adding them across the power supply of your display. A 0.1uF ceramic in parallel with a 47uF electrolytic should do it.