Display showing Gibberrish


(I shared that question in the past, but didn’t have the entire information to share, so I am sharing this again).

I have an UNO controller connected to a 16*2 LCD display, and the display is showing gibberish from unknown reason.

I replaced almost everything - the display itself, the UNO and also the screw-shield connected to it. It seems like all connections and soldering are OK, but some other reason is causing it.

Attached -
1- a photo of how it looks.
2,3,4 - photos of the controller and display.
5- photo of second control box (relays and connections going out to the ‘real world’). This is in the first reply (from some reason it didn’t let me post it here).

Schematics (you can see control-box-1 , control-box-2, external-connections)

As much as I tried to cut on irrelevant pieces from the code, my message exceeded 9000 characters (upper limit), so it is attached as a PDF.

I appreciate your help!

CB code.pdf (81 KB)

V5.T.pdf (134 KB)

Here is photo #5





Here is photo #5

Maybe not!

I am having issues uploading the photos - the system suddenly tells me that the format is not jpg etc, but only for a specific photo, and not the rest, although all photos are coming from the exactly same source.

Photo #5 is attached here (I hope) :o :


Any ideas how to approach this situation are appreciated :slight_smile: !

Can that be from some coupling of the data-wires, or power/gnd wires of the display?

I added the capacitor at the power inlet, as instructed here before. Can that cause that issue?

Since i replaced all components in the arduino control box (the small box with the UNO in it) and the problem still persists - I guess it is something with my wiring or power source (the 24v->5v buck), or maybe some other reason...?

Thank you!

What happens if you press the RESET button on the controller?

I have seen the same behavior when having bad connection on the I2C bus to the LCD display. Reseting the controller seem to fix (for a short time until the bad connection disturbe the display again).

Reset works well.
But as you said - it is only a short while (a very short while) until I get this again.

I don't have I2C connection here. I work with 4 DATA signals.

If you have the rime - it is possible to see the schematics in PDF format in my first post (file names V5).


If RESET help for a short period, I would check the data wires again. It may be a loose connection.

I replaced the display itself and all wires... Same problem...