Static from Raspberry Pi 3b+ After 8 Chained 32x64 LED Panels

What’s up everyone!

I am currently running a chain of 11 LED panels and am getting static on the panels after 8 panels.

Currently have two 5v40a switching power supplies (6 panels powered from 1 and 5 panels powered by the other). Also, the panels are being driven by a raspberry pi 3b+.

Any suggestions on how to fix this, or the root cause?

I remember some message from @hzeller where he said that when the chain is long enough, the clock that gets moved from panel to panel, can get out of sync with the pixel signal being pushed from one panel to the next.
One way to get around that is to increase timing/delays to avoid having the two get out of sync

Yes, I had exactly the same problem! It isn’t static; it is the signals on the bus degrading as it get longer. I solved this problem with a REPEATER board that I made to re-transmit (amplify) the signals. It plugs in-line with the ribbon cables every 4-6 panels. You may find my thread on this forum for more details.

Here’s a pic of the repeater board

Thanks both!

@tjr I am looking for your thread, but haven’t found it quite yet. I wanted to connect regardless as I’d love to see more about how you fabricated these repeater boards.

Could you email me:

Happy to purchase some too!

that’s super interesting. I’m not sure I understand this though.
Each board shifts bits and generates shifted out bits on its output plug. Those bits should be a full signal level.
Is the problem that the clock and latch are just passed through passively and lose signal strength after enough panels?
If that’s true, could you use a thick wire, connect it to those data lines on the first panel, and re-inject passively from the thicker wire to the 6th panel or somesuch?

Hey Marcmerlin,

I really don’t know if that would work; I tend to doubt if it would. My repeater board worked great for me in mt ESP32 application, but not in an application from another member using RPi. I still don’t understand the reason .