LEDs flickering when attached to long lead cable

rcarmichael · 7. März 2022

Good evening all,

I've been searching the forums and found some similar posts, but was wondering if anyone smarter than me can have a look at my setup and tell me where the most likely culprit is to continue my troubleshooting:

I currently have 291 W2812B RGB LEDs powered by a 5v 14A Power Supply (I know this is underpowered, but I have lowered my maximum brightness to 70% which should compensate). They are run from two sides (with ONLY the data line connected in the middle - not sure if I should still connect positive and ground in this case?)

The PSU has a capacitor attached and the data line a resistor as per. best practice. Running on a RPi through GPIO Pin 18 with ground attached between it and the PSU, it works great. For completeness: I am also using a USB Input device, though I doubt this is the issue.

My issue is, I am trying to run the LEDs in another room; 3x 5 meter 18 AWG Cables (which I believe may be the culprit, as they are too small? What gauge should I be going for, 16?) connect the power from the 14A PSU and the data line. They are currently connected using WAGOs for ease in troubleshooting, which I guess could also be a failure point. When connected using these 5m cables instead of directly to the PSU/RPi (apx. 5 cm over similar gauge cable) the LEDs will randomly flicker.

At first I thought this might be a power issue, but I dropped my max brightness all the way to 1% and was still getting the flicker.

If anyone could help me narrow down what the issue is and how I can rectify it, I would greatly appreciated it!

Sincere regards,

Ryan

rcarmichael · 8. März 2022

I have upgraded my power lines to 16 AWG but the result is the same.

I tested running the 5m power lines with the 5cm data line. The flicker disappeared, so the issue is with the 5m 18 AWG Data line. Anyone know how I can overcome this?

Sincere regards,

Ryan

theovlit · 8. März 2022

Can I ask why you are trying to run lights in a different room?

It sounds like you've narrowed it down to signal degradation on your data line. I think there might be a couple different solutions / methods to get around this depending on your use case.

The first thing that comes to mind would be a signal repeater, but I'd honestly have no idea how to go about getting that or making one. I'm sure someone smarter than both of us could weigh in on that topic. Maybe do a little bit of research on W2812B long distance data signal strengthening or something along those lines.

The next idea would be to use wled or spinning up a second instance of Hyperion closer to your physical LED strips where you can send the data from your first instance to your second instance over the network. I've never had to do this but if I'm understanding correctly that's what the Bob light service is for. Again maybe someone can weigh in with a little bit more knowledge on this topic.

Hope this helps get some ideas brewing for you.

rcarmichael · 11. März 2022

Thank you for your reply @theolvit.

I've got all my source devices running in another room which means my mounted TV is the only thing on the wall - a very clean look!

That's what I got it down to; I did read that I should move the resistor closer to the first LED (it is currently at the PSU side), and use a single LED every 2m length to act as a repeater of sorts.

TBH, that was more work than it was worth so I've ended up just running a HDMI cable to the RPi4/USB Input device which I've mounted behind the TV and so far its working well. Not exactly what I wanted, but the result LOOKs the same anyway!

Openupshop · 11. März 2022

Zitat von rcarmichael

the LEDs will randomly flicker.

Unless I am missing something, I believe you may need a level shifter, especially for any run of a decent length. When I was setting mine up, many of the tutorials I read said something to the effect of:

"The logic level converter converts the 3.3v signal from the Raspberry Pi to a 5v signal and allows you to send the data over a much longer distance."

I was using APA102's on Pins 19 & 23 and ended up having all the wires really really short, hence didn't need to use one. However, the tutorials were not specific to any specific LED and the image below is actually utilizing the WS2812B's that you mentioned using.

Here is an image of its use (Links at end of this post for source of image and also for tutorials I used):

LINKS:

Tutorial Using It

Written Tutorial

The level shifters are about 10 bucks. I put the alternate level shifter link as you get a bunch for the same price where as with the first one, you only receive one. I hope this is the issue and it fixes the flickering issue for you.

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