What can I do against flickering caused by 2m data cable?

Questions
1

Hi,

I am new to WLED. Just let me describe my setup: I have connected 4 LED stripes (WS2815) to a ESP32 and each is connected to a different GPIO. Two of them have around 100 LEDs and two only around 60 LEDs. Three of the four LED stripes are close to the ESP32 and only one with 60 LEDs starts in a distance of around 2 meters. This LED stripe flickers (i.e. changing the color for a second) for around every 5 seconds or less. All LED stripes are powered by the same external 12V 10A power supply that is also next to the ESP32.

When I put this led stripe close to the ESP32 like the other ones, flickering stops. If I insert the long data wire again, flickering starts again. So I assume the cause is the long data wire. I use AWG18 cables like recommended by some overhyped you tube guide called chris.

After some research, I put a single LED after around 50 cm to amplify the data signal, and the flickering is reduced to around one flicker for very 20 seconds.

Do I have to connect that single LED closer to my ESP32? I did not try it because it requires a lot of effort since the LEDS are already mounted on the furniture. Are there any other solutions for this issue? What else information is necessary for diagnosing?

2

This is a common issue often remedied by including a levelshifter, checkout the KB - Levelshifters.

You can also look up KB - Long Data Lines, although that’s probably overkill for 2m :wink:

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3

Thank you so much for your reply.

So based on the list of level shifters, I will buy this one: https://www.amazon.de/8X-SN74AHCT125N-IC-digital-buffer/dp/B0115TLMMY

Does this work for my setting?

And I would wire it as follows: https://canada1.discourse-cdn.com/free1/uploads/wled/original/2X/b/be4b7d08d8a4714e39c60065d6f231078c383ce4.jpeg

Any recommendations or further notes for me? Is there somewhere an easily understandable explanation of the problem and what a level shifter does? Sorry, I am really new to this topic …

4

Google “level shifter for LEDs”

But in a nut shell, your lights are designed for 5v data. Your ESP outputs 3v3 data. If your controller is very close to the lights, the signal is right on the edge of the range it can read. But the voltage drop through several meters of wire will drop the voltage out of that range. A level shifter converts the signal from 3.3v to 5v

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5

That level shifter should work fine.

A better wiring diagram can be found: 74AHCT125 Wiring
Which shows unused inputs tied down and the ceramic bypass capacitor. Note the 62ohm resistor is optional, especially in shorter runs.

As @Artacus mentioned, the issue is ESP outputs of 3.3V not being quite high enough to properly trigger the 1st LED in your strip (it probably needs some thing closer to 4V to be really reliable). The longer your data line from the ESP32 to the LEDs, the more your signal gets distorted and unreliable.

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6

Very in depth video on the issue (if someone else finds this thread looking for explanations) Logic Level Shifter and WS2812b LEDs - YouTube

7

Amazing, I just wanted to look up how I have to wire the one I ordered actually, which is the one that is used in your video :slight_smile: I decided to order that one because it was much cheaper than the one I had in mind originally. I will give an update after I have wired it and the flickering is over. Thank you all for your great support and help!!!

8

If you are talking about buying these: Amazon.com from that video they are not recommended to be used because they are too slow. Thus it says this in the KB “I2C shifters are generally too slow for WLED, so don’t use them.” The 74AHCT125 is a MUCH better choice.

9

Check prev posts in this thread, already referenced a '125 buy (albeit in German…), it’s all good.