LED color glitches/flashes

[coelner]

Hey, I use 120 WS2812 wit a 4A 5V power supply (limit 3800mAh). The firmware is 0.8.5 on two different ESP8266 boards. I want to use a self soldered ESP12E board with minimal space requirements. With this board I have some LED glitches. Most of the time the selected color is shown, but randomly short burst with a different color appears. A single level shifter is also used, but the led stripe works flawless with a nodemcu even without a level shifter. If I set the brightness the glitches don't appear, all other glitches are with full brigthness. If I use only a red color, those glitches are mostly green, sometimes blue. Most of the time the complete stripe is affected, but sometimes only the first LEDs burst the wrong color.

Any hints where to search for solving the issue?

[theshadowsvk]

Hello, please, which pin/method are you using ? Are you sure that voltage drop is not big ? Sometimes this could be the issue of random color glitches.

[coelner]

I use GPIO2. I flashed it with a CH340G directly over the gpio pins and took this one: WLED_0.8.5_ESP8266.bin Which voltage drop do you mean? with full brightness it is 4.9V and at end 4.2V (With power limit set to 3800mA). But this should not be a problem, the nodemcu can be used for this and there are no glitches at all (at the end 3.8V)

[theshadowsvk]

Hmm okay, can you drop schematics of your board ? This sounds like other problem

[coelner]

[theshadowsvk]

One question, is the common ground shared between 5v and 3.3v line ?

Sorry I see now, it's shared. I saw that cross line wrong. I'll check my schematics of my board and let you know

[coelner]

Yes, it is.

[Aircoookie]

Your setup looks good to me. I actually believe that this is indeed a software issue because I have had it too on two of my lights. I was suspecting that the reason was a missing levelshifter, but might be an occasional flipped or dropped bit in the UART after all.

[coelner]

I'm not sure. The nodemcu works well even without a levelshifter. At least I get there no glitches. And the single ESP12 feels hotter than the nodemcu (measured with my finger tip...) but this could be the missing pcb underneath. I assume two issues, one with flipped values in the UART, but somewhere a hardware vault. https://streamable.com/o8lsz

[Aircoookie]

Thanks for the video! For me it looks exactly the same, albeit at a much lower frequency at one glitch per 20-60 minutes, not every few seconds. This indeed seems like more of a hardware issue, but since there is no hardware difference with the pin between ESP12 and NodeMCU I can't see where. Did you try without the levelshifter? I've recently heard that some models modify the waveform enough to cause issues.

[coelner]

Yes, I added the level shifter after these glitches appear. Those esp12 are mass products, maybe something is broken inside (which would explain the hotter surface). sadly I have no oszilloscope otherwise I would inspect this furthermore.

You can close the issue and leave a reminder if LEDs are flickering that it is maybe a direct hardware issue.

[coelner]

Ok, even the nodemcu has got the glitches, but more like one in a hour.

[frustreermeneer]

I'm experiencing the same random flashing problem with 249 LEDs on an older Lolin NodeMCU on pin D4/GPIO2. I didn't have this problem with FastLED on another GPIO pin.

[kcoop99]

Experiencing the same issue. Random color flashes. Running 12v lights. Has this been determined to be hardware only?

Here is video of my glitch examples. Solid blue then with Halloween effect. https://youtu.be/TGyMkZldP5s

[kcoop99]

Swapped my wemos d1 mini for a node mcu and am running into same issue. Leads me to think it's software and not hardware.

[wardwygaerts]

My leds seems to flicker all together when changing color. Will make a video tomorrow.

[dhami220]

I get the flashes as well (every few seconds) with couple interesting observations below.

My setup: Two LED strips controlled by two nodeMCUs, two level shifters and 40amp power supply.

1. If only one LED strip is running, I don't get any flashes.
2. If I turn the second LED strip on, the flashes appear.
3. If both LED strips are set to halloween, no flashes. I have tried other effects, but only found halloween working without flashes when both are ON.

[dhami220]

Tried a few additional items without success:

• I have wire nut on the data cables. Replaced that with soldered joint. Same result.
• Removed level shifter (connected directly to nodemcu). Same result.

Next steps:

• I have two small strips. Going to give those a try right next to mcu to rule out data cable length and/or excessice number of LEDs on my main strips (~320 per strip is what i have. the small ones have ~20 LEDs). RESULTS: No flashes. Could be the length of the data cables or number of LEDs or some abnormality with connections on the main strips.

• Used LED as the signal booster with the main strips. RESULT: Flashes.

• Replicate flashes with longer data cable and small strips (Isolate longer data cable variable from the number of LED or connection abnormality). RESULT: -

• I have seen some posts about capacitor. Will give that a try if I can find a similar capacitor. RESULT:

• Place Nodemcus closer to the strips. RESULT: inconsistent node MCU power behavior. When the strips are on, the nodemcus turned off. I measured the voltage and it was close to 3.04V. It appears that this may be related to voltage drop from the power supply. I had nodemcus connected to the same power supply, and may be nodemcus (even when closer to the power supply) are not getting sufficient power and that causes data signal issues. Two items to try: Ordered 60amp power supply from amazon; try powering nodemcus from a separate power supply.

Final Outcome: After watching Dr's stream today, gave the booster LED another shot. This time, I ran both strips from one NodeMCU (same signal split to both). Soldered all joints (replaced jumper cables with 20 gage wire segments and soldered). Flashes are gone!!!

[kcoop99]

Can anyone confirm or deny that a logic level shifter DOES work???

[theshadowsvk]

Yes I'm using it, without any problem

[kcoop99]

Would you be able to share which one you are using and how you have it wired?

[Physikus74]

Hello, that sounds to me like EMV problems, or actually voltage dips due to pulsating currents in the effects. A good buffering with capacitors near the MCU should help. It is even better if the MCU gets its own power supply. So the "big power supply" for the LEDs can be switched from the MCU and the MCU itself is independent from the currents of the LED's. When designing the GND line you have to be careful that the current through the LED's does not influence the voltage of the MCU! For me such a setup with more than 900 LED's works very well.

[palengh]

Thank you for your great effort with this project. I really appreciate it. I too experience the random flashing of the lights. Running WLED 0.8.5, and using a 5 m 300 LED strip. My power supply is 12V (12.5 A) directly to the LEDs sharing the common ground with the NodeMCU. My NodeMCU has D4 connected to the LED´s program wire. When setting Max current to 12500 mA, the LEDs flashes like strobe light. I need to set the LED Max current to below 2000 mA, to stabilize it, but even then it will flash randomly. When I disconnect the D4 connection, it's stable, even at 12500 mA.

The D4 connecting cable is 8 cm long. Setting "skip the first led" in the configuration dit not help

EDIT: Upgraded to WLED 0.8.6, and the strobe-like flashing is gone, even at 12.5A. Now it only dips to lower intensity randomly. This behavior seems to be gone when max power is set to 5A, but then the brightness/intensity is too low.

[austwhite]

I am using WS2811 LED's and I get the flickering issue quite badly when using default GPIO2 (D4 on D1 Mini) or GPIO3(Rx on D1 Mini) for the LED data. Strangely, the flicker only happened if I set the current to above 1000mA. If I limit the brightness, no flicker at all. I decided to play with this. I changed to use GPIO14 (D5 on the D1 Mini). The compiler warned me it would use software bitbanging which may cause flicker, but the exact opposite has happened. The flicker I was previously getting is now totally gone. Even at full brightness no flickering.
It isn't a hardware issue either as I have used 3 different D1 Mini's to test with (one was a D1 Mini Pro, genuine WEMOS, two are clones). I haven't got a WS2812 to play with at the moment, so I can't comment on that, but on the 12V version WS2811 I have this seems to have solved the flickering completely.

[matt-from-uk]

#87 led me here. I have the same issue as many. 12v WS2815 Using ESP32 dev board No logic shifter required - i actually tried a falcon f-amp initially but this caused a flicker whenever changing colour - once removed all was stable.

All worked well when using 193 pixels, now i have added some more (with necessary power injection from same supply with plenty of power) i get flickering, almost like a flash every so often. The frequency is different based on which effect is used.

I found the 'pride' effect a good test as this makes it flicker/flash very quickly. Something like twinklefox only every few minutes.

What is strange is that it is only really affecting the last 203 pixels, not the first 193. These numbers also coincide with what was seen in #87

Please let me know if i can provide any more info. Matt

[austwhite]

My flickering issue is resolved in the latest versions, as long as I use a logic shifter. As soon as I remove the logic shifter, the flicker returns toward the end of the strip. I know the LEDs are meant to be data repeaters, but this issue definitely seems related to logic level for me.

[kcoop99]

I can't recommend enough the QuinLed Uno boards. Eliminates every possible issue in my opinion.

[meekell]

I ran into the same issues as many have described here while running my under and top cabinet light strips. Each is controlled by a separate nodemcu. I determined the issue to be due to signal coupling between the two data signals. When running more than one data signal together, make sure you have sufficient wire separation so that the radiated emissions are not picked up by the other wire.

[rayperkins1]

I am having this issue now, I noticed when I am touching the signal wire the flickering goes away. I tried adding a capacitor to between D4 and GND, but that stops all color changing. Maybe I need a smaller capacitor, but I only have a few on hand to try.

Any other ideas?

[rayperkins1]

I read the uber guide to neo pixels on ada fruit and realized I needed to add a resistor between the ESP8266 signal pin and the data in on the LED string, now it works great.

[rawframe]

Prob1 : Mostly random flickers and colours. Fix : Make sure the circuits share the same ground (i.e. esp and lights have a common ground connection) Prob2 : Random flashes intermittently. Fixed by powering the esp unit via the 5v input and not 3.3v. (Perhaps transformer introduced noise/voltage fluctuation, or isolation/stability of gpio is better via 5v input) . Didn't try @rayperkins1 solution but could work in a similar way. [Wemos D1 mini & 5v SK6812]