Flicker is internal to WLED

Issues
1

I’ve just completed a project and I had some issues with flickering which generally manifest themselves as a short off-blink. My setup uses an ESP32 Dev Board V1 and 102 WS2811 pixels followed by a strip of 59 WS2815’s mounted in a channel, all on the same logical strip. Although I could have used a separate output pin for the WS2815’s, I went ahead and attached it to the end of the 2811 string, full knowing that the colors would be off due to the different RGB vs GRB protocols. This wasn’t a problem for this application, an automotive turn signal setup. Also, note that the WS2815’s are at the END of the string.

When I assign a Solid FX to the string, it glows steadily. When I assign the Blink FX to the string, it blinks on and off, but also flickers (briefly off) when on. After having read dozens of posts regarding flickering, null pixels, level shifting, power injection, power line noise, capacitors, series resistors, etc., it sure looked like an electrical problem to me.

The problem was that when using the Web UI, I turned on the Peek function to see what was going out to the strip and sure enough, the pixels shown by PEEK were also flickering. So, that leaves me to conclude that the flicker comes from Software, not hardware! Maybe it’s some stray interrupt, WiFi traffic, or something else, but so far I have not figured it out. The flickering isn’t completely random but rather happens at regular intervals.

Just on the basis of the web UI display, I can’t really see an electrical problem or noise spikes on the strip as being the source of the problem. I would expect a line noise problem to cause flicker downstream of the output pin, but the data being sent to the Web UI isn’t downstream from the CPU as it is generated by the wled program itself.

My final workaround was to choose an FX that gave me close to what II’ wanted but didn’t flicker. I ended up using the Stream FX which apparently doesn’t flicker.

The problem was especially bad using the Blink FX. The Blink FX has a solid-on, solid-off pattern and it’s during the ON time that you see the flicker.

I’m willing to be proven wrong by anyone reading this, but my bet is on this being caused by software.

2

What version of WLED are you using? The v.0.13.x version allows you to specify the LED strip type.

Since you have 2 different types of LED strips, depending on which LED strip type selected, it could cause problems along the entire strip, or just the WS2815’s at the end.

Be sure and select WS2811 as the LED strip type. If that part of the strip starts behaving correctly, you know you cannot mix and match off the same data pin without testing it first.

3

Yes, I’m using v.0.13.x and was aware of the string mismatch. I opted for using a single output pin for convenience (I already had the controller built). As far as I can tell, the only difference is that red and green are swapped in the data stream. They seem to work perfectly otherwise. Since the WS2815’s are at the end of the strip, I address them as a separate segment and simply be mindful of the red/green reversal when choosing colors.

4

I have some flicker using 0.13.0-b2.
But it goes away when I chose Config.
Strange.

5

0.13.0-b2 had/has flickering issues because of an updated dependency (asynctcp).
I downgraded to 0.12 and flickering was gone but I think there was already a fix to the main branch a few days ago but did not tested it sofar

6

Yep. Fixed in code.

7

Just tested with the latest build from master and the flickering is gone here as well! I wonder what asnyctcp screwed up :wink: