One WS2811 pixel: red only

Troubleshooting
1

So I just put up my Christmas tree frame again. Everything is working great, except for one of my 135 pixels:

  • red when RGB(1,0,0)
  • off when RGB (0,1,0)
  • off when RGB(0,0,1)
  • red when RGB([0-1],[0-1],[0-1])

So the pixel is always red when it receives just a bit of red.

Pretty sure the problem is in the pixel WS2811 pixel itself, since it happens in any 2D pattern I use.

My suspicion is that this one pixel is just faulty and will need to be replaced.

Can someone confirm my suspicion? Or is there something else I can try in code to fix this?

2

Yes, that is almost certainly a bad pixel. It can happen if the green and blue elements become damaged or disconnected. With strips there are a number of factors that can cause it, often damage to the clear lens area.

If it is super distracting, you could add a bit of code to keep it black. Something like

export function render(index) {
  if (index == 123) {
    //"bad" pixel
    rgb(0,0,0)
    return;
  }
  // rest of pattern render code...
}
3

Thanks for your quick reply!

I think my WS2811’s are 7 years old now, and being one and half month outside each year is taking its toll.

And I just remembered that I replaced quite some pixels last year, because they were faulty as well. Luckily it’s just one this season, and it’s in a corner, so not affecting the patterns much.

Thanks for the code! I’ll add that.

4

Could you explain why you added return at the bottom?

5

This is so that the normal pattern code beneath it (see “// rest of pattern render code...”_ doesn’t also execute and overwrite the rgb(0,0,0).

Alternately you can put the if (index == 123 at the bottom of render() { and skip the return statement. It will overrule previous calls to rgb() and hsv(). This is a little less efficient though. If I’m disabling larger portions of my pixels than just a few, I at least like reclaiming the compute cycles.

6

It has the same effect as putting the rest of the code in else {, correct? Is it equally efficient?

I was under the impression that return is only used to return a value of a method, first time I see it used in such a manner.

Thanks for the quick and thorough reply btw:)

7

Yes! Same effect and equally efficient.

A minor advantage of the return version is that the main portion of the render code isn’t indented and contained within another set of braces. I generally try to avoid code blocks that span longer than a screen worth, because you can lose the context of what you’re nested in.

1 Like
8

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