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Neopixel strips have sometimes wrong colours
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Neopixel strips have sometimes wrong colours

by mouha on Sun Sep 26, 2021 12:15 pm

Hi,

Here is the context of my issue :
    * I've bought 3 x 1507 (144 rgb ) which I cut to have 6.
    * I've connected all of them to a fadecandy and to a 5V/5A wall power supply.
    * I'm using the test patterns from the FC server page.

The issue : 3 strips are properly display white colors, some of the others are displaying some colors (randomly) and some nothing.

So I've used another FC to check that it's not the problem with only 2 strips.
Same : the strip that was ok is still ok , and one of the wrong strip still wrong.

The picture shows it well:
    with no pattern some weird colors for the bad strip + 1 led (!!) for the good one
    with 50% pattern : the good diplays everything properly + the wrong is not changing

no pattern.jpg
no pattern.jpg (134.52 KiB) Viewed 108 times

50pct_partern.jpg
50pct_partern.jpg (581.29 KiB) Viewed 108 times

mouha
 
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Re: Neopixel strips have sometimes wrong colours

by dastels on Sun Sep 26, 2021 2:18 pm

Did you test them before cutting them?

Have you double and tribble checked your wiring? Specifically the connection at the end of the strip.

Dave

dastels
 
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Re: Neopixel strips have sometimes wrong colours

by mouha on Mon Sep 27, 2021 4:05 am

I just checked 1 from the 3.


Not only I've checked the wiring but 2 of them have been removed to be re-wired to another Fade Candy.
These are the one you can see on the picture.

mouha
 
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Re: Neopixel strips have sometimes wrong colours

by mouha on Mon Sep 27, 2021 11:36 am

Is there something that can be done to get the strips working ?

mouha
 
Posts: 42
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Re: Neopixel strips have sometimes wrong colours

by dastels on Mon Sep 27, 2021 12:26 pm

I would test each (half) strip with a simple test. One of the neopixel examples will do. No fade candy, just a simple board (even an Arduino UNO should do) to test the basic function of each strip. Describe precisely how the problematic strinps behave.

Dave

dastels
 
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Re: Neopixel strips have sometimes wrong colours

by mouha on Mon Sep 27, 2021 3:36 pm

I don't have Arduino. what is possible to do with a PI please ?

mouha
 
Posts: 42
Joined: Tue May 20, 2014 6:50 pm

Re: Neopixel strips have sometimes wrong colours

by dastels on Mon Sep 27, 2021 5:31 pm

Try the example code in this guide:
Code: Select all | TOGGLE FULL SIZE
https://learn.adafruit.com/neopixels-on-raspberry-pi/raspberry-pi-wiring
.

Dave

dastels
 
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Re: Neopixel strips have sometimes wrong colours

by mouha on Mon Sep 27, 2021 5:38 pm

Last question : but what if after the half that have been cut : it still doesn't work properly while testing like you propose ?
I've been reading the Uberguide / tech detail / etc . and I understood that it was easily possible to cut a strip to make 2 .

I never found anything to set a common ground between the power supply and the strip when using the FC so ...

mouha
 
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Joined: Tue May 20, 2014 6:50 pm

Re: Neopixel strips have sometimes wrong colours

by dastels on Mon Sep 27, 2021 5:43 pm

Yes, cutting them should not cause a problem. Hmm.. can you post clear, closeups of the ends where you chut, and where you've connected to the resulting strips.

Hmm again, the half strips that are causing a problem.. are you connecting to a cut end on them as opposed to the original wired end?

Dave

dastels
 
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Re: Neopixel strips have sometimes wrong colours

by mouha on Wed Sep 29, 2021 4:50 am

Some close up from these strips.
20210929_103418.jpg
20210929_103418.jpg (643.34 KiB) Viewed 60 times

20210929_103402.jpg
20210929_103402.jpg (788.06 KiB) Viewed 60 times

20210929_103408.jpg
20210929_103408.jpg (753.91 KiB) Viewed 60 times


Each strip have been cut around its middle for some strips, and 65 or 66 Neopixels for others . Because the FC manage up to 64 I did this.

Thus, each strip is soldered to the FC by using the existent connector part, not from the cut side of it.

mouha
 
Posts: 42
Joined: Tue May 20, 2014 6:50 pm

Re: Neopixel strips have sometimes wrong colours

by dastels on Wed Sep 29, 2021 9:44 am

OK. Each end of the strips is different. One end has Data-in... the other has data-out. You need to connect to the data-in sides. So in half the cases, that will be the cut end.

Dave

dastels
 
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Re: Neopixel strips have sometimes wrong colours

by mouha on Wed Sep 29, 2021 9:57 am

I see, indeed the one that doesn't works has the arrows in a reversed way.
So : is it enough to switch the 2 data wires of this strip from the FC ?

mouha
 
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Re: Neopixel strips have sometimes wrong colours

by dastels on Wed Sep 29, 2021 10:11 am

Connecting the data from the FC to the Data-in of the strip will probably fix your problem barring anything other issues, though no damage should have been done by the connection to Data-out.

Dave

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Re: Neopixel strips have sometimes wrong colours

by mouha on Sun Oct 03, 2021 12:23 pm

I have retry all the strips that were blank, by reversing the 2 wires (white & black) : none of them worked.

Does this means that if you just reverse these 2 wires, the strip get damaged all the time ?

mouha
 
Posts: 42
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Re: Neopixel strips have sometimes wrong colours

by dastels on Sun Oct 03, 2021 2:00 pm

Why did you do that? black is ground and white is signal (generally)... is that how they are connected on the FC?

You nned to connect the data signals from the FC to the Data-in end of the strips. As you say, there are arrows that indicate the flow of data through the strip. The arrows point from the Data-in end to the Data-out end.

Dave

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