Neopixel Strip Random Colors, Damaged?

EL Wire/Tape/Panels, LEDs, pixels and strips, LCDs and TFTs, etc products from Adafruit

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rajington
 
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Neopixel Strip Random Colors, Damaged?

Post by rajington »

I'm pretty sure my strip is damaged but I wanted to verify. In my project I have 7 strips all with their own dedicated data pin, and I adjust the brightness of the strip according to an ambient light sensor.

MOST of the time the strip works fine, in fact it sometimes passes the sample color_test. However, whenever I go to really low brightness that specific strip goes all random-rainbowy-glowy at various sections of the strip. It will happen other times as well even with static light, but it almost always happens when I change the ambient light. I'm pretty sure the first pixel in the strip may be damaged but wanted to verify that and there's no way to save it (it's just weird that it works SOMETIMES).

If I do have to discard that one pixel, can I just solder OVER it? Keep positive and negative through the first pixel (I've verified with a multimeter I can read 5V all the way to the end), and then just solder directly to the second pixel's data in? Do I have to Remove the first pixel completely and resolder everything?

Thanks.


P.S. HOW I RULED OUT OTHER ISSUES:
  • The code being supplied to the rainbow-y strip works on every other strip.
  • I've swapped around power wiring, and tested it with a multimeter.
  • I've swapped out the data pin with other strips and that works.

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Franklin97355
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by Franklin97355 »

How do you have them wired? Have you made sure your wires to the controller are good, not broken internally and how is your soldering? Could you post clear pictures of your board and the connections to it?

rajington
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by rajington »

The power wires are connected with a 2.1mm jack to screw terminal block (https://www.adafruit.com/products/368 ) and I have all the adapters wired up with this octopus: http://www.amazon.com/gp/product/B004EAHJAG

I've tried swapping out the barrel adapter that is being used, and tried using different arms of the octopus, I've also multimeter measured a consistent ~5.0V at the end of the strip even when the random rainbow flashing was occurring so I really don't think it's a power wire issue.

As for my data wire, I've tried varying levels of "connected". From simple braiding of threaded wires to full on soldering. I can measure continuity using the multi-meter to the first data pin on the strip (after the first pixel the data continuity goes away, but I think that is supposed to be expected as all my strips do that) so I don't think it's a data wiring issue either but I could be wrong.

Here is the picture of the data connection anyway, don't worry this isn't how I have had it the entire time, and this isn't how I plan to have it long-term, but this does show it in the state it is right now behaving randomly, how it behaves no matter what the state. On the strip end of it, it was factory-soldered by Adafruit and shrink-wrapped so I haven't checked that at all (like I said, I checked continuity with the multi-meter so I didn't push past that). On the other side it's just plugged into the breadboard (I've also connected it directly to the Arduino, and other places on the breadboard with the same result).

Image

Thanks for helping me with this even though it is a holiday weekend.

rajington
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by rajington »

And here's the breadboard as well if you think that would help. It's probably hard to see, if you still think that the issue might be there vs a bad first pixel I can show it better but I'd have to unmount it: Image

There's an Arduino Micro, a real-time clock, a light sensor, a capacitor, and 9 pins connected in succession. The top 7 are the data pins going directly to 6-12 on the Arduino Micro, and then to the 7 strips. The bottom two are power (I just used wires to get the power from the Micro's righthand ports to the left hand so I could have a makeshift 9 port jumper cable to the breadboard from the wood part of the project.

rajington
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by rajington »

Finally here is a youtube video showing the whole 7-strip assembly with breadboard to the right. In the video I'm turning the light off and on and you start seeing some weird behavior. It doesn't go crazy-rainbowy-flashy here, but it definitely isn't acting correctly like the other strips are.

https://www.youtube.com/watch?v=2-NDEtbAUyQ

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pburgess
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by pburgess »

Since you've swapped the data pin with other strips, I think a defect is more likely, in which case we can replace it. Email [email protected] with your order # and a link to this thread to set that up.

If you're in a rush and want to just get on with the project and can do without one pixel, then yes, you can usually wire into the input of the second pixel. In that case, you'll still need to sever the connection between the Arduino and the first pixel, or between the output of the first pixel and input of the second (so only the Arduino's feeding it).

rajington
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by rajington »

Thanks, it's been months since I've ordered the strip and I'm just getting around to building it now, not sure about the exchange policy. As long as only one pixel is damaged, going to 59 LEDs is no problem. It's supposed to represent seconds so 0-59 is all I need. Thanks for the help.

rajington
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by rajington »

I removed the first pixel and that fixed everything. I've always had a capacitor in my circuit but I just noticed that you now also recommend a resistor on the data line, is that a new addition? I just want to make sure that my 59th pixel stops working.

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pburgess
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by pburgess »

Yeah, it's been a learning process as we try different ways of protecting the data input. Current preferred methodology has a 330-ish Ohm resistor on the data line (as close to the strip as possible) along with a 100K resistor between data and ground. And the big cap on the power input.

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ubiyubix
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by ubiyubix »

pburgess wrote:Yeah, it's been a learning process as we try different ways of protecting the data input. Current preferred methodology has a 330-ish Ohm resistor on the data line (as close to the strip as possible) along with a 100K resistor between data and ground. And the big cap on the power input.
Why do you recommend to place the resistor as close to the strip as possible? What if I place the resistor along with the microcontroller on a board and have a neopixel ring connected over say 3 feet of wires?

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Franklin97355
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by Franklin97355 »

and have a neopixel ring connected over say 3 feet of wires?
You then have three feet of wire to cause problems.

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ubiyubix
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by ubiyubix »

Ok, thank you. I am going to place the resistor close to the neopixels then. I would like to understand *why* though. Perhaps I am missing some fundamentals, but I thought that if I have multiple resistors in series, then the order of those resistors does not matter. Here we have the 330-ish resistor and a wire, i.e. another, very small resistor. Why does the order matter?

rajington
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by rajington »

If you mess up and there is a short on the wire leading to the pixel's data line then the spike would hit the strip before the resistor. Lemme know if I didn't explain that well enough.

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ubiyubix
 
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Re: Neopixel Strip Random Colors, Damaged?

Post by ubiyubix »

rajington wrote:If you mess up and there is a short on the wire leading to the pixel's data line then the spike would hit the strip before the resistor.
This make sense. Thank you!

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