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Neopixel strip. Did I burn out DIN or bad Neopixel or other
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Neopixel strip. Did I burn out DIN or bad Neopixel or other

by djcyph on Tue May 07, 2019 6:40 pm

Semi-newbie here. My strip is a WS2812b 5m strip (300 leds) and when I first got it, I mistakenly attached a 9v adapter for a few seconds. I got the right power supply, a 5v 12a and after wiring, only the first 10 seem to be getting some data. It's hard to see in the picture below but the first led is a dim blue, second is super bright white then the next few are either not lit or the dim blue color. After led 10, last dim blue one, the rest do not light up.

Image

I'm using the strandtest code from the neopixel library and my wiring is the same as below.

Image

To test wiring and code were correct, I cut off the last 8 neopixels in the strand, changed pixel count in code to 8, wired and they worked perfectly. I went to the strandtest code and modified pixel amount to 292 hooked those up and still the same as my original problem.

While trying to troubleshoot online, I read that blue leds could mean data not flowing correctly. So any chance I blew a DIN connection or neopixel when I hooked up the 9v power supply? Or could it be that I'm not using a capacitor or resistor with the wiring?

I was going to cut off the first 10, solder new wires and test again but figured I'd ask here first.


Thanks!

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by adafruit_support_bill on Wed May 08, 2019 6:19 am

The pixels are designed for 5v operation. With the older WS2812 strips, anything over 6v would easily toast the whole strip. The newer SK6812 is a little more resilient. But a 9v supply voltage is likely to cause some damage.

Since all pixels are powered from the same +5v and GND rails, all of the pixels would be at risk when connected to a higher voltage source. Failure modes may vary from pixel to pixel. But if the data forwarding function is damaged, it will affect all of the downstream pixels as well.

You can try injecting your data signal to the DIN pin at various points along the strip to see which ones may still be functional. You don't need to cut the strip to do that. Just use a jumper wire from D6 on your UNO and touch it to the DIN pads at various points along the strip.

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by djcyph on Mon May 13, 2019 5:38 pm

Thanks for your response Bill. I tried what you said with the jumper wire and on the DIN pin after pixel 5, it makes the dim blue pixel 5 flicker. Nothing happens with the other ones. Does that give you any insight to the problem? I'm using a sketch now that just lights up one LED at a time to ensure it can cycle through each LED on the strip with no power issues. I know resistor & capacitor is needed for a full strip to work without any hiccups but from what I was reading, doesn't seem like I'd need it with my test sketch of one LED lighting up at a time. Or is that wrong?

If the issue is not from capacitor/resistor should I just cut first ten off now? Again, the last 8 I cut off work fine with any sketch.

Thanks again!

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by adafruit_support_bill on Mon May 13, 2019 5:58 pm

I don't think the issue is related to a missing cap or resistor. The 9v most likely damaged a number of pixels on the strip. And if a pixel is damaged enough to keep it from relaying the signal from DIN to DOUT, it will affect all the downstream pixels too. You can try injecting the signal at various points along the strip. If you find some still healthy sections between the dead pixels, you can cut those out and use them separately.

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by djcyph on Mon May 13, 2019 7:17 pm

Ok cool....So now I think I can confirm that I did damage at least one of the first ten LEDS. I used jumper wire to connect 5v, GND and DIN to the pins after the first ten pixels in the my original post pic and the rest of the strip works as programmed! So I'm going to just cut off first ten.

Now my next question is related to the capacitor and resistor and a full strip of 300 LEDs being programmed to do various things instead of my one LED on at a time test sketch. If a capacitor & resistor is not used, can damage be done to entire strip or just first pixel? I only have 100uf capacitors and will order the correct ones but just curious if I can mess around without the capacitor now or will it possibly blow out a bunch of the LEDs once I upload a more advanced sketch?

Once again, much appreciated Bill!

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by adafruit_support_bill on Mon May 13, 2019 7:31 pm

The purpose of the resistor is to protect the input of the first pixel from the 'ringing' that can occur on a longer signal line. For shorter runs, it is less of an issue. The resistor will have no effect at all below about 8".

The capacitor is to protect against power-on surges from your power supply. Sometimes we run across a power supply that will put out a high voltage spike on power-up before the regulators have a chance to stabilize. The capacitor is just some relatively inexpensive insurance against a possibly strip damaging spike.

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by djcyph on Mon May 13, 2019 7:35 pm

Got it!! Much appreciated!

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by DJDevon3 on Tue May 14, 2019 3:03 am

It's fine to power LED's from the Uno with a small # of LED's as long as it's under the rated max amperage of the Uno which I believe is somewhere around 800mA. The problem with your configuration is that you have split the external power supply directly to the Uno. If you were to add 300 LED's in that configuration you're going to fry LED's and/or your Uno. Therefore you current configuration is not upgradeable and in my opinion a bad habit to get into instead of an upgradeable configuration.

Below is a diagram that will allow you to safely control from 1 to 300 WS2812B LED's. All it needs is the common GND and DATA to control the LED's. Running a secondary power 5v USB or DC in power source to the Uno is a much safer way to do it.

I've personally never done more than 300 (2 full reels of 150x WS2812B's). It will safely draw the max rating of my power supply which is about 1.5 Amps thanks to FastLED power management. I'm almost guaranteed never to blow my LED's or PSU when FastLED power management is setup correctly. I do not use a capacitor.

I have this setup running on an external 9V PSU, to a barrel on/off switch purchased from Adafruit :), stepped down to 5.0V with a buck converter to the LED strip and USB powering my Uno connected to a PC so I can change the sketch anytime I want. This is a permanent PC fixture and might not be the ideal solution for everyone if you want to run the lights away from a PC in which case you would use the 7-9V DC in jack instead. Running 300 LED's on an Arduino Nano 24/7 for about 3 years in my garage, it cycles through the DemoReel preset just to add some color to my garage.

The reason I went with a 9V PSU and step down buck converter instead of a 5V PSU is because it helps cull out some of the voltage drop. Set the buck converter to 5.0V and it will dynamically regulate itself to keep the target voltage you set at 5.0V. When combined with FastLED power management it's a safety concise combination. Also a great way to ensure you're at 5.0v otherwise your strips will go haywire. Also excellent feature to monitor your amperage use per sketch.

I've run this same configuration successfully on 3 different types of Arduino's (Nano, Uno, Metro Mini). No, they never failed I just liked trying it out with different Arduinos. The problem with these Arduinos is the very limited storage for sketches. They will definitely run any 300 addressable LED sketch you can throw at it even on Nano but it will only be able to run 1 at a time. You wouldn't be able to build a menu that will cycle through sketches there simply isn't enough storage for it... on a Metro M4 Express or Grand Central though yes and that's where I'm headed next with a bigger project box, more power, and more LED's.

As you can see from 1 LED to 300 LED's this is the way to do it.
Attachments
Nano_FastLED_300StripLight.png
Nano_FastLED_300StripLight.png (707.84 KiB) Viewed 224 times
Nano_FastLED_300StripLight_Interior.png
Common ground is soldered together on the LED strip itself, in hindsight it puts weight on the solder pad not ideal but works beautifully.
Nano_FastLED_300StripLight_Interior.png (643.06 KiB) Viewed 224 times
WS2812B_UnoSetup.png
WS2812B_UnoSetup.png (116.4 KiB) Viewed 224 times

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by adafruit_support_bill on Tue May 14, 2019 6:12 am

If you were to add 300 LED's in that configuration you're going to fry LED's and/or your Uno. Therefore you current configuration is not upgradeable and in my opinion a bad habit to get into instead of an upgradeable configuration.

That is not correct. In the OP's circuit diagram, both LEDs and UNO are being fed directly by the power supply. Adding more LEDs to that configuration does not increase the current flow through the UNO in any way. Similarly, adding an UNO load in parallel with the pixels poses no danger to the pixels.

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by DJDevon3 on Mon Aug 12, 2019 5:37 pm

How many amps can an Uno take on the 5V pin @5V before it fries? From everything I've reading it's not much more than 800ma. If you're running 600 LED's for example it's going to draw about 3-6 amps (if provided power from both ends of the strip) and I'm pretty sure that'll fry the Uno parallel or not. That's why I separate the Uno for dedicated data and GND side switching only. If I'm misunderstanding please let me know because I do intend to eventually go up to 600-1200 LED's to surround a room.

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by adafruit_support_bill on Mon Aug 12, 2019 6:57 pm

Powered as in your diagram (copied below) the LEDs are not drawing any power at all from the 5v pin. They are drawing power directly from the 5v power supply. This is a safe way to do it and poses no danger to your UNO.

The only current flowing through the 5v pin is the current drawn by the UNO That will be about 25-30 mA.

Image

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by DJDevon3 on Wed Aug 14, 2019 6:02 pm

Awesome thank you. It's only when you attempt to power the strip 5V from an Uno GPIO you'd fry it? Is that where people go wrong in trying to drive LED's from an UNO? I've always separated the LED 5V from the Uno 5V because it seems the safest way. Always figured if I connected main 5V line to it I'd see smoke and kill the Uno.

Is there any benefit to having the Uno connected to 5V line instead of using a separate power supply other than only requiring 1 power supply? I have a project where I'll need to connect 3 Uno's. Can I connect them all to the same 5V source now instead of having ummm 6 power supplies lol?

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Re: Neopixel strip. Did I burn out DIN or bad Neopixel or o

by adafruit_support_bill on Wed Aug 14, 2019 7:01 pm

Powering multiple UNOs from one supply is not a problem as long as your supply can handle the load. Allow about 30 mA each. Plus extra for any attached circuitry. If you are connecting big loads like led strips, run power to those directly as in the diagram.

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Please be positive and constructive with your questions and comments.