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Help with Neopixel required equipment?
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Help with Neopixel required equipment?

by LovePotion on Thu Dec 03, 2020 2:43 pm

Hi there, I’d like to try coding the neopixel but I don’t have any soldering experience. I noticed a 30 led neopixel with a 3 pin jst (PID: 4801) which I am planning to use. I need some advice on what board to use as well as power solutions. I’m thinking some type of feather but I don’t know how to pick the right one. I’d like it to be bright but I noticed the 5V power supply isn’t in stock.
Any advice is appreciated! I’ve read the neopixel guide but it doesn’t go over much stemma and jst connectors.
Thanks

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Re: Help with Neopixel required equipment?

by dastels on Thu Dec 03, 2020 5:46 pm

Look for boards with the 3-pin JST connector. PyPortal https://www.adafruit.com/product/4116 boards have it, as does the Prop-Maker FeatherWing which can be bought pre-assembled https://www.adafruit.com/product/4145 that can be used with most feathers (the M4 Express is a good choice), but alas there doesn't seem to be a pre-assembled option.

If you just want to do some NeoPixel related coding in CircuitPython without a specific project that requires a a long strip, have a look at the CircuitPlayground Express https://www.adafruit.com/product/3333 or CircuitPlayground Bluefruit https://www.adafruit.com/product/4333. If working in C++ is fine, then the CircuitPlayground Classic https://www.adafruit.com/product/3000 is an option as well (note that the Classic DOES NOT support CircuitPython). The advantage of the CircuitPlayground boards is that they are completely pre-assembled and have 10 NeoPixels on-board. You can connect a strip that has alligator clips such as https://www.adafruit.com/product/3811.

Dave

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Re: Help with Neopixel required equipment?

by LovePotion on Thu Dec 17, 2020 12:43 am

Thanks for the response.
I've been mulling over my purchase and have a few more questions just to make sure I have everything I need.

I want to get the NeoPixel starter pack. It includes:
    -Adafruit NeoPixel Digital RGB LED Strip - Black 30 LED/m - One Meter with JST connector on input side
    -Female DC Power adapter - 2.1mm jack to screw terminal block
    -2-pin JST SM Plug + Receptacle Cable Set
    -5V 2A (2000mA) switching power supply - UL Listed

- How would I attach the 2pin JST SM receptacle Cable to the microcontroller? Are there any 2 pin JST SM to male header cables I could use to connect to the metro with headers. Can I plug male to male jumper cables from the 2 pin JST to the headers? How would I connect a ground wire from the power to the metro?
-Will I need to add a capacitor? I've read I can use the 4700uF 10v.
- I am willing to purchase soldering equipment or learn how to use a breadboard but I just want to make sure I have everything I need first and trying to see if I can do it without.


I would also like to pick up a NeoPixel UV LED strip as well and would like it to be as most plug and play as possible between the two (as the "Female DC Power adapter - 2.1mm jack to screw terminal block" is out of stock right now)

Thanks for the help.
LP

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Re: Help with Neopixel required equipment?

by blnkjns on Thu Dec 17, 2020 3:09 am

Unless you plan to use it as wall flood light, there is absolutely no need to mess with an external PSU. We code 16x16 pixel games for neopixels in our classroom, and drive that fully from USB bus power. That is 256 LED's on 500mA!
But we set them on 10% brightness because you don't want to burn that Pac-Man maze in your retina.
What is your use goal?
Who came up with that ridiculous way to attach a wall socket to your project. Seriously? Screw terminal with crimp connector?
The best way to power LED's is with decent USB phone chargers, you propably have a few spares! They do 2-3A, their 5V is much more precise, and a breadboard USB socket is more elegant than those huge old fashioned EIAJ-type PSU's.

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Re: Help with Neopixel required equipment?

by dastels on Thu Dec 17, 2020 11:23 am

Yes, figure out roughly how much power you pixels will need. 30 neopixels all set to white at full brightness will need close to 2A. That's the most it would ever need. Using a lower brightness and colors closer to red, green, or blue will reduce it. While LEDs aren't all that linear with brightness, 10% brightness could be close to 200mA. Of course if only a subset of the pixels are ever lit, then power requirements are going to be proportionally less.

The cap is a good idea to mitigate the potential current demand surge when the strip gets power. However, with such a small strip it's not imperative.

To connect:

The data input to the strip always connects to your controller board. Ground always connects to ground. ALL grounds need to be connected together. Power is connected to power of your controller if you're not using an external supply. That limits you to a few 100 mA for the pixels. If you need more, you'll need an exteral supply. In which case the strip power connects to the +ive from the power supply, and as before, ALL grounds connect together.

In the pack you got, both black wires from the strip are ground (and are connected already on the strip), red is power, and white is data in.

You will need to solder in some way to connect to the supplied wires. It's a skill well worth having. See https://learn.adafruit.com/adafruit-guide-excellent-soldering for a good soldering tutorial.

Dave

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Re: Help with Neopixel required equipment?

by LovePotion on Wed Jan 13, 2021 10:32 am

Thanks for all the help. I've been taking my time, looking things over before I pull the trigger. My last lasting question is for the uv neopixel and the regular neopixel in the starter pack - they both are listed as having 2 pin jst connectors - is that only for the data or is that the power and data combined? I'm planning on powering it separately with the ac adapter and a barrel screw adapter but I'm unsure of how to get the data pin into a header on the metro. My plan was to use wire strippers and a jumper cable - strip one side of the jumper cable and make a wiring harness from the 2 pin jst receptacle to data for the metro. Does this make sense or will the jst connector be all 3 wires?
Thanks

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Re: Help with Neopixel required equipment?

by DanGR on Wed Jan 13, 2021 11:05 am

LovePotion wrote:-2-pin JST SM Plug + Receptacle Cable Set


The boards Dave mentioned have a 3-pin JST-PH connection to attach to them without soldering you need a strip with a matching 3-pin JST-PH connector.
https://www.adafruit.com/product/4801
https://www.adafruit.com/product/3919

The strips are labeled on each solder pad so you can tell which wire goes to what. Black ground Red +5 V and the data wire can vary as to color.

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Re: Help with Neopixel required equipment?

by dastels on Wed Jan 13, 2021 11:51 am

I am trying unsuccessfully to find the NeoPixel starter pack you mention. Can you post a link?

Dave

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Re: Help with Neopixel required equipment?

by DanGR on Wed Jan 13, 2021 12:17 pm

Dave this is the link:
https://www.adafruit.com/product/2562

I did not notice it at first either.

Dan

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Re: Help with Neopixel required equipment?

by dastels on Wed Jan 13, 2021 1:51 pm

Ah. Ok. That strip has 2 sets of wire pairs:
- both blacks are ground and are connected together at the strip.
- white is the data-in line
- red is power (an external source or connected to power on your controller board. It's 30 pixels so it's likely fine to power from the board unless you plan to have them all on most of the time, very bright, and using colors closer to white (i.e. using all 3 LEDs in the pixels).

So the 2-pin JST is the data connection, and the plain wires are for power.

Now.. what's this UV NeoPixel you mention? There's not such a thing as far as I know.

Dave

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Re: Help with Neopixel required equipment?

by LovePotion on Wed Jan 13, 2021 2:05 pm

Thanks for the response's everyone, sorry for being a noob.
Here's the uv neopixel:
https://www.adafruit.com/product/3851

So just to get this right before I dive in:
The black (ground) and red (power) from the neopixel connect to the screw block adapter (a large capicator is added to the screw block adapter connecting red and black). The 2 pin jst connector from the neopixel connects to a female 2 pin jst connector receptacle and one wire goes to data on the metro and the other to ground on metro? Could I use this: https://www.adafruit.com/product/677 to connect the wires from the jst receptacle to jumper wires to plug into the metro? Or is there a better practice for jumpers? I am planning on trying this first and learning soldering later! I'd like it to be plug and play between the uv neo pixel and led if possible.

Almost there!!
Thanks

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Re: Help with Neopixel required equipment?

by dastels on Wed Jan 13, 2021 2:09 pm

AH. I haven't run into that one before! From the photos it looks like the wiring will be the same.

Dave

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Re: Help with Neopixel required equipment?

by LovePotion on Wed Jan 13, 2021 2:16 pm

Thanks Dave. How about connecting the jst receptacle to the headers? Can I just strip one side of a jumper and wrap the wire around the jst cable and tape it in order to connect it to the metro headers? Or would you recommend the euro style connector to connect two wires? I'm almost ready to purchase while everything is in stock!

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Re: Help with Neopixel required equipment?

by dastels on Wed Jan 13, 2021 2:38 pm

I don't recommend the wrap&tape approach. You need reliable connections so they should be soldered. Yes, you could use the terminal block to connect it; that would work well.. Sorry... I stopped reading after the UV strip thing.

Dave

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Re: Help with Neopixel required equipment?

by DanGR on Wed Jan 13, 2021 3:27 pm

I agree with Dave about soldering and reliable connections. The JST-SM cables can be made up without solder. This requires a kit and special crimping pliers. Adafruit does not sell the kit I got mine from Amazon but they do sell the special crimping pliers. You can make both male and female connectors with the kit and crimpers.

https://www.adafruit.com/product/350
https://www.adafruit.com/product/349

I measured the pins that came with the kit and both the crimpers will work. The choice is what size wire you will be working with the RC guys like the PA-09 for the smaller servo wires.

The photo of the Metro and the UV strip show alligator clips and they are good for testing but not reliable for a finished project.
https://www.adafruit.com/product/3448

Dan

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Please be positive and constructive with your questions and comments.