NeoPixel strips have three copper solder pads between each pixel. You can cut the strip through any of the copper pads to get the length you want.
Step 1: Identify Your Solder Pads
- 5V (or sometimes +) -- a RED wire comes pre-soldered to this pad.
- G (or sometimes GND) -- a BLACK wire comes pre-soldered to this pad.
- IN / OUT (or sometimes with arrows) -- a WHITE wire comes pre-soldered to this pad, and often a female JST connector for IN and a male JST connector for OUT.
Step 2: Find the IN End
Now that you've identified the three different pads, find the end of the strip marked IN. If there are little arrows, they'll be pointing away from the IN end and toward the OUT end.
We'll solder all three wires to the IN end.
If your strip is brand new, it probably has wires and a connector already soldered to one or both ends. Take a look at the Connecting Wires page (link in the sidebar) if you want to use these.
Step 3: Expose the Pads
Use your flush cutters to carefully cut through the center of the copper pads, "upstream" of your first pixel. Then, trim out a window in the silicone casing so it's out of your way.
Step 4: Heat Shrink
Cut about 3/4 inch of clear heat shrink tubing. Slide it onto your strip and pull it down past exposed soldering pads a bit so it's out of your way. Don't shrink it down yet, just get it in place. When we're done soldering, we'll use this to seal up our connections so they're bulletproof.
Step 5: Tin the Pads
Turn on your soldering iron and wait until it's fully heated. If it has a temperature gauge, set it to 750 degrees. Otherwise, just wait about 3-5 minutes so you can strike while the iron is hot.
While you're waiting, get the little sponge in your soldering iron stand wet so you can clean off the tip of your iron. Go ahead and clean it off now, once your iron is hot. It's easier to solder with a clean iron.
Unspool a bit of solder. Touch one of the copper pads with your soldering iron to heat it up. Touch the solder to the copper pad at the same time. Once the copper is hot enough, it will melt the solder which will then flow onto the pad and cover it in liquid metal.
Once this happens, lift your soldering iron away and clean off the tip with the sponge on your stand.
Repeat with the other pads. They should look shiny and have a nice dome-shape when you're done.
If you'd like more help with soldering, see this guide for all the details.
Step 6: Prepare your Wires
Unspool and cut three wires of about equal length in red, black, and white. These will connect to your microcontroller, so think about how far you want to place your controller from the pixel strip and before cutting them to length.
Your data signal will start to degrade if the wires are more than about 3 feet long, so keep them shorter than that.
Use your wire strippers to strip a tiny bit off the end of each wire -- no more than 1/16" / 2mm. This will attach to the copper pad so it's helpful to strip just enough wire to sit on the copper without hanging over.
Step 7: Tin your Wires
Bend your wires up so they're away from your work surface a bit, or use a third hand to hold them steady. Give the ends a twist to be sure all the little wire strands are stuck together.
Heat the exposed wire with your soldering iron, and touch your solder to the wire at the same time. The solder will melt and flow along the wire just a little bit so it gets coated. Do this for all three wires.
If you end up with a ball of solder on the tip of the wire, snip it off with your flush cutters.
Step 8: Solder Wires to Pads
Place your tinned wire right on top of its corresponding tinned pad: red goes to 5V, white to DIN, and black to G.
Hold the wire on top of the pad. Touch the soldering iron to both the wire and the pad at the same time, to melt the tinning on both. If all goes well, the solder will melt and flow together, and you'll end up with a beautiful shiny joint.
Repeat with the other two wires, being sure to keep each copper pad self-contained and not touching the other pads.
Step 9: Test Your Strip
Before we seal up our connections, it's always important to test the strip to be sure it's working. Chasing down a bad solder joint in the middle of a complicated project can be a nightmare -- much better to catch any mistakes early.
Strip about 1/4" of shielding off the free end of your three wires. Get out your alligator clips and hook them up to the color-corresponding wires, then attach the other end of the clips to your microcontroller. If you're using a Circuit Playground Express, hook red to VOUT, white to A1, and black to G.
If you haven't done so yet, upload some test code to your microcontroller. Here's some test code you can use with the Circuit Playground Express or a Gemma M0 that will run a rainbow along your strip if you attach it to pin A1.
- Download the appropriate UF2 file
- Plug your microcontroller into your computer with a good USB cable. The lights on the face will turn green. If they don't, click or double-click the tiny "reset" button in the center of the board until they do.
- A drive will appear on your computer called CPLAYBOOT (for Circuit Playground) or GEMMABOOT (for Gemma M0). Drag the file you downloaded onto this drive. You're done!
If you're having trouble, head over to the Circuit Playground guide to get things working.
Step 10: Seal it Up
Hooray, your strip is working! Let's make sure it doesn't break.
Slide that clear heat shrink down until it closes the little "window" you cut in the silicone casing. Squirt a little bit of hot glue inside the heat shrink, then use a heat gun to shrink the heat shrink while the hot glue is still wet.
Once the whole assembly cools, your shiny new solder joints will be fully encased in plastic, waterproof, and virtually unbreakable.
If you ever need to open the strip up again, for any reason, it's easy to do. Slide your flush-cutters up under the heat shrink and cut it open as far as you can. Then, pour a little 99% isopropyl alcohol onto the hot glue and connections. After a couple seconds, the hot glue will release and you'll be able to pull it free without damaging your solder joints.
It's like an "undo" button for glue! Hot glue is the best.