Begin by measuring how many LEDs your sunglasses will need. It’s easiest just to hold the strip behind the glasses and slide it around to settle on a position, then count the LEDs. Try to place the LEDs above center, toward your forehead…this way they’ll block less of your field of view.

Using the high-density NeoPixel strip (144 LEDs/meter), one of our pairs of glasses required 20 LEDs, another required 22. The 60 and 30 LEDs/meter strip would have proportionally fewer LEDs.
NeoPixel strip has a definite “in” and “out” end. Look for the arrows — these indicate the direction of data from the microcontroller, moving from in to out.

The Trinket/Gemma board will connect to the “in” end…that would be to the left in this view.
If using the high-density strip (144 LEDs/meter), you might choose to cut just to the left of the marked cut lines. When using the remainder of the strip in another project, this makes it easier to connect wires to the input.

This doesn’t apply to 60 or 30 LEDs/m strip — these have connection points on both sides of the cut line.
Flush cutters work well for cutting the strip. You might need to make two cuts to cover the full width; one from below, one from above.
Optional: I’m not comfortable with little sharp points right next to my eyes. The strip will certainly hold in place when installed, but as an extra precaution the corners were rounded slightly at both ends of the strip. Just in case.
The vias (wire holes) on the strip are very tiny! When connecting wires, you might find it necessary to widen these holes slightly by inserting the point of a pair of tweezers and turning.

The circuit is incredibly simple, with just a few connections needed…

If using Trinket: Though data moves only one way through a NeoPixel strip, power transfers both ways. We use this to our advantage here, making the strip itself function as a power bus for the whole circuit. Cut the JST battery extension cable about 4" (10 cm) from the plug end (the end that connects with the battery). Strip the ends of the wires, give them a twist and then insert them anywhere along the strip; black wire to –, red wire to +, and solder in place.

The wires should be inserted back to front (soldered on the LED side); the diagram below has the wires on the front just to show how they’re routed.

At the input end of the strip, three wires are then connected between the strip and Trinket board: (minus) on the strip to Gnd on Trinket, + on the strip to 3V (or 5V) on Trinket, and the remaining connection to Pin #4 on Trinket.

If using 60 or 30 LEDs/meter NeoPixel strip, the connections are in a different order than shown here, and are labeled GND, +5V and DIN (rather than –, + and unmarked, respectively).
This diagram uses the original Gemma and Trinket but you can also use the Gemma M0 or Trinket M0 with the exact same wiring!
Gemma is even easier. There’s already a JST connector on this board, so clipping a plug off a battery extension isn’t needed. Just connect (minus) on the strip to GND on Gemma, + to Vout, and the remaining pin to D1.

If using 60 or 30 LEDs/meter strip, the note above about pin order applies to Gemma as well.
With the glasses we built upon, Trinket fit perfectly turned 90 degrees with respect to the strip (like the wiring diagram above) — the USB connector is then accessible along the top edge, for loading new code. But every pair of shades will be different. You’ll probably want to use longer wires between the Trinket and strip, so you have more options when folding the pieces together; I just got carried away here with the ultra-short wires.
Reiterating a prior point: wires are run along the back side of the strip, and soldered on the front.

After soldering, all of the protruding wire points were trimmed.

This guide was first published on Sep 23, 2013. It was last updated on Jun 23, 2024.

This page (Wiring & Soldering) was last updated on Sep 20, 2013.

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