LEDS / LED PIXELS ARDUINO COMPATIBLES / TRINKET ARDUINO COMPATIBLES / ADAFRUIT GEMMA WEARABLES

Wiring & Soldering

Before starting, take inventory of all your parts:

Goggles
NeoPixel rings (2)
Trinket M0 or Trinket Mini Microcontroller
JST connector
Micro LiPo USB charger
LiPoly battery
Wire

Your kit might have a couple of extra bits; a small power cable and some pin headers. If present, they can be tossed in your spare parts drawer; they’re not used here.

If this is your first time using the Adafruit Trinket microcontroller, work through the Adafruit Trinket M0 or Introducing Trinket guide first. This explains how to set up the Arduino IDE software and load code onto the board. Don’t continue here until you have something like the “pulse” example working.

If you encounter problems, post on the Adafruit Forums for help…it’s much easier to troubleshoot and replace parts before they’re soldered together and glued into some goggles!

Let’s get the trickiest soldering out of the way first, installing the JST battery connector on the underside side of the Trinket board…

	Start by “tinning” one of the JST pads on the back of the Trinket…heat the pad and apply solder so the whole surface is covered. Hold the JST socket in place (tweezers recommended) and re-melt the solder, allowing the part to sink into position. Once this first pin is tacked down, the rest are easy. Remember to heat the parts, then apply solder…do not melt solder on the iron and “wipe” it on the parts…that makes a weak cold solder joint. Properly done, the connections should be shiny and smooth. Congrats, you’ve done surface-mount soldering!
	Next, peel away two sets of three wires each from the included bit of ribbon cable. (If you’re building your own custom goggles, you can just use separate pieces of wire for this, it’s all good.) If using our costume goggles, one of these 3-wire cables will be visible on the outside, so pick a color combination that you like.
	Separate the wires by about 1 inch at both ends, strip away a little insulation and give the wires a twist to prevent fraying. Optionally tinning the wire ends makes them a little more manageable…heat each one with a soldering iron and melt just a tiny bit of solder into the strands. If you mess this part up, that’s okay. Trim the wires back a little further and try again. Or use the left-over wire from the original ribbon cable.

Here’s a circuit diagram of what we’re aiming for. Of course the real thing won’t be all rectilinear like this…we’ll walk you through each step.

This diagram uses the original Trinket but you can also use the Trinket M0 with the exact same wiring!

Solder one end of the 3-wire cables to the IN, V+ and G points on the two NeoPixel rings. There are two V+ and two G holes on each ring…either one is fine, they’re connected.

Keep track of the colors you use for IN, V+ and G…it’s vitally important to make the right connections at the other end.

(These are the labels on the front of the rings. The back-side labels are a little more verbose.)

Notice how the wires are inserted from the front, then soldered on the back of the ring. Do it this way if you’re new to soldering…it’s much easier. It can work the other way too…insert from back, solder on front…but the component tolerances are extremely tight and beginners often get a blob of solder in the wrong place and the LEDs don’t work.

Next we connect the other ends of the 3-wire cables…first one to the Trinket, second one joins the two rings…

Trinket	First Ring
BAT+	V+ (either one)
Gnd	G (either one)
#0	IN

First Ring	Second Ring
V+ (either one)	V+ (either one)
G (either one)	G (either one)
out	IN

The second cable is the “visible from the outside” one, if that matters to your color scheme.

Notice here how the second cable enters the first ring from behind, then the wires are inserted from the front and soldered on the back…the cables should not overlap any LEDs on the front.

If possible, try to align the rings so they’re pointed nearly the same direction (use a landmark like the Adafruit logo for reference). This is not required, but it’s a little easier to program animation effects when both rings have the same orientation.

If using the “bring your own goggles” method, things may be a lot more complex…for example, these goggles have wires passing in and out through side perforations, so it’s not possible to build and test the whole circuit separately first…it must be built around the goggles and is later folded into place. This is tricky!

We’ll clip the wire ends flush in a moment, but let’s test that everything works first…

This guide was first published on Sep 13, 2013. It was last updated on Sep 13, 2013. This page (Wiring & Soldering) was last updated on May 19, 2019.

Wiring & Soldering

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