You'll need two (or more) boxes for the Glitter Positioning System to work. This section of the guide describes the build for a single box.
Since the FeatherWing Tripler forms the base of the entire project, it makes sense to start there. Solder female headers onto the top of the Tripler, as seen here:
Solder plain male headers onto the Feather M4 Express:
Solder plain male headers onto the Ultimate GPS FeatherWing, and install a CR1220 battery:
Solder plain male headers onto the LoRa Radio Featherwing. Because each Feather uses a different processor, there's also some light wiring that needs to be done on the FeatherWing to configure the radio pins. Additionally, you'll need to attach an antenna.
You will want to solder three short wires for CS, RST and IRQ, as follows:
When plugged into the FeatherWing Tripler, A maps to pin 11 on the Feather M4, B to pin 10, and D to pin 6.
Next, attach an antenna. There are detailed instructions here. For this project, a 3-inch length of wire works well - remember you'll need to adjust the length if you're using a module other than the 900 MHz RFM95W LoRa Radio FeatherWing. You can also use an external antenna, but you'll need to consider mounting it on your enclosure.
As you can see in the photos, for my build, I soldered a single pin in place and used it to connect a length of jumper wire. This worked well for testing, but you're probably better off just soldering the wire directly to the board.
The NeoPixel ring and the LSM9DS1 breakout need to be connected to the FeatherWing Tripler underneath the Feather M4 Express. It's helpful to have the Feather ready but not yet seated on the Tripler, so you can double-check which pins you're soldering to.
When finished with this section, your build should look like this:
Start by cutting four pieces of hookup wire for the LSM9DS1. You'll want enough length to tuck the breakout board into a corner of the enclosure, next to the battery. I used roughly 8cm pieces. Solder these as follows:
- Tripler power rail to LSM9DS1 VIN
- Tripler ground rail to LSM9DS1 GND
- Tripler / Feather SCL to LSM9DS1 SCL
- Tripler / Feather SDA to LSM9DS1 SDA
Next, cut three pieces of hookup wire for the NeoPixels. You'll want enough length to position the NeoPixel within the enclosure without creating too much of a tangle. I used roughly 15cm pieces of the silicone-cover wire. Solder these as follows:
- Tripler ground rail to NeoPixel Ground
- Tripler power rail to NeoPixel Power 5V DC
- Tripler / Feather A1 to NeoPixel Data Input
Plug the Feather M4 Express, Ultimate GPS FeatherWing, and Radio FeatherWing into the FeatherWing Tripler. The Feather M4 Express should be seated on the section of the FeatherWing Tripler where you connected the NeoPixel ring and LSM9DS1.
Next, prepare the enclosure. I used a small sheet of acrylic to shield the battery and the compass, self-adhesive Velcro fasteners to hold things in place, and some strips of felt to line the bottom of the enclosure. The felt turned out to be more trouble than it was worth, but the Velcro is a good way to keep things in place without permanently fastening them.
Install the compass and battery:
The LSM9DS1 should be installed in the corner of the enclosure with the X and Y axis labels pointed outwards, at the same end as the Feather M4 Express, like so:
Now fit the rest of the electronics on top of the battery, LSM9DS1, and acrylic divider:
With everything else in place, mount the NeoPixel ring on the lid of the enclosure. I used a handful of pieces of electrical tape to make later adjustments easy. Again, orientation matters. Locate the first LED on the ring, just counter-clockwise from the Data Out / out pin:
It can be helpful to mark the edge of this LED with a permanent marker for quick identification. Once you've got it located, orient it directly opposite the solid arrow on the Y axis marker of the LSM9DS1:
Finally, connect the battery to the JST connector on the Feather M4 Express.
You should now be ready to move on to programming the unit and calibrating the compass.