Build log

The Story So Far

Where it started

SpotterBoard didn't start as an LED matrix project at all. The first version was a lot closer to a FlightRadar24-style spotter display — a screen sitting on a desk showing whatever aircraft happened to be overhead. That first build used a 5-inch IPS capacitive touchscreen: sharp, colourful, touch-responsive, everything you'd want from a proper little display.

The original 5-inch touchscreen FlightRadar24-style prototype, housed in an orange case with RTL-SDR receivers — The original build — a 5" touchscreen, an orange case, and a pair of RTL-SDR receivers

And it worked. But something about it felt... expected. A flight tracker on a small touchscreen is a well-worn idea — it's basically what FlightRadar24's own app already gives you, just running on a dedicated screen instead of a phone. It did the job, but it didn't feel like a build. It felt like an app in a box.

The switch to LED

The move to a 64×64 LED matrix panel changed that completely. There's something about the aircraft data rendering out in blocky, glowing pixels — the callsign, the altitude, the climb or descent — that feels more like a piece of hardware and less like a screen. It's got presence. It looks like something built specifically for this one job, rather than a general-purpose display pressed into service.

The LED matrix panel, lit up and impossible to mistake for a phone screen

It's also just a better fit for the actual audience. Plane spotters and Raspberry Pi tinkerers aren't chasing the smoothest, highest-resolution display — they're drawn to things that feel handmade, a bit retro, a bit chunky. The LED matrix leans into that instead of fighting it.

What's actually running underneath

Behind the display, SpotterBoard pulls live ADS-B data — the position-broadcast signals aircraft transmit constantly — from public aggregators like adsb.lol and adsbdb.com, and renders it out in real time: callsign, altitude, speed, route, whether the aircraft's climbing or descending. It runs on a Raspberry Pi (4, 5, or Zero 2 W, depending which one you've got spare) driving the panel through an Adafruit RGB Matrix Bonnet.

The Raspberry Pi, bonnet, ribbon cable, and LED panel wired together on the bench — Pi, bonnet, ribbon cable, panel — how it all actually connects

Some of the trickier problems ended up being less about the flight data and more about just keeping a small embedded device reliable — things like automatically detecting when the data feed drops out and showing a "Lost feed / retrying" message instead of silently freezing, or making sure the boot screen actually displays "SPOTTER / BOARD" perfectly centred regardless of which font characters happen to be wider than others. Small details, but the kind that separate a demo from something you'd actually want sitting on a shelf.

The panel showing a 'Lost feed / retrying' message — The auto-recovery message — no user intervention needed if the feed drops

Some of those small details took more work than you'd expect. The climb and descend arrows are a good example — rather than using a generic symbol, each one was hand-drawn pixel by pixel on graph paper first, checking how a handful of lit squares would actually read at real size on the panel before a single line of code got written.

An early hand-drawn pixel grid sketch, testing shapes for the climb/descend arrows — Working out the climb/descend arrows, one pixel at a time, before writing any code

Where it's heading

The current build (a full Raspberry Pi plus a bonnet) is the flagship version — but it's not the cheapest way to get a SpotterBoard running. That's the thinking behind SpotterBoard Lite: a stripped-down version built around a single ESP32 chip instead of a full Raspberry Pi, wired directly into the same style of LED panel. No SD card, no operating system to manage — just a small, inexpensive board doing one job well. It's still early, but the core wiring and driver library have already been worked out on the bench.

ESP32 development boards laid out on the bench next to the LED matrix panel

ESP32 boards and a smaller secondary LED matrix panel on the bench

Early bench work on SpotterBoard Lite — a few ESP32 variants and a smaller panel size under test

Making it real

Alongside the hardware, SpotterBoard's been going through the more grown-up motions of becoming an actual project rather than just a personal build: a UK trademark application under the SpotterBoard name, and a genuine visual identity — the orange, the pixel-radar mark — worked out together with Ralph rather than bolted on as an afterthought. The project actually started out under a different working name, FlightMatrix, before settling on SpotterBoard ahead of launch.

The SpotterBoard boot screen

A few of the directions explored — the bottom-right concept is what became the final mark

None of that changes what it fundamentally is, though: a small screen that tells you what's flying over your house, built because a phone app doing the same thing just isn't as satisfying as watching it happen in glowing pixels on your own hardware.

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