DIY train departure board: build one or buy one?

A DIY train departure board is a very doable weekend-and-then-some project. You need HUB75 LED panels, a small controller such as the Adafruit Matrix Portal S3 or a Raspberry Pi, a properly sized 5V power supply, live data from National Rail's Darwin system and a fair bit of code. If you enjoy the process, it's a satisfying build. If you just want one on the shelf, expect the code and the fiddly bits to take longer than you'd guess.

What hardware do you need?

The usual shopping list looks like this:

• HUB75 RGB LED matrix panels. One 64 by 32 panel is too narrow for a proper board, so two side by side, chained, make a 128 by 32 display. At 2.5 mm pitch that's 320 by 80 mm.
• A controller. The Adafruit Matrix Portal S3 plugs straight onto the back of a panel and has WiFi built in. A Raspberry Pi with an RGB matrix add-on board is the other common route.
• A 5V power supply sized for two panels. A full white screen draws far more than amber text on black, so size the supply for the worst case and measure it on the bench.
• A second ribbon cable to link the panels, and the power leads that usually come with them.
• Something to hold it all: a printed case, a wooden frame or a backing plate to keep the two panels butted edge to edge.

Buy both panels from the same listing. Cheap HUB75 panels vary, and some have quirks like green and blue swapped or a different scan rate, which you then have to handle in code.

Where do you get the train data?

From Darwin, National Rail's live train information system. Developers get at it through the Rail Data Marketplace: you register, subscribe to the departure board products and get an access key. Read the terms while you're there.

A couple of things to plan for. Keep the key out of your code and out of any public repository. And handle times defensively: Darwin's times can arrive as a simple clock time or as a full date and time, so your parser needs to cope with both. Our explainer on what Darwin is covers what the data contains.

What does the code need to do?

More than you'd guess from looking at a station screen. At minimum:

1. Join WiFi and stay joined, reconnecting after a router restart.
2. Fetch departures for your station on a sensible interval.
3. Lay them out on a 128 by 32 grid. A 5 by 7 pixel font gives you about 25 characters a line, so long destinations need to scroll inside their slot.
4. Run a scrolling calling points line without the rest of the screen flickering.
5. Show a clock, which means getting the time from the network.
6. Cope with errors: no departures, a timeout, a cancelled train, a station that doesn't publish platforms.
7. Dim at night, because a full brightness LED board in a dark hallway is a lot.

Then come the nice-to-haves: a way to set WiFi without editing a file, filters for your destination or platform, a walking time filter, updates without plugging it into a laptop.

What does it cost?

The parts are within reach for a hobbyist, and prices change, so check current ones before you start. The real cost is time. A basic board that shows the next train can come together in an evening or two. One that you'd happily leave running for months, that handles every odd thing the railway throws at it and that a non-technical person in your house can set up, takes a lot longer.

Build or buy: a side by side

When should you build one?

If the project is the point. If you enjoy soldering, flashing microcontrollers and tinkering with fonts until the destination scrolls just right, a DIY train departure board is a great build. It also makes a nice centrepiece for a model railway room, which is why it turns up in our gifts for model railway enthusiasts.

When does buying make more sense?

If you mostly want the board working on the shelf on Monday morning. Or you're buying it as a present for someone who won't want to touch a line of code. TrainTicker does everything on the list above: live Darwin data checked every 10 seconds, any National Rail station in Great Britain, filters for your destination, platform and walk, two layouts, station notices and a clock with seconds. It's £199.99 once with no subscription, and there's more on what it does in what is a home train departure board.

You can see the layout running in the free live demo before you decide. If it saves you a few weekends, order one here.