Train Departure Board

I built a departure board to find my quickest public transport to the city. This was a fun side project to learn about dotmatrix displays and microcontrollers. The panels are connected to a single ESP32 microcontroller via a custom PCB which drives everything.

The microcontroller connects over wifi to a local server which streams bitmap data to the displays, turning them into a full colour dot matrix monitor.

Features

• A 2 panel dotmatrix display to show the next bus, train times
• Shows the next bus and train times in real time (including capacity)
• Shows the current time and weather
• Shows the latest arrivals at Leeds Bradford Airport

Tech

Frontend

• PIXI.js to render the dotmatrix display to a headless canvas.
• Allows for easy UI development and testing via a web browser.

Backend

• Simple Node.js server to poll data from transport APIs
• Streams transport and weather data to the frontend via websockets
• Streams compressed bitmap data to the dotmatrix display via websockets
• Dumb ESP32 websocket clinet to recieve bitmap data and display it

Hardware

• 2x 16x32 HUB75 RGB dotmatrix displays
• ESP32 microcontroller - ensure compatibility with your PCB
• PCB - ESP32 i2s Matrix Shield
• 5V, 8A power supply
• 3D printed case

Outcome

Works well day to day but has a few issues:

• The 3D printed case reduces wifi signal significantly to the ESP32, so I had to move it closer to my router
• Due to the architecture, I have to run a headless browser on my homelab to display the UI, which is a bit of a hack
  • I still stand that streaming bitmap data works better than driving from the ESP32 to give more flexibility…