InkLink

This week, I built a collaborative e-paper display as a gift that I’m calling InkLink.

This fun conversation piece updates every three minutes based on what people have drawn on a web interface.

The web interface supports real-time multi-user canvas drawing. Try it out at inklink.winans.io! (This isn’t connected to the actual display, feel free to draw whatever you want)

How it works

Hardware

The hardware side of things is pretty simple. The display is a 7.5-inch tri-color e-paper display from Waveshare. It’s connected to an ESP32 microcontroller running CircuitPython that fetches the image from a server every three minutes.

Software

The website is a React app and a Bun server communicating real-time over WebSockets. The Bun server has its own server-side canvas thanks to @napi-rs/canvas. Each action is applied to the server canvas and then sent to all clients in real-time. The server also exposes a /drawing.bmp endpoint that the ESP32 fetches every three minutes.

Side note: This was my first time using Bun, and I’m impressed. Its built-in WebSocket support is fantastic, and the server uses just 10MB of RAM at idle.

Build your own

This project is simple to make and makes a great gift. It’s open source and available on GitHub at github.com/Nicell/InkLink including a full build guide. All the parts are readily available and the total cost is around ~$45-$85 depending on where you source the parts. Feel free to make your own or contribute to the project!