Electronic conference badges are always a delight and we love seeing the creative concepts that people come up. But most of those badges are novelties (which is part of the point) and they don’t tend to be useful for much after that initial exploration is over. Igor Brkić was tasked with designing the badge for the DORS/CLUC 2025 conference in Croatia and wanted to make something that would still be useful after the event was done. He came up with this charming badge for fun shenanigans at the conference and also utility after the conference.
The hardware on the badge, which is the traditional enclosure-free PCB on a lanyard, includes a row of nine-segment displays, a mini LED matrix, two buttons, a USB port, an NFC reader, a battery, and an STM32L053 microcontroller to oversee it all. A laser-cut acrylic panel covers the LEDs, providing both protection and diffusion.
That hardware made it possible to create games for attendees to experience at the conference. The first game was a kind of scavenger hunt for NFC tags that were hidden around the venue. If a badge-holder found a hidden tag, they could scan it and increase the score displayed on the badge. The second game helped foster the social aspect of the conference by giving badge-holders an incentive to interact with each other. By getting scanning another attendee’s badge, they could increase that all-important score.
And, of course, because this was a conference championing everything open source, one person even managed to hack the badge — something Brkić was pleased to see. That person was able to find the obfuscated tag IDs in the badge firmware and then emulated those using a Flipper Zero, so they could increase their score without needing to leave their seat.
Best of all, the badges are still useful, even though the conference’s final day was May 23rd. By connecting a USB cable from the badge to a computer, the user can use the badge for both input and output. The buttons can launch actions on the PC and the badge can display data sent by the PC. One could, for example, use the badge as a time-tracking device to increase their productivity.
As you would expect, the badge itself is open source and you can build your own if you’d like. The design files and firmware are available on GitLab for anyone to access.