Conference badge

The DC2024 conference badge has multiple functionalities:

  • blinking lights! Touch the penguin’s beak to change the blinking pattern
  • configurable screen: the screen content can be changed using the small web app (instructions below)
  • social game: socialize with others to uncover hidden image and collect points.

From the hardware side the badge has an e-ink screen, IR transmitter and receiver, light sensor, touch key and 26 LEDs.

Setting the text

Badge text can be set using the configuration web app. The configuration requires that the light sensor on the badge is positioned in front of the screen/monitor where the configuration app is running. The configuration app will start flashing the screen and transfer the data that way.

This type of data transfer is quite slow and unreliable. It also heavily depends on the ambient lighting and the type of the screen on the device (some smartphones work great, some are problematic, some need the fast mode enabled, some don’t).

Hints for successful text transfer:

  • turn off LED animation on the badge before the transfer as LED light reflecting off of the screen can send false signals
  • increasing the screen brightness can help
  • reliability is better with lower ambient light (can’t really be used outside)
  • immediately after starting the transfer place the phone screen over the light sensor
  • the LEDs in the upper part of the badge will indicate the data transfer and start blinking in sync with the data if the transfer is recognized.
  • if the phone screen is flashing for over 2-3 seconds and the LEDs on the badge aren’t indicating this, start over. It can take multiple tries. Same if the LEDs start blinking and then stop during the transfer (the successful transfer will be announced with three blinks and a screen update)

WARNING: do not look at the screen while the data is being transferred!

Configuration app is available here:


The badge is released as open hardware device. The schematic, PCB and the firmware source code can be found at

Badge is also certified as open source hardware by Open Source Hardware Association (OSHWA) with a certification mark HR000116 (