Bluetooth Visualizer Badge
This ESP32-based badge displays Bluetooth devices present in array of addressable LEDs.
After attending an apparently badge-intensive conference in 2022, Jeremy Geppert was inspired to build his own badge-format device. What he came up with is a badge that passively scans its surroundings to show a graph of Bluetooth devices in the area.
This new badge uses an ESP32-based dev board for Bluetooth sensing and device control, along with an SK6812 8x8 LED matrix and a small OLED display for user feedback. The LED matrix reveals the number of Bluetooth devices as a graph of blue dots. LEDs in the lower-left of the screen show how many "pages" of LEDs are present, accommodating more than 64 devices as needed. The OLED shows a numerical device count, as a less complicated, if not as visually interesting, reference.
To fit in with its badge theme, the device features a 3D-printed shell to which a lanyard clips on with two hooks. The LED matrix sits above the ESP32 board and OLED, which are both soldered into a perfboard. This puts all the main components on display, which would not only give it some extra hacker interest, but would facilitate troubleshooting as well.
The latest version of the device also has a 10x mode, which represents 10 devices per pixel, allowing it to show up to 640 devices on the matrix. It’s a rather fun little hack, and while code and build files don’t appear to be available as of this writing, it shouldn’t be too hard to use this as inspiration for your own badge!