Add-on dossier

BLE message and LED control

A linkable lifecycle record for hardware expansions, app ecosystems, firmware upgrades, cases, radio parts, and post-event badge experiments.

H2HC 2018 Badge source-backed

firmware feature

The writeup describes BLE write handling that switches LEDs and shows text messages across badge display pages.

Badge context

Related Resources

project page

Security-Bits writeup documenting bottle-shaped ESP32 badge hardware, OLED, BLE behavior, LEDs, programming, power, and practical warnings.

Source trail

Security-Bits.de · retrieved 2026-05-15

Primary writeup source for ESP32 WROOM, OLED display, BLE behavior, LEDs, power, Arduino workflow, and programming warnings.