RC18 Badge Walkthrough by AND!XOR

### Overview In this walkthrough at ROOTCON, the creators from AND!XOR introduce the electronic badge designed for the event. Following up on their previous year's UFO badge, the team developed a new hardware design centered around the event's theme: building connections between people and leaving a digital footprint. The badge is powered by a Raspberry Pi Pico and runs CircuitPython, encouraging attendees to interact with each other during the conference and hack the device on their own.

### Key Topics - **Theme and Inter-Badge Communication:** Addressing ROOTCON's focus on connecting attendees, the badges feature a physical linking mechanism using audio cables. Linking badges allows attendees to transmit patterns and accumulate points toward a scoreboard. - **Customization and Serial Control:** Attendees can interface directly with the badge over a serial connection from a computer to set custom text messages, configure visual "bling modes," and persist these configurations across reboots. - **Extensibility and 3D Printing:** In addition to open-sourcing the firmware and exposing a Python REPL, custom 3D-printed faceplates were designed and distributed, with STL model files planned for public release.

### Technical Details - **Microcontroller & Firmware:** The badge is built around the Raspberry Pi Pico microcontroller and runs CircuitPython, providing an accessible REPL interface for custom programming. - **Badge-to-Badge Linking:** Badges connect physically via audio cables to synchronize and repeat visual patterns down a daisy-chained line. While mono AUX cables included in attendee bags suffered a hardware defect preventing their use, connecting badges using a standard stereo audio cable enables communication and awards points on an onboard scoreboard. - **Serial Interface & Character Support:** By opening a serial COM port to the badge from a laptop, users can send custom display messages and select startup bling modes. The display firmware supports standard printable ASCII text, several special characters, and a limited selection of emojis entered directly or via Unicode designations. - **Hardware Enclosures:** Custom faceplate STL files developed approximately three weeks prior to the event were printed by organizers and friends, with plans to publish the STLs for attendee customization.

### Takeaways The badge offers both an interactive social game during the conference and an open hardware hacking platform afterwards. Attendees are encouraged to connect badges via stereo cables to compete on the scoreboard, explore the CircuitPython REPL over serial, and use the upcoming open firmware and 3D-printable STL files to build their own modifications.