Hacker Con Badges

THOTCON 0xB · United States · 2021

THOTCON 0xB Badge

ESP32 retro-controller badge with LEDs, buzzer, accelerometer, and Wi-Fi

The THOTCON 0xB badge was a rescheduled-2021 Chicago electronic conference badge in a retro controller / circus-ticket form factor. Rob Rehrig's first-hand writeup documents an ESP32 main controller, reverse-mount RGB and single-color LEDs driven by an IS32FL3731 LED driver, capacitive touch buttons, piezo buzzer, accelerometer, 2.4 GHz Wi-Fi node behavior, IRC remote connectivity, and serial interface.

THOTCON United States Chicago ESP32 Retro Controller D-pad Capacitive Touch IS32FL3731 Reverse-Mount LED Piezo Buzzer Accelerometer Wi-Fi IRC Serial North America
EventTHOTCON 0xB
SeriesTHOTCON
LocationChicago, Illinois
CountryUnited States

People

Authors & Credits

badge electronic design, schematic capture, board layout, and driver development

Rob Rehrig

Rehrig's project writeup describes joining the THOTCON badge team and contributing electronic design, schematic capture, board layout, and driver development.

Source

badge maker and portfolio publisher

Fourfold

Fourfold's work portfolio lists THOTCON 0xB as a retro gaming / D-pad design / PCB-art hardware badge project.

Source

badge workshop presenter

Jay Margalus

InfoconDB lists Jay Margalus as a presenter for `Hacking the Thotcon 0xB Badge`.

Source

badge workshop presenter

Rudy Ristich

InfoconDB lists Rudy Ristich as a presenter for `Hacking the Thotcon 0xB Badge`.

Source

event and schedule publisher

THOTCON

The official THOTCON archive establishes the 2021 Chicago event, badge pickup, badge-required party entry, and badge-hacking workshop.

Source

Why It Mattered

It closes another THOTCON lineage gap with a source-backed intermediate badge between the DePaul-linked 0xA and the modern 0xD touch-wheel build, showing how the series evolved through themed PCB art, richer LED drive, audio feedback, motion input, and production rework.

Hardware

Rob Rehrig describes the badge as an ESP32 design that reused prior-year schematic and code snippets while adding reverse-mount RGB LEDs behind the THOTCON letters, single-color reverse-mount LEDs near the capacitive touch buttons, an IS32FL3731 LED driver, a piezo buzzer, an accelerometer, 2.4 GHz connectivity, and a serial interface. Fourfold describes the badge as retro controller-inspired PCB art with D-pad and button layout.

Software & Apps

The writeup describes 2.4 GHz operation mostly as a Wi-Fi node, remote connectivity through IRC, serial access, capacitive-button feedback, buzzer jingles, and a tilt-based tone generator/synthesizer using the accelerometer. The official schedule and InfoconDB preserve a `Hacking the THOTCON 0xB Badge` workshop by Jay Margalus and Rudy Ristich.

Lore

The badge art mashed up an NES-style controller and circus ticket for THOTCON 0xB's Bozo the Clown theme. Rehrig joined the badge team after winning the THOTCON 0xA Digerati's Atlas CTF and contributed electronic design, schematic capture, board layout, and driver development.

Lifecycle

Add-ons & Upgrades

audio feedback source-backed

Piezo buzzer jingle output

The badge added a piezo buzzer for simple tones, including circus-themed and button-feedback jingles.

Compatibility: THOTCON 0xB Badge

Source
connectivity and control source-backed

Wi-Fi node, IRC, and serial interfaces

Returning badge features included capacitive touch buttons, 2.4 GHz connectivity mostly as a Wi-Fi node, remote connectivity via IRC, and a serial interface.

Compatibility: THOTCON 0xB Badge

Source
hardware architecture source-backed

ESP32 retro-controller badge core

Rob Rehrig describes the 0xB badge as an ESP32-based design in an NES-controller and circus-ticket form factor.

Compatibility: THOTCON 0xB Badge

Source
motion input source-backed

Accelerometer tilt synthesizer

An accelerometer was added and paired with the buzzer to create a tone-generator/synthesizer controlled by badge tilt.

Compatibility: THOTCON 0xB Badge

Source
production recovery documented

GPIO0/DTR production rework

A late GPIO0 buffer design caused battery-powered badges to enter Download boot mode until the team fixed DTR with an R19 pull-up resistor before conference shipment.

Compatibility: THOTCON 0xB Badge

Source
visual interface source-backed

Reverse-mount LED and IS32FL3731 lighting

The badge used reverse-mount RGB LEDs behind the THOTCON letters, single-color reverse-mount LEDs near capacitive buttons, and an IS32FL3731 driver for animation without heavy CPU load.

Compatibility: THOTCON 0xB Badge

Source

Operational history

Issues & Camp Impact

missing rights-cleared image note

No THOTCON 0xB Badge image is published because the current public source trail has not been paired with a reusable original badge or artifact photo or official upstream raster render with source URL, license or permission basis, attribution, and processing notes.

The United States record remains source-backed and image-free rather than copying source-page media, documentation screenshots, event photos, social media, placeholders, or generated approximations.

Confidence
local project policy
Status
needs licensed original replacement
Timeframe
current catalogue build
Source note
badge.gallery image policy and THOTCON official 0xB schedule, Rob Rehrig project writeup, Fourfold work page, and InfoconDB workshop source trail.
source-depth caveat note

Rob Rehrig's first-hand writeup documents the 0xB badge electronics and production fix, but this pass did not recover a public schematic, Gerber set, BOM, firmware repository, binary archive, or full badge manual.

The catalogue records verified hardware behavior and production context without claiming that the complete design archive is public.

Confidence
source-backed but incomplete
Status
needs deeper archive recovery
Timeframe
current THOTCON 0xB pass
Source note
Rob Rehrig THOTCON 0xB writeup, official THOTCON 0xB schedule, Fourfold work page, and InfoconDB workshop listing.

Resources

Fourfold work portfolio maker portfolio · Fourfold source identifying THOTCON 0xB as a retro controller-inspired hardware badge with D-pad design and PCB art framing. Hacking the Thotcon 0xB Badge workshop listing · InfoconDB source for the rescheduled THOTCON 0xB badge workshop, Oct. 8, 2021 timing, presenters Jay Margalus and Rudy Ristich, and board-layout/component/code workshop scope. THOTCON 0xB Electronic Conference Badge first-hand project writeup · Rob Rehrig source for ESP32 badge design, reverse-mount LEDs, IS32FL3731 LED driver, piezo buzzer, accelerometer, capacitive touch, Wi-Fi node behavior, IRC, serial interface, GPIO0/DTR production fix, and design-team role. THOTCON 0xB schedule official event schedule · Official THOTCON archive source for Oct. 8-9, 2021 Chicago dates, badge/swag check-in, party-entry badge requirement, and the Track X `Hacking the THOTCON 0xB Badge` workshop.

Sources

Fourfold: Fourfold work portfolio Retrieved 2026-05-15 · Maker portfolio source for the 0xB badge's retro gaming, D-pad design, and PCB-art framing. InfoconDB: Hacking the Thotcon 0xB Badge Retrieved 2026-05-15 · Workshop metadata source for THOTCON 0xB badge-hacking session timing, presenters, board-layout, component, and code scope. Rob Rehrig: THOTCON 0xB Electronic Conference Badge Retrieved 2026-05-15 · First-hand technical source for the ESP32 badge design, LEDs, LED driver, buzzer, accelerometer, capacitive touch, Wi-Fi/IRC/serial behavior, GPIO0/DTR production fix, and schematic/board/driver development role. THOTCON: THOTCON 0xB schedule Retrieved 2026-05-15 · Official event source for the Oct. 8-9, 2021 Chicago edition, badge pickup, party-entry badge requirement, and badge-hacking workshop title.