By Joe Grand
DEFCON 18 Badge
Every summer, thousands of hackers and computer security enthusiasts descend
into Las Vegas for DEFCON ( www.defcon.org) — the largest and oldest
continuously running event of its kind. It’s a mix of good guys, bad guys,
government officials, and everyone in between, all focused on having fun, sharing
technical information, seeing old friends, and learning new things.
Fifth Time’s the Charm
For the fifth year in a row, I’ve had the honor of
designing the conference badge for DEFCON. Past badges
have blinked patterns of LEDs, allowed you to create your
own custom scrolling text messages, turned off your
television, transferred files from a SecureDigital card over
infrared, and pulsed to music using Fast Fourier transforms.
People have hacked the badge to become a flame
thrower, an audio VU meter, a password generator, an
amusement park game, an anti-surveillance system, a
blue box, and a polygraph, just to name a few.
The badges have incorporated technologies like
capacitive touch sensors, jumbo LEDs, RGB LEDs, MEMs-based microphones, and microcontrollers ranging in size
from tiny six-pin devices to powerful 64-pin behemoths.
Badge development has happened on airplanes, in shuttle
buses, on my honeymoon, in hotel rooms, and while on
safari. Badges have arrived with plenty of time before
DEFCON and twice they’ve arrived the first day of
The DEFCON 18 badge is a culmination of prior
years’ experiences, both good and bad. This article covers
the engineering behind the DEFCON 18 badge and the
problems I encountered along the way. Previous badge
designs have been detailed in earlier Nuts & Volts issues.
In a nutshell, the DEFCON 18 badge is designed to
display small, 30 pixel by 30 pixel pre-defined “glyphs” on
the LCD which allow the wearer to publicly share their
hobbies or interests. Other features include a command-based API for controlling the LCD and a static bootloader
for in-the-field firmware upgrades. A single CR2032 3V
Lithium coin cell battery provides the required power and
there is support for seamless power switching if the badge
is connected to a computer via USB. Two pushbuttons are
Figure 1. Back side of the DEFCON 18 badge showing the major subsystems.