Our friends in the Whiskey Pirates crew sent me the unofficial DEF CON badge they built this year. The Internet of Batteries QUANTUM provides power and connectivity to the all-important add-on badges of DC28. The front of the badge is absolutely gorgeous to the point I don’t really want to solder on my add-on headers and disrupt that aesthetic.

The gold-plated copper makes for a uniformed and reflective contrast to the red solder mask which occupies the majority of the front. Here we see the great attention to detail that [TrueControl] includes in his badges. The white stripe of silk screen separating the two colors is covered by some black detailing tape that looks much better than the white.

The antenna of the ESP32 module poking out the underside of the gold cover end of the badge gets its own rectangle of the holographic sticker material, the same as the sheet of stickers that was included in the box. Both decals are small details that make a huge difference to your eye.

The line of nine RGB LEDs have black bezels which goes along with the black stripe motif and underscores the typography of the badge name. These lights are hosted on a daughter board soldered to the underside of the badge with a slot for the LEDs to pass through. They are addressed in a 2×15 matrix that is scanned on the low side by the PSoC5 that drives the badge. This low-res image shows that daughter board before the lithium cell is placed.

User control is provided by a number of capacitive touch pads, one under the word DEF, another under the word CELL, and finally a row of five chevron shaped pads just above those words. The role of the badge is to provide power to add-ons so it makes sense that recharging is built in via a micro USB port.

One trademark design choice worth mentioning is the treatment of four white LEDs, one next to each of the SAO (“Shitty Add-on”) footprints. At first I thought these used cutouts in the board just like the RGB strip, but that isn’t the case. Instead, copper has been kept out of this area to expose the FR4 substrate. A normal surface-mount LED is hand soldered upside down so that it shines toward the board, using this keepout area in the PCB design as a diffuser. This is a trick that [TrueControl] used on last year’s Space Force badge, and while I personally found it quite tricky to get the hang of soldering them, it’s more cost effective than sourcing proper undermount LEDs.

As with many badgelife offerings, this is still a work in progress. The firmware that shipped with the badge is still in the “Hello World” phase. Development is ongoing, but many bold feature claims are made on the project’s GitHub page. The planned wireless features include a “Captive Arcade” which can be logged into via the WiFi access point provided by the ESP32. This makes it possible to to display analytics for power usage on each of the four SAO ports, and there’s even plans for a mesh network that incorporates socially interactive features like a chat room and private messages. On a battery?!

Speaking of those SAO ports, there are both male and female headers provided. The idea is that the DEF CELL can be used to power not only an add-on, but a badge as well. When equipped with the female shrouded pin header it effectively becomes an add-on for another badge, with the important distinction that this add-on has a Lithium battery and will “back-power” the host badge via the SAO port. Is that in the spec? No, that’s why this standard is known as “shitty”, there is inherent risk to connecting devices by different makers using these ports. But it might work without problems, it really depends on the host badge.

With both Bluetooth and WiFi available through the ESP32, and an I2C pin as part of each SAO footprint, it should be possible to use DEF CELL to show meaningful changes on add-on boards based on triggers from the Internet, or devices within wireless range of the badge. That’s a hack for the future, and certainly something we hope to see around your neck at next year’s DEF CON.

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