GAT Nametag DC27 Addon

An addon nametag badge

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This is a simple nametag badge addon.

Supports multiple fonts (fixed and variable width) on an OLED display.
And some buttons on the back to set it up.
And programmable RGBLEDs. Because why not.
And an accelerometer....

Will be released at DEF CON 27.

Reservation form (now closed):

Note: WP is not "badgelife."

I don't know how I came up with this idea. I just thought, it would be neat to have an addon nametag.  An addon that's a little bit less shit. And I was planning on getting some accelerometers for the other badge project. Why not make a nametag where the name is always upright?

So here it is.

Another reason for making this is that I want to make a kickass WP badge for DEF CON and have no money. WP doesn't sell badges. So I'm doing this as a project under my own name to raise money for the WP badge project at DC28.

The result is pretty neat. The nametag has several selectable fonts and LED color modes, and will show your name in various configurations - including having the letters always upright relative to the ground.

The MCU selection was simple: I got a deal on some EFM8UB20F32G-A-QFP32. These are C8051 core MCUs with USB. Roughly guessing space used by fonts and features, I figured it would be tough to make everything fit but still possible. Turns out that with all the fonts I wanted and the abstractions in the code to make things border on readable and maintainable that this wasn't going to be enough. Thankfully there is a 64K version of this micro available but at full price... now with the code mostly written, I went ahead and upgraded.

I hadn't worked with an 8051 before but my badge designs will often use new parts or systems so that I can use them as an opportunity to learn. In this case, the micro and the rotation code were the things to learn.

USB support is helpful for firmware updates or possibly other features. The built in LDO means less components to be powered by USB. I was able to use a dual P channel FET and a diode to select power from USB or addon power and also prevent back-powering the USB connector. It's really a neat design with this micro.

What does "GAT" mean? I don't know, but maybe something like "Greater Addon Technology." We don't like making shit, so we made it greater...

I'm not sure how successful this will be yet. If people like it and constantly bug me about it then I might make some more for HAD Supercon.

If there's anything you think I should add, let me know.


Initial DC27 firmware release, source and binary

7-Zip - 179.98 kB - 08/01/2019 at 02:18



REV3 Schematic

Portable Network Graphics (PNG) - 67.63 kB - 07/29/2019 at 03:22


  • 1 × EFM8UB20F64G-B-QFP32
  • 1 × 0.91" SSD1306 I2C 128x32 OLED Module
  • 10 × Various Passives
  • 1 × 4x4mm SMD Buttons
  • 1 × ADXL345 Semiconductors and Integrated Circuits / Misc. Semiconductors and Integrated Circuits

View all 11 components

  • Production Progress: 88% Yield

    true07/29/2019 at 03:28 0 comments

    As of today, about a week and a half before DEF CON 27, the GAT Nametag project is effectively complete.

    Today I've built and packaged 113 working nametags. Some failures should be easily reworkable and I will get these operational if I can find time. Between now and con I still have about 40 IoB badges and about 250 Space Force badges to assemble, as well as code. Nametags are now a low priority.

    I've left 10 badges that still need button and OLEDs assembled. Some people like putting things together - these "80%" built units are for those people.

    I was not able to get the game code done. I hope to have that done before Supercon in November. As this micro has a USB HID bootloader - which was tested on every badge - it shouldn't be difficult for others to load code.

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