The KeebCard, an open-source, low-power, mechanical switch computer keychain

This is the home of the KeebCard project. Originally designed as a business card, people loved it so much I decided to release a version of it as open-source (TODO: add a license).

The KeebCard is centered around an SSD1306-powered 128x32 monochromatic display and an ATTINY85-10SU. The code uses the wonderful Tiny4kOLED library to communicate with the screen via i2c. With 8 kilobytes of program space and 512 bytes of RAM, it's a fun challenge getting anything to run on this thing!

DIY Assembly

Head here for the current DIY assembly video. I may reshoot this, we'll see

Case Assembly (Button and LowPro)

Watch this quick video if you want to know how to use the cases! Especially important for button cases, they can be tricky

Flashing/Code

At the base of this project (currently) is the code that runs on the machine, you can git clone or download zip and open the KeebCard.ino file in Arduino. I don't normally program in C++, so it's a little rough. You can change what program is flashed by changing the define at the top of KeebCard.ino.

The KeebCard code is currently compiled and flashed with an ISP programmer via the Arduino suite. check out the flashing tutorial here

A note about dependencies

Currently, all dependencies can be installed via the Arduino library manager, check out the flashing tutorial.

There used to be a dependency on the Arduino Entropy Library that needed to be downloaded separately, but it was causing memory errors due to how the Arduino suite includes files. I'll be breaking programs out into separate folders eventually, after which we'll reinstate the entropy library.

Flashing your own programs

I made a guide on how Conway's Game of Life works on the KeebCard, which will hopefully help you write your own programs! you can check that out here

Troubleshooting

Having successfully hand-soldered >30 of these now, I put the two most common problems people encounter in this video. If you're having issues take a look!

Fabbing

If you want to make your own run of KeebCard boards, check out the GERBERS directory. These are gerbers produced by the standard settings in Kicad. They are confirmed to work with JLCPCB, but probably work just fine at a bunch of other board shops.

BOM

All parts are available from Mouser save the screen

• 1x SMTU2032-LF
• 1x 0805 0.1uF capacitor
• 4x 0805 22kOhm resistors
• 2x 0805 4.7 kOhm resistors
• 1x ATTINY85V-10SU
• Some headers
• 1x screen
• 3x cherry MX or Kailh Choc switches and keycaps

Modifying

If you want to modify the design, check out the KeebCard directory, which houses the original Kicad project.

KeebCard in media

If you've seen the KeebCard elsewhere, please let me know!

• Unilad Tech: https://www.facebook.com/UNILADTech/videos/1574779679325114/?v=1574779679325114
• AlexGyver's Youtube channel: https://www.youtube.com/watch?v=djgHV5JCNTk