• Simple, Open, Flexible, Easy

  • Fits entirely inside a standard USB Type-A slot

  • Turn any USB port into an input device

  • Load your own programs onto Tomu


Tomu is simple. It hides out in a USB port of your computer and waits for you to use it. It has two LEDs to let you know what’s going on, and two buttons for interaction. There’s no fancy setup or complex user interface.

Tomu is open. You can download the hardware schematics, make your own circuit board, and inspect how all the pieces work together. You can download the software source code and trace programs as they run. You can even load your own programs onto Tomu and have it do exactly what you want.

Tomu is flexible. Maybe you want volume buttons on the side of your laptop. You can load software onto Tomu that uses the two buttons for Volume Up and Volume Down. Or maybe you want to be able to put your computer to sleep or wake it up from a USB hub. With Tomu, you can turn any USB port into an input device simply by uploading new software to it.

Tomu is easy. It can be used as something called a Universal 2nd Factor (U2F) token. Many sites support two-factor authentication (2FA) to ensure you’re you, even if your password gets stolen. Two-factor authentication options range from sending you an SMS to requiring you use a one-time-password authenticator. U2F simplifies this process by simply requiring you press a button on a specialized device. With U2F software loaded, Tomu can act as that token.

CPU: Silicon Labs Happy Gecko EFM32HG309

Speed: 25 MHz ARM Cortex-M0+


Storage: 64 KB Flash

Connectivity: USB 2.0 FS

Buttons: 2

LEDs: 2 (red + green)

Components: Literally 12 parts + PCB

Tomu fits entirely inside a standard USB Type-A slot, except for a small area that pokes out to give you access to two buttons and two status LEDs. It contains an ARM Cortex-M0+ CPU running at 25 MHz, which can be reprogrammed without specialized hardware.