There are a number of USB stick computers available on the market at a variety of price points. One that really stands out is the Tomu – a tiny ARM processor that fits perfectly inside your computer's USB port.
Tomu is based on Silicon Labs' Happy Gecko EFM32HG309 Arm Cortex-M0+ microcontroller running at 25 MHz. It has 8 kb of RAM and 60 kb of flash. Despite its small size, it supports two LEDs and two capacitive touch buttons.
Once you connect this little computer, you can simulate a hard drive or mouse and send MIDI data. Tomu is an open source project that can act as a Universal Second Factor security token. The hardware is fully documented and the bootloader as well as the rest of the code is accessible on GitHub.
You can also turn the USB hub into a power switch for your computer. Tomu is not a full-fledged computer due to its limited input/output options, but it is certainly an exciting tool for those who want to get involved with open source computing.
Tim Ansell, the designer of the Tomu, says the YubiKey 4 Nano is the inspiration behind this tiny computer. Its software still needs improvement, but the necessary bootloader code is complete and working.
You can purchase the Tomu from Crowd Supply starting at $30. Just make sure you don't accidentally lose this super small PC while cleaning out your desk!
