First post, nothing big, but useful details. :)

diy-VT100 uses unicore-mx (fork of libopencm3 - "create an open-source firmware library for various ARM Cortex-M3 microcontrollers")

Released under LGPLv3 or later.

And uses the newly written USB host stack (i wrote because of USB Keyboard support)

[Already merged in unicore-mx]