Developing and repairing electronic circuits is one of my hobbies since I was young.
Many circuits employ microcontrollers, mainly Atmel’s AVR family. The Unix toolchain with avr-gcc and avr-libc is very good, that’s why I use those microcontrollers since 2007, first in assembler, later in C.
If possible, their firmware is released under a license offering as much freedom to the user as possbile: The BSD license.The GPL is IMHO more restrictive.
Proceed to the list of measurement devices that I own.