Eduardo Corpeño's Brainfuino [-]+ Is an Arduino Uno Clone Programmable Only in Brainf**k
Not exactly designed for ease of use, the Brainfuino [-]+ runs Brainf**k code, supplied as ASCII text made up of just eight characters.
Maker Eduardo Corpeño has designed an Arduino clone with a difference: While it mimics the Arduino Uno in appearance, it can only be programmed in the deliberately-challenging programming language hereafter referred to as Brainf**k.
Originally developed by Urban Müller in 1993 as an extension to Corrado Böhm's 1964 language P′′, Brainf**k is a Turing-complete programming language comprised of just eight single-character commands: >, <, +, -, ., ,, [, and ]. Any and all other characters in the source code are ignored - making Brainf**k programs exceedingly difficult to both write and understand once written.
Corpeño's Brainfuino [-]+ is a clone of the Arduino Uno microcontroller development board, but the traditional ATmega328 microcontroller is replaced by an STM32 and a Lattice Semiconductor MachXO2 field-programmable gate array (FPGA) — the latter holding a Brainf**k-specific microprocessor core dubbed the brainf**k_uP.
"This is not a joke," Corpeño clarifies of the project. "It is about a joke programming language, but a joke lots of nerds are very fond of. When I say nerds, I mean real geeks: Not gamers or technophiles, but geeks who like to read The Art of Computer Programming just for kicks!"
"The Brainfuino [-]+. (pronounced 'Brainfuino Uno') is a development board for a Brainf**k soft processor I wrote in Verilog, named brainf**k_uP (as in 'brainf**k microprocessor'), which runs brainf**k code natively, that is, the plain text of a Brainf**k source file, yes, ASCII characters."
Details of the hardware are available on the project's GitHub repository under the permissive MIT License, as are the source code for the firmware and the brainf**k_uP core.