Raphael Stäbler's Breadboard Game Boy Emulates Nintendo's Classic Handheld on a Teensy 4.1
Designed around as few components as possible, bar some filtering on the audio, this breadboard Game Boy runs at full speed.
Software developer and self-described electronics hobbyist Raphael Stäbler has built a fully-working full-speed Nintendo Game Boy on a breadboard — farming off the hard work of running teh games on a Teensy 4.1 microcontroller board.
"Ever wanted to play the original Game Boy's Tetris on a breadboard? Well, now you can," Stäbler writes of his project. "This fully functional Game Boy emulation assembled on a breadboard is running on top of the popular Teensy 4.1 development board and features a beautiful, large display and full 4-channel audio support."
As Stäbler admits, his breadboard creation is dramatically simplified by avoiding having to reimplement the original Game Boy's hardware — a customised Sharp LR35902 processor running at 4.19MHz and a compact 64kB address space split into 8kB of working RAM, 9kB of display RAM, up to 16 switchable 8kB pages in the attachable cartridges, and 32kB of external ROM space — from scratch. Instead, Stäbler's rebuild uses a software emulator running on a Teensy 4.1.
The resulting breadboard build, then, has surprisingly few components/ There's the Teensy 4.1 board itself, to which buttons are directly wired — using the microcontroller's internal resistors — for control. The audio portion is somewhat more involved, requiring an amplifier and some filter circuitry — with Stäbler recommended a speaker designed as a replacement part for a real Game Boy for maximum authenticity.
The games, loaded from an SD Card, are displayed on an FT81x-based 4" TFT LCD connected to an open-hardware driver board of Stäbler's own design — a far cry from the 2.6" super-twist nematic (STN) reflective screen used on the original hardware. Despite having a bigger and higher-resolution display to drive, though, the Teensy 4.1 proves more than up to the task, with Stäbler promising the build is capable of running Tetris — the Game Boy's most-popular title — at full speed with no glitches.
The project is documented on Hackaday.io, while the source code is available on GitHub under the reciprocal GNU General Public License 3.
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.