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.