Tetris was as a perfect complement to Nintendo’s original Game Boy when it came out in 1989, and now “Copper Dragon” has been able to fit an entire system for it — sans monitor or speakers — inside of a faux NES controller.
Impressively, this feat was accomplished with an Arduino Nano and a few passive components, producing not only very believable grayscale blocks, but also playing the familiar tune to accompany the video.
Two signal pins are used for the gray levels, plus a pin for sync, and video generation is programmed in AVR assembler code. Audio is not just PWM, but a simple DAC circuit created by charging and discharging a capacitor at the video line frequency.
I wanted to build a game console into the case of a small USB game pad (a NES controler look-alike). To make the work a challenge, I wanted to only use an Arduino Nano clocked at 16 MHz and some passive components (diodes are OK) and create the best possible video and audio signal that is imaginable with such restrictions.
As it turned out, a monochrome 288p video signal with 4 gray scales is possible when progamming the controller at machine level. 4-channel music is also possible.
My game of choice is Tetris in a version that comes pretty close to the original GameBoy version with a very similar audio track.