The Tiny Bit Machine Is a Self-Contained, Solar-Powered Eight-Bit Microcomputer — in a Tic Tac Box
Powered by a Microchip ATtiny85 and programmed with push buttons and two LEDs, this tiny handheld has its own on-board interpreter.
Pseudonymous maker "g0730n" has turned a Microchip ATtiny85 microcontroller into a self-contained game-capable eight-bit microcomputer with built-in interpreter — squeezed into a Tic Tac box and powered by the sun: the Tiny Bit Machine.
"[The Tiny Bit Machine is] solar powered, battery free hardware to run an interpreter on the [Microchip] ATTiny85," g0730n explains of the compact project. "User input is 5 buttons on a resistor ladder on ADC2 of attiny85. Depending on what menu the user is in, they will do different things. The devices output are two red LEDs. I chose red due to low forward voltage, and it is easier on the eyes if using the device in low light."
The front of the gadget, originally built on prototyping board with a custom PCB version in the works, has just two LEDs, labelled "1" and "0". Below this are left and right buttons, and three more labelled "S", "T", and "R" for "Toggle", "Save", and "Run" respectively. Impressively, that's everything you need: with patience, it's possible to write programs directly on-device using g0730n's Tiny General Reusable Keywords (TGRK), an interpreter made specifically for the ATtiny85.
For power, the compact gadget uses a 1.5F 5.5V supercapacitor, charged through a small solar cell installed in the rear of the upcycled transparent Tic Tac case. Thanks to the minimalist hardware, it's enough for a surprisingly long runtime: after between 3-6 minutes of charging, you can get 30-45 minutes of active use before the Tiny Bit Machine enters a deep-sleep mode — at which point you'll need to recharge it if you don't want to lose your progress.
"I was able to pack a 'fully' functional 'RPG' [Role-Playing Game] game in 127 bytes," g0730n writes of the device's first fully-fledged software title. "Think Pokémon on a one dimensional linear map with only 2 LEDs to know what is going on in the game. This was quite the challenge, but I am glad I was able to program it in TGRK instead of adding it into the Arduino sketch."
"It ended up having a lot less features then originally planned," the maker admits, "but I think with the right tweaks the difficulty can make it enjoyable to play. That is if you don't mind reading the binary codes blinked out to monitor your health level, and subtracting or adding to those blinks to know how many hit points you lost in the last battle, or how much gold you just spent on healing at the inn."
Full project details, including a bill of materials and source code, are available on Hackaday.io; the TGRK source code is available on GitHub under the permissive MIT license.