Table of contents
Abstract
This tree ornament goes beyond a passive attractive display ornament to be a full on interactive experience complete with sound effects and the challenge of a game. This is Space Invaders that can hang on a tree.
Project
Intro
This project was inspired by a tree ornament my wife acquired shaped like an arcade game. I though why not make it actually playable?
So I set about designing a microcontroller with OLED display that was small enough to be a tree ornament. The result was a tiny game system that has all the features, sound effects and addiction of the original game.
The build
I had found a great program developed by Nicholaus D. Cranch that implemented a full featured version of Space Invaders on an Arduino Pro Mini, and I happened to have a Pro Mini, so the main challenge for me was to do an electronic and mechanical design and then build it. The build was non-trivial because I was trying to keep everything compact.
Electronics Design
I designed a schematic and PCB to interface all the components of the system. There are four through-hole modules, so stacking them above each other on a small compact PCB requires some non-recommended practices such as soldering pins on the top side of the PCB.
Schematic
PCB
The Video
Some screen shots:
Discussion
When trying to jam a project into a small ergonomic form factor, the problems increase exponentially. When I designed the PCB to dictate the size based on minimal ergonomic button spacing I knew it would present assembly difficulties and I was right, Stacking the 4 through-hole soldered modules above each other with reasonably minimal spacing was a challenge to my soldering skills and this step had to be completed before tackling the mechanical design, so that accurate measurements could be taken and accommodated. The mechanical design had to be broken into several pieces in order to be printable, which always presents an issue of making them fit each other. The result is satisfying, but I don't think I would recommend this method of design and assembly. It is way too non-deterministic and fiddly. Even though this device is cute and popular, I don't expect to be building the other 9 PCBs into finished devices.
The game would work fine with a monochrome display, but I think it adds something to use this multi-color OLED.
The device is turning out to be very popular, one of my sons and grandson happened to show up just as I was finishing the build, so naturally they wanted to try it out. It turned out to be a big hit. Fortunately the battery had a decent charge, since they played it all afternoon. The novel form factor was addictively playable and the high scores feature kept them vying for better scores. We will see what my other son thinks when he shows up at Christmas.
Switching from doing decorative displays to fully interactive ornaments has really increased the fun factor, and having fun with family is what the holidays are all about.
Happy holidays everyone.
References
https://www.youtube.com/watch?v=FOn4Yli62UM&ab_channel=N%C2%B7I%C2%B7XConsulting
https://cdn.hackaday.io/files/1834837850136672/Invaders%20code.zip
https://docs.arduino.cc/retired/boards/arduino-pro-mini
https://docs.arduino.cc/retired/getting-started-guides/ArduinoProMini
