Wednesday, June 29, 2016

Homemade Handheld Videogame Console: Part 1

Ever since I started programming games, I've always been keen on the idea of building my own custom hardware to run them. Its one thing to write a game that runs on a PC or laptop, but running on hardware specifically designed for games is just more exciting. I've found often when I'm writing a game I am imagining holding a gamepad in my hand, and that a keyboard is just a poor substitute. I'd previously played around making an Arduino-based video game console and I wanted to make something with a bit more performance (colour graphics!). Other design criteria were:
  1. Ability to play games written in python: because I'd already written a few from previous pyweek comps and its the language I'm most comfortable with and hence most likely to want to develop more games in.
  2. Portable: I wanted to try something portable ever since I saw the PiGRRL.
Another cool thing about this project is its a good chance to try out some 3D printing, which I've not had any experience with but am keen to try!

The first video game device I owned as a kid was the original gameboy ... it has a special place in my heart; so many hours spent playing Tetris, Metroid II, Super Mario Land, R-type, Adventure Island :) ... it was still working perfectly up until about 8 years ago when it reached a stage where it would chew through a pack of double As in about 180 seconds. Sadly it no longer powers up, but the memory lives on. The only other handheld I have is a DS Lite, which I did a bit of homebrew development on, but never finished anything.

Based on the inspiration provided by the PiGRRL, I decided to go with a Raspberry Pi 3 as the core of the console, as I'd had experience with it before, runs pygame reliably, could find a good screen (PiTFT 2.8 LCD screen capable of 320 x 240 pixels) and GPIOs make it easy to design custom buttons. I decided to go with the same audio amp and power boost converter/USB battery charger used in the PiGRRL2, as I hadn't had much experience with these before, and they seemed to play well with the RPi. Good thing about the RPi3 is that it also has built-in wifi and bluetooth, which means I can debug/copy code on/off without having to open up the case or worry about feeding out a USB port from the case, which would put constraints on the case shape.

So I started doing some research on different handheld consoles to get a feel for what I liked/didn't like. I was keen on a landscape format (i.e. DS Lite or PSP) rather than a portrait format (i.e. Gameboy), and I started sketching out some case shapes. I walked around JB HiFi for a bit trying out the new PSP Vita and the 3DS: the thing that gets me about these modern handhelds is that the case is thin, the buttons are super small and located pretty close to the edge of the device. I find them kind of uncomfortable to play after a while ... I dunno, I guess they are more designed for a younger market these days with smaller hands, but my hands aren't that big either. I pick up my old gameboy again and it's more comfortable: a combination of being slightly fatter and a bit heavier too.

So I finalise some sketches for the shape I like and it's time for some CAD. Last time I did any serious CAD was in undergrad, so I had some rehashing to do. From a random conversation I had with someone about 3D printing, I remember them mentioning parametric cad modelling and "OpenSCAD", in which objects are "programmed" ... the concept was appealing to me (as was the fact that I could get OpenSCAD free and open source). A week (and a bit) later, I've got the case design finished:

Man, it took me such a long time (learning curves in OpenSCAD, and "programming" the shape I wanted took a few goes, implementations that didn't work) but I'm happy with the end result, and because its parametric I can easily adjust anything that is not working out further down the line.

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