Ever since I was a kid, there were two things I’ve always wanted to build: a computer and my own video game ‘console.’ Now, I grew up in the seventies and eighties, so both of these things were pretty crude, some even crude when they were new (RCA Cosmac, I’m looking at you!) While in the intervening years, I did ‘build’ both, I cheated in doing so. With the computer, ‘building’ one was simply buying premade cards and a motherboard and installing them, hardly building one. With the video game ‘console’, I assembled a ‘pong’ style game from a kit (which I wrote about here.)
Today’s microcontrollers are as powerful, if not more so, than yesterday’s microcomputers. For instance, the ATMega 328 is every bit as capable as the 8080, one of the mainstays in the 1970’s. Because of this, you can build real computers that are very small and require little power. They also require substantially fewer parts to work and be useful.
While I am no electronics engineer, these chips are simple enough for even someone like myself to design and build a working computer that can, subsequently, become a game console. Companies like Adafruit, iConstrux, Spark Fun, Arduino and others all have components that are geared toward these nifty little devices. Adafruit, for example, sells the Nunchucky, which is a tiny little board that allows you to easily interface a Nintendo Wii Nunchuck controller. These controllers are, themselves, very cool and underrated. They feature accelerometers, a joystick and two buttons and are easily read by these little processors. And, with the Nunchucky, you do not need to cut its cable.
While it is old news, it is new news to me…the Arduino’s are capable of limited video generation and, hence, limited graphics. Now, while the graphics ability will never threaten nVIdia or AMD, they will give the aforementioned RCA Cosmac a run for its money.
Armed with this knowledge, the Nunchuck/Nunchucky, some basic soldering skill and enough knowledge of electronics to be somewhat dangerous, I have set out to build that computer/game console.
I am actually doing two consoles: a handheld for my stepson and a somewhat more capable one as my exercise in designing and constructing said system. The handheld will utilize a small joystick, a Nokia 5110 LCD and a speaker in addition to the Mega328 Mini Pro.
Unfortunately, I ordered a great deal of my parts from eBay and just about all are shipping from China, apparently by foot as they have not all arrived.
However, since my Uno did arrive, I’ve been able to design and build the Half Byte game shield and start working on a prototype game, based on the Super Mario games. No, the game will not be made public, but, perhaps, a modified version with different characters may be. I do not have license to distribute any copyrighted material from Nintendo.
The game shield currently features the audio and video out connectors, the 1kohm and 470ohm resistors that allow the video to work (along with a library for the Arduino), the Nunchucky board, Arduino I/O pins and the header for the Parallax Serial LCD (which uses digital pin 2.) I may add digitized sound output as well and, perhaps, blinky LED’s and support for my custom three button controller.
The tricky thing with the video is that it is all handled by the processor. The resistors ‘fool’ most televisions into ‘thinking’ there is a legit video signal. The 1k resistor handles the sync while the other handles the video itself. It was very easy to do and only involved the sacrifice of one video cable (and, since then, I acquired actual connectors so I can use better cables.) Because the processor does all of the work, and has a very limited memory space (2k of ram, tops) the resolution is a paltry 120×96, though I had to back it down a bit to about 100×96, I needed a bit more ram. There is a common library, called TVOUT, available that most people use, though a few have written their own. The common library provides for three different fonts, lines, circles, inverse video and other niceties. It also can display bitmaps, though they MUST be correctly formatted and converting a bitmap for use is a bit of a pain. You must first resize the bitmap to fit the tiny screen, then you have to save it as a monochrome bitmap, process that file through another program that creates the hex codes that go into an array in the Arduino PROGRAM memory (NOT RAM, but the Flash memory that stores your code.) I’ll post more instructions in a later post.
So, once I got the video and audio up and working, I played around with some code. First, the TVOUT demo then my own code. The TVOUT demo is pretty cool with a nice rotation sequence. It also displays the bitmap for the schematic to generate the video, an interesting inclusion.
My ‘mario’ game began as a demo. I wanted to move an image around, controlled by the Nunchuck. I wanted to use Spongebob, but I could never get him to look right in such low resolution. Now, how damned hard is it to represent a SPONGE? UGH. Mario looked much more recognizable and that’s what I went with. Once I had my bitmaps done, moving them around was easy. I now have Mario, a Koopa Troopa and a Warp Pipe in my level. I am using another game called Poofy for some direction. Poofy is a side scroller for Arduino that uses some interesting methods and code that are in the public domain (and developed by the people who brought us Hackvision, an Arduino based console similar to what I am doing.)
My next step with the game is a scrolling world, Mario’s ‘weapon’ and a story.
I will be documenting the process, so stay tuned!
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TVOut Library, demo video and more.
Discussion about color video out
Info on a text out video shield
Games – Asteroids, Space Invaders, Poofy, Snakes!