• entries
    222
  • comments
    607
  • views
    587895

ATmega644P CHIP-8/SCHIP interpreter

Sign in to follow this  
benryves

1528 views

In an attempt to solve the screen resolution problem issue I've bought a very cheap 320x240 pixel graphical LCD - a PG320240H-P9 on eBay for $24. Part of the reason for its cheapness may be down to its the lack of a controller; you need to constantly refresh the LCD with pixel data yourself (easier to use modules have integrated controllers that refresh the display for you from some on-board RAM). If I manage to get it working I'll have a 128x64 pixel graphical LCD going spare - finding a use for it could make an interesting project.

I have a bit of a soft spot for the CHIP-8 programming language, having previously written an few implementations. The CHIP-8 environment requires just under 3.5KB of RAM, and my recent investment in an ATmega644P boasting 4KB of RAM provided me with a microcontroller that was up to the task.

Complete CHIP-8/SCHIP system

Beyond the ATmega644P and LCD the hardware is pretty simple; a potentiometer is provided to adjust the speed of the interpreter when it's running, from 1/8th speed up to 8x speed. Sound is output using a piezo transducer, which I've taped to the hard plastic lid from a tube of chocolates to amplify it. Games rely on a 4x4 hex keypad for input, and as I do not have a 4x4 keypad - hex or otherwise - I assembled my own on another breadboard. I don't even have sixteen switches of the same type, hence the mixture in the above photo. A schematic of the hardware can be downloaded in PDF format.

Game menu

When you reset the circuit a list of all of the programs stored on the microcontroller is shown on the LCD. The 64KB of flash memory on the ATmega644P is enough to store the code for the interpreter and all of the CHIP-8 and SCHIP games available on the Internet. For a change I've decided to have a go at designing a variable width font rather than use one of my existing fixed-width fonts; I don't think it looks too shabby.

'Joust' summary

When a game has been selected a (gramatically incorrect) summary of the game is shown. To the right of the screen is a 4x4 grid informing the player which key does what; arrows for directional controls, a diamond for "fire" or confirmation actions and a tick/cross for yes/no input. There doesn't seem to be any particular convention for keypad input in CHIP-8/SCHIP games, which makes this feature invaluable!

Ant

Click here to download the source code.
Sign in to follow this  


3 Comments


Recommended Comments

Quote:
Original post by Wavesonics
Very cool little project, would be neat to see this packaged up into a hand held :D
Aye, that was the intention behind the name "Portable" Vinegar, even though it would be less portable than the original (which ran on the TI-83+). [wink] However, the LCD backlight consumes a whopping 390mA (the 1A +5V regulator gets very hot) so I don't think battery life would be very good.

Share this comment


Link to comment
Only one word: WOW!!!

This is amazing! A complete RCA COSMAC VIP computer with the CHIP-8 interpreter
all-in-1 chip with also the Super Chip-8 integrated.

But what i would like to see is your project would display on any A/V
tv/monitor, like a "Plug & Play" game system (like those Jakks TV units). Would
it be easy to to do with A/V ouput instead ?

Keep up the great work! :)

Share this comment


Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now