SPACE INVADERS

By : Les Johnson

October 2003

Introduction

After many weeks of taking an hour here and there out of my schedule to work on it, I'm happy to say my Space Invaders game is now ready. (see also revision description)

It is developed on a PROTON Develoment board using a Graphic LCD. This version uses the LCDWRITE and PLOT commands to produce the graphics Which allows smooth movements on a pixel by pixel basis.

Three (seperate) buttons control left, right and fire. It also has 3 independent sound channels. The sound interrupt is the only piece of ASM in the program, but the game itself is written purely using BASIC.

BUTTON CONNECTIONS

• LEFT Button connects to PORTB.0
• RIGHT Button connects to PORTB.1
• FIRE Button connects to PORTB.2

Because of the 3 channel sound, the game requires an 8MHz crystal, but it will run (somewhat slower) using a 4MHz crystal.

SOUND CHANNEL CONNECTIONS

• Each channel is output from PORTA.0,1,2 Channel 1.
• PORTA.0 is the INVADER noise Channel 2.
• PORTA.1 is the MISSILE noise Channel 3.
• PORTA.2 is the SAUCER noise
• Each pin should have a current limiting resistor in order to stop pin to pin shorts.

Some pictures

ADDITIONS AND CONTRIBUTIONS

This game has triggered the imagination of some users. In this section, you will find here their 'best' improvements. We would like to thank them. It shows that sharing projects is useful.

Olivier

ADDING SCORE By : Mark Rodgers (January 2004)

After building my own Proton board I used the Space Invaders Game written by Les to test it. I have made a very small addition to this prog by adding a high score routine that is stored in the onboard eeprom.

All the instructions are in the attached High_Score.bas file.

I have had a play with this great game for a couple of days and done some little tweeks in order to learn a bit more about how to write code a little better. It will now only work on an 18F452 as it is too big for anything else and I can not get any sound as I have no idea how to set the registers. The download is the full updated code and should run on a Proton Development Board. :  Download full  program 

Conclusion

I hope you enjoy the game, and I mainly hope that I inspire you to create your own masterpiece.

I fancy writing a Pacman game next, then a 3D space shoot-em-up.

Have you checked out the Pong game in the samples folder of PROTON plus?

Les

October 2003

(Last revision: OdB 19/01/04)