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This is a three-reeled slot machine with 25 symbols on each reel. The game is configurable.

This project is my implementation of an alien themed slot machine using two ATmega328P-PU micro-controllers. I was inspired by Cory Potter’s Alien Invasion Slot Machine, and I wanted to expand on that idea. The slot machine is for entertainment and educational purposes only. I tried my best to make the game simulate a real slot machine as closely as possible. The project is currently bread boarded. An enclosure will be added as soon as the parts arrive from China and I’ve had a chance to solder everything up. The project took about two months for me to build in my spare time. The most difficult part of the build for me was understanding all of the math involved in making the game behave the way the casino industry would expect a simple slot machine it to behave after a half billion or so simulations.

How the Game Works
The game has three reels with the same unique 25 symbols appearing on each reel (one of the 8x8 matrices on the component with 4 8x8 matrices isn’t used.) There are five different ways to win. If you get three spaceships, you win the jackpot. If you get one or two spaceships you also win some credits. If you get two or three symbols to match you also win. If you get a spaceship and two symbols matching, as depicted below, the game pays out based on the winning event with the lowest probability/highest payout; in other words winning events are mutually exclusive, you can’t win two different ways on a single spin of the reels. This kept the programming a little simpler. There were plenty of other challenges for me.

The slot machine has several interesting features which are accessed via the 20 x 4 I2C capable LCD display using two navigation buttons and a select button. The buttons use a fairly sophisticated de-bouncing algorithm that takes advantage of the micro-controller’s external interrupt capability. This is the main menu.”

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