Can You Build an Arduino Slot Machine?

The fun thing about Arduino, by nature, is the range of projects it allows you to work on and customize. We’ve touched on a number of cool examples in the past, including remote-controlled LEDs, automated mini parking garages, and battery charge monitors, to name a few. By no means to those examples show the full range of possibilities that exist with Arduino, but they do speak to the variety.

Even among bigger collections of Arduino ideas though, there’s one you may not have come across before that can make for a complex and fascinating project: a functioning digital slot machine. Believe it or not, this is actually something that people have figured out how to make with Arduino, and while it requires a little more effort than rigging an LED to flicker on and off, some will find it to be a worthy challenge.

So, beyond basic Arduino components, what will you need and how will this work?

First, you’ll need to acquire two different kinds of display — one for inputting commands for the slot machine, and another to actually show the reels. As MakeUseOf points out (with some helpful examples), there are various types of displays that can work within an Arduino project. And for the most part they’ll be whole components that you purchase separately. But speaking generally, you’ll want to acquire an LCD screen for the command menu, and an LED board that can show the slot reel icons as they “swivel” and come into place. You’ll also need to purchase some buttons for the apparatus — a minimum of three (for scrolling up and down and making selections on the LCD menu).

Next you’ll need to gather your additional components. These can vary somewhat depending on the specific design of the slot machine you’re making (and we’ll get to more detailed blueprints below). But at minimum, you’ll need a breadboard, jumper wires, soldering materials, LEDs and resistors, and relevant capacitors and switches. You will also need a power supply adequate for the project you’re working on (five volts minimum).

Before you program and build, you’ll also need to decide how many digital reels you’re going to design, and what symbols will be on them. And here is where you can get a little bit creative and pick an actual theme for your machine (even if the LED symbols will be somewhat crude). For this step, it’s advisable to look to existing digital slot games for inspiration, because particularly in recent years they have excelled at using design themes. Foxy Games, which has done perhaps the best job of a popular site at gathering a selection of well-liked digital slots from different providers together in one place, showcases a lot of examples you can draw from. There are designs based on ancient warriors (swords, shields, and helmets); on jungle themes and adventures; on gems and treasures; and even on classic slot reels featuring fruits, lucky 7’s and such. Browsing through these can give you some ideas as to what symbols you want to design and program into your LED display.

Once you have your symbols worked out, you’ll need to do the math — what many would consider the hard part — to work out the probabilities for each possible combination of symbols, and the probability that each outcome occurs. The goal here is to establish a realistic “volatility index,” or VI, which essentially means to make the game appropriately random without being too random. It involves some tinkering, to be sure, but in simple terms it means determining how often each combination should occur, mathematically, and then plug the numbers into a spreadsheet that can simulate outcomes to ensure that the desired VI is achieved. This doesn’t involve coding skill so much as a bit of spreadsheet savvy, but it is almost a sort of extra programming step for this particular Arduino project.

The good news though is that once all of the above is worked out, you’re ready to build the machine! With the right screens and components, a plan for your LED slot symbols, and a mathematical foundation for outcome randomness, all that’s left is to build the circuit and program it through the Arduino software. For those who know their way around Arduino well enough to try it for themselves, this should be enough to at least start experimenting with. That said, there are also existing instructions for a project of this nature that you can access here.

This is ultimately a project for people with a high degree of confidence and some experience with Arduino, as well as the patience for a more involved project than the average “alarm clock” or “garage opener” gimmick. But it’s also a very engaging project, and one you can get a lot of fun out of even once it’s finished.