This is Part 3 in a series on learning how to program your own Arduboy game. If you have skipped the previous parts, please read over Part 1 and Part 2.

Variables

Computers work a lot with calculations and data. To make most video games, you’re going to need to be able to store data, like high scores, or player location, or lives remaining. In order to remember data, a computer must set aside some memory to put that data into. Then, the computer can be told to change the data stored there.

Loops

Remember how I said that computers have to be given specific instructions? Ever notice how the back of shampoo bottles say to 1. Lather, 2. Rinse, 3. Repeat? If a computer were given those instructions, they would be stuck in an infinite loop of lathering, rinsing, and repeating. In programming, having instructions repeat in a loop can be very useful. I’ll show you how to use the loop() function to do this.

Getting Started

In this program, we’re going to make the Arduboy keep track of a number and display it to you as it is increased.

Let’s do it! Grab the code from the previous tutorial so that we can build off of it:

//Jonathan Holmes (crait)
//October 18th, 2016
//Printing Text

#include <Arduboy.h>
Arduboy arduboy;

void setup() {
  // put your setup code here, to run once:
  arduboy.begin();
  arduboy.clear();
  arduboy.print("Holmes is cool!");
  arduboy.display();
}

void loop() {
  // put your main code here, to run repeatedly:

}

Initialization

Whenever you create a variable, you have to initialize it, which is setting aside memory for the data and giving it a name. You’ve already done this but didn’t realize it. Check out the Arduboy arduboy; line. You initialized an object called arduboy. Objects are a lil’ more complex than I want to get into during this tutorial, but there are different kinds of variables that you can initialize. Here are some: Integers, booleans, characters, objects, doubles, and many more.

We’ll initialize our number that’s going to increase as an integer. This basically means that it’s a whole number, without fractions. Integers will appear as int inside of C++ code.

To initialize a variable, you must put 3 things: The type of variable, the name of the variable, then a semi-colon. Let’s call our variable counter. Here’s the code: int counter; Put it under the Arduboy arduboy; line.

Assignment

Whenever you create a variable, you can give it a value. This is called assignment. We don’t know what counter‘s value is because we never gave it one.

Let’s clean up the code by removing the arduboy.print(); and arduboy.display() functions from setup(). Instead, let’s put the assignment there:

counter = 0;

This line of code is saying that counter‘s value is now equal to 0. Instead of 0, you could put another number, a mathematical formula, or some other things that I’ll explain below.

Here’s what your code should look like:

//Jonathan Holmes (crait)
//October 18th, 2016
//Counter

#include <Arduboy.h>
Arduboy arduboy;

int counter;

void setup() {
  // put your setup code here, to run once:
  arduboy.begin();
  arduboy.clear();
  counter = 0;
}

void loop() {
  // put your main code here, to run repeatedly:

}

Incrementing

Okay, our program will be repeating a few simple instructions over and over again. Basically, we’ll change the value of counter, then display the value of counter, then repeat. To do this, we should add some code into the loop() function.

counter = counter + 1;

This line of code means that you are assigning the value of counter to itself plus 1. Or, in other words, counter‘s value is now equal to the value of counter + 1.

Displaying The Variable’s Value

Now that we have the variable increasing, let’s display it! Remember how we used arduboy.print() to print some text to the screen? Well, we can use that same function to display numbers to the screen, too. Add arduboy.print(counter); .

If you were to run this code as it is, now, then the Arduboy’s screen would fill up with numbers. If we’re going to print something new, we need to be sure to erase what was previously on the screen. We need to add in arduboy.clear(); at the beginning of loop() and arduboy.display(); at the end to display the updated screen.

Have you ever used a type writer? Whenever you type letters, the cursor moves over. The arduboy.print()function works similarly. Every time you use the arduboy.print() function, it moves the cursor over. So we need to reset the cursor to the top of the screen with arduboy.setCursor(0, 0); . I will explain this more in a later tutorial, but just throw that at the top of the loop().

The Completed Code

I’ve added in some comments, but your code should look like the following:

//Jonathan Holmes (crait)
//October 18th, 2016
//Printing Text

//Include the Arduboy Library
#include <Arduboy.h>
//Initialize the arduboy object
Arduboy arduboy;
//Initialize our counter variable
int counter;
//The setup() function runs once when you turn your Arduboy on
void setup() {
  //Start the Arduboy properly and display the Arduboy logo
  arduboy.begin();
  //Get rid of the Arduboy logo and clear the screen
  arduboy.clear();
  //Assign our counter variable to be equal to 0
  counter = 0;
}
//The loop() function repeats forever after setup() is done
void loop() {
  //Clear whatever is printed on the screen
  arduboy.clear();
  //Move the cursor back to the top-left of the screen
  arduboy.setCursor(0, 0);
  //Increase counter's value by 1
  counter = counter + 1;
  //Print out the value of counter
  arduboy.print(counter);
  //Refresh the screen to show whatever's printed to it
  arduboy.display();
}

Running The Code

Connect your Arduboy to your computer and upload this code to it. Your Arduboy should start counting up!

What’s Next?

In the next tutorial, we’ll be learning about testing the values of variables, booleans, and pressing buttons!

This tutorial is copied and abridged from the original by Jonathan Holmes.

Using the Arduino IDE, go to File > New. This will create a new window with a new sketch. A sketch is a file with your code in it. Sometimes you’ll hear it called “source code”.

Reviewing Our Code

In that new window, you should see the following code:

void setup() {
  // put your setup code here, to run once:
}
void loop() {
  // put your main code here, to run repeatedly:
}

Whenever you write code, you’re going to put a lot of it inside of braces, which look like { and }. That is to split up different lines of code that occur at different times. You’ll learn more specifics about what those different times are later on. All you need to worry about is that you have some code that will be put into the setup()section and the loop() section. These are called functions, but we don’t need to know much about them right now. All we need to know is that whatever code that’s inside of the setup() function will be run once whenever the Arduboy turns on and whatever code is inside the loop() function will be run later on.

Comments

The next thing I want to bring to your attention are the comments. These are lines of code that are completely ignored. They’re great for adding in notes so that you can read your code easier. I’m going to use them a lot, so I thought we should start with them.

It’s very typical to use comments to explain the purpose of functions, variables, and at the beginning of your code to explain the purpose of your program/game.

Let’s go ahead and add some comments to the top of the program! At the top, add a few new lines of text that starts with two slashes, then your name, date, and the title of this program.

Your code should now look like this:

//Jonathan Holmes (crait)
//October 18th, 2016
//Printing Text
void setup() {
  // put your setup code here, to run once:
}
void loop() {
  // put your main code here, to run repeatedly:
}

Those lines of text should turn grey.

Getting Arduboy-Specific Instructions

Okay, that was simple enough, but we need to start adding in our instructions, now. To add in a lot of Arduboy-specific instructions, we need to import the Arduboy Library into our code. Make a new line of code after your comments and add #include <Arduboy.h> . This line of code says that you want to grab a lot of instructions from the Arduboy.h file. There’s nothing more about that that you need to know.

Make a new line after that, and add Arduboy arduboy; . Don’t worry about this too much. Like I said, this is part of getting Arduboy-Specific instructions.

Our code should look like this:

//Jonathan Holmes (crait)
//October 18th, 2016
//Printing Text

#include <Arduboy.h>
Arduboy arduboy;

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

The setup() Function

Sweet! I’m glad you got this far. Add the following lines of code inside of the braces of the setup() function:

 arduboy.begin();
  arduboy.clear();
  arduboy.print("Hello");
  arduboy.display();

Notice that each line of code ends in a semi-colon ; . This is because all instructions in C++ need to end in one. Otherwise, the computer will think it’s something else that I’ll explain later.

Next, notice that all of these lines of code include arduboy. at the beginning. This is because our instructions are stored inside of the arduboy library.

Last thing I want you to look at is the parenthesis, ( and ) . All functions have these. Some include things inside of them and some do not.

The arduboy.begin(); function pretty much tells the Arduboy to turn on properly. Once that is done, the next instruction is followed.

arduboy.clear(); tells the Arduboy to erase everything on the screen.

arduboy.print("Hello"); tells the Arduboy to write some text to the screen. Notice that we actually have something inside of the ( and ) this time. To tell the Arduboy what we want to print, we need to it inside of the parenthesis. Any time you’re working with text, you have to put quotation marks around the text, so we gotta do that, too. You can actually put whatever you want inside of those quotations. Maybe play around with it and put your own name into it.

Last, we have to tell the Arduboy to actually refresh the screen and show you what you just printed to it. That’s what the arduboy.display(); does.

You’re done!

That’s it! You’ve programmed your first program for the Arduboy! This is what the finished code should look like:

//Jonathan Holmes (crait)
//October 18th, 2016
//Printing Text

#include <Arduboy.h>
Arduboy arduboy;

void setup() {
  // put your setup code here, to run once:
  arduboy.begin();
  arduboy.clear();
  arduboy.print("Holmes is cool!");
  arduboy.display();
}

void loop() {
  // put your main code here, to run repeatedly:

}

Installing

Like we did in the previous tutorial, connect your Arduboy with a USB data cable, select the correct port and board, then click the button to transfer it to your Arduboy!

What’s Next?

Next, let’s learn about storing data and loops! Click here to go to that tutorial!

Credits

This tutorial is copied and abridged from the original by Jonathan Holmes.

I wrote this tutorial in order to give back to the programming community that taught me to get into it about 10 years ago. If you’d like to follow me on Twitter, please do so at http://www.twitter.com/crait19 . I’d greatly appreciate that.

Poly Ed

Robotics, Mathematics, Science, Engineering, Tutoring

Category Archives: Arduino

Make Your Own Arduboy Game – Storing Data & Loops

This is Part 3 in a series on learning how to program your own Arduboy game. If you have skipped the previous parts, please read over Part 1 and Part 2.

Variables

Loops

Getting Started

Initialization

Assignment

Incrementing

Displaying The Variable’s Value

The Completed Code

Running The Code

What’s Next?

Credits

Make Your Own Arduboy Game – Printing Text

This is Part 2 in a series on learning how to program your own Arduboy game. If you have yet to install the Arduino IDE and Arduboy Library, please go back to Part 1.

Creating A New Sketch

Reviewing Our Code

Comments

Getting Arduboy-Specific Instructions

The setup() Function

You’re done!

Installing

What’s Next?

Credits

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Emic 2 Sample Code

Ultrasonic Sensor HC-SR04 Sample Code