Our first program in Arduino

In the world of programming, when you learn a new language, tradition dictates that the first thing you should do is write a program that says “Hello World” on the screen.

In the world of electronics and Arduino, our “Hello World” is not text on a screen. It’s something much more physical: making a light blink.

Today we are going to write our first Sketch (that’s what Arduino programs are called). And the best part is that you don’t need to connect anything yet. We are going to use a small LED that already comes on the Arduino board itself.

The Anatomy of a Sketch

Open your Arduino IDE. If you create a new file (File > New), you’ll see it’s not empty. Arduino always gives us a basic skeleton.

This skeleton has two fundamental parts that must always exist. They are the heart of any Arduino program:

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

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

Let’s understand them with an analogy from your daily life:

Our First Program

To test the operation of our setup, we are going to use one of the examples included in the Arduino IDE.

We select the example Basics / Blink, and a code similar to the following will appear.

const int pinLED= 13;    //assign variable led as 13

void setup()
{
  pinMode(pinLED, OUTPUT);     //define pin 13 as output
}

void loop() {
  digitalWrite(pinLED, HIGH);   // turn LED on
  delay(1000);                  // wait for a second
  digitalWrite(pinLED, LOW);    // turn LED off
  delay(1000);                  // wait for a second
}

This example turns an LED on and off every second. The LED used is integrated into many Arduino boards (UNO, MEGA, etc) physically connected to PIN 13.

The function of each line is commented on the right, but for now we won’t worry about the meaning (we’ll see these aspects later).

The 3 Basic Commands

For this first program, we have used three essential functions that you will use 90% of the time.

Uploading the Program

First, we connect our Arduino board using the corresponding cable. The first models used a USB A-B, but other models use mini, micro or even USB-C.

No additional power connection or cable is needed for programming; the USB connection alone is sufficient.

Next, we open the Arduino IDE. We select the board model we are using.

We select the communication port to which it is connected.

We now have the connection configured and ready to load our first program.

Loading an Example

Finally, we click the highlighted button to compile and send the program to our Arduino board. After a few seconds, the IDE will compile the program and the screen should look similar to the following.

After a few blinks, the board will start executing the program, turning the LED on and off.