First Steps with Arduino

Arduino is a hardware and software platform built around a microcontroller. A small board can read signals from sensors, process them, and then control LEDs, motors, relays, displays or other devices.

Thanks to simple wiring, a huge number of examples and extensive library support, Arduino is ideal for beginners as well as for rapid prototyping in school and project work.

Why the Arduino Uno?

The Uno is the most common first board: stable, well documented and easy to use. It has enough input/output pins for school experiments without unnecessary complexity. Once you know the Uno, moving to a Nano, Mega or ESP32 is easy.

A breadboard lets you connect components without soldering, so you can change connections, test ideas and re-verify circuits quickly. Inside, each short row of 5 holes is connected; the long rails along the edges are usually used for 5V and GND.

A resistor limits current. An LED has almost no resistance of its own, so without a resistor it would draw too much current and burn out — or damage the Arduino pin.

How big should the resistor be?

Use Ohm’s law. The resistor “uses up” the voltage the LED doesn’t need. With a 5 V pin, a red LED that drops about 2 V, and a safe current of about 15 mA:

Programs for Arduino are usually written in the Arduino IDE: this is where code is written, checked for errors and uploaded to the board. Tinkercad and Circuit Designer let you plan and simulate a circuit before building it for real.

• ▸writing and editing programs (sketches),
• ▸uploading programs to the Arduino board,
• ▸monitoring program execution via the Serial Monitor,
• ▸adding libraries for sensors and other components.

The IDE is free on the official Arduino website. After installing, select the correct board type and COM port, then upload.

Sensors & actuators you will meet later

This lab checks that the board is connected, the right COM port is selected and a program uploads successfully. We use the built-in LED on pin 13, so no external circuit is needed — the best possible first test.

const int ledPin = 13;      // built-in LED

void setup() {
  pinMode(ledPin, OUTPUT);  // runs once
}

void loop() {               // repeats forever
  digitalWrite(ledPin, HIGH);
  delay(1000);
  digitalWrite(ledPin, LOW);
  delay(1000);
}

How to upload

1. 01Open the Arduino IDE.
2. 02Go to Tools → Board → Arduino Uno.
3. 03Go to Tools → Port and select the correct COM port.
4. 04Click Upload (the → arrow icon).
5. 05The built-in LED should start blinking once per second.

Now move from the built-in LED to an external one and build a real circuit for the first time. Notice how the schematic, the physical wiring and the program connect.

const int ledPin = 8;

void setup() {
  pinMode(ledPin, OUTPUT);
}

void loop() {
  digitalWrite(ledPin, HIGH);
  delay(500);
  digitalWrite(ledPin, LOW);
  delay(500);
}

The program turns the LED on pin 8 on, waits half a second (500 ms), turns it off, waits again — and repeats forever.

1. Q01

   Which function runs only once when the Arduino starts?

   Aloop()Bsetup()Cmain()Dstart()
2. Q02

   Which leg of an LED connects to GND?

   AThe longer leg (anode)BThe shorter leg (cathode)CEither — LEDs work both waysDNeither — it connects to 5V
3. Q03

   What does delay(250) do?

   AWaits 250 secondsBWaits 0.25 secondsCBlinks 250 timesDSets the brightness to 250
4. Q04

   Why do we always put a resistor in series with an LED?

   ATo make it brighterBTo limit the current so the LED and pin are not damagedCTo change its colourDBecause the code needs it
5. Q05

   Which pin is connected to the built-in LED on an Arduino Uno?

   APin 0BPin 8CPin 13DA0