The first time you hold an Arduino in your hand, it can be a bit intimidating. You see a black chip, a bunch of tiny components, letters, numbers, and connectors everywhere.
But in reality Arduino is designed to be intuitive.
Now let’s understand the parts that make up our board so we know where to connect things without fear of breaking anything.
We will use the Arduino UNO model as a reference, which is the standard for learning. If you have a Nano or a Mega, the parts are almost identical, only the number of pins changes.
The Power System
For Arduino to work, it needs to “eat” electricity. We mainly have three ways to give it to it:
It’s the large silver connector that looks like a USB, smells like a USB and… yes, that one! The USB.
It is the most important connector of all, and it serves a dual purpose:
- It allows loading code from the computer.
- It powers the board with the 5V from the computer’s USB. This is what we will use 99% of the time when starting out.
It is used to connect batteries (9V) or wall adapters when we want our project to work autonomously, without being attached to the computer.
For advanced users who want to power the board directly with wires.
For now, let’s forget about these.
The Microcontroller
It’s the long, black chip (or small and square in some versions) that dominates the center of the board.
It is the Microcontroller (usually an ATmega328p). This is where your code is stored and where decisions are made. It’s the brain of your board.
The Power Pins
If you look at the rows of black holes on the edges, you’ll see they are grouped. One group is labeled POWER.
This is where Arduino gives us power to power our sensors and LEDs.
- 5V: Provides stable 5 Volts.
- 3.3V: Provides 3.3 Volts (for more delicate components).
- GND (Ground): The negative. It’s fundamental. You’ll see there are several GND pins scattered around the board. They are all the same and are connected internally. Remember: the circuit must always close to GND.
Digital Pins
You’ll see a long row numbered from 0 to 13. These are the digital pins and they can work in two ways:
- As OUTPUT: To turn things on or off (0V or 5V).
- As INPUT: To read whether a button is pressed or not.
The Special PWM Pins (~)
Look closely. Next to some numbers (3, 5, 6, 9, 10, 11) there is a small wavy symbol, a tilde: ~.
Those are PWM (Pulse Width Modulation) pins. They are normal digital pins, but they can also turn on and off so fast that they can simulate intermediate voltages.
We will use them to regulate intensity (LED brightness, motor speed), not just to turn on and off.
Analog Pins
At the bottom right we have the pins labeled ANALOG IN (A0, A1… A5).
Unlike digital ones (which only understand “All” or “Nothing”), these pins can measure voltages with decimals (0.3V, 2.7V, etc.).
We will use them to read analog sensors: temperature, light, distance, potentiometers… anything that gives us a range of values and not just a yes/no.
