Do I need to buy hardware for this tutorial?

No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.

Which components are used?

Arduino UNO board, 5 mm LED, 220 Ω resistor. They are already available in the simulator library.

How long does it take?

About 15 minutes, intermediate level, in 3 guided steps.

What should I know before starting?

The previous tutorial in the series, “5-LED chaser”, is enough preparation. No software install is required.

Is the code provided and checked?

The simulator checks your wiring and your code automatically at every step, and shows the commented solution if you get stuck.

All tutorials

1 · First steps

SOS message in Morse code

Intermediate15 min

Goal

Send ··· ––– ··· on the LED with exact timings.

Why it matters

Your first encoding of information over time: this is already modulation.

What you need

Arduino UNO board
5 mm LED
220 Ω resistor

Nothing to buy: every component below is simulated in the browser.

Steps

01Write two functions dot() and dash() lighting the LED for 200 ms / 600 ms.
02Call them in the right order inside loop().
03Add a 1 s pause between each letter.

This tutorial runs inside the Circuitly simulator: your wiring and your code are checked automatically at every step.

Run this tutorial in the simulator Free 30-day classroom trial

Frequently asked questions

Do I need to buy hardware for this tutorial?: No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.
Which components are used?: Arduino UNO board, 5 mm LED, 220 Ω resistor. They are already available in the simulator library.
How long does it take?: About 15 minutes, intermediate level, in 3 guided steps.
What should I know before starting?: The previous tutorial in the series, “5-LED chaser”, is enough preparation. No software install is required.
Is the code provided and checked?: The simulator checks your wiring and your code automatically at every step, and shows the commented solution if you get stuck.

For teachers

Get the teaching pack: 6 ready-to-run sessions

Full progression, objectives, student steps and an assessment grid — printable, free.

One address, no spam: just the pack and classroom updates.