Your first project in five minutes

An Arduino Uno, one LED, one resistor and eight lines of code, built from an empty canvas.

Clear the bench

Open the editor. The first time, it opens on this very circuit, already built: an Uno blinking an LED, called First blink. Press Run to see it, then start from scratch: select everything with Ctrl/Cmd+A and press Delete, or open Save, then Built-in projects, and pick something to start from instead. Nothing here is lost: the browser keeps the last state of every project you open.

Put a breadboard and a board down

Press + on the canvas toolbar, or the A key. The part panel opens docked on the left, with a search box and a category rail. Type breadboard, then drag the tile onto the canvas, or click it to drop it at the middle of the view.

Do the same for Arduino Uno. The Uno does not push into a breadboard: its headers are two inches apart, which is wider than the board is, so it sits beside the breadboard and is wired to it with jumpers, exactly like the real thing.

The LED and its resistor

Add an LED and a resistor, and drop both onto the breadboard so their pins land in holes. A breadboard strip is five holes long, so two pins in the same strip are the same net. Put the LED's cathode and one end of the resistor in the same strip.

Select the resistor. The properties panel opens beside it with its value in ohms; 220 is the usual choice for an LED on 5 V. Select the LED and you can pick its color.

Wire it

Drag from the Uno's 13 pin to the strip the LED's anode is in, and from the free end of the resistor to a GND pin. While you drag, the hole or pin under the pointer gets a ring and its name, so you can see what you are about to land on. Let go and the wire is drawn with square corners you can drag afterwards.

Nothing needs a power rail here: the Uno drives the LED from its own pin.

Write the sketch

The right-hand pane is now the Uno's project. Replace what is in sketch.ino with this:

void setup() {
  pinMode(13, OUTPUT);
}

void loop() {
  digitalWrite(13, HIGH);
  delay(500);
  digitalWrite(13, LOW);
  delay(500);
}

Run it

Press Run. The first build downloads clang once and caches it, so it takes a few seconds; every build after that is a fraction of a second. The Build tab shows the steps, and a diagnostic there is clickable and takes you to the line.

The LED blinks once a second and the header readout settles near 1.00x, which means the simulated circuit is keeping pace with real time.

Keep it

Press Save. Signed out, that writes to this browser. Signed in, it also writes to your account, and Share gives you a link to send someone. See saving and autosave and sharing a project.

Next: placing parts, wiring, or the whole Arduino Uno model.