1 · First steps
Blink an LED
Beginner10 min
Goal
Turn an LED on pin 13 on and off every second.
Why it matters
This is the “Hello World” of electronics: it proves the board, the code and the wiring all work.
Steps
- 01Drop an Arduino UNO, a 220 Ω resistor and an LED on the canvas.
- 02Set the LED pin to 13 and wire it through the resistor.
- 03Call pinMode(13, OUTPUT) inside setup().
- 04Alternate digitalWrite(13, HIGH/LOW) with delay(1000) inside loop().
This tutorial runs inside the Circuitly simulator: your wiring and your code are checked automatically at every step.
Next tutorials
- Two alternating LEDs
Alternate two LEDs (pins 12 and 13) like a level crossing.
- 5-LED chaser
Run a light across 5 LEDs using a for loop and an array.
- SOS message in Morse code
Send ··· ––– ··· on the LED with exact timings.
- Blink without delay() (millis)
Replace delay() with a time comparison based on millis().