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Blinking LED — Your First Arduino Project
Admiral OOM

Created by

Admiral OOM

09. March 2026
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Blinking LED — Your First Arduino Project

The classic first electronics project! Build a blinking LED circuit using an Arduino, a breadboard, a resistor, and a single LED. Perfect for absolute beginners — no soldering required.

Instructions

1

Gather Your Components

Collect all components listed below. No soldering needed — everything plugs into the breadboard.

Materials for this step:

SparkFun Inventor's Kit - V3.2SparkFun Inventor's Kit - V3.21 kit
Arduino Uno R3Arduino Uno R31 piece
5mm LED (any color)5mm LED (any color)1 piece
220 ohm Resistor (1/4W)220 ohm Resistor (1/4W)1 piece
BreadboardBreadboard1 piece
Jumper Wires (Male-to-Male)Jumper Wires (Male-to-Male)2 piecess
USB-B CableUSB-B Cable1 piece

Tools needed:

Computer with Arduino IDE
2

Circuit Schematic

Signal flows from Arduino Pin 13 → 220Ω resistor (R1) → LED (D1) → GND. The resistor limits current to protect the LED.

Materials for this step:

Arduino Uno R3Arduino Uno R31 piece
5mm LED (any color)5mm LED (any color)1 piece
220 ohm Resistor (1/4W)220 ohm Resistor (1/4W)1 piece
3

Wire It Up

  1. Insert the LED into the breadboard — long leg (anode +) in one row, short leg (cathode −) in the next.
  2. Insert one leg of the 220Ω resistor into the same row as the LED cathode. Other leg in a separate row.
  3. Jumper wire from LED anode row → Arduino Pin 13.
  4. Jumper wire from resistor free row → Arduino GND.
Tip: The resistor can go on either side of the LED — it just needs to be in series.

Materials for this step:

5mm LED (any color)5mm LED (any color)1 piece
220 ohm Resistor (1/4W)220 ohm Resistor (1/4W)1 piece
BreadboardBreadboard1 piece
Jumper Wires (Male-to-Male)Jumper Wires (Male-to-Male)2 piecess
4

Upload the Blink Code

Connect Arduino via USB. Open Arduino IDE, select Tools → Board → Arduino Uno, paste the code, and click Upload.
blink.inoarduino
// Blinking LED — Your First Arduino Project
// Turns an LED on for one second, then off for one second, repeatedly.

const int LED_PIN = 13;  // Pin connected to the LED

void setup() {
  pinMode(LED_PIN, OUTPUT);  // Set pin 13 as an output
}

void loop() {
  digitalWrite(LED_PIN, HIGH);  // Turn LED ON
  delay(1000);                  // Wait 1 second

  digitalWrite(LED_PIN, LOW);   // Turn LED OFF
  delay(1000);                  // Wait 1 second
}

// EXPERIMENT IDEAS:
// - Change delay(1000) to delay(100) for fast blinking
// - Change delay(1000) to delay(2000) for slow blinking
// - Try delay(50) for a strobe effect
// - Use different values for ON and OFF times:
//   delay(200) ON, delay(800) OFF = short flash
//   delay(800) ON, delay(200) OFF = long flash

Materials for this step:

Arduino Uno R3Arduino Uno R31 piece
USB-B CableUSB-B Cable1 piece

Tools needed:

Computer with Arduino IDE
5

PCB Layout (Reference)

This shows the circuit as a PCB layout. Not needed for this project — the breadboard works perfectly — but shows how the same circuit would look if manufactured as a real board.
6

Test and Experiment

LED blinks? Congratulations! You just programmed hardware.

Troubleshooting:
  • LED does not light up? Flip the LED — long leg toward Pin 13.
  • LED stays on? Check code uploaded successfully.
  • Nothing happens? Verify wiring matches the schematic in Step 2.

Next experiments:
  • Change delay() values to control blink speed
  • Add a second LED on Pin 12
  • Replace with an RGB LED (see SIK Circuit 3)

Materials

7

Tools Required

2
Estimated Total
$105.00

CC0 Public Domain

This blueprint is released under CC0. You are free to copy, modify, distribute, and use this work for any purpose, without asking permission.

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