Beginner Friendly
How LEDs create light, safe wiring with resistors, display types (single LED, 7‑segment, strips), and a first blink project.
What is an LED?
An LED (Light Emitting Diode) is a tiny semiconductor that glows when current flows in the forward direction.
It’s efficient, fast, and lasts a long time — perfect for indicators, displays, and colorful effects.
Polarity check: The anode (+) is usually the longer lead, and the cathode (−) sits next to a flat edge on the LED’s rim.
Safe Wiring — Use a Resistor
LEDs don’t limit their own current. Always add a current‑limiting resistor so they don’t burn out.
Common LED “Display” Options
Single LEDs & Arrays
- Status indicators
- Bar graphs
- Through‑hole or SMD parts
Seven‑Segment Displays
- Shows numbers using 7 bars
- Common anode or common cathode
- Can be driven with shift registers
Your First Blink Project
const int LED_PIN = 13; // onboard LED
void setup() {{ pinMode(LED_PIN, OUTPUT); }}
void loop() {{
digitalWrite(LED_PIN, HIGH); delay(500);
digitalWrite(LED_PIN, LOW); delay(500);
}}Tip: Move the LED to a breadboard: Pin → Resistor → Anode, Cathode → GND.
Where You’ll Use It
- Indicators and dashboards
- Clocks and counters (7‑segment)
- Decor and data‑viz (addressable strips)