4.4.1 Light Emitting Diode

An LED (Light Emitting Diode) is an electronic component that produces light when current flows through it in the correct direction.

LEDs are commonly used in Arduino projects as indicators or simple output devices.

A typical LED circuit requires:

• Arduino board
• LED
• Current-limiting resistor
• Jumper wires
• Breadboard

The resistor is used to limit current and protect the LED.

4.4.2 Basic LED Control

Example:

int ledPin = 13;

 

void setup() {

  pinMode(ledPin, OUTPUT);

}

 

void loop() {

  digitalWrite(ledPin, HIGH);

  delay(1000);

 

  digitalWrite(ledPin, LOW);

  delay(1000);

}

4.4.3 Controlling LED Brightness

PWM can be used to control LED brightness.

int ledPin = 9;

 

void setup() {

  pinMode(ledPin, OUTPUT);

}

 

void loop() {

  analogWrite(ledPin, 50);

  delay(1000);

 

  analogWrite(ledPin, 150);

  delay(1000);

 

  analogWrite(ledPin, 255);

  delay(1000);

}

The LED will produce different brightness levels.

4.4.4 Applications of LEDs

LEDs can be used to indicate:

• Power status
• Sensor activation
• Warning conditions
• System errors
• Communication status
• Alarm conditions
• Device operating modes