How to control LED brightness using Arduino

How to control LED brightness using Arduino

How to Control LED Brightness Using Arduino

To control the brightness of an LED using Arduino, we use a technique called Pulse Width Modulation (PWM). PWM allows you to vary the amount of time the LED is on versus off, effectively controlling the perceived brightness. Arduino supports PWM on certain pins, which makes this task easy.

Materials Required:

• 1 x Arduino Board (e.g., Arduino Uno)
• 1 x LED (any standard 5mm LED)
• 1 x 220-ohm Resistor (to limit current and protect the LED)
• 1 x Breadboard (optional but helpful)
• 1 x Jumper Wire

Step-by-Step Guide:

1. Wiring the LED to the Arduino

• Anode (positive leg) of the LED: Connect this leg to one of the PWM-enabled pins on the Arduino (for example, Pin 9).
• Cathode (negative leg) of the LED: Connect the shorter leg of the LED to the Ground (GND) pin on the Arduino.
• Resistor: Place a 220-ohm resistor in series with the LED’s anode to limit the current and prevent damage to the LED.

Here's a simple connection diagram:

Arduino Pin 9 ----> Anode (Long leg) of LED ----> Resistor (220Ω) ----> Cathode (Short leg) of LED ----> GND (Ground pin of Arduino)

2. Writing the Code

To control the brightness, you need to use the analogWrite() function, which works by sending a PWM signal to the pin. The value passed to analogWrite() will control the brightness of the LED.

• PWM Range: The analogWrite() function takes a value between 0 (fully off) and 255 (fully on).
• Code Structure:
  • Use analogWrite() in the loop() function to gradually change the LED brightness.
  • Use delay() to control how fast the brightness changes.

Here’s a simple code to control the LED's brightness by gradually fading it in and out:

// Pin where the LED is connected

int ledPin = 9;  // PWM pin on Arduino

void setup() {

  // Initialize the pin as an output

  pinMode(ledPin, OUTPUT);

}

void loop() {

  // Fade the LED from off (0) to bright (255)

  for (int brightness = 0; brightness <= 255; brightness++) {

    analogWrite(ledPin, brightness);  // Set LED brightness

    delay(10);  // Wait for 10ms to see the change

  }

  // Fade the LED from bright (255) to off (0)

  for (int brightness = 255; brightness >= 0; brightness--) {

    analogWrite(ledPin, brightness);  // Set LED brightness

    delay(10);  // Wait for 10ms to see the change

  }

}

Code Explanation:

• pinMode(ledPin, OUTPUT);: This sets Pin 9 as an output pin for controlling the LED.
• analogWrite(ledPin, brightness);: This function writes a PWM value to the pin. The value can range from 0 (completely off) to 255 (fully on). The brightness value will determine how much the LED will light up.
• delay(10);: This delay creates a small pause between each step, allowing the LED to visibly fade in and out.

3. Upload the Code to Arduino

• Open the Arduino IDE and paste the code into a new sketch.
• Connect the Arduino to your computer via USB.
• Select the correct board and port from the Tools menu.
• Click the Upload button (right arrow) to upload the code to the Arduino.

4. Test the LED Behavior

• After uploading, the LED should gradually fade in (from off to full brightness) and then fade out (from full brightness to off).

Conclusion

You’ve now learned how to control the brightness of an LED using PWM with Arduino. The analogWrite() function is used to send varying voltage to the LED, creating the effect of fading it in and out. You can modify the code to experiment with different speeds or create more complex lighting effects!