int redPin= 11;
int greenPin = 10;
int bluePin = 9 ;
void setup() {
 pinMode(redPin, OUTPUT);
 pinMode(greenPin, OUTPUT);
 pinMode(bluePin, OUTPUT);
}
void loop() {
 setColor(255, 0, 0); // Red Color
 delay(1000);
 setColor(0, 255, 0); // Green Color
 delay(1000);
 setColor(0, 0, 255); // Blue Color
 delay(1000);
 setColor(255, 255, 255); // White Color
 delay(1000);
 setColor(170, 0, 255); // Purple Color
 delay(1000);
 setColor(255,255,0);
 delay(1000);
 setColor(128,0,128);
 delay(1000);
 setColor(64,224,208);
 delay(1000);
 setColor(0,128,128);
 delay(1000);
 setColor(128,0,0);
 delay(1000);
 setColor(0,0,128);
 delay(1000);
}
void setColor(int redValue, int greenValue, int blueValue) {
 analogWrite(redPin, redValue);
 analogWrite(greenPin, greenValue);
 analogWrite(bluePin, blueValue);
}

Understanding RGB Color Mixing

An RGB LED is essentially three LEDs (Red, Green, and Blue) packed into a single module with shared connections (either a Common Cathode or Common Anode). By adjusting the brightness of each internal LED independently, we can create almost any color in the visible spectrum through Additive Color Mixing.

Hardware Setup

• Arduino Pins: We use Pins 9, 10, and 11 because they are hardware-enabled PWM (Pulse Width Modulation) pins. This allows the Arduino to simulate varying voltages by rapidly switching the output ON and OFF.
• Connection:
  • Red Pin -> Digital Pin 11
  • Green Pin -> Digital Pin 10
  • Blue Pin -> Digital Pin 9
  • Common Pin -> Ground (for Common Cathode) or 5V (for Common Anode)

Code Explanation: The setColor Function

The core of this project is a custom function setColor(int r, int g, int b). It simplifies the code by allowing us to pass values from 0 (off) to 255 (full brightness) for each color channel.

void setColor(int redValue, int greenValue, int blueValue) {
  analogWrite(redPin, redValue);
  analogWrite(greenPin, greenValue);
  analogWrite(bluePin, blueValue);
}

Using analogWrite(), the Arduino generates a square wave with a duty cycle corresponding to the input value, which our eyes perceive as dimmed or bright color levels.

Experimenting with Colors

By combining different values, you can create specialty colors:

• Purple: setColor(170, 0, 255)
• Turquoise: setColor(64, 224, 208)
• Yellow: setColor(255, 255, 0)

This project's logical structure makes it easy to add more complex patterns, such as smooth color transitions (rainbow fades) or environmental color sensing in future iterations.