Code for interfacing RGB LED with Arduino.

Arduino_RGB_LED_Interface.ino

const int redPin = 6;
const int greenPin = 5;
const int bluePin = 3;

void setup() 
{
  pinMode(redPin,OUTPUT);
  pinMode(greenPin,OUTPUT);
  pinMode(bluePin,OUTPUT);
}

void loop()
{
  delay(1000);
  primaryColors(1,0,0); // Red
  delay(2000);
  primaryColors(0,1,0); // Green
  delay(2000);
  primaryColors(0,0,1); // Blue
  delay(2000);
  primaryColors(1,1,0); // Yellow
  delay(2000);
  primaryColors(1,0,1); // Magenta
  delay(2000);
  primaryColors(0,1,1); // Cyan
  delay(2000);
  primaryColors(1,1,1); // White
  delay(2000);
  
  RGBFading();
}
void primaryColors(int redValue, int greenValue, int blueValue)
{
  digitalWrite(redPin, redValue);
  digitalWrite(greenPin, greenValue);
  digitalWrite(bluePin, blueValue);
}

void RGBFading()
{
int x;  
int redBrightness;
int greenBrightness;
int blueBrightness;

for (x = 0; x < 768; x++)
{
  if (x <= 255)
  {
    redBrightness = 255 - x;
    greenBrightness = x;
    blueBrightness = 0;
  }
  else if (x <= 511)
  {
    redBrightness = 0;
    greenBrightness = 255 - (x - 256);
    blueBrightness = (x - 256);
  }
  else
  {
    redBrightness = (x - 512);
    greenBrightness = 0;
    blueBrightness = 255 - (x - 512);
  }
  
analogWrite(redPin, redBrightness);
analogWrite(bluePin, blueBrightness);
analogWrite(greenPin, greenBrightness);

delay(10);
}
}