RGB LED COLOUR FADE

// RGB LED — Colour Mixing & Fade
// Fades smoothly through the colour wheel using PWM on all three channels.

const int RED_PIN = 9;
const int GREEN_PIN = 10;
const int BLUE_PIN = 11;

void setColor(int r, int g, int b) {
  analogWrite(RED_PIN, r);
  analogWrite(GREEN_PIN, g);
  analogWrite(BLUE_PIN, b);
}

// Simple HSV-ish wheel: returns an RGB triple for position 0–255
void wheel(byte pos, int &r, int &g, int &b) {
  if (pos < 85) {
    r = 255 - pos * 3; g = pos * 3;       b = 0;
  } else if (pos < 170) {
    pos -= 85;
    r = 0;             g = 255 - pos * 3; b = pos * 3;
  } else {
    pos -= 170;
    r = pos * 3;       g = 0;             b = 255 - pos * 3;
  }
}

void setup() {
  pinMode(RED_PIN, OUTPUT);
  pinMode(GREEN_PIN, OUTPUT);
  pinMode(BLUE_PIN, OUTPUT);
}

void loop() {
  for (int i = 0; i < 256; i++) {
    int r, g, b;
    wheel(i, r, g, b);
    setColor(r, g, b);
    delay(15);
  }
}