RGB_HSV.ino

int red = 255;
int green = 127;
int blue = 240;

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

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

void loop() {
  for (int i = 0; i < 360; i++){
    setColorByHSV(i, 100, 255);
    delay(10); 
  }
  
}
void setColorByHSV(int hue, int sat, int val) { 
  /* convert hue, saturation and brightness ( HSB/HSV ) to RGB
     The dim_curve is used only on brightness/value and on saturation (inverted).
     This looks the most natural.      
  */

  int colors[3];

  sat = 255-sat;

  int r;
  int g;
  int b;
  int base;

  if (sat == 0) { // Acromatic color (gray). Hue doesn't mind.
    setLedColor(val, val, val);  
  } else  { 

    base = ((255 - sat) * val)>>8;

    switch(hue/60) {
    case 0:
        r = val;
        g = (((val-base)*hue)/60)+base;
        b = base;
    break;

    case 1:
        r = (((val-base)*(60-(hue%60)))/60)+base;
        g = val;
        b = base;
    break;

    case 2:
        r = base;
        g = val;
        b = (((val-base)*(hue%60))/60)+base;
    break;

    case 3:
        r = base;
        g = (((val-base)*(60-(hue%60)))/60)+base;
        b = val;
    break;

    case 4:
        r = (((val-base)*(hue%60))/60)+base;
        g = base;
        b = val;
    break;

    case 5:
        r = val;
        g = base;
        b = (((val-base)*(60-(hue%60)))/60)+base;
    break;
    }

    setLedColor(r, g, b);
  } 
}

void setLedColor(int r, int g, int b){
  analogWrite(redPin, r);
  analogWrite(greenPin, g);
  analogWrite(bluePin, b);
}