const int redPin   = 3;
const int greenPin = 5;
const int bluePin  = 6;
int delayValue     = 10;

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

void loop() {
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);

// red
  for (int i = 0; i <= 255; i++) {
    analogWrite(redPin, i);
    delay(delayValue);
  }
  analogWrite(redPin, 255);

// yellow
  for (int i = 0; i <= 255; i++) {
    analogWrite(redPin, 255);
    analogWrite(greenPin, i);
    delay(delayValue);
  }
  analogWrite(redPin, 0);

// green
  for (int i = 0; i <= 255; i++) {
    analogWrite(greenPin, i);
    delay(delayValue);
  }
  analogWrite(greenPin, 255);

// cyan
  for (int i = 0; i <= 255; i++) {
    analogWrite(greenPin, 255);
    analogWrite(bluePin, i);
    delay(delayValue);
  }
  analogWrite(greenPin, 0);analogWrite(bluePin, 0);

// blue
  for (int i = 0; i <= 255; i++) {
    analogWrite(bluePin, i);
    delay(delayValue);
  }
  analogWrite(bluePin, 0);

// magenta
  for (int i = 0; i <= 255; i++) {
    analogWrite(redPin, i);
    analogWrite(bluePin, i);
    delay(delayValue);
  }
  analogWrite(redPin, 0);analogWrite(bluePin, 0);

}