RGB_LED.ino

//www.elegoo.com
//2016.12.8

// define pins
#define BLUE 3
#define GREEN 5
#define RED 6

void setup()
{
  pinMode(RED, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(BLUE, OUTPUT);
  digitalWrite(RED, HIGH);
  digitalWrite(GREEN, LOW);
  digitalWrite(BLUE, LOW);
}

// define variables
int redValue;
int greenValue;
int blueValue;

// main loop
void loop()
{
#define delayTime 10 // fading time between colors

  redValue = 255; // choose a value between 1 and 255 to change the color.
  greenValue = 0;
  blueValue = 0;

  // this is unnecessary as we've either turned on RED in SETUP
  // or in the previous loop ... regardless, this turns RED off
  // analogWrite(RED, 0);
  // delay(1000);

  for (int i = 0; i < 20; i += 1) // fades out red bring green full when i=255
  {
    redValue -= 1;
    greenValue += 1;
    // The following was reversed, counting in the wrong directions
    // analogWrite(RED, 255 - redValue);
    // analogWrite(GREEN, 255 - greenValue);
    analogWrite(RED, redValue);
    analogWrite(GREEN, greenValue);
    delay(delayTime);
  }

  redValue = 0;
  greenValue = 255;
  blueValue = 0;

  for (int i = 0; i < 20; i += 1) // fades out green bring blue full when i=255
  {
    greenValue -= 1;
    blueValue += 1;
    // The following was reversed, counting in the wrong directions
    // analogWrite(GREEN, 255 - greenValue);
    // analogWrite(BLUE, 255 - blueValue);
    analogWrite(GREEN, greenValue);
    analogWrite(BLUE, blueValue);
    delay(delayTime);
  }

  redValue = 0;
  greenValue = 0;
  blueValue = 255;

  for (int i = 0; i < 20; i += 1) // fades out blue bring red full when i=255
  {
    // The following code has been rearranged to match the other two similar sections
    blueValue -= 1;
    redValue += 1;
    // The following was reversed, counting in the wrong directions
    // analogWrite(BLUE, 255 - blueValue);
    // analogWrite(RED, 255 - redValue);
    analogWrite(BLUE, blueValue);
    analogWrite(RED, redValue);
    delay(delayTime);
  }
}