const int redPin = 11;
const int greenPin = 10;

int val;

void setup() {
   pinMode(redPin, OUTPUT);
   pinMode(greenPin, OUTPUT);
   Serial.begin(9600);
}

void loop() {
   for (val = 255; val > 0; val--) {
      analogWrite(redPin, val);
      analogWrite(greenPin, 255 - val);
      delay(10);
   }
   Serial.println("Green");
   delay(1000);

   for (val = 0; val < 255; val ++) {
      analogWrite(redPin, val);
      analogWrite(greenPin, 255 - val);
      delay(10);
   }
   Serial.println("Red");
   delay(1000);
}