int LED =2;
int PWM= 6;
int i; 

void setup() {
pinMode(LED, OUTPUT);
pinMode(PWM, OUTPUT);

}
void loop() {


 digitalWrite(LED, HIGH);   
   
  for(i=0;i<256; i++)
  {
    analogWrite(PWM, i);
    delay(20); 
  }
  for(i=255;i>=0; i--)
  {              
    analogWrite(PWM, i);
    delay(20); 
  }
 delay(1000);
  
  }