#define sw1 2
#define gnd 3
#define led 11
bool choice;
void setup()
{
 pinMode(sw1, INPUT_PULLUP);
 pinMode(gnd, OUTPUT);
 pinMode(led, OUTPUT);
 digitalWrite(gnd, LOW);
}

void loop() 
{
choice = digitalRead(sw1);
if(choice == 0)
{
  for (int i=0;i<256;++i)
  {
    analogWrite(led,i);
    delay(2);
  }
    for (int j=255;j>0;--j)
  {
    analogWrite(led,j);
    delay(2);
  }
}
  else 
  digitalWrite(led, LOW);
}