const int ledpin=27;
void setup() 
{
pinMode(27, OUTPUT);
  // put your setup code here, to run once:
  
}

void loop() {
for(int i=0; i<1023; i++)
{
  analogWrite(ledpin,i);
  delay(5);
}
for(int j=1023;j>0;j--)
{
  analogWrite(ledpin,j);
  delay(10);
}
}