int led = 5;
int pot = 27;
int potValue = 0;

void setup() 
{
  pinMode(led, OUTPUT);
  pinMode(pot, INPUT);
}

void loop() 
{
  int potValue = analogRead(pot);
  int ledValue= map(potValue, 0, 1023, 0, 255);

  analogWrite(led, ledValue); 

}