#define ledPin 9
#define analogPin A3
int val = 0;

void setup() {
  // put your setup code here, to run once:
pinMode(ledPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
val = analogRead(analogPin);
val = map(val, 0, 1023, 0, 255);
analogWrite(ledPin, val);
}