const int motorPin = 3; //PWM pin
const int potentiometer = A0; //Analog read

int reading;

void setup() {
  
  pinMode(motorPin, OUTPUT);
  pinMode(potentiometer, INPUT);

}

void loop() {
  reading = analogRead(potentiometer);
  reading = map(reading,0,1023,0,255);
  analogWrite(motorPin,reading);
}