void setup() {
  // put your setup code here, to run once:
  #define enA 3
  #define in1 6
  #define in2 8

  pinMode (enA, OUTPUT);
  pinMode (in1, OUTPUT);
  pinMode (in2, OUTPUT);
  pinMode (A0, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  int inValue = analogRead(A0);
  inValue = map(inValue, 0, 1023, 0, 255);
  analogWrite(enA, inValue);
}