void setup(){
  pinMode(A0, INPUT);
  pinMode(3, OUTPUT);
  Serial.begin(9600);



}
void loop(){
  
  int a = analogRead(A0);

  int data = map(a, 0, 1023, 0, 255);

  Serial.print("value analog = ");
  Serial.println(a);
  Serial.print("value PWM = ");
  Serial.println(data);
  delay(250);
  analogWrite(3, data);

}