/*www.theorycircuit.com*/
#include <DistanceGP2Y0A21YK.h>
int ledGreen = 9;
int ledRed = 10;
int proximity = 0;

void setup(){

Serial.begin(9600);

}

void loop () {
  int value = analogRead(proximity);
  Serial.println(value);
  int redValue = map(value,0,1023,0,255);
  int greenValue = map(value,0,1023,255,0);
  analogWrite(ledRed,redValue);
  analogWrite(ledGreen,greenValue);

delay(100);
}




https://github.com/jeroendoggen/Arduino-GP2Y0A21YK-library