const int sensorPin = 0;
const int ledPin = 9;
int lightLevel, high = 0, low = 1023;
void setup() {
pinMode(ledPin, OUTPUT);
Serial.begin(9600);
}
void loop() {
lightLevel = analogRead(sensorPin);
autoTune();
analogWrite(ledPin, lightLevel);
Serial.println(lightLevel);
}
void autoTune()
{
if(lightLevel<low)
{
 low=lightLevel;
}
if(lightLevel>high)
{
 high=lightLevel;
}
lightLevel=map(lightLevel, low+30, high-30, 0, 255);
lightLevel=constrain(lightLevel, 0, 255);
}