class3_sensorAutoCalibrate

/*
Analog input from photocell to determine LED brightness
 Auto theshold calibration
 Matt Richard
 http://idblab.blogspot.com
 */

int sensorPin = A0; // select the input pin for the potentiometer
int ledPin = 3; // select the pin for the LED
int sensorValue = 0; // variable to store the value coming from the sensor
int minThresh = 1023;// replace this number with a lowest number from the serial monitor
int maxThresh = 0;// replace this number with a highest number from the serial monitor

void setup() {
  Serial.begin(9600);
  // use the LED attached to pin 13 as a signal when we are autocalibrating
  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);

  // begin auto calibration
  for( int i = 0; i < 1000; i++){
    // grab the sensor value
    sensorValue = analogRead(sensorPin);

    // check to see if the sensor value is lower than the minimum threshold
    if( sensorValue < minThresh){
      // if it is, set the minimum threshold to the current sensorValue
      minThresh = sensorValue;
    }
    // check to see if the sensor value is higher than the maximum threshold
    if( sensorValue > maxThresh){
      // if it is, set the maximum threshold to the current sensorValue
      maxThresh = sensorValue;
    }
    delay(5);
  }

  digitalWrite(13, LOW);
}

void loop() {
  // read the value from the sensor
  sensorValue = analogRead(sensorPin);
  // print the value from the sensor
  Serial.println(sensorValue);
  // constrain the sensor value so that it does not exceed the thresholds
  sensorValue = constrain(sensorValue, minThresh, maxThresh);
  // map the sensor value to the PWM range
  pwmValue = map(sensorValue, minThresh, maxThresh, 0, 255);
  // power the LED using the pwmValue
  analogWrite(ledPin, pwmValue);
}