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This example is for Wiring version 1.0 build 0100+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.

Sensor calibration
Get the maximum and minimum value from a sensor to help finding its operation range at current conditions. Any analog sensor, (photoresistor or potentiometer) connected to analog pin 0 will be fine.

    int sensorValue = 0;   // The sensor value
    int sensorMin = 1023;  // Minimum sensor value
    int sensorMax = 0;     // Maximum sensor value

    void setup()
    {
      Serial.begin(9600);  // Open the serial at 9600
      Serial.println("Starting calibration for 10 seconds");
      // calibrate during the first five seconds
      while (millis() < 10000)
      {
        sensorValue = analogRead(0);    // read sensor connected to analog pin 0

        if (sensorValue > sensorMax)    // save the maximum sensor value found
        {
          sensorMax = sensorValue;
        }

        if (sensorValue < sensorMin)    // save the minimum sensor value found
        {
          sensorMin = sensorValue;
        }
      }
      Serial.println("Finished calibration");
    }

    void loop()
    {
      // read sensor connected to analog pin 0
      sensorValue = analogRead(0);

      // use the calibration to print values between 0 and 100
      sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 100);

      // keep the value in the desired range
      sensorValue = constrain(sensorValue, 0, 100);

      // fade the LED using the calibrated value:
      Serial.println(sensorValue, DEC);
    }