/****************************************
    Example Sound Level Sketch for the
    Adafruit Microphone Amplifier
    ****************************************/

    const int sampleWindow = 50; // Sample window width in mS (50 mS = 20Hz)
    unsigned int sample;

    void setup()
    {
    Serial.begin(9600);
    }

     boolean coin = true;
     float maxValue = 0.00;
    void loop()
    {

    unsigned long startMillis= millis(); // Start of sample window
    unsigned int peakToPeak = 0; // peak-to-peak level

    unsigned int signalMax = 0;
    unsigned int signalMin = 1024;

    // collect data for 50 mS
    while (millis() - startMillis < sampleWindow)
    {
    sample = analogRead(0);
    if (sample < 1024) // toss out spurious readings
    {
    if (sample > signalMax)
    {
    signalMax = sample; // save just the max levels
    }
    else if (sample < signalMin)
    {
    signalMin = sample; // save just the min levels
    }
    }
    }
    peakToPeak = signalMax - signalMin; // max - min = peak-peak amplitude
    double volts = (peakToPeak * 5.0) / 1024; // convert to volts
     if(volts > maxValue) {
      maxValue = volts;
     }
    if(coin == true) {
      Serial.println(volts);
    }
    if(volts > 0.60) {
      coin = false;
    }

    }