AdaptedKnockSensor

const int ledPin = 5;      // led connected to digital pin 5
const int knockSensor = A0; // the piezo is connected to analog pin 0
const int threshold = 20;  // threshold value to decide when the detected sound is a knock or not

int sensorReading = 0;      // variable to store the value read from the sensor pin
int ledState = LOW;         // variable used to store the last LED status, to toggle the light
unsigned long lastPeakTime = 0; //used for calculating peak
int currentPeak = 0;
int blinkCounter = 0;

void setup() {
 pinMode(ledPin, OUTPUT); // declare the ledPin as as OUTPUT
 Serial.begin(9600);       // use the serial port for debugging
}

void loop() {
  // read the sensor and store it in the variable sensorReading:
  sensorReading = analogRead(knockSensor);
  if (sensorReading > currentPeak) {
    currentPeak = sensorReading;
  }

  // if the sensor reading is greater than the threshold:
if (sensorReading >= threshold) {
    Serial.print(sensorReading);
        Serial.println(" Knock! ");

        while(blinkCounter <= 3)
            {
            Serial.println(blinkCounter);
            digitalWrite(ledPin, HIGH);
            delay(250);
            digitalWrite(ledPin, LOW);
            delay(250);
            blinkCounter++;
            }
        blinkCounter = 0;
        delay(50);
  }
    //DEBUG CODE THAT GETS WRITTEN TO SERIAL, NOT NECESSARY TO LEAVE IN
    if(millis() - lastPeakTime > 2000) {
        Serial.print("Peak value: ");
        Serial.println(currentPeak);
        lastPeakTime = millis();
        currentPeak = 0;
    }


}