Piezo Histogram Demo

// borrowed code, fidgeted around

const int ledPin = 7;      // led connected to digital pin 7
const int knockSensor = 1 ; //A0; // the piezo is connected to analog pin 0
const int threshold = 5000;  // threshold value to decide when the detected sound is a knock or not

const int smoothKick = 100 ;

// these variables will change:
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

int smooth = 0 ;

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

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

    smooth = smooth - smooth/2 ;

  //if (sensorReading>10)
  {
    smooth += sensorReading ;
  }

  // if the sensor reading is greater than the threshold:
  //if (sensorReading >= threshold)
  {
    // toggle the status of the ledPin:
    //ledState = !ledState;
    // update the LED pin itself:
    bool on = smooth>smoothKick ;

    digitalWrite(ledPin, on ? HIGH : LOW );

    // send the string "Knock!" back to the computer, followed by newline
    //Serial.println("Knock" );
    //Serial.println(sensorReading);
    //Serial.println(smooth);

    if (smooth>100)
    {
      for( int i=0; i<smooth/10; ++i )
      {
        Serial.print("*");
      }
      Serial.println( on ? "+" : ".");
    }
  }
  //delay(100);  // delay to avoid overloading the serial port buffer
}