Piezo Knock - Some values are not recognized

Other Hardware Sensors
1

Hi all,
I am using a piezo to detect hits(knocks) as in

I tried different modifications of the arduino code, right now I use:

// these constants won't change:
const int ledPin = 13; // led connected to digital pin 13
const int knockSensor = A0; // the piezo is connected to analog pin 0
const int threshold = 10; // threshold value to decide when the detected sound is a knock or not

// 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

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);
Serial.println(sensorReading);
delay(10); // delay to avoid overloading the serial port buffer
}

And I use a max patch to read the values with a [serial a 9600] object which is banged every ms.

Still sometimes some knocks are not recognized even though I touch the piezo as hard as before (when it was recognized).
It's not a matter of being below a threshold - it's a matter of not getting a value different from 0.

Are there any ways to make this more reliable?

Thanks a lot,
Frank

2

It's not reliable now, because microprocessor spend a lot of time on printing and delay instead of checking sensor more often.
Wrap this two line in a if statement:
Serial.println(sensorReading);
delay(10); // delay to avoid overloading the serial port buffer
so they work only when you touch sensor.

// 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 touch = 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);   

if (sensorReading >  100){

  Serial.println(sensorReading); 
  delay(10);  // delay to avoid overloading the serial port buffer
}
}

You can adjust sensitivity to different value (default 100).

3

good idea!
Thanks a lot
Frank