Finger Tap Time

int sensorPin = 4;                // 220 or 1k resistor connected to this pin
long result = 0;
double start = 0;
double time = 0;
double duration = 3000;
int touch = 0;
double rate = 0;
void setup()                      // run once, when the sketch starts
{
Serial.begin(9600);
//Serial.println("start");
}
void loop()                       // run over and over again
{
//Serial.println( RCtime(sensorPin));
delay(10);

start = millis();
//Serial.print("start = ");
//Serial.println(start);
time = millis();
  while(time<(start+duration)){
//    Serial.println("while");
    if(RCtime(sensorPin)>2000){
      touch = touch + 1;
//      Serial.print("touch = ");
//      Serial.println(touch);
      time=millis();
//      Serial.print("time = ");
//      Serial.println(time);
    }
  }
  if(time>(start+duration)){
//    Serial.println("more than 3 sec");
    rate = touch/(duration/1000);
//    Serial.println(touch);
    Serial.print("You tapped at a rate of ");
    Serial.print(rate);
    Serial.println(" taps per second.");
    time=millis();
    start=millis();
    touch = 0;
  }
}

long RCtime(int sensPin){
long result = 0;
pinMode(sensPin, OUTPUT);         // make pin OUTPUT
digitalWrite(sensPin, HIGH);      // make pin HIGH to discharge capacitor - study the schematic
delay(10);                         // wait a ms to make sure cap is discharged

pinMode(sensPin, INPUT);          // turn pin into an input and time till pin goes low
digitalWrite(sensPin, LOW);       // turn pullups off - or it won't work
while(digitalRead(sensPin)){      // wait for pin to go low
result++;
}
return result;                    // report results
}


Circuit: