Arduino Low Pass Filter

  int pin = 9;
  int value;
 
  float xn1= 0;
  float yn1 = 0;
  int k = 0;



void setup (){
 
    Serial.begin(9600); 
    pinMode(pin, INPUT); 

}

void loop (){

  
    value = pulseIn(pin, HIGH);  //read pwm output from remote control receiver

    float t = micros () / 1.0e6; 
    float xn = value; 

    float yn = 0.969*yn1 + 0.0155*xn + 0.0155*xn1;  //compute filtered signal

    delay(1);
    xn1  = xn;
    yn1 = yn;

if (k % 3 == 0) {
    Serial.print(xn);
    Serial.print(",");
    Serial.println(yn);
}

k = k+1;

}