//Ultrasonic distance measurement Sub function
int Distance_test() {
    digitalWrite(Trig, LOW);
    delayMicroseconds(2);
    digitalWrite(Trig, HIGH);
    delayMicroseconds(20);
    digitalWrite(Trig, LOW);

    float Fdistance = pulseIn(Echo, HIGH);
    Fdistance = Fdistance / 58;
    
    return (int)Fdistance;
}