bono

void loop()
{

    digitalWrite(Trig, LOW);
    delay(5);
    digitalWrite(Trig, HIGH);
    delay(10);
    digitalWrite(Trig, LOW);
    dauer = pulseIn(Echo, HIGH);
    entfernung = (dauer/2) * 0.03432;

    if (entfernung >= 1000 || entfernung <= 0)
    {
        Serial.println("Kein Messwert");
    }
    else
    {
        Serial.print(entfernung);
        Serial.println(" cm");
    }

    getstr = Serial.read();

    switch(getstr)
    {
        case 'a':
            stateChange();
            break;

        case 'f':
            if (entfernung >= 80)
            {
                forward();
            }
            else
            {
                stop();
            }
            break;

        case 'b':
            back();
            break;

        case 'l':
            left();
            break;

        case 'r':
            right();
            break;

        case 's':
            stop();
            break;

        default:
            break;
    }

    delay(100);
}