pxt-ev3/docs/coding/reverse-beeper-2.md

Reverse Beeper Activity 2

forever(function () {
    if (motors.largeB.speed() != 0 && sensors.ultrasonic4.distance() < 20) {
        music.playTone(440, sensors.ultrasonic4.distance());
        pause(50)
    }
})
motors.largeBC.setSpeed(-20);
sensors.ultrasonic4.pauseUntil(UltrasonicSensorEvent.ObjectNear);
motors.largeBC.stop();