buzzer.py 文件源码

def note(frequency, duration=1.0):
    """Play a single note.

    :param frequency: Musical frequency in hertz
    :param duration: Optional duration in seconds, use None to sustain note

    """

    global _timeout

    if frequency <= 0:
        raise ValueError("Frequency must be > 0")

    if duration is not None and duration <= 0:
        raise ValueError("Duration must be > 0")

    clear_timeout()

    pwm.ChangeFrequency(frequency)
    GPIO.setup(BUZZER, GPIO.OUT)    

    if duration is not None and duration > 0:
        _timeout = Timer(duration, stop)
        _timeout.start()