gpio.py 文件源码

def __init__(self, channel, polarity=GPIO.FALLING,
                 pull_up_down=GPIO.PUD_UP):
        super().__init__()

        self.channel = channel
        self.polarity = polarity

        if polarity not in [GPIO.FALLING, GPIO.RISING]:
            raise ValueError('polarity must be GPIO.FALLING or GPIO.RISING')

        self.expected_value = polarity == GPIO.RISING
        self.event_detect_added = False

        GPIO.setmode(GPIO.BCM)
        GPIO.setup(channel, GPIO.IN, pull_up_down=pull_up_down)