threshold_button.py

#!/usr/bin/env python3

'''
Trigger a print message when sensor value meets test condition

To Run: python3 trigger.py --pin 13 --chn 0
'''

from gpiozero import MCP3008
from gpiozero import Button
from time import sleep
import argparse


if __name__ == '__main__':
    try:
        parser = argparse.ArgumentParser()
        parser.add_argument("--pin", type=int, default=16,
            help="The GPIO pin the button is on")
        parser.add_argument("--chn", type=int, default=0,
            help="The MCP3008 chn the sensor is on")
        args = parser.parse_args()

        sensor = MCP3008(channel=args.chn) # make the sensor object
        button = Button(args.pin)

        print("ready!")

        while True:
            sense_val = sensor.value
            if button.value == True and button.value != prev_val:
                print("button is pressed")
            elif button.value == False:
                if sense_val < 0.3:
                    print("light is low!")
            prev_val = button.value
            sleep(0.05)
    except KeyboardInterrupt:
        print("interrupted!")
        sensor.close()
        button.close()