68 lines
2.0 KiB
Python
68 lines
2.0 KiB
Python
'''
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IR and magnetic sensors
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'''
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import RPi.GPIO as GPIO
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import logging, time
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from functools import partial
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from threading import Timer
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logger = logging.getLogger(__name__)
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# this importantly controls which sensor events get logged. DEBUG logs
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# everything, INFO logs only events that occur when state machine in
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# "sensitive states" (armed, trippedCountdown, tripped)
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logger.setLevel(logging.INFO)
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# delay GPIO init to avoid false positive during powerup
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INIT_DELAY = 60
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def _lowPassFilter(pin, targetVal, period=0.001):
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'''
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Crude implementation of an LPF for a binary signal. This exists to filter
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out voltage spikes that are induced by mains current fuctuations.
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Basically uses a timed loop to determine if a pin is changing within a
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given period. If a change occurs within period, this is considered 'high
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frequency' and the function returns False. If not, the pin is evaluated with
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a target value, which returns a boolean result that can be used elsewhere
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'''
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divisions = 10
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sleepTime = period/divisions
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for i in range(0, divisions):
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time.sleep(sleepTime)
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if GPIO.input(pin) != targetVal:
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return False
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return GPIO.input(pin) == targetVal
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def _initGPIO(name, pin, GPIOEvent, callback):
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logger.debug('starting \"%s\" on pin %s', name, pin)
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GPIO.setup(pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
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GPIO.add_event_detect(pin, GPIOEvent, callback=callback, bouncetime=500)
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def startMotionSensor(pin, location, action):
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name = 'MotionSensor@' + location
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def trip(channel):
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if _lowPassFilter(pin, 1):
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action(location, logger)
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logger.debug('waiting %s for %s to power on', INIT_DELAY, name)
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t = Timer(INIT_DELAY, partial(_initGPIO, name, pin, GPIO.RISING, trip))
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t.daemon = True
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t.start()
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def startDoorSensor(pin, action):
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def trip(channel):
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nonlocal closed
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val = GPIO.input(pin)
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if val != closed:
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if _lowPassFilter(pin, val):
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closed = val
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action(closed, logger)
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_initGPIO('DoorSensor', pin, GPIO.BOTH, trip)
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closed = GPIO.input(pin)
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