120 lines
3.7 KiB
Python
120 lines
3.7 KiB
Python
import time
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from platypush.plugins import action
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from platypush.plugins.gpio import GpioPlugin
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from platypush.plugins.gpio.sensor import GpioSensorPlugin
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class GpioSensorDistancePlugin(GpioPlugin, GpioSensorPlugin):
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"""
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You can use this plugin to interact with a distance sensor on your Raspberry
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Pi (tested with a HC-SR04 ultrasound sensor).
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Requires:
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* ``RPi.GPIO`` (``pip install RPi.GPIO``)
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"""
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def __init__(self, trigger_pin: int, echo_pin: int,
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timeout: float = 1.0, warmup_time: float = 2.0, *args, **kwargs):
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"""
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:param trigger_pin: GPIO PIN where you connected your sensor trigger PIN (the one that triggers the
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sensor to perform a measurement).
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:param echo_pin: GPIO PIN where you connected your sensor echo PIN (the one that will listen for the
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signal to bounce back and therefore trigger the distance calculation).
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:param timeout: The echo-wait will terminate and the plugin will return null if no echo has been
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received after this time (default: 1 second).
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:param warmup_time: Number of seconds that should be waited on plugin instantiation
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for the sensor to be ready (default: 2 seconds).
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"""
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GpioPlugin.__init__(self, *args, **kwargs)
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self.trigger_pin = trigger_pin
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self.echo_pin = echo_pin
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self.timeout = timeout
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self.warmup_time = warmup_time
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self._initialized = False
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self._init_gpio()
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def _init_gpio(self):
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if self._initialized:
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return
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import RPi.GPIO as gpio
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gpio.setmode(self.mode)
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gpio.setup(self.trigger_pin, gpio.OUT)
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gpio.setup(self.echo_pin, gpio.IN)
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gpio.output(self.trigger_pin, gpio.LOW)
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self.logger.info('Waiting {} seconds for the sensor to be ready'.format(self.warmup_time))
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time.sleep(self.warmup_time)
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self.logger.info('Sensor ready')
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self._initialized = True
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def _get_data(self):
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import RPi.GPIO as gpio
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pulse_start = pulse_end = pulse_on = pulse_off = time.time()
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self._init_gpio()
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gpio.output(self.trigger_pin, gpio.HIGH)
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time.sleep(0.00001) # 1 us pulse to trigger echo measurement
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gpio.output(self.trigger_pin, gpio.LOW)
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while gpio.input(self.echo_pin) == 0:
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pulse_on = time.time()
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if pulse_on - pulse_start > self.timeout:
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raise TimeoutError('Distance sensor echo timeout after {} seconds: 0'.
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format(self.timeout))
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pulse_start = pulse_on
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pulse_end = pulse_off = time.time()
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while gpio.input(self.echo_pin) == 1:
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pulse_off = time.time()
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if pulse_off - pulse_end > self.timeout:
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raise TimeoutError('Distance sensor echo timeout after {} seconds: 1'.
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format(self.timeout))
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pulse_end = pulse_off
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pulse_duration = pulse_end - pulse_start
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# s = vt where v = 1/2 * avg speed of sound in mm/s
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return round(pulse_duration * 171500.0, 2)
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@action
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def get_measurement(self):
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"""
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Extends :func:`.GpioSensorPlugin.get_measurement`
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:returns: Distance measurement as a scalar (in mm):
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"""
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try:
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return self._get_data()
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except TimeoutError as e:
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self.logger.warning(str(e))
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return
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except Exception as e:
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self.close()
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raise e
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@action
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def close(self):
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import RPi.GPIO as gpio
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if self._initialized:
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gpio.cleanup()
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self._initialized = False
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def __enter__(self):
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self._init_gpio()
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def __exit__(self):
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self.close()
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# vim:sw=4:ts=4:et:
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