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ac8b5dbc3b7d179b9105965368cc1221ad91236c
python-gpiozero/gpiozero/input_devices.py
Dave Jones ce6217c14f Fix #459 - properly support remote SPI with pigpio 
Sorry! Dave's messing around with the pin implementations again.
Hopefully the last time. The pin_factory is now really a factory object
which can be asked to produce individual pins or pin-based interfaces
like SPI (which can be supported properly via pigpio).
2017-06-16 13:28:55 +01:00

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# vim: set fileencoding=utf-8:
from __future__ import (
unicode_literals,
print_function,
absolute_import,
division,
)
from time import sleep, time
from threading import Event
from .exc import InputDeviceError, DeviceClosed
from .devices import GPIODevice
from .mixins import GPIOQueue, EventsMixin, HoldMixin
class InputDevice(GPIODevice):
"""
Represents a generic GPIO input device.
This class extends :class:`GPIODevice` to add facilities common to GPIO
input devices. The constructor adds the optional *pull_up* parameter to
specify how the pin should be pulled by the internal resistors. The
:attr:`~GPIODevice.is_active` property is adjusted accordingly so that
``True`` still means active regardless of the :attr:`pull_up` setting.
:param int pin:
The GPIO pin (in Broadcom numbering) that the device is connected to.
If this is ``None`` a :exc:`GPIODeviceError` will be raised.
:param bool pull_up:
If ``True``, the pin will be pulled high with an internal resistor. If
``False`` (the default), the pin will be pulled low.
"""
def __init__(self, pin=None, pull_up=False):
super(InputDevice, self).__init__(pin)
try:
self.pin.function = 'input'
pull = 'up' if pull_up else 'down'
if self.pin.pull != pull:
self.pin.pull = pull
except:
self.close()
raise
self._active_state = False if pull_up else True
self._inactive_state = True if pull_up else False
@property
def pull_up(self):
"""
If ``True``, the device uses a pull-up resistor to set the GPIO pin
"high" by default.
"""
return self.pin.pull == 'up'
def __repr__(self):
try:
return "<gpiozero.%s object on pin %r, pull_up=%s, is_active=%s>" % (
self.__class__.__name__, self.pin, self.pull_up, self.is_active)
except:
return super(InputDevice, self).__repr__()
class DigitalInputDevice(EventsMixin, InputDevice):
"""
Represents a generic input device with typical on/off behaviour.
This class extends :class:`InputDevice` with machinery to fire the active
and inactive events for devices that operate in a typical digital manner:
straight forward on / off states with (reasonably) clean transitions
between the two.
:param float bounce_time:
Specifies the length of time (in seconds) that the component will
ignore changes in state after an initial change. This defaults to
``None`` which indicates that no bounce compensation will be performed.
"""
def __init__(self, pin=None, pull_up=False, bounce_time=None):
super(DigitalInputDevice, self).__init__(pin, pull_up)
try:
self.pin.bounce = bounce_time
self.pin.edges = 'both'
self.pin.when_changed = self._fire_events
# Call _fire_events once to set initial state of events
self._fire_events()
except:
self.close()
raise
class SmoothedInputDevice(EventsMixin, InputDevice):
"""
Represents a generic input device which takes its value from the mean of a
queue of historical values.
This class extends :class:`InputDevice` with a queue which is filled by a
background thread which continually polls the state of the underlying
device. The mean of the values in the queue is compared to a threshold
which is used to determine the state of the :attr:`is_active` property.
.. note::
The background queue is not automatically started upon construction.
This is to allow descendents to set up additional components before the
queue starts reading values. Effectively this is an abstract base
class.
This class is intended for use with devices which either exhibit analog
behaviour (such as the charging time of a capacitor with an LDR), or those
which exhibit "twitchy" behaviour (such as certain motion sensors).
:param float threshold:
The value above which the device will be considered "on".
:param int queue_len:
The length of the internal queue which is filled by the background
thread.
:param float sample_wait:
The length of time to wait between retrieving the state of the
underlying device. Defaults to 0.0 indicating that values are retrieved
as fast as possible.
:param bool partial:
If ``False`` (the default), attempts to read the state of the device
(from the :attr:`is_active` property) will block until the queue has
filled. If ``True``, a value will be returned immediately, but be
aware that this value is likely to fluctuate excessively.
"""
def __init__(
self, pin=None, pull_up=False, threshold=0.5,
queue_len=5, sample_wait=0.0, partial=False):
self._queue = None
super(SmoothedInputDevice, self).__init__(pin, pull_up)
try:
self._queue = GPIOQueue(self, queue_len, sample_wait, partial)
self.threshold = float(threshold)
except:
self.close()
raise
def close(self):
try:
self._queue.stop()
except AttributeError:
# If the queue isn't initialized (it's None) ignore the error
# because we're trying to close anyway
if self._queue is not None:
raise
except RuntimeError:
# Cannot join thread before it starts; we don't care about this
# because we're trying to close the thread anyway
pass
else:
self._queue = None
super(SmoothedInputDevice, self).close()
def __repr__(self):
try:
self._check_open()
except DeviceClosed:
return super(SmoothedInputDevice, self).__repr__()
else:
if self.partial or self._queue.full.is_set():
return super(SmoothedInputDevice, self).__repr__()
else:
return "<gpiozero.%s object on pin %r, pull_up=%s>" % (
self.__class__.__name__, self.pin, self.pull_up)
@property
def queue_len(self):
"""
The length of the internal queue of values which is averaged to
determine the overall state of the device. This defaults to 5.
"""
self._check_open()
return self._queue.queue.maxlen
@property
def partial(self):
"""
If ``False`` (the default), attempts to read the :attr:`value` or
:attr:`is_active` properties will block until the queue has filled.
"""
self._check_open()
return self._queue.partial
@property
def value(self):
"""
Returns the mean of the values in the internal queue. This is compared
to :attr:`threshold` to determine whether :attr:`is_active` is
``True``.
"""
self._check_open()
return self._queue.value
@property
def threshold(self):
"""
If :attr:`value` exceeds this amount, then :attr:`is_active` will
return ``True``.
"""
return self._threshold
@threshold.setter
def threshold(self, value):
if not (0.0 < value < 1.0):
raise InputDeviceError(
'threshold must be between zero and one exclusive'
)
self._threshold = float(value)
@property
def is_active(self):
"""
Returns ``True`` if the device is currently active and ``False``
otherwise.
"""
return self.value > self.threshold
class Button(HoldMixin, DigitalInputDevice):
"""
Extends :class:`DigitalInputDevice` and represents a simple push button
or switch.
Connect one side of the button to a ground pin, and the other to any GPIO
pin. Alternatively, connect one side of the button to the 3V3 pin, and the
other to any GPIO pin, then set *pull_up* to ``False`` in the
:class:`Button` constructor.
The following example will print a line of text when the button is pushed::
from gpiozero import Button
button = Button(4)
button.wait_for_press()
print("The button was pressed!")
:param int pin:
The GPIO pin which the button is attached to. See :ref:`pin-numbering`
for valid pin numbers.
:param bool pull_up:
If ``True`` (the default), the GPIO pin will be pulled high by default.
In this case, connect the other side of the button to ground. If
``False``, the GPIO pin will be pulled low by default. In this case,
connect the other side of the button to 3V3.
:param float bounce_time:
If ``None`` (the default), no software bounce compensation will be
performed. Otherwise, this is the length of time (in seconds) that the
component will ignore changes in state after an initial change.
:param float hold_time:
The length of time (in seconds) to wait after the button is pushed,
until executing the :attr:`when_held` handler. Defaults to ``1``.
:param bool hold_repeat:
If ``True``, the :attr:`when_held` handler will be repeatedly executed
as long as the device remains active, every *hold_time* seconds. If
``False`` (the default) the :attr:`when_held` handler will be only be
executed once per hold.
"""
def __init__(
self, pin=None, pull_up=True, bounce_time=None,
hold_time=1, hold_repeat=False):
super(Button, self).__init__(pin, pull_up, bounce_time)
self.hold_time = hold_time
self.hold_repeat = hold_repeat
Button.is_pressed = Button.is_active
Button.pressed_time = Button.active_time
Button.when_pressed = Button.when_activated
Button.when_released = Button.when_deactivated
Button.wait_for_press = Button.wait_for_active
Button.wait_for_release = Button.wait_for_inactive
class LineSensor(SmoothedInputDevice):
"""
Extends :class:`SmoothedInputDevice` and represents a single pin line sensor
like the TCRT5000 infra-red proximity sensor found in the `CamJam #3
EduKit`_.
A typical line sensor has a small circuit board with three pins: VCC, GND,
and OUT. VCC should be connected to a 3V3 pin, GND to one of the ground
pins, and finally OUT to the GPIO specified as the value of the *pin*
parameter in the constructor.
The following code will print a line of text indicating when the sensor
detects a line, or stops detecting a line::
from gpiozero import LineSensor
from signal import pause
sensor = LineSensor(4)
sensor.when_line = lambda: print('Line detected')
sensor.when_no_line = lambda: print('No line detected')
pause()
:param int pin:
The GPIO pin which the sensor is attached to. See :ref:`pin-numbering`
for valid pin numbers.
:param int queue_len:
The length of the queue used to store values read from the sensor. This
defaults to 5.
:param float sample_rate:
The number of values to read from the device (and append to the
internal queue) per second. Defaults to 100.
:param float threshold:
Defaults to 0.5. When the mean of all values in the internal queue
rises above this value, the sensor will be considered "active" by the
:attr:`~SmoothedInputDevice.is_active` property, and all appropriate
events will be fired.
:param bool partial:
When ``False`` (the default), the object will not return a value for
:attr:`~SmoothedInputDevice.is_active` until the internal queue has
filled with values. Only set this to ``True`` if you require values
immediately after object construction.
.. _CamJam #3 EduKit: http://camjam.me/?page_id=1035
"""
def __init__(
self, pin=None, queue_len=5, sample_rate=100, threshold=0.5,
partial=False):
super(LineSensor, self).__init__(
pin, pull_up=False, threshold=threshold,
queue_len=queue_len, sample_wait=1 / sample_rate, partial=partial
)
try:
self._queue.start()
except:
self.close()
raise
@property
def line_detected(self):
return not self.is_active
LineSensor.when_line = LineSensor.when_deactivated
LineSensor.when_no_line = LineSensor.when_activated
LineSensor.wait_for_line = LineSensor.wait_for_inactive
LineSensor.wait_for_no_line = LineSensor.wait_for_active
class MotionSensor(SmoothedInputDevice):
"""
Extends :class:`SmoothedInputDevice` and represents a passive infra-red
(PIR) motion sensor like the sort found in the `CamJam #2 EduKit`_.
.. _CamJam #2 EduKit: http://camjam.me/?page_id=623
A typical PIR device has a small circuit board with three pins: VCC, OUT,
and GND. VCC should be connected to a 5V pin, GND to one of the ground
pins, and finally OUT to the GPIO specified as the value of the *pin*
parameter in the constructor.
The following code will print a line of text when motion is detected::
from gpiozero import MotionSensor
pir = MotionSensor(4)
pir.wait_for_motion()
print("Motion detected!")
:param int pin:
The GPIO pin which the sensor is attached to. See :ref:`pin-numbering`
for valid pin numbers.
:param int queue_len:
The length of the queue used to store values read from the sensor. This
defaults to 1 which effectively disables the queue. If your motion
sensor is particularly "twitchy" you may wish to increase this value.
:param float sample_rate:
The number of values to read from the device (and append to the
internal queue) per second. Defaults to 100.
:param float threshold:
Defaults to 0.5. When the mean of all values in the internal queue
rises above this value, the sensor will be considered "active" by the
:attr:`~SmoothedInputDevice.is_active` property, and all appropriate
events will be fired.
:param bool partial:
When ``False`` (the default), the object will not return a value for
:attr:`~SmoothedInputDevice.is_active` until the internal queue has
filled with values. Only set this to ``True`` if you require values
immediately after object construction.
"""
def __init__(
self, pin=None, queue_len=1, sample_rate=10, threshold=0.5,
partial=False):
super(MotionSensor, self).__init__(
pin, pull_up=False, threshold=threshold,
queue_len=queue_len, sample_wait=1 / sample_rate, partial=partial
)
try:
self._queue.start()
except:
self.close()
raise
MotionSensor.motion_detected = MotionSensor.is_active
MotionSensor.when_motion = MotionSensor.when_activated
MotionSensor.when_no_motion = MotionSensor.when_deactivated
MotionSensor.wait_for_motion = MotionSensor.wait_for_active
MotionSensor.wait_for_no_motion = MotionSensor.wait_for_inactive
class LightSensor(SmoothedInputDevice):
"""
Extends :class:`SmoothedInputDevice` and represents a light dependent
resistor (LDR).
Connect one leg of the LDR to the 3V3 pin; connect one leg of a 1µF
capacitor to a ground pin; connect the other leg of the LDR and the other
leg of the capacitor to the same GPIO pin. This class repeatedly discharges
the capacitor, then times the duration it takes to charge (which will vary
according to the light falling on the LDR).
The following code will print a line of text when light is detected::
from gpiozero import LightSensor
ldr = LightSensor(18)
ldr.wait_for_light()
print("Light detected!")
:param int pin:
The GPIO pin which the sensor is attached to. See :ref:`pin-numbering`
for valid pin numbers.
:param int queue_len:
The length of the queue used to store values read from the circuit.
This defaults to 5.
:param float charge_time_limit:
If the capacitor in the circuit takes longer than this length of time
to charge, it is assumed to be dark. The default (0.01 seconds) is
appropriate for a 1µF capacitor coupled with the LDR from the
`CamJam #2 EduKit`_. You may need to adjust this value for different
valued capacitors or LDRs.
:param float threshold:
Defaults to 0.1. When the mean of all values in the internal queue
rises above this value, the area will be considered "light", and all
appropriate events will be fired.
:param bool partial:
When ``False`` (the default), the object will not return a value for
:attr:`~SmoothedInputDevice.is_active` until the internal queue has
filled with values. Only set this to ``True`` if you require values
immediately after object construction.
.. _CamJam #2 EduKit: http://camjam.me/?page_id=623
"""
def __init__(
self, pin=None, queue_len=5, charge_time_limit=0.01,
threshold=0.1, partial=False):
super(LightSensor, self).__init__(
pin, pull_up=False, threshold=threshold,
queue_len=queue_len, sample_wait=0.0, partial=partial
)
try:
self._charge_time_limit = charge_time_limit
self._charged = Event()
self.pin.edges = 'rising'
self.pin.bounce = None
self.pin.when_changed = self._charged.set
self._queue.start()
except:
self.close()
raise
@property
def charge_time_limit(self):
return self._charge_time_limit
def _read(self):
# Drain charge from the capacitor
self.pin.function = 'output'
self.pin.state = False
sleep(0.1)
# Time the charging of the capacitor
start = time()
self._charged.clear()
self.pin.function = 'input'
self._charged.wait(self.charge_time_limit)
return (
1.0 - min(self.charge_time_limit, time() - start) /
self.charge_time_limit
)
LightSensor.light_detected = LightSensor.is_active
LightSensor.when_light = LightSensor.when_activated
LightSensor.when_dark = LightSensor.when_deactivated
LightSensor.wait_for_light = LightSensor.wait_for_active
LightSensor.wait_for_dark = LightSensor.wait_for_inactive
class DistanceSensor(SmoothedInputDevice):
"""
Extends :class:`SmoothedInputDevice` and represents an HC-SR04 ultrasonic
distance sensor, as found in the `CamJam #3 EduKit`_.
The distance sensor requires two GPIO pins: one for the *trigger* (marked
TRIG on the sensor) and another for the *echo* (marked ECHO on the sensor).
However, a voltage divider is required to ensure the 5V from the ECHO pin
doesn't damage the Pi. Wire your sensor according to the following
instructions:
1. Connect the GND pin of the sensor to a ground pin on the Pi.
2. Connect the TRIG pin of the sensor a GPIO pin.
3. Connect a 330Ω resistor from the ECHO pin of the sensor to a different
GPIO pin.
4. Connect a 470Ω resistor from ground to the ECHO GPIO pin. This forms
the required voltage divider.
5. Finally, connect the VCC pin of the sensor to a 5V pin on the Pi.
The following code will periodically report the distance measured by the
sensor in cm assuming the TRIG pin is connected to GPIO17, and the ECHO
pin to GPIO18::
from gpiozero import DistanceSensor
from time import sleep
sensor = DistanceSensor(echo=18, trigger=17)
while True:
print('Distance: ', sensor.distance * 100)
sleep(1)
:param int echo:
The GPIO pin which the ECHO pin is attached to. See
:ref:`pin-numbering` for valid pin numbers.
:param int trigger:
The GPIO pin which the TRIG pin is attached to. See
:ref:`pin-numbering` for valid pin numbers.
:param int queue_len:
The length of the queue used to store values read from the sensor.
This defaults to 30.
:param float max_distance:
The :attr:`value` attribute reports a normalized value between 0 (too
close to measure) and 1 (maximum distance). This parameter specifies
the maximum distance expected in meters. This defaults to 1.
:param float threshold_distance:
Defaults to 0.3. This is the distance (in meters) that will trigger the
``in_range`` and ``out_of_range`` events when crossed.
:param bool partial:
When ``False`` (the default), the object will not return a value for
:attr:`~SmoothedInputDevice.is_active` until the internal queue has
filled with values. Only set this to ``True`` if you require values
immediately after object construction.
.. _CamJam #3 EduKit: http://camjam.me/?page_id=1035
"""
def __init__(
self, echo=None, trigger=None, queue_len=30, max_distance=1,
threshold_distance=0.3, partial=False):
if max_distance <= 0:
raise ValueError('invalid maximum distance (must be positive)')
self._trigger = None
super(DistanceSensor, self).__init__(
echo, pull_up=False, threshold=threshold_distance / max_distance,
queue_len=queue_len, sample_wait=0.0, partial=partial
)
try:
self.speed_of_sound = 343.26 # m/s
self._max_distance = max_distance
self._trigger = GPIODevice(trigger)
self._echo = Event()
self._echo_rise = None
self._echo_fall = None
self._trigger.pin.function = 'output'
self._trigger.pin.state = False
self.pin.edges = 'both'
self.pin.bounce = None
def callback():
if self._echo_rise is None:
self._echo_rise = time()
else:
self._echo_fall = time()
self._echo.set()
self.pin.when_changed = callback
self._queue.start()
except:
self.close()
raise
def close(self):
try:
self._trigger.close()
except AttributeError:
if self._trigger is not None:
raise
else:
self._trigger = None
super(DistanceSensor, self).close()
@property
def max_distance(self):
"""
The maximum distance that the sensor will measure in meters. This value
is specified in the constructor and is used to provide the scaling
for the :attr:`value` attribute. When :attr:`distance` is equal to
:attr:`max_distance`, :attr:`value` will be 1.
"""
return self._max_distance
@max_distance.setter
def max_distance(self, value):
if value <= 0:
raise ValueError('invalid maximum distance (must be positive)')
t = self.threshold_distance
self._max_distance = value
self.threshold_distance = t
@property
def threshold_distance(self):
"""
The distance, measured in meters, that will trigger the
:attr:`when_in_range` and :attr:`when_out_of_range` events when
crossed. This is simply a meter-scaled variant of the usual
:attr:`threshold` attribute.
"""
return self.threshold * self.max_distance
@threshold_distance.setter
def threshold_distance(self, value):
self.threshold = value / self.max_distance
@property
def distance(self):
"""
Returns the current distance measured by the sensor in meters. Note
that this property will have a value between 0 and
:attr:`max_distance`.
"""
return self.value * self._max_distance
@property
def trigger(self):
"""
Returns the :class:`Pin` that the sensor's trigger is connected to.
"""
return self._trigger.pin
@property
def echo(self):
"""
Returns the :class:`Pin` that the sensor's echo is connected to. This
is simply an alias for the usual :attr:`pin` attribute.
"""
return self.pin
def _read(self):
# Make sure the echo pin is low then ensure the echo event is clear
while self.pin.state:
sleep(0.00001)
self._echo.clear()
# Fire the trigger
self._trigger.pin.state = True
sleep(0.00001)
self._trigger.pin.state = False
# Wait up to 1 second for the echo pin to rise
if self._echo.wait(1):
self._echo.clear()
# Wait up to 40ms for the echo pin to fall (35ms is maximum pulse
# time so any longer means something's gone wrong). Calculate
# distance as time for echo multiplied by speed of sound divided by
# two to compensate for travel to and from the reflector
if self._echo.wait(0.04) and self._echo_fall is not None and self._echo_rise is not None:
distance = (self._echo_fall - self._echo_rise) * self.speed_of_sound / 2.0
self._echo_fall = None
self._echo_rise = None
return min(1.0, distance / self._max_distance)
else:
# If we only saw one edge it means we missed the echo because
# it was too fast; report minimum distance
return 0.0
else:
# The echo pin never rose or fell; something's gone horribly
# wrong (XXX raise a warning?)
return 1.0
@property
def in_range(self):
return not self.is_active
DistanceSensor.when_out_of_range = DistanceSensor.when_activated
DistanceSensor.when_in_range = DistanceSensor.when_deactivated
DistanceSensor.wait_for_out_of_range = DistanceSensor.wait_for_active
DistanceSensor.wait_for_in_range = DistanceSensor.wait_for_inactive
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