Lots of fixes

* Move `is_active` to `GPIODevice`; it's equally applicable to inputs
  and outputs so there's no point having it just in inputs
* Flip the pull-up status for `MotionSensor` (it was backwards leading
  to reversed readings from the sensor)
* Add a `threshold` to `MotionSensor` (optional), and `value` (similar
  to `LightSensor`)
* Also expose `pull_up` as a simple bool property
* Rejig `LightSensor` so it also derives from `InputDevice` (it inherits
  enough to make it worthwhile) and so that its API is similar to
  `MotionSensor` (a `value` property with a `*_detected` property, and a
  background threaded queue which constantly monitors values)

gpiozero/devices.py

@@ -12,11 +12,17 @@ class GPIODevice(object):
         if pin is None:
             raise GPIODeviceError('No GPIO pin number given')
         self._pin = pin
+        self._active_state = 1
+        self._inactive_state = 0
 
     @property
     def pin(self):
         return self._pin
 
+    @property
+    def is_active(self):
+        return GPIO.input(self.pin) == self._active_state
+
 
 _GPIO_THREADS = set()
 def _gpio_threads_shutdown():

gpiozero/input_devices.py

@@ -1,6 +1,6 @@
 from __future__ import division
 
-from time import sleep
+from time import sleep, time
 from threading import Event
 from collections import deque
 
@@ -15,17 +15,18 @@ class InputDeviceError(GPIODeviceError):
 
 
 class InputDevice(GPIODevice):
-    def __init__(self, pin=None):
+    def __init__(self, pin=None, pull_up=True):
         super(InputDevice, self).__init__(pin)
-        self._pull = GPIO.PUD_UP
-        self._edge = GPIO.FALLING
-        self._active_state = 0
-        self._inactive_state = 1
-        GPIO.setup(pin, GPIO.IN, self._pull)
+        self._pull_up = pull_up
+        self._edge = (GPIO.RISING, GPIO.FALLING)[pull_up]
+        if pull_up:
+            self._active_state = 0
+            self._inactive_state = 1
+        GPIO.setup(pin, GPIO.IN, (GPIO.PUD_DOWN, GPIO.PUD_UP)[pull_up])
 
     @property
-    def is_active(self):
-        return GPIO.input(self.pin) == self._active_state
+    def pull_up(self):
+        return self._pull_up
 
     def wait_for_input(self):
         GPIO.wait_for_edge(self.pin, self._edge)
@@ -44,9 +45,14 @@ class Button(InputDevice):
 
 
 class MotionSensor(InputDevice):
-    def __init__(self, pin=None, queue_len=20, sample_rate=10, partial=False):
-        super(MotionSensor, self).__init__(pin)
+    def __init__(
+            self, pin=None, queue_len=5, sample_rate=10, threshold=0.5,
+            partial=False):
+        super(MotionSensor, self).__init__(pin, pull_up=False)
+        if queue_len < 1:
+            raise InputDeviceError('queue_len must be at least one')
         self.sample_rate = sample_rate
+        self.threshold = threshold
         self.partial = partial
         self._queue = deque(maxlen=queue_len)
         self._queue_full = Event()
@@ -57,6 +63,36 @@ class MotionSensor(InputDevice):
     def queue_len(self):
         return self._queue.maxlen
 
+    @property
+    def value(self):
+        if not self.partial:
+            self._queue_full.wait()
+        try:
+            return sum(self._queue) / len(self._queue)
+        except ZeroDivisionError:
+            # No data == no motion
+            return 0.0
+
+    @property
+    def motion_detected(self):
+        return self.value > self.threshold
+
+    def _get_sample_rate(self):
+        return self._sample_rate
+    def _set_sample_rate(self, value):
+        if value <= 0:
+            raise InputDeviceError('sample_rate must be greater than zero')
+        self._sample_rate = value
+    sample_rate = property(_get_sample_rate, _set_sample_rate)
+
+    def _get_threshold(self):
+        return self._threshold
+    def _set_threshold(self, value):
+        if value < 0:
+            raise InputDeviceError('threshold must be zero or more')
+        self._threshold = value
+    threshold = property(_get_threshold, _set_threshold)
+
     def _fill_queue(self):
         while (
                 not self._queue_thread.stopping.wait(1 / self.sample_rate) and
@@ -67,53 +103,83 @@ class MotionSensor(InputDevice):
         while not self._queue_thread.stopping.wait(1 / self.sample_rate):
             self._queue.append(self.is_active)
 
-    @property
-    def motion_detected(self):
-        if not self.partial:
-            self._queue_full.wait()
-        return sum(self._queue) > (len(self._queue) / 2)
 
-
-class LightSensor(object):
-    def __init__(self, pin=None, darkness_level=0.01):
-        if pin is None:
-            raise InputDeviceError('No GPIO pin number given')
-
-        self._pin = pin
-        self.darkness_level = darkness_level
+class LightSensor(InputDevice):
+    def __init__(
+            self, pin=None, queue_len=5, darkness_time=0.01,
+            threshold=0.1, partial=False):
+        super(LightSensor, self).__init__(pin, pull_up=False)
+        if queue_len < 1:
+            raise InputDeviceError('queue_len must be at least one')
+        self.darkness_time = darkness_time
+        self.threshold = threshold
+        self.partial = partial
+        self._charged = Event()
+        GPIO.add_event_detect(self.pin, GPIO.RISING, lambda channel: self._charged.set())
+        self._queue = deque(maxlen=queue_len)
+        self._queue_full = Event()
+        self._queue_thread = GPIOThread(target=self._fill_queue)
+        self._queue_thread.start()
 
     @property
-    def pin(self):
-        return self._pin
+    def queue_len(self):
+        return self._queue.maxlen
 
     @property
     def value(self):
-        return self._get_average_light_level(5)
+        if not self.partial:
+            self._queue_full.wait()
+        try:
+            return 1.0 - (sum(self._queue) / len(self._queue)) / self.darkness_time
+        except ZeroDivisionError:
+            # No data == no light
+            return 0.0
 
-    def _get_light_level(self):
-        time_taken = self._time_charging_light_capacitor()
-        value = 100 * time_taken / self.darkness_level
-        return 100 - value
+    @property
+    def light_detected(self):
+        return self.value > self.threshold
 
-    def _time_charging_light_capacitor(self):
+    def _get_darkness_time(self):
+        return self._darkness_time
+    def _set_darkness_time(self, value):
+        if value <= 0.0:
+            raise InputDeviceError('darkness_time must be greater than zero')
+        self._darkness_time = value
+        # XXX Empty the queue and restart the thread
+    darkness_time = property(_get_darkness_time, _set_darkness_time)
+
+    def _get_threshold(self):
+        return self._threshold
+    def _set_threshold(self, value):
+        if value < 0:
+            raise InputDeviceError('threshold must be zero or more')
+        self._threshold = value
+    threshold = property(_get_threshold, _set_threshold)
+
+    def _fill_queue(self):
+        try:
+            while (
+                    not self._queue_thread.stopping.is_set() and
+                    len(self._queue) < self._queue.maxlen
+                ):
+                self._queue.append(self._time_charging())
+            self._queue_full.set()
+            while not self._queue_thread.stopping.is_set():
+                self._queue.append(self._time_charging())
+        finally:
+            GPIO.remove_event_detect(self.pin)
+
+    def _time_charging(self):
+        # Drain charge from the capacitor
         GPIO.setup(self.pin, GPIO.OUT)
         GPIO.output(self.pin, GPIO.LOW)
         sleep(0.1)
+        # Time the charging of the capacitor
+        start = time()
+        self._charged.clear()
         GPIO.setup(self.pin, GPIO.IN)
-        start_time = time()
-        end_time = time()
-        while (
-            GPIO.input(self.pin) == GPIO.LOW and
-            time() - start_time < self.darkness_level
-        ):
-            end_time = time()
-        time_taken = end_time - start_time
-        return min(time_taken, self.darkness_level)
-
-    def _get_average_light_level(self, num):
-        values = [self._get_light_level() for n in range(num)]
-        average_value = sum(values) / len(values)
-        return average_value
+        self._charged.wait(self.darkness_time)
+        return min(self.darkness_time, time() - start)
 
 
 class TemperatureSensor(W1ThermSensor):