Tweaks, docstrings

library/grow/moisture.py

@@ -1,5 +1,4 @@
 import time
-import atexit
 import RPi.GPIO as GPIO
 
 MOISTURE_1_PIN = 23
@@ -9,7 +8,20 @@ MOISTURE_INT_PIN = 4
 
 
 class Moisture(object):
-    def __init__(self, channel=0):
+    """Grow moisture sensor driver."""
+
+    def __init__(self, channel=0, wet_point=None, dry_point=None):
+        """Create a new moisture sensor.
+
+        Uses an interrupt to count pulses on the GPIO pin corresponding to the selected channel.
+
+        The moisture reading is given as pulses per second.
+
+        :param channel: One of 0, 1 or 2. 3 can optionally be used to set up a sensor on the Int pin (BCM4)
+        :param wet_point: Wet point in pulses/sec
+        :param dry_point: Dry point in pulses/sec
+
+        """
         self._gpio_pin = [MOISTURE_1_PIN, MOISTURE_2_PIN, MOISTURE_3_PIN, MOISTURE_INT_PIN][channel]
 
         GPIO.setwarnings(False)
@@ -18,40 +30,84 @@ class Moisture(object):
 
         self._count = 0
         self._reading = 0
-        self._wet_point = 0
+        self._wet_point = wet_point if wet_point is not None else 100
-        self._dry_point = 0
+        self._dry_point = dry_point if dry_point is not None else 900
         self._time_start = time.time()
         GPIO.add_event_detect(self._gpio_pin, GPIO.RISING, callback=self._event_handler, bouncetime=1)
 
-    def set_wet_point(self, value=None):
-        self._wet_point = value if value is not None else self.raw_moisture
-
-    def set_dry_point(self, value=None):
-        self._dry_point = value if value is not None else self.raw_moisture
-
     def _event_handler(self, pin):
         self._count += 1
-        if self.time_elapsed >= 1.0:
+        if self._time_elapsed >= 1.0:
-            self._reading = self._count / self.time_elapsed
+            self._reading = self._count / self._time_elapsed
             self._count = 0
             self._time_start = time.time()
+            self._new_data = True
 
     @property
-    def time_elapsed(self):
+    def _time_elapsed(self):
         return time.time() - self._time_start
 
-    @property
+    def set_wet_point(self, value=None):
-    def raw_moisture(self):
+        """Set the sensor wet point.
-        return self._reading
+
+        This is the watered, wet state of your soil.
+
+        It should be set shortly after watering. Leave ~5 mins for moisture to permeate.
+
+        :param value: Wet point value to set in pulses/sec, leave as None to set the last sensor reading.
+
+        """
+        self._wet_point = value if value is not None else self._reading
+
+    def set_dry_point(self, value=None):
+        """Set the sensor dry point.
+
+        This is the unwatered, dry state of your soil.
+
+        It should be set when the soil is dry to the touch.
+
+        :param value: Dry point value to set in pulses/sec, leave as None to set the last sensor reading.
+
+        """
+        self._dry_point = value if value is not None else self._reading
 
     @property
     def moisture(self):
-        return self.raw_moisture
+        """Return the raw moisture level.
+
+        The value returned is the pulses/sec read from the soil moisture sensor.
+
+        This value is inversely proportional to the amount of moisture.
+
+        Full immersion in water is approximately 50 pulses/sec.
+
+        Fully dry (in air) is approximately 900 pulses/sec.
+
+        """
+        self._new_data = False
+        return self._reading
+
+    @property
+    def new_data(self):
+        """Check for new reading.
+
+        Returns True if moisture value has been updated since last reading moisture or saturation.
+
+        """
+        return self._new_data
 
     @property
     def range(self):
+        """Return the range sensor range (wet - dry points)."""
         return self._wet_point - self._dry_point
 
     @property
     def saturation(self):
-        return float(self.moisture - self._dry_point) / self.range
+        """Return saturation as a float from 0.0 to 1.0.
+
+        This value is calculated using the wet and dry points.
+
+        """
+        saturation = float(self.moisture - self._dry_point) / self.range
+        saturation = round(saturation, 3)
+        return max(0.0, min(1.0, saturation))