updating SI Units

adafruit_mpl3115a2.py

@@ -197,7 +197,7 @@ def _poll_reg1(self, mask):
 
     @property
     def pressure(self):
-        """Read the barometric pressure detected by the sensor in Pascals."""
+        """Read the barometric pressure detected by the sensor in Hectopascals."""
         # First poll for a measurement to be finished.
         self._poll_reg1(_MPL3115A2_CTRL_REG1_OST)
         # Set control bits for pressure reading.
@@ -254,7 +254,7 @@ def altitude(self):
 
     @property
     def temperature(self):
-        """Read the temperature as measured by the sensor in degrees Celsius."""
+        """Read the temperature as measured by the sensor in Celsius."""
         # First poll for a measurement to be finished.
         self._poll_reg1(_MPL3115A2_CTRL_REG1_OST)
         # Initatiate a one-shot measurement
@@ -278,16 +278,16 @@ def temperature(self):
     def sealevel_pressure(self):
         """Read and write the pressure at sea-level used to calculate altitude.
         You must look this up from a local weather or meteorological report for
-        the best accuracy.  This is a value in Pascals.
+        the best accuracy.  This is a value in Hectopascals.
         """
         # Read the sea level pressure in bars.
         self._read_into(_MPL3115A2_BAR_IN_MSB, self._BUFFER, count=2)
-        # Reconstruct 16-bit value and scale back to pascals.
+        # Reconstruct 16-bit value and scale back to Hectopascals.
         pressure = (self._BUFFER[0] << 8) | self._BUFFER[1]
-        return pressure * 2.0
+        return pressure * 2.0 / 100
 
     @sealevel_pressure.setter
     def sealevel_pressure(self, val):
-        # Convert to bars of pressure and write to the sealevel register.
-        bars = val // 2
+        # Convert from hectopascals to bars of pressure and write to the sealevel register.
+        bars = int(val * 50)
         self._write_u16_be(_MPL3115A2_BAR_IN_MSB, bars)

examples/mpl3115a2_simpletest.py

@@ -21,15 +21,15 @@
 # This value has to be looked up from your local weather forecast or meteorological
 # reports.  It will change day by day and even hour by hour with weather
 # changes.  Remember altitude estimation from barometric pressure is not exact!
-# Set this to a value in pascals:
-sensor.sealevel_pressure = 102250
+# Set this to a value in hectopascals:
+sensor.sealevel_pressure = 1022.5
 
 # Main loop to read the sensor values and print them every second.
 while True:
     pressure = sensor.pressure
-    print("Pressure: {0:0.3f} pascals".format(pressure))
+    print("Pressure: {0:0.3f} hectopascals".format(pressure))
     altitude = sensor.altitude
     print("Altitude: {0:0.3f} meters".format(altitude))
     temperature = sensor.temperature
-    print("Temperature: {0:0.3f} degrees Celsius".format(temperature))
+    print("Temperature: {0:0.3f} Celsius".format(temperature))
     time.sleep(1.0)