Adding temp rh resolution

README.rst

@@ -59,11 +59,10 @@ Usage Example
 
     import time
     import board
-    import busio
     from adafruit_htu21d import HTU21D
 
-    # Create library object using our Bus I2C port
-    i2c = busio.I2C(board.SCL, board.SDA)
+    # Create sensor object, communicating over the board's default I2C bus
+    i2c = board.I2C()  # uses board.SCL and board.SDA
     sensor = HTU21D(i2c)
 
 

adafruit_htu21d.py

@@ -16,16 +16,17 @@
 
 **Hardware:**
 
-* Adafruit `HTU21D-F Temperature & Humidity Sensor Breakout Board
+* `Adafruit HTU21D-F Temperature & Humidity Sensor Breakout Board
   <https://www.adafruit.com/product/1899>`_ (Product ID: 1899)
 
 **Software and Dependencies:**
 
 * Adafruit CircuitPython firmware for the supported boards:
-  https://github.com/adafruit/circuitpython/releases
+  https://circuitpython.org/downloads
 
 * Adafruit's Bus Device library:
   https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
+
 """
 try:
     import struct
@@ -42,9 +43,12 @@
 HUMIDITY = const(0xF5)
 TEMPERATURE = const(0xF3)
 _RESET = const(0xFE)
+_WRITE_USER1 = const(0xE6)
 _READ_USER1 = const(0xE7)
 _USER1_VAL = const(0x3A)
 
+_TEMP_RH_RES = (0, 1, 128, 129)
+
 
 def _crc(data):
     crc = 0
@@ -62,36 +66,32 @@ def _crc(data):
 class HTU21D:
     """
     A driver for the HTU21D-F temperature and humidity sensor.
-
-    :param i2c_bus: The `busio.I2C` object to use. This is the only required parameter.
+    :param i2c_bus: The I2C bus the device is connected to
     :param int address: (optional) The I2C address of the device. Defaults to :const:`0x40`
 
+    **Quickstart: Importing and using the HTU21D-F**
 
-    **Quickstart: Importing and using the HTU21D temperature sensor**
-
-        Here is one way of importing the `HTU21D` class so you can use it with the name ``htu``.
+        Here is an example of using the :class:`HTU21D` class.
         First you will need to import the libraries to use the sensor
 
         .. code-block:: python
 
-            import busio
             import board
-            import adafruit_htu21d
+            from adafruit_htu21d import HTU21D
 
-        Once this is done you can define your `busio.I2C` object and define your sensor object
+        Once this is done you can define your `board.I2C` object and define your sensor object
 
         .. code-block:: python
 
-            i2c = busio.I2C(board.SCL, board.SDA)
-            htu = adafruit_htu21d.HTU21D(i2c)
+            i2c = board.I2C()  # uses board.SCL and board.SDA
+            sensor = HTU21D(i2c)
 
-        Now you have access to the temperature and humidity using
-        the :attr:`temperature` and :attr:`relative_humidity` attributes
+        Now you have access to the :attr:`temperature` and :attr:`relative_humidity` attributes
 
         .. code-block:: python
 
-            temperature = htu.temperature
-            relative_humidity = htu.relative_humidity
+            temperature = sensor.temperature
+            relative_humidity = sensor.relative_humidity
 
 
     """
@@ -100,6 +100,7 @@ def __init__(self, i2c_bus, address=0x40):
         self.i2c_device = I2CDevice(i2c_bus, address)
         self._command(_RESET)
         self._measurement = 0
+        self._buffer = bytearray(3)
         time.sleep(0.01)
 
     def _command(self, command):
@@ -157,3 +158,43 @@ def measurement(self, what):
         elif self._measurement != what:
             raise RuntimeError("other measurement in progress")
         self._measurement = what
+
+    @property
+    def temp_rh_resolution(self):
+        """The temperature and relative humidity resolution
+
+        Have one of the following values: [#f1]_
+
+            =======  ==============  ==============
+             value       RH res %        T res C
+            =======  ==============  ==============
+               0      0.04 (12bit)    0.01 (14bit)
+               1      0.7  (8bit)     0.04 (12bit)
+               2      0.17 (10bit)    0.02 (13bit)
+               3      0.08 (11bit)    0.08 (11bit)
+            =======  ==============  ==============
+
+
+        .. [#f1] HTU21D(F) RH/T Sensor IC Datasheet. TE connectivity. 2017. p13
+
+        """
+
+        self._buffer[0] = _READ_USER1
+        with self.i2c_device as i2c:
+            i2c.write_then_readinto(self._buffer, self._buffer, out_end=1)
+
+        return self._buffer[0]
+
+    @temp_rh_resolution.setter
+    def temp_rh_resolution(self, value):
+        self._buffer[0] = _READ_USER1
+        with self.i2c_device as i2c:
+            i2c.write_then_readinto(self._buffer, self._buffer, out_end=1)
+
+        register = (self._buffer[0] & 0xFE) | _TEMP_RH_RES[value]
+
+        self._buffer[0] = 0xE6
+        self._buffer[1] = register
+
+        with self.i2c_device as i2c:
+            i2c.write(self._buffer)

examples/htu21d_simpletest.py

@@ -3,11 +3,10 @@
 
 import time
 import board
-import busio
 from adafruit_htu21d import HTU21D
 
-# Create library object using our Bus I2C port
-i2c = busio.I2C(board.SCL, board.SDA)
+# Create sensor object, communicating over the board's default I2C bus
+i2c = board.I2C()  # uses board.SCL and board.SDA
 sensor = HTU21D(i2c)