Add I2c HTU21D temperature and humidity sensor for Raspberry Pi (#8049)

* Add new HTU21D temperature and humidity sensor

* new sensor platform
* requirements_all and .coveragerc update

* fix lint

* review changes: move sensor code to external module

* remove debug log msg

* add i2csense to COMMENT_REQUIREMENTS, require i2csense 0.0.3

* Add new HTU21D temperature and humidity sensor

* new sensor platform
* requirements_all and .coveragerc update

* fix lint

* review changes: move sensor code to external module

* remove debug log msg

* add i2csense to COMMENT_REQUIREMENTS, require i2csense 0.0.3

* change style for hass

* fix requirements

.coveragerc

@@ -419,6 +419,7 @@ omit =
     homeassistant/components/sensor/haveibeenpwned.py
     homeassistant/components/sensor/hddtemp.py
     homeassistant/components/sensor/hp_ilo.py
+    homeassistant/components/sensor/htu21d.py
     homeassistant/components/sensor/hydroquebec.py
     homeassistant/components/sensor/imap.py
     homeassistant/components/sensor/imap_email_content.py

homeassistant/components/sensor/htu21d.py

@@ -0,0 +1,122 @@
+"""
+Support for HTU21D temperature and humidity sensor.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.htu21d/
+"""
+import asyncio
+from datetime import timedelta
+from functools import partial
+import logging
+
+import voluptuous as vol
+
+from homeassistant.components.sensor import PLATFORM_SCHEMA
+import homeassistant.helpers.config_validation as cv
+from homeassistant.const import CONF_NAME, TEMP_FAHRENHEIT
+from homeassistant.helpers.entity import Entity
+from homeassistant.util import Throttle
+from homeassistant.util.temperature import celsius_to_fahrenheit
+
+REQUIREMENTS = ['i2csense==0.0.3',
+                'smbus-cffi==0.5.1']
+
+_LOGGER = logging.getLogger(__name__)
+
+CONF_I2C_BUS = 'i2c_bus'
+DEFAULT_I2C_BUS = 1
+
+MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=5)
+
+DEFAULT_NAME = 'HTU21D Sensor'
+
+SENSOR_TEMPERATURE = 'temperature'
+SENSOR_HUMIDITY = 'humidity'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
+    vol.Optional(CONF_I2C_BUS, default=DEFAULT_I2C_BUS): vol.Coerce(int),
+})
+
+
+# pylint: disable=import-error
+@asyncio.coroutine
+def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
+    """Set up the HTU21D sensor."""
+    import smbus
+    from i2csense.htu21d import HTU21D
+
+    name = config.get(CONF_NAME)
+    bus_number = config.get(CONF_I2C_BUS)
+    temp_unit = hass.config.units.temperature_unit
+
+    bus = smbus.SMBus(config.get(CONF_I2C_BUS))
+    sensor = yield from hass.async_add_job(
+        partial(HTU21D, bus, logger=_LOGGER)
+    )
+    if not sensor.sample_ok:
+        _LOGGER.error("HTU21D sensor not detected in bus %s", bus_number)
+        return False
+
+    sensor_handler = yield from hass.async_add_job(HTU21DHandler, sensor)
+
+    dev = [HTU21DSensor(sensor_handler, name, SENSOR_TEMPERATURE, temp_unit),
+           HTU21DSensor(sensor_handler, name, SENSOR_HUMIDITY, '%')]
+
+    async_add_devices(dev)
+
+
+class HTU21DHandler:
+    """Implement HTU21D communication."""
+
+    def __init__(self, sensor):
+        """Initialize the sensor handler."""
+        self.sensor = sensor
+        self.sensor.update()
+
+    @Throttle(MIN_TIME_BETWEEN_UPDATES)
+    def update(self):
+        """Read raw data and calculate temperature and humidity."""
+        self.sensor.update()
+
+
+class HTU21DSensor(Entity):
+    """Implementation of the HTU21D sensor."""
+
+    def __init__(self, htu21d_client, name, variable, unit):
+        """Initialize the sensor."""
+        self._name = '{}_{}'.format(name, variable)
+        self._variable = variable
+        self._unit_of_measurement = unit
+        self._client = htu21d_client
+        self._state = None
+
+    @property
+    def name(self) -> str:
+        """Return the name of the sensor."""
+        return self._name
+
+    @property
+    def state(self) -> int:
+        """Return the state of the sensor."""
+        return self._state
+
+    @property
+    def unit_of_measurement(self) -> str:
+        """Return the unit of measurement of the sensor."""
+        return self._unit_of_measurement
+
+    @asyncio.coroutine
+    def async_update(self):
+        """Get the latest data from the HTU21D sensor and update the state."""
+        yield from self.hass.async_add_job(self._client.update)
+        if self._client.sensor.sample_ok:
+            if self._variable == SENSOR_TEMPERATURE:
+                value = round(self._client.sensor.temperature, 1)
+                if self.unit_of_measurement == TEMP_FAHRENHEIT:
+                    value = celsius_to_fahrenheit(value)
+            else:
+                value = round(self._client.sensor.humidity, 1)
+            self._state = value
+        else:
+            _LOGGER.warning("Bad sample")

requirements_all.txt

@@ -316,6 +316,7 @@ https://github.com/wmalgadey/PyTado/archive/0.1.10.zip#PyTado==0.1.10
 https://github.com/wokar/pylgnetcast/archive/v0.2.0.zip#pylgnetcast==0.2.0
 
 # homeassistant.components.sensor.bme280
+# homeassistant.components.sensor.htu21d
 # i2csense==0.0.3
 
 # homeassistant.components.influxdb
@@ -823,6 +824,7 @@ sleepyq==0.6
 
 # homeassistant.components.sensor.bme280
 # homeassistant.components.sensor.envirophat
+# homeassistant.components.sensor.htu21d
 # smbus-cffi==0.5.1
 
 # homeassistant.components.media_player.snapcast