Serial CO2 sensor support (#2885)

* Added support for serial HM-Z19 CO2 sensor

* Minor pylint bug fixes

* Added new files to .coveragerc

* Removed newline

* Changes in requirements after change of pmsensor library

* Change the implementation of default name

* Check if serial interface is working before adding the sensor

* Maximum sensor value is 5000ppm

.coveragerc

@@ -216,6 +216,7 @@ omit =
     homeassistant/components/sensor/google_travel_time.py
     homeassistant/components/sensor/gpsd.py
     homeassistant/components/sensor/gtfs.py
+    homeassistant/components/sensor/hmz19.py
     homeassistant/components/sensor/hp_ilo.py
     homeassistant/components/sensor/imap.py
     homeassistant/components/sensor/lastfm.py

homeassistant/components/sensor/hmz19.py

@@ -0,0 +1,85 @@
+"""
+Support for CO2 sensor connected to a serial port.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.hmz19/
+"""
+import logging
+import voluptuous as vol
+
+from homeassistant.const import CONF_NAME
+from homeassistant.helpers.entity import Entity
+import homeassistant.helpers.config_validation as cv
+from homeassistant.components.sensor import PLATFORM_SCHEMA
+
+REQUIREMENTS = ['pmsensor==0.3']
+
+
+_LOGGER = logging.getLogger(__name__)
+
+CONF_SERIAL_DEVICE = "serial_device"
+DEFAULT_NAME = 'CO2 Sensor'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
+    vol.Required(CONF_SERIAL_DEVICE): cv.string,
+})
+
+
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """Setup the available CO2 sensors."""
+    from pmsensor import co2sensor
+
+    try:
+        co2sensor.read_mh_z19(config.get(CONF_SERIAL_DEVICE))
+    except OSError as err:
+        _LOGGER.error("Could not open serial connection to %s (%s)",
+                      config.get(CONF_SERIAL_DEVICE), err)
+        return False
+
+    dev = HMZ19Sensor(config.get(CONF_SERIAL_DEVICE), config.get(CONF_NAME))
+    add_devices([dev])
+
+
+class HMZ19Sensor(Entity):
+    """Representation of an CO2 sensor."""
+
+    def __init__(self, serial_device, name):
+        """Initialize a new PM sensor."""
+        self._name = name
+        self._state = None
+        self._serial = serial_device
+
+    @property
+    def name(self):
+        """Return the name of the sensor."""
+        return self._name
+
+    @property
+    def state(self):
+        """Return the state of the sensor."""
+        return self._state
+
+    @property
+    def unit_of_measurement(self):
+        """Return the unit of measurement of this entity, if any."""
+        return "ppm"
+
+    def update(self):
+        """Read from sensor and update the state."""
+        from pmsensor import co2sensor
+
+        _LOGGER.debug("Reading data from CO2 sensor")
+        try:
+            ppm = co2sensor.read_mh_z19(self._serial)
+            # values from sensor can only between 0 and 5000
+            if (ppm >= 0) & (ppm <= 5000):
+                self._state = ppm
+        except OSError as err:
+            _LOGGER.error("Could not open serial connection to %s (%s)",
+                          self._serial, err)
+            return
+
+    def should_poll(self):
+        """Sensor needs polling."""
+        return True

requirements_all.txt

@@ -254,6 +254,7 @@ pilight==0.0.2
 # homeassistant.components.sensor.plex
 plexapi==2.0.2
 
+# homeassistant.components.sensor.hmz19
 # homeassistant.components.sensor.serial_pm
 pmsensor==0.3