Platform example

Development
1

I have an Arduino with 8 HTD21D temperature and humidity sensors, connected via TCA9548A I2C multiplexer. Code that works fine from CLI on my laptop:

import serial
import sys
import time
import struct
import array


ser = serial.Serial('/dev/ttyUSB0', 115200)  # open serial port

ser.timeout = 3

# Wait for port to get ready and send a data request
time.sleep(3)
ser.write(255)

# Read 8 temperature values
rawData = ser.read(4 * 8)
temperatures = array.array('f')
temperatures.frombytes(rawData)

# Read 8 humidity values
rawData = ser.read(4 * 8)
humidities = array.array('f')
humidities.frombytes(rawData)

# Print to console
for i in range(8):
    print('temperatures ', i, temperatures[i])
for i in range(8):
    print('humidities ', i, humidities[i])

ser.close()

I have repeatedly read the section for developers, include https://developers.home-assistant.io/docs/en/creating_platform_example_sensor.html but cannot to make first step.

  • What do I need to write in my custom component ‘sensor.py’?
  • What do I need to write in the configuration.yaml to see 16 values stored in arrays?
2

Found the answer to my questions
My custom ‘sensor.py’

import sys
import time
import struct
import array

from homeassistant.const import (
    TEMP_CELSIUS, DEVICE_CLASS_HUMIDITY,
    DEVICE_CLASS_TEMPERATURE)
from homeassistant.helpers.entity import Entity


REQUIREMENTS = ['pyserial==3.4']

import serial
import logging

_LOGGER = logging.getLogger(__name__)


def setup_platform(hass, config, add_entities, discovery_info=None):
    
    """Set up the sensors."""
    add_entities([
        multiHTU21DSensor('Temperature1', 11.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 1),
        multiHTU21DSensor('Temperature2', 12.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 2),
        multiHTU21DSensor('Temperature3', 13.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 3),
        multiHTU21DSensor('Temperature4', 14.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 4),
        multiHTU21DSensor('Temperature5', 15.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 5),
        multiHTU21DSensor('Temperature6', 16.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 6),
        multiHTU21DSensor('Temperature7', 17.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 7),
        multiHTU21DSensor('Temperature8', 18.6, DEVICE_CLASS_TEMPERATURE, TEMP_CELSIUS, None, 8),
        multiHTU21DSensor('Humidity1', 10, DEVICE_CLASS_HUMIDITY, '%', None, 1),
        multiHTU21DSensor('Humidity2', 20, DEVICE_CLASS_HUMIDITY, '%', None, 2),
        multiHTU21DSensor('Humidity3', 30, DEVICE_CLASS_HUMIDITY, '%', None, 3),
        multiHTU21DSensor('Humidity4', 40, DEVICE_CLASS_HUMIDITY, '%', None, 4),
        multiHTU21DSensor('Humidity5', 50, DEVICE_CLASS_HUMIDITY, '%', None, 5),
        multiHTU21DSensor('Humidity6', 60, DEVICE_CLASS_HUMIDITY, '%', None, 6),
        multiHTU21DSensor('Humidity7', 70, DEVICE_CLASS_HUMIDITY, '%', None, 7),
        multiHTU21DSensor('Humidity8', 80, DEVICE_CLASS_HUMIDITY, '%', None, 8),
    ])


class multiHTU21DSensor(Entity):
    """Representation of a sensor."""

    handler = None


    def __init__(self, name, state, device_class,
                 unit_of_measurement, battery, sensorNumber):
        """Initialize the sensor."""
        self._name = name
        self._state = state
        self._device_class = device_class
        self._unit_of_measurement = unit_of_measurement
        self._battery = battery
        self.sensorNumber = sensorNumber
 
        if self.sensorNumber == 1 and self._device_class == DEVICE_CLASS_TEMPERATURE:
            multiHTU21DSensor.handler = multiHTU21DSensorHandler()

    @property
    def should_poll(self):
        return True

    @property
    def device_class(self):
        """Return the device class of the sensor."""
        return self._device_class

    @property
    def name(self):
        """Return the name of the sensor."""
        return self._name

    @property
    def state(self):
        """Return the state of the sensor."""
        if self._device_class == DEVICE_CLASS_TEMPERATURE:
            value = self.handler.get_temperature(self.sensorNumber)
        else:
            value = self.handler.get_humidity(self.sensorNumber)

        return value 


    @property
    def unit_of_measurement(self):
        """Return the unit this state is expressed in."""
        return self._unit_of_measurement

    def update(self):
        """Get the latest data and updates the states. Update only once for 16 sensors. """
        if self.sensorNumber == 1 and self._device_class == DEVICE_CLASS_TEMPERATURE:
            self.handler.update()


class multiHTU21DSensorHandler:
    """Implement HTU21D communication."""

    def __init__(self):
        # Operations with Arduino and values storage
        #self.temperatures = array.array('f')
        #self.humidities = array.array('f')
        self.temperatures = [10.0, 20.0, 30.0, 40.0, 50.0, 60.0, 70.0, 80.0]
        self.humidities = [11.0, 21.0, 31.0, 41.0, 51.0, 61.0, 71.0, 81.0]

        # Open port.
        self.ser = serial.Serial('/dev/ttyUSB0', 115200)  # open serial port
        self.ser.timeout = 3

        # Wait for port to get ready
        time.sleep(3)
        self.update()

    def get_temperature(self, index):
        """Return the temperature of the sensor with index."""
        return self.temperatures[index - 1]

    def get_humidity(self, index):
        """Return the humidity of the sensor with index."""
        return self.humidities[index - 1]

    def update(self):
        """Read raw data and calculate temperature and humidity."""

        # Send request.
        self.ser.reset_input_buffer()
        self.ser.write(1)

        # Read 8 float values of temperature
        rawData = self.ser.read(4 * 8)
        self.temperatures = array.array('f')
        self.temperatures.frombytes(rawData)
 
        # Read 8 float values of humidity
        rawData = self.ser.read(4 * 8)
        self.humidities = array.array('f')
        self.humidities.frombytes(rawData)

Into ‘configuration.yaml’

sensor:
  - platform: multiHTU21D