sensor.py

import logging
import asyncio
from datetime import timedelta
import voluptuous as vol

import homeassistant.helpers.config_validation as cv
from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.const import (
    CONF_NAME,
    CONF_ICON,
    CONF_UNIT_OF_MEASUREMENT,
    STATE_UNKNOWN,
)
from homeassistant.helpers.entity import Entity

_LOGGER = logging.getLogger(__name__)

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {
        vol.Optional(CONF_NAME): cv.string,
        vol.Optional(CONF_ICON): cv.string,
        vol.Optional(CONF_UNIT_OF_MEASUREMENT): cv.string,
    }
)

def setup_platform(hass, config, add_entities, discovery_info=None):
    """Set up the Custom Sensor platform."""
    name = config.get(CONF_NAME)
    icon = config.get(CONF_ICON)
    unit = config.get(CONF_UNIT_OF_MEASUREMENT)

    add_entities([KartaxBasicSensor(name, icon, unit)], True)

class KartaxBasicSensor(Entity):

    def __init__(self, name, icon, unit):
        self._name = name
        self._icon = icon
        self._unit = unit
        self._state = STATE_UNKNOWN
        self._counter = 0

    @property
    def name(self):
        return self._name

    @property
    def icon(self):
        return self._icon

    @property
    def state(self):
        return self._state

    @property
    def unit_of_measurement(self):
        return self._unit

    async def async_added_to_hass(self):
        self.hass.helpers.event.async_track_time_interval(
            self.update, timedelta(seconds=10)
        )

    def update(self, now=None):
        self._counter += 0.1
        self._state = self._counter