Binary sensor depending on other sensor's last time of change

Configuration
1

I have a Tellstick temperature sensor in my car. It reports fine. However, I would like to also have a binary presence detection sensor for this car. Something like this:

carIsHome = (car.state.secondsSinceLastUpdate < 600)

As in, if the temperature in the car hasn’t changed for 10 minutes, set the value to OFF (as in “away”). And the opposite.

I’m new to Home Assistant, so sorry for the newbie question. Thanks!

2

With a template sensor :

sensor:
  - carl_home:
      friendly_name: "Carl's Home"
      value_template: >-
        {% as_timestamp(now()) - as_timestamp(states.sensor.tellstick_sensor_name.last_updated) < 600%}
          Home
        {% else %}
          Away
        {% endif %}