Dennis Hwang dot net

So you’ve got a device pushing MQTT messages. If you do the bare minimum configuration,

mqtt:
  sensor:
    - name: "Pico W Air"
      state_topic: "enviro/picowair"

you get an entity in Home Assistant that gives you something like this:

{"pm100 env": 1, "particles 03um": 224, "pm100 standard": 1, "particles 25um": 0, "pm25 standard": 1, "pm10 env": 0, "pm10 standard": 0, "pm25 env": 1, "particles 05um": 62, "particles 10um": 14, "particles 100um": 0, "particles 50um": 0}

This does not give you anything that you can actually use. Add this below state_topic:

      value_template: "{{ (value|from_json)['particles 03um'] }}"

This now returns an actual value that you can work with. In this case it would return 224.

I got stock on value_json for a long time, which as far as I can tell should let you just specify the “field” you want and return the data. Evidently this would work if the data was in quotes.

https://community.home-assistant.io/t/template-variable-error-value-json-is-undefined-mqtt/388902/20

Developer tools > Services > Utility Meter: Calibrate

I would imagine there is a way to get this into a button, but have no idea how to do that.

This is useful for things like tracking air purifier run times, where you don’t want the meter reset until you actually change the filter. For most things, automatic reset based on a time period is probably fine.

Source: https://community.home-assistant.io/t/manual-reset-utility-meter/320665/5

To track something over time, you need a sensor that outputs a unit of something over time (kilowatt-hours), outputs a state that you can track (on), or outputs instantaneous usage (watts).

The simplest example is tracking electricity usage. Most smart plugs will output instantaneous usage in watts, while some will give a total of kilowatt-hours. If you have a device that does the latter, you can simply create a utility meter from the sensor.

If your device only outputs instantaneous usage, use a Reimann sum helper to get usage over time. Then create a utility meter from the helper.

The most complicate situation is when you need to track something’s state over time. For example, getting total runtime of an air purifier to know when to change its filter. In this situation, you need something that will provide an on/off state (usually the device itself, but you could also create your own helper sensor). Then create a history_stats sensor, then create a utility meter from that.

Here’s my example, which is largely copied-and-pasted from the Home Assistant documentation:

sensor:
  - platform: history_stats
    name: Bedroom Air Purifier On History
    entity_id: binary_sensor.bedroom_air_purifier_on_off
    state: "on"
    type: time
    start: "{{ now().replace(hour=0, minute=0, second=0) }}"
    end: "{{ now() }}"

This says look at the helper sensor I created to determine when the air purifier is on, and then track how much time it is on.

When doing anything involving utility meters from within the UI (or maybe especially when doing it using the UI), reload Home Assistant. There can be some weird behaviors if you don’t.

If you’ve entered in the IP address and the API key but the integration doesn’t connect, that’s because by default Syncthing is only accessible from the local machine. You have to change the GUI listen address to 0.0.0.0 from 127.0.0.1.

Source:

https://community.home-assistant.io/t/how-to-integrate-your-syncthing-and-even-make-it-talk/209116