Using MQTT to control devices?

Configuration
1

In MQTT components, I can use MQTT Statesteam to receive state changes.

How do I control non-MQTT devices using MQTT? Or I have to use the REST / WebSocket API to control them?

Is this possible?

$ mosquitto_pub -t "homeassistant/switch/bedroom_light" -m ON
1 Like
2

This is an introduction to MQTT, which I think is really what you need.
https://www.hivemq.com/blog/how-to-get-started-with-mqtt

3

The answer is in a careful reading of your question.

4

Let me try to rephrase my question -

I have a TP-Link Switch named “fan_switch”, and I have configured MQTT statestream to publish state changes to MQTT broker, so if “fan_switch” is turned ON, it will publish on to "homeassistant/switch/fan_switch/state".

Is there a way for HASS to subscribe to "homeassistant/switch/fan_switch/command" so that I can publish “off” to that topic to have HASS turn OFF the “fan_switch”?

mqtt_statestream:
  base_topic: homeassistant
  include:
    domains:
      - switch
5

How does your TP-Link communicate with MQTT?

6

TP-link is not using MQTT, it is using - https://www.home-assistant.io/components/switch.tplink/

I’m using TP-Link as an example, it can be any of the switches under the “switches” component.

I can use REST API /api/services/switch/turn_off + entity_id to OFF the switch. Is there an equivalent for using MQTT topics to turn the switch on/off ?

7

Why would you need that? HA can control it without putting MQTT between them.

8

Yea, I know. I’m building a bridge to sync all devices between HA and another smart home hub.

9

To do this you would write an automation that triggers off the MQTT message and sets the switch state accordingly in the action.

10

But that would require me to set a MQTT trigger for each of the HA devices…

11

You may be able to use templates to reduce that number, but I don’t know too much about that.

Personally, I use appdaemon so I write all automations in Python.

12

Thanks for pointing me in the right direction!

- alias: Control switches via MQTT
  trigger:
    platform: mqtt
    topic: +/switch/+/cmd
  action:
    - service_template: >
        homeassistant.turn_{{trigger.payload}}
      data_template:
        entity_id: >-
          {{ trigger.topic.split('/')[-3] }}.{{ trigger.topic.split('/')[-2] }}
9 Likes
13

This worked great, thanks for posting.

I copied the code into automations.yml.

Posting an MQTT message containing either on or off to topic:
<anything>/switch/<entityName>/cmd allowed me to control my device over MQTT.

My use case is adapting an existing Node-RED scenes system I built to work with Home Assistant devices that don’t have MQTT.