[OH3] Tasmota relay via MQTT (Sonoff Basic with optional DHT22)

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Foreword

This tutorial is for openHAB3. If you are on openHAB2 you will need to use my older tutorial.

This tutorial was written with openHAB3 running on a headless Raspberry Pi 3B with Raspberry Pi OS, with SSH access.

Overview

This tutorial assumes you have openHAB3 installed.

This tutorial will show you how to:

  1. Install an MQTT broker, install the MQTT binding, and connect the two
  2. Setup device to read the DHT22 temperature sensor
  3. Setup device to connect to the MQTT broker
  4. Configure openHAB3 to connect to the relay
  5. Configure openHAB3 to control the relay
  6. Configure openHAB3 to read temperature and humidity values

Hardware

The hardware is setup as described on this page, with the main differences being:

  • I used DuPont wires.
  • The DHT22 was pre-soldered to a board which already had its own resistor

Method

1. Install an MQTT broker, install the MQTT binding, and connect the two

In order to use MQTT devices, the following is required:

  1. An MQTT broker installed
  2. MQTT Binding installed in openHAB
  3. MQTT Bridge Thing configured in openHAB

Follow the steps in this tutorial to achieve the above three goals.

2. Setup device to read the DHT22 temperature sensor

In a browser navigate to the Tasmota Module parameters configuration page of your device, normally at:

  • http://<sonoff-ip-address>/md
  • device home -> Configuration -> Configure Module

I connected the DHT22 data pin to the Sonoff GPIO3 pin (Serial In). If you used a different sensor, or a different pin, make the required changes here.

image

Back on the device home page (http://<sonoff-ip-address>), check that the temperature and humidity are displayed (may take a little while to show real values).

image

3. Setup device to connect to the MQTT broker

In a browser navigate to the Tasmota MQTT parameters configuration page of your device, normally at:

  • http://<sonoff-ip-address>/mq
  • device home -> Configuration -> Configure MQTT

Configure the following. Leave everything else as default:

  • Host: IP address of the device running the Mosquitto MQTT broker.
  • Port: Only change if you have changed the default port for the Mosquitto MQTT broker.
  • User: Give your device a unique name. Mine switches on a short light in the living room.
  • Topic: Give your device a unique topic. I match mine to the User.

4. Configure openHAB3 to connect to the relay

To control the relay, we need to configure a Generic MQTT Thing

  • Settings -> Things -> Blue + -> MQTT Binding -> Generic MQTT Thing

Enter the initial configuration information:

  • Unique ID: You can leave this default, or provide a more convenient ID. Once created, the ID cannot be changed. I usually use the same name as used for the Tasmota User.
  • Label: Friendly name for your device
  • Location: Physical location of your device

Connect this Generic MQTT Thing to your MQTT broker via your Bridge Thing:

  • Bridge -> Select Bridge Thing previously created

Configure the availability topics - this ensure that openHAB knows whether the device is online.

Click on Show advanced. For Tasmota devices, the Availability Topic is usually tele/<TOPIC>/LWT, where <TOPIC> is as configured in the Tasmota MQTT parameters page. Messages that are published are either Online or Offline.

Click Create Thing. Your Generic MQTT Thing will be created and appear in your list of Things. After a couple of seconds, it will appear as ONLINE.

YAML Code

You can view the YAML code for you Generic MQTT Thing by opening the Code tab within your Generic MQTT Thing.

show_mqtt_thing_code

The code for this example is below:

UID: mqtt:topic:MosquittoMqttBroker:swLivingRoomShort
label: Living room short light
thingTypeUID: mqtt:topic
configuration:
  payloadNotAvailable: Offline
  availabilityTopic: tele/swLivingRoomShortLight/LWT
  payloadAvailable: Online
bridgeUID: mqtt:broker:MosquittoMqttBroker
location: Living Room

5. Configure openHAB3 to control the relay

We now need to create a Channel to control the relay. Click the Channels tab in your Generic MQTT Thing, followed by Add Channel.

Configure the Channel:

  • Channel Identifier: Channel ID used internally by openHAB. No spaces allowed.
  • Label: Friendly name for the Channel. Spaces allowed.
  • Channel type: On/Off Switch

Continue the configuration of the Channel:

  • MQTT State Topic: If you left Full topic default in the Tasmota MQTT parameters, the State Topic will be stat/<TOPIC>/POWER.
  • MQTT Command Topic: If you left Full topic default in the Tasmota MQTT parameters, the State Topic will be cmnd/<TOPIC>/POWER.
  • Custom On/Open Value: ON
  • Custom Off/Closed Value: OFF

Click Create. The Channel will appear in the Channels tab of your Generic MQTT Thing.

YAML Code
UID: mqtt:topic:MosquittoMqttBroker:swLivingRoomShort
label: Living room short light
thingTypeUID: mqtt:topic
configuration:
  payloadNotAvailable: Offline
  availabilityTopic: tele/swLivingRoomShortLight/LWT
  payloadAvailable: Online
bridgeUID: mqtt:broker:MosquittoMqttBroker
location: Living Room
channels:
  - id: power
    channelTypeUID: mqtt:switch
    label: Power
    description: ""
    configuration:
      commandTopic: cmnd/swLivingRoomShortLight/POWER
      stateTopic: stat/swLivingRoomShortLight/POWER
      off: OFF
      on: ON

Within the Channels tab, click Add Equipment to Model.

You are now creating an Item. If you have your Model setup, choose the Parent Group. Configure the Item:

  • Name: Item ID used internally by openHAB. No spaces allowed.
  • Label: Friendly name for the Item. Spaces allowed.
  • Category: lightbulb. This is used for the icon.
  • Semantic Class: Lightbulb

Link the previously created Power Channel to the Item by selecting it. Configure the link:

  • Name: Link ID used internally by openHAB. No spaces allowed.
  • Label: Friendly name for the Link. Spaces allowed.
  • Type: Switch
  • Category: Select the category to use for the icon.
  • Semantic Class: Switch
  • Semantic Property: Light

Click Add to Model. You can now control the switch from your Item.

  • When you click the switch On, openHAB will send ON to cmnd/<TOPIC>/POWER.
  • When you click the switch Off, openHAB will send OFF to cmnd/<TOPIC>/POWER.

6. Configure openHAB3 to read temperature and humidity values

To read the temperature and humidity values we need to do three specific things:

  1. Install the JSONPath Transformation Service
  2. Create two new Number Channels to read the temperature and humidity values published by Tasmota
  3. Create Items linked to the Channels

6.1 Install the JSONPath Transformation Service

Settings -> Transformations -> Blue + -> JSONPath Transformation -> Install

6.2 Create two new Number Channels

Click Add Channel within the Channels tab of your Generic MQTT Thing.

Configure as follows. YAML Code is below the images. Only fields which need modification are shown in the screenshots. Note that Show advanced is selected.

6.2.1 Temperature Channel

YAML Code
  - id: temperature
    channelTypeUID: mqtt:number
    label: Temperature
    description: ""
    configuration:
      stateTopic: tele/swLivingRoomShortLight/SENSOR
      transformationPattern: JSONPATH:$.AM2301.Temperature
      unit: °C

6.2.2 Humidity Channel

YAML Code
  - id: humidity
    channelTypeUID: mqtt:number
    label: Humidity
    description: ""
    configuration:
      stateTopic: tele/swLivingRoomShortLight/SENSOR
      transformationPattern: JSONPATH:$.AM2301.Humidity
      unit: "%"

6.3 Create Items linked to the Channels

Within the Channels tab, click Add Points to Model. Select the Temperature and Humidity Channels.

Configure the Items:

Click Add to Model

Within Model you will find the Temperature and Humidity Items (Points).

Summary

openHAB is now connected to the Tasmota device, and can operate the relay and read the temperature and humidity values. Things and Items have been created, which can be added to the Model to suite.

5 Likes

Great tutorial and right in time for me!

I just completed a small project with tasmota and was prepared to dedicate many hours to integrate it with Openhab, but I just found your post and was able to do that in minutes! Thanks!

EDIT: I documented my project here, just in case anybody is interested.

Thank you! I created the MQTT Broker linking it to Mosquitto.

The Broker is online, as is Mosquitto. I created a generic thing to read the power values from a Sonoff PoW. The topics are not discovered under advanced, even creating a channel and item doesnt populate the values.

The sensor works just fine in MQTT 1.x, all I did on the sensor is point it to the new OH3 machine

Any suggestions? I want to migrate over from 1.x in 2.4 to OH3 with MQTT

My old configuration using an item file for Voltage was:

Number AtticVoltage "Attic Voltage [%.1f V]" { mqtt="<[broker:tele/atticcomms/SENSOR:state:JSONPATH($.ENERGY.Voltage)]" }

Thanks!

I’m not sure what this means - are you expecting fields in the UI configuration to be filled in automatically?

Is that where your Mosquitto is now?

Can you show the YAML of your new configuration? Otherwise we can’t really see what’s going on.

Its OK, i got it working using this tutorial

1 Like

Just a small recommendation if you don’t want to hassle with all the channels. Enable Homeassistant auto discovery by sending SETOPTION19 1 to your tasmota device using the console. Then you can simply add your things from the inbox with all the channels configured automatically.

https://tasmota.github.io/docs/Home-Assistant/#enable-autodiscovery

If you want to do that, follow this tutorial:

I added this as a side note for people who are not aware of the auto discovery feature which also works for openhab.

1 Like