home-assistant.io/source/_integrations/sensor.mqtt.markdown

title	description	ha_category	ha_release	ha_iot_class	ha_domain
MQTT Sensor	Instructions on how to integrate MQTT sensors within Home Assistant.	Sensor	0.7	Configurable	mqtt

This mqtt sensor platform uses the MQTT message payload as the sensor value. If messages in this state_topic are published with RETAIN flag, the sensor will receive an instant update with last known value. Otherwise, the initial state will be undefined.

Configuration

To use your MQTT sensor in your installation, add the following to your {% term "configuration.yaml" %} file:

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Bedroom Temperature"
      state_topic: "home/bedroom/temperature"

{% configuration %} availability: description: A list of MQTT topics subscribed to receive availability (online/offline) updates. Must not be used together with availability_topic. required: false type: list keys: payload_available: description: The payload that represents the available state. required: false type: string default: online payload_not_available: description: The payload that represents the unavailable state. required: false type: string default: offline topic: description: An MQTT topic subscribed to receive availability (online/offline) updates. required: true type: string value_template: description: "Defines a template to extract device's availability from the topic. To determine the devices's availability result of this template will be compared to payload_available and payload_not_available." required: false type: template availability_mode: description: When availability is configured, this controls the conditions needed to set the entity to available. Valid entries are all, any, and latest. If set to all, payload_available must be received on all configured availability topics before the entity is marked as online. If set to any, payload_available must be received on at least one configured availability topic before the entity is marked as online. If set to latest, the last payload_available or payload_not_available received on any configured availability topic controls the availability. required: false type: string default: latest availability_template: description: "Defines a template to extract device's availability from the availability_topic. To determine the devices's availability result of this template will be compared to payload_available and payload_not_available." required: false type: template availability_topic: description: The MQTT topic subscribed to receive availability (online/offline) updates. required: false type: string device: description: "Information about the device this sensor is a part of to tie it into the device registry. Only works when unique_id is set. At least one of identifiers or connections must be present to identify the device." required: false type: map keys: configuration_url: description: 'A link to the webpage that can manage the configuration of this device. Can be either an http://, https:// or an internal homeassistant:// URL.' required: false type: string connections: description: 'A list of connections of the device to the outside world as a list of tuples [connection_type, connection_identifier]. For example the MAC address of a network interface: "connections": [["mac", "02:5b:26:a8:dc:12"]].' required: false type: list hw_version: description: The hardware version of the device. required: false type: string identifiers: description: A list of IDs that uniquely identify the device. For example a serial number. required: false type: [string, list] manufacturer: description: The manufacturer of the device. required: false type: string model: description: The model of the device. required: false type: string model_id: description: The model identifier of the device. required: false type: string name: description: The name of the device. required: false type: string serial_number: description: "The serial number of the device." required: false type: string suggested_area: description: 'Suggest an area if the device isn’t in one yet.' required: false type: string sw_version: description: The firmware version of the device. required: false type: string via_device: description: 'Identifier of a device that routes messages between this device and Home Assistant. Examples of such devices are hubs, or parent devices of a sub-device. This is used to show device topology in Home Assistant.' required: false type: string device_class: description: The type/class of the sensor to set the icon in the frontend. The device_class can be null. required: false type: device_class enabled_by_default: description: Flag which defines if the entity should be enabled when first added. required: false type: boolean default: true encoding: description: The encoding of the payloads received. Set to "" to disable decoding of incoming payload. required: false type: string default: "utf-8" entity_category: description: The category of the entity. When set, the entity category must be diagnostic for sensors. required: false type: string entity_picture: description: "Picture URL for the entity." required: false type: string expire_after: description: If set, it defines the number of seconds after the sensor's state expires, if it's not updated. After expiry, the sensor's state becomes unavailable. Default the sensors state never expires. required: false type: integer default: 0 force_update: description: Sends update events even if the value hasn't changed. Useful if you want to have meaningful value graphs in history. required: false type: boolean default: false icon: description: "Icon for the entity." required: false type: icon json_attributes_template: description: "Defines a template to extract the JSON dictionary from messages received on the json_attributes_topic." required: false type: template json_attributes_topic: description: The MQTT topic subscribed to receive a JSON dictionary payload and then set as sensor attributes. Implies force_update of the current sensor state when a message is received on this topic. required: false type: string last_reset_value_template: description: "Defines a template to extract the last_reset. When last_reset_value_template is set, the state_class option must be total. Available variables: entity_id. The entity_id can be used to reference the entity's attributes." required: false type: template name: description: The name of the MQTT sensor. Can be set to null if only the device name is relevant. required: false type: string default: MQTT Sensor object_id: description: Used instead of name for automatic generation of entity_id required: false type: string options: description: List of allowed sensor state value. An empty list is not allowed. The sensor's device_class must be set to enum. The options option cannot be used together with state_class or unit_of_measurement. required: false type: list payload_available: description: The payload that represents the available state. required: false type: string default: online payload_not_available: description: The payload that represents the unavailable state. required: false type: string default: offline platform: description: Must be sensor. Only allowed and required in MQTT auto discovery device messages. required: true type: string suggested_display_precision: description: The number of decimals which should be used in the sensor's state after rounding. required: false type: integer qos: description: The maximum QoS level to be used when receiving and publishing messages. required: false type: integer default: 0 state_class: description: The state_class of the sensor. required: false type: string state_topic: description: The MQTT topic subscribed to receive sensor values. If device_class, state_class, unit_of_measurement or suggested_display_precision is set, and a numeric value is expected, an empty value '' will be ignored and will not update the state, a 'null' value will set the sensor to an unknown state. The device_class can be null. required: true type: string unique_id: description: "An ID that uniquely identifies this sensor. If two sensors have the same unique ID, Home Assistant will raise an exception. Required when used with device-based discovery." required: false type: string unit_of_measurement: description: Defines the units of measurement of the sensor, if any. The unit_of_measurement can be null. required: false type: string value_template: description: "Defines a template to extract the value. If the template throws an error, the current state will be used instead." required: false type: template {% endconfiguration %}

Examples

In this section, you find some real-life examples showing how to use this sensor.

Processing Unix EPOCH timestamps

The example below shows how an MQTT sensor can process a Unix EPOCH payload.

{% raw %}

Set up via YAML:

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "turned on"
      state_topic: "pump/timestamp_on"
      device_class: "timestamp"
      value_template: "{{ as_datetime(value) }}"
      unique_id: "hp_1231232_ts_on"
      device:
        name: "Heat pump"
        identifiers:
          - "hp_1231232"

{% endraw %}

Or set up via MQTT discovery:

Discovery topic: homeassistant/sensor/hp_1231232/config

{% raw %}

{
  "name": "turned on",
  "state_topic": "pump/timestamp_on",
  "device_class": "timestamp",
  "value_template": "{{ as_datetime(value) }}",
  "unique_id": "hp_1231232_ts_on",
  "device": {
    "name": "Heat pump",
    "identifiers": [
      "hp_1231232"
    ]
  }
}

{% endraw %}

To test, you can use the command line tool mosquitto_pub shipped with mosquitto or the mosquitto-clients package to send MQTT messages.

Payload topic: pump/timestamp_on Payload: 1707294116

To set the state of the sensor manually:

mosquitto_pub -h 127.0.0.1 -p 1883 -u username -P some_password -t pump/timestamp_on -m '1707294116'

Make sure the IP address of your MQTT broker is used and that user credentials have been set up correctly.

The value_template will render the Unix EPOCH timestamp to correct format: 2024-02-07 08:21:56+00:00.

JSON attributes topic configuration

The example sensor below shows a configuration example which uses the following separate topic and JSON structure to add extra attributes.

Topic: home/sensor1/attributes

{
   "ClientName": <string>,
   "IP": <string>,
   "MAC": <string>,
   "RSSI": <string>,
   "HostName": <string>,
   "ConnectedSSID": <string>
}

It also makes use of the availability topic.

Extra attributes will be displayed in the frontend and can also be extracted in Templates. For example, to extract the ClientName attribute from the sensor below, use a template similar to: {% raw %}{{ state_attr('sensor.bs_rssi', 'ClientName') }}{% endraw %}.

{% raw %}

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "RSSI"
      state_topic: "home/sensor1/infojson"
      unit_of_measurement: "dBm"
      value_template: "{{ value_json.RSSI }}"
      availability:
        - topic: "home/sensor1/status"
      payload_available: "online"
      payload_not_available: "offline"
      json_attributes_topic: "home/sensor1/attributes"

{% endraw %}

JSON attributes template configuration

The example sensor below shows a configuration example which uses the following topic and JSON structure with a template to add Timer1.Arm and Timer1.Time as extra attributes.

Topic: tele/sonoff/sensor

{
    "Timer1": {
        "Arm": <status>,
        "Time": <time>
    },
    "Timer2": {
        "Arm": <status>,
        "Time": <time>
    }
}

To instead only add Timer1.Armas an extra attribute, change json_attributes_template to: {% raw %}"{{ {'Arm': value_json.Timer1} | tojson }}"{% endraw %}.

Extra attributes will be displayed in the frontend and can also be extracted in Templates. For example, to extract the Arm attribute from the sensor below, use a template similar to: {% raw %}{{ state_attr('sensor.timer1', 'Arm') }}{% endraw %}.

{% raw %}

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Timer 1"
      state_topic: "tele/sonoff/sensor"
      value_template: "{{ value_json.Timer1.Arm }}"
      json_attributes_topic: "tele/sonoff/sensor"
      json_attributes_template: "{{ value_json.Timer1 | tojson }}"

    - name: "Timer 2"
      state_topic: "tele/sonoff/sensor"
      value_template: "{{ value_json.Timer2.Arm }}"
      json_attributes_topic: "tele/sonoff/sensor"
      json_attributes_template: "{{ value_json.Timer2 | tojson }}"

{% endraw %}

{% warning %} If json_attributes_topic and state_topic share the same topic, a state update will happen only once, unless the state update did not change the state or force_update was set to true.

Setting up MQTT sensor's with extra state attributes that contain values that change at every update, like timestamps, or enabling the force_update option, is discouraged, as this will trigger state writes for every update. This can have a serious impact on the total system performance. A better option is creating separate sensors instead. {% endwarning %}

Usage of entity_id in the template

The example below shows how a simple filter, that calculates the value by adding 90% of the new value and 10% of the previous value, can be implemented in a template.

{% raw %}

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Temp 1"
      state_topic: "sensor/temperature"
      value_template: |-
        {% if states(entity_id) == None %}
          {{ value | round(2) }}
        {% else %}
          {{ value | round(2) * 0.9 + states(entity_id) * 0.1 }}
        {% endif %}

{% endraw %}

Owntracks battery level sensor

If you are using the OwnTracks and enable the reporting of the battery level then you can use an MQTT sensor to keep track of your battery. A regular MQTT message from OwnTracks looks like this:

Topic: owntracks/tablet/tablet

{
    "_type": "location",
    "lon": 7.21,
    "t": "u",
    "batt": 92,
    "tst": 144995643,
    "tid": "ta",
    "acc": 27,
    "lat": 46.12
} 

Thus the trick is extracting the battery level from the payload.

{% raw %}

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Battery Tablet"
      state_topic: "owntracks/tablet/tablet"
      unit_of_measurement: "%"
      value_template: "{{ value_json.batt }}"

{% endraw %}

Temperature and humidity sensors

If you are using a DHT sensor and a NodeMCU board (esp8266), you can retrieve temperature and humidity with a MQTT sensor. A code example can be found here. A regular MQTT message from this example looks like this:

Topic: office/sensor1

  {
    "temperature": 23.20,
    "humidity": 43.70
  }

Then use this configuration example to extract the data from the payload:

{% raw %}

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Temperature"
      state_topic: "office/sensor1"
      suggested_display_precision: 1
      unit_of_measurement: "°C"
      value_template: "{{ value_json.temperature }}"
    - name: "Humidity"
      state_topic: "office/sensor1"
      unit_of_measurement: "%"
      value_template: "{{ value_json.humidity }}"

{% endraw %}

Get sensor value from a device with ESPEasy

Assuming that you have flashed your ESP8266 unit with ESPEasy. Under "Config" set a name ("Unit Name:") for your device (here it's "bathroom"). A "Controller" for MQTT with the protocol "OpenHAB MQTT" is present and the entries ("Controller Subscribe:" and "Controller Publish:") are adjusted to match your needs. In this example the topics are prefixed with "home". Please keep in mind that the ESPEasy default topics start with a / and only contain the name when writing your entry for the {% term "configuration.yaml" %} file.

• Controller Subscribe: home/%sysname%/# (instead of /%sysname%/#)
• Controller Publish: home/%sysname%/%tskname%/%valname% (instead of /%sysname%/%tskname%/%valname%)

Also, add a sensor in the "Devices" tap with the name "analog" and "brightness" as value.

As soon as the unit is online, you will get the state of the sensor.

home/bathroom/status Connected
...
home/bathroom/analog/brightness 290.00

The configuration will look like the example below:

# Example configuration.yaml entry
mqtt:
  sensor:
    - name: "Brightness"
      state_topic: "home/bathroom/analog/brightness"