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 configuration.yaml file:

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

{% configuration %} 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 through MQTT discovery and when unique_id is set." required: false type: map keys: 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 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 name: description: The name of the device. 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. required: false type: device_class default: None expire_after: description: Defines the number of seconds after the sensor's state expires, if it's not updated. After expiry, the sensor's state becomes unavailable. 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: The icon for the sensor. 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 name: description: The name of the MQTT sensor. required: false type: string default: MQTT Sensor 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 qos: description: The maximum QoS level of the state topic. required: false type: integer default: 0 state_topic: description: The MQTT topic subscribed to receive sensor values. 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: false type: string unit_of_measurement: description: Defines the units of measurement of the sensor, if any. required: false type: string value_template: description: "Defines a template to extract the value." required: false type: template {% endconfiguration %}

Examples

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

JSON attributes topic configuration

The example sensor below shows a configuration example which uses a JSON dict: {"ClientName": <string>, "IP": <string>, "MAC": <string>, "RSSI": <string>, "HostName": <string>, "ConnectedSSID": <string>} in a separate topic home/sensor1/attributes to add extra attributes. 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
sensor:
  - platform: mqtt
    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 a JSON dict: {"Timer1":{"Arm": <status>, "Time": <time>}, "Timer2":{"Arm": <status>, "Time": <time>}} on topic tele/sonoff/sensor with a template to add Timer1.Arm and Timer1.Time as extra attributes. 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
sensor:
  - platform: mqtt
    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 }}"
  - platform: mqtt
    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 %}

The state and the attributes of the sensor by design do not update in a synchronous manner if they share the same MQTT topic. Temporal mismatches between the state and the attribute data may occur if both the state and the attributes are changed simultaneously by the same MQTT message. An automation that triggers on any state change of the sensor will also trigger both on the change of the state or a change of the attributes. Such automations will be triggered twice if both the state and the attributes change. Please use a MQTT trigger and process the JSON in the automation directly via the {% raw %}{{ trigger.payload_json }}{% endraw %} trigger data for automations that must synchronously handle multiple JSON values within the same MQTT message.

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:

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
sensor:
  - platform: mqtt
    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:

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
sensor:
  - platform: mqtt
    name: "Temperature"
    state_topic: "office/sensor1"
    unit_of_measurement: '°C'
    value_template: "{{ value_json.temperature }}"
  - platform: mqtt
    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 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:

{% raw %}

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

{% endraw %}