---
title: "MQTT Sensor"
description: "Instructions on how to integrate MQTT sensors within Home Assistant."
ha_category:
- Sensor
ha_release: 0.7
ha_iot_class: Configurable
ha_domain: 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:
```yaml
# Example configuration.yaml entry
mqtt:
sensor:
- state_topic: "home/bedroom/temperature"
```
<a id='new_format'></a>
{% details "Previous configuration format" %}
The configuration format of manual configured MQTT items has changed.
The old format that places configurations under the `sensor` platform key
should no longer be used and is deprecated.
The above example shows the new and modern way,
this is the previous/old example:
```yaml
sensor:
- platform: mqtt
state_topic: "home/bedroom/temperature"
```
{% enddetails %}
{% 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](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) 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](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) 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](https://developers.home-assistant.io/docs/en/device_registry_index.html). Only works through [MQTT discovery](/docs/mqtt/discovery/) and when [`unique_id`](#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 or HTTPS link.'
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
name:
description: The name 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](/integrations/sensor/#device-class) of the sensor to set the icon in the frontend.
required: false
type: device_class
default: None
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](https://developers.home-assistant.io/docs/core/entity#generic-properties) of the entity.
required: false
type: string
default: None
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](/docs/configuration/customizing-devices/#icon) for the entity."
required: false
type: icon
json_attributes_template:
description: "Defines a [template](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) 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](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) to extract the last_reset. Available variables: `entity_id`. The `entity_id` can be used to reference the entity's attributes."
required: false
type: string
name:
description: The name of the MQTT sensor.
required: false
type: string
default: MQTT Sensor
object_id:
description: Used instead of `name` for automatic generation of `entity_id`
required: false
type: string
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_class:
description: The [state_class](https://developers.home-assistant.io/docs/core/entity/sensor#available-state-classes) of the sensor.
required: false
type: string
default: None
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](/docs/configuration/templating/#using-templates-with-the-mqtt-integration) 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 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](/docs/configuration/templating/#attributes). 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 %}
```yaml
# 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 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.Arm`as 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](/docs/configuration/templating/#attributes). For example, to extract the `Arm` attribute from the sensor below, use a template similar to: {% raw %}`{{ state_attr('sensor.timer1', 'Arm') }}`{% endraw %}.
{% raw %}
```yaml
# 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 %}
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](/docs/automation/trigger/#mqtt-trigger) and process the JSON in the automation directly via the {% raw %}`{{ trigger.payload_json }}`{% endraw %} [trigger data](/docs/automation/templating/#mqtt) for automations that must synchronously handle multiple JSON values within the same MQTT message.
### 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 %}
```yaml
# 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](/integrations/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:
```bash
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 %}
```yaml
# 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](https://github.com/mertenats/open-home-automation/tree/master/ha_mqtt_sensor_dht22). A regular MQTT message from this example looks like this:
```json
office/sensor1
{
"temperature": 23.20,
"humidity": 43.70
}
```
Then use this configuration example to extract the data from the payload:
{% raw %}
```yaml
# Example configuration.yaml entry
mqtt:
sensor:
- name: "Temperature"
state_topic: "office/sensor1"
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](https://github.com/letscontrolit/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.
```bash
home/bathroom/status Connected
...
home/bathroom/analog/brightness 290.00
```
The configuration will look like the example below:
```yaml
# Example configuration.yaml entry
mqtt:
sensor:
- name: "Brightness"
state_topic: "home/bathroom/analog/brightness"
```