MQTT Sensor
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
The configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] file:
# Example configuration.yaml entry
mqtt:
sensor:
- name: "Bedroom Temperature"
state_topic: "home/bedroom/temperature"
Configuration Variables
A list of MQTT topics subscribed to receive availability (online/offline) updates. Must not be used together with availability_topic
.
The payload that represents the available state.
The payload that represents the unavailable state.
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.
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
.
The MQTT topic subscribed to receive availability (online/offline) updates.
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.
A link to the webpage that can manage the configuration of this device. Can be either an http://
, https://
or an internal homeassistant://
URL.
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"]]
.
A list of IDs that uniquely identify the device. For example a serial number.
The type/class of the sensor to set the icon in the frontend. The device_class
can be null
.
Flag which defines if the entity should be enabled when first added.
The encoding of the payloads received. Set to ""
to disable decoding of incoming payload.
The category of the entity. When set, the entity category must be diagnostic
for sensors.
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.
Sends update events even if the value hasn’t changed. Useful if you want to have meaningful value graphs in history.
Defines a template to extract the JSON dictionary from messages received on the json_attributes_topic
.
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.
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.
The name of the MQTT sensor. Can be set to null
if only the device name is relevant.
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
.
The payload that represents the available state.
The payload that represents the unavailable state.
The number of decimals which should be used in the sensor’s state after rounding.
The maximum QoS level to be used when receiving and publishing messages.
The state_class of the sensor.
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
.
An ID that uniquely identifies this sensor. If two sensors have the same unique ID, Home Assistant will raise an exception.
Defines the units of measurement of the sensor, if any. The unit_of_measurement
can be null
.
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.
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"
Or set up via MQTT discovery:
Discovery topic: homeassistant/sensor/hp_1231232/config
{
"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"
]
}
}
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: {{ state_attr('sensor.bs_rssi', 'ClientName') }}
.
# 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"
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.Arm
as an extra attribute, change json_attributes_template
to: "{{ {'Arm': value_json.Timer1} | tojson }}"
.
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: {{ state_attr('sensor.timer1', 'Arm') }}
.
# 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 }}"
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.
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.
# 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 %}
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.
# Example configuration.yaml entry
mqtt:
sensor:
- name: "Battery Tablet"
state_topic: "owntracks/tablet/tablet"
unit_of_measurement: "%"
value_template: "{{ value_json.batt }}"
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
Topic: office/sensor1
{
"temperature": 23.20,
"humidity": 43.70
}
Then use this configuration example to extract the data from the payload:
# 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 }}"
Get sensor value from a device with ESPEasy
Assuming that you have flashed your ESP8266 unit with ESPEasy/
and only contain the name when writing your entry for the configuration.yaml
The configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] 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"