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https://github.com/agners/micropython-ha-mqtt-device

MicroPython module which allows to create Entites for HomeAssistant using MQTT Discovery
https://github.com/agners/micropython-ha-mqtt-device

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MicroPython module which allows to create Entites for HomeAssistant using MQTT Discovery

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# MicroPython library to create sensors for HomeAssistant using MQTT Discovery



This is a simple MicroPython library which allows to create sensors and group of

sensors for HomeAssistant. The library makes use of the HomeAssistant [MQTT

Discovery](https://www.home-assistant.io/docs/mqtt/discovery/) method by

announcing the devices through a configuration topic.



## Getting Started



### Prerequisites



* MicroPython board capable of sending MQTT messages

* HomeAssistant with MQTT Broker running

* Some kind of sensor (not mandatory, but useful ;-))



### Usage



#### MQTT Client



First a MQTT Client needs to be created. The module

[umqtt.simple](https://github.com/micropython/micropython-lib/tree/master/umqtt.simple)

provides a simple MQTT client. The module can be installed using upip. Make

sure you are connected to the internet, e.g. using WiFi:



```

import network

wl = network.WLAN(network.STA_IF)

wl.active(True)

wl.connect(, )

wl.config(dhcp_hostname="Testboard")

```



Install the `umqtt.simple` module and create a MQTTClient object:

```

upip.install("micropython-umqtt.simple")

from umqtt.simple import MQTTClient

mqttc = MQTTClient(b"umqtt-testboard", , keepalive=10)

mqttc.connect()

```



#### Basic sensor



This example creates a single sensor and announces values. The second argument

to the `Sensor` constructor is the name argument and will be the entity name in

HomeAssistant. The argument `extra_config` allows to pass additional

configuration values as specified by the [MQTT Sensor

Component](https://www.home-assistant.io/integrations/sensor.mqtt/). In this

case the device class and unit of measurement of the sensor is specified.



With the creation of the Sensor object a persistent MQTT message is sent to the

discovery topic. The configuration will be picked up by HomeAssistant and a

sensor is created. The topic for the entites states update is handled by the

class.



The `publish_state()` function will send the MQTT message to the state topic

which will update the state of the particular entity in HomeAssistant.



```

# Temperature sensor...

import time

temp_config = { "unit_of_measurement": "°C", "device_class": "temperature" }

temp = Sensor(mqttc, b"temperature_sensor", b"sensorid", extra_conf=temp_config)

for i in range(10, 30):

    temp.publish_state(str(i))

    time.sleep(1)



# This deletes the sensor from HomeAssistant as well!

temp.remove_entity()

```



#### Multiple sensors



Multiple entities can share the same MQTT state topic. This allows to send a

single (JSON formatted) MQTT message to update multiple entites in

HomeAssistant. For this each entity needs to have a `value_template` specified

so each entity know which value it needs to parse.



```

group = EntityGroup(mqttc, b"testboard")

sensor1_config = { "unit_of_measurement": "°C", "device_class": "temperature",

    "value_template": "{{ value_json.temperature }}" }

sensor1 = group.create_sensor(b"test1", b"test1id", extra_conf=sensor1_config)



sensor2_config = { "unit_of_measurement": "%", "device_class": "humidity",

    "value_template": "{{ value_json.humidity }}" }

sensor2 = group.create_sensor(b"test2", b"test2id", extra_conf=sensor2_config)

```



To update the group the `publish_state()` function on the group object needs to

be used:

```

for i in range(10, 30):

    group.publish_state({ "temperature": str(i), "humidity": str(10 + i) })

    time.sleep(1)

```



To delete all entities of this group:

```

group.remove_group()

```



#### Multiple sensors with Device registry



HomeAssistant allows to group entites into devices via the [Device

Registry](https://developers.home-assistant.io/docs/device_registry_index/)

concept. MQTT entities allow to use the [device

registry](https://www.home-assistant.io/integrations/sensor.mqtt/#device) to

group individual entities to a device as well.



For this to work a `device` dictionary needs to be added to the configuration

variable. A `unique_id` property with a unique ID for each entity is required

too.



```

device_conf = { "identifiers": [ "common_identifier" ], "name": "Testboard",

    "manufacturer": "MicroPython", "model": "TinyPico", "sw_version": "0.1" }

common_conf = { "device": device_conf }

group = EntityGroup(mqttc, b"testboarder", extra_conf=common_conf)



sensor1_config = { "unit_of_measurement": "°C", "device_class":

    "temperature", "value_template": "{{ value_json.temperature }}"),

    "unique_id": mqtt_status + "sensor1"}

sensor1 = group.create_sensor(b"test1", b"test1id", extra_conf=sensor1_config)



sensor2_config = { "unit_of_measurement": "%", "device_class":

    "humidity", "value_template": "{{ value_json.humidity }}",

    "unique_id": mqtt_status + "sensor2"}

sensor2 = group.create_sensor(b"test2", b"test2id", extra_conf=sensor2_config)

```



Publishing state and removing the group stays the same as regular entity

groups.



#### Using availability topic



MQTT allows to specify a last will message which is sent to the specified topic

when a device does not connect for a certain period. The last will message is

transmitted when connecting, hence this needs to be configured before

connecting. Also choose a keep alive timeout which is higher than your expected

sensor update time. E.g. if you plan to update the sensor value every minute,

a value higher than 60 seconds make sense. The same topic then needs to be

specified when creating the sensor:



```

mqtt_availability_topic = b"testboard/status"

mqttc = MQTTClient(b"umqtt-testboard", , keepalive=70)

mqttc.set_last_will(mqtt_status, b"offline", True)

mqttc.connect()

mqttc.publish(mqtt_status, b"online", retain=True)



temp_config = { "availability_topic": mqtt_availability_topic }

temp = Sensor(mqttc, b"temperature_sensor", b"sensorid", extra_conf=temp_config)

```



## License



This project is licensed under the MIT License - see the

[LICENSE](LICENSE) file for details