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28 lines
992 B
Markdown
28 lines
992 B
Markdown
---
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title: Sensor Entity
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sidebar_label: Sensor
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---
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A sensor is a read-only entity that provides some information. Information has a value and optionally, a unit of measurement.
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## Properties
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> Properties should always only return information from memory and not do I/O (like network requests). Implement `update()` or `async_update()` to fetch data.
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| Name | Type | Default | Description
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| ---- | ---- | ------- | -----------
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| state | string | **Required** | The value of the sensor.
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| unit_of_measurement | string | `None` | The unit of measurement that the sensor is expressed in.
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| device_class | string | `None` | Type of sensor.
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### Available device classes
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If specifying a device class, your sensor entity will need to also return the correct unit of measurement.
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| Type | Unit | Description
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| ---- | ---- | -----------
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| battery | % | % of battery that is left.
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| humidity | % | % of humidity in the air.
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| illuminance | lx/lm | Light level.
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| temperature | C/F | Temperature.
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