developers.home-assistant/docs/bluetooth.md

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Bluetooth	Building a Bluetooth integration

Best practices for integration authors

• Integrations that need to use a Bluetooth adapter should add bluetooth_adapters in dependencies in their manifest.json. The manifest.json entry ensures that all supported remote adapters are connected before the integration tries to use them.

• Call the bluetooth.async_get_scanner API to get a BleakScanner instance and pass it to your library. The returned scanner avoids the overhead of running multiple scanners, which is significant. Additionally, the wrapped scanner will continue functioning if the user changes the Bluetooth adapter settings.

• Avoid reusing a BleakClient between connections since this will make connecting less reliable.

• Use a connection timeout of at least ten (10) seconds as BlueZ must resolve services when connecting to a new or updated device for the first time. Transient connection errors are frequent when connecting, and connections are not always successful on the first attempt. The bleak-retry-connector PyPI package can take the guesswork out of quickly and reliably establishing a connection to a device.

Connectable and non-connectable Bluetooth controllers

Home Assistant has support for remote Bluetooth controllers. Some controllers only support listening for advertisement data and do not support connecting to devices. Since many devices only need to receive advertisements, we have the concept of connectable devices and non-connectable devices. Suppose the device does not require an active connection. In that case, the connectable argument should be set to False to opt-in on receiving data from controllers that do not support making outgoing connections. When connectable is set to False, data from connectable and non-connectable controllers will be provided.

The default value for connectable is True. If the integration has some devices that require connections and some devices that do not, the manifest.json should set the flag appropriately for the device. If it is impossible to construct a matcher to differentiate between similar devices, check the connectable property in the config flow discovery BluetoothServiceInfoBleak and reject flows for devices needing outgoing connections.