Skip to main content

Bluetooth APIs

Subscribing to Bluetooth discoveries​

Some integrations may need to know when a device is discovered right away. The Bluetooth integration provides a registration API to receive callbacks when a new device is discovered that matches specific key values. The same format for bluetooth in manifest.json is used for matching. In addition to the matchers used in the manifest.json, address can also be used as a matcher.

The function bluetooth.async_register_callback is provided to enable this ability. The function returns a callback that will cancel the registration when called.

The below example shows registering to get callbacks when a Switchbot device is nearby.

from homeassistant.components import bluetooth

...

@callback
def _async_discovered_device(service_info: bluetooth.BluetoothServiceInfoBleak, change: bluetooth.BluetoothChange) -> None:
    """Subscribe to bluetooth changes."""
    _LOGGER.warning("New service_info: %s", service_info)

entry.async_on_unload(
    bluetooth.async_register_callback(
        hass, _async_discovered_device, {"service_uuid": "cba20d00-224d-11e6-9fb8-0002a5d5c51b", "connectable": False}, bluetooth.BluetoothScanningMode.ACTIVE
    )
)

The below example shows registering to get callbacks for HomeKit devices.

from homeassistant.components import bluetooth

...

entry.async_on_unload(
    bluetooth.async_register_callback(
        hass, _async_discovered_homekit_device, {"manufacturer_id": 76, "manufacturer_data_first_byte": 6}, bluetooth.BluetoothScanningMode.ACTIVE
    )
)

The below example shows registering to get callbacks for Nespresso Prodigios.

from homeassistant.components import bluetooth

...

entry.async_on_unload(
    bluetooth.async_register_callback(
        hass, _async_nespresso_found, {"local_name": "Prodigio_*")}, bluetooth.BluetoothScanningMode.ACTIVE
    )
)

The below example shows registering to get callbacks for a device with the address 44:33:11:22:33:22.

from homeassistant.components import bluetooth

...

entry.async_on_unload(
    bluetooth.async_register_callback(
        hass, _async_specific_device_found, {"address": "44:33:11:22:33:22")}, bluetooth.BluetoothScanningMode.ACTIVE
    )
)

Fetch the shared BleakScanner instance​

Integrations that need an instance of a BleakScanner should call the bluetooth.async_get_scanner API. This API returns a wrapper around a single BleakScanner that allows integrations to share without overloading the system.

from homeassistant.components import bluetooth

scanner = bluetooth.async_get_scanner(hass)

Determine if a scanner is running​

The Bluetooth integration may be set up but has no connectable adapters or remotes. The bluetooth.async_scanner_count API can be used to determine if there is a scanner running that will be able to receive advertisements or generate BLEDevices that can be used to connect to the device. An integration may want to raise a more helpful error during setup if there are no scanners that will generate connectable BLEDevice objects.

from homeassistant.components import bluetooth

count = bluetooth.async_scanner_count(hass, connectable=True)

Subscribing to unavailable callbacks​

To get a callback when the Bluetooth stack can no longer see a device, call the bluetooth.async_track_unavailable API. For performance reasons, it may take up to five minutes to get a callback once the device is no longer seen.

If the connectable argument is set to True, if any connectable controller can reach the device, the device will be considered available. If only non-connectable controllers can reach the device, the device will be considered unavailable. If the argument is set to False, the device will be considered available if any controller can see it.

from homeassistant.components import bluetooth

def _unavailable_callback(info: bluetooth.BluetoothServiceInfoBleak) -> None:
    _LOGGER.debug("%s is no longer seen", info.address)

cancel = bluetooth.async_track_unavailable(hass, _unavailable_callback, "44:44:33:11:23:42", connectable=True)

Finding out the availability timeout​

Availability is based on the time since the device's last known broadcast. This timeout is learned automatically based on the device's regular broadcasting pattern. You can find out this with the bluetooth.async_get_learned_advertising_interval API.

from homeassistant.components import bluetooth

learned_interval = bluetooth.async_get_learned_advertising_interval(hass, "44:44:33:11:23:42")

If the advertising interval is not yet known, this will return None. In that case, unavailability tracking will try the fallback interval for that address. The below example returns the interval that has been set manually by an integration:

from homeassistant.components import bluetooth

bluetooth.async_set_fallback_availability_interval(hass, "44:44:33:11:23:42", 64.0)

fallback_interval = bluetooth.async_get_fallback_availability_interval(hass, "44:44:33:11:23:42")

If there is no learned interval or fallback interval for the device, a hardcoded safe default interval is used:

from homeassistant.components import bluetooth

default_fallback_interval = bluetooth.FALLBACK_MAXIMUM_STALE_ADVERTISEMENT_SECONDS

Fetching the bleak BLEDevice from the address​

Integrations should avoid the overhead of starting an additional scanner to resolve the address by calling the bluetooth.async_ble_device_from_address API, which returns a BLEDevice for the nearest configured bluetooth adapter that can reach the device. If no adapters can reach the device, the bluetooth.async_ble_device_from_address API, will return None.

Suppose the integration wants to receive data from connectable and non-connectable controllers. In that case, it can exchange the BLEDevice for a connectable one when it wants to make an outgoing connection as long as at least one connectable controller is in range.

from homeassistant.components import bluetooth

ble_device = bluetooth.async_ble_device_from_address(hass, "44:44:33:11:23:42", connectable=True)

Fetching the latest BluetoothServiceInfoBleak for a device​

The latest advertisement and device data are available with the bluetooth.async_last_service_info API, which returns a BluetoothServiceInfoBleak from the scanner with the best RSSI of the requested connectable type.

from homeassistant.components import bluetooth

service_info = bluetooth.async_last_service_info(hass, "44:44:33:11:23:42", connectable=True)

Checking if a device is present​

To determine if a device is still present, call the bluetooth.async_address_present API. This call is helpful if your integration needs the device to be present to consider it available.

from homeassistant.components import bluetooth

bluetooth.async_address_present(hass, "44:44:33:11:23:42", connectable=True)

Fetching all discovered devices​

To access the list of previous discoveries, call the bluetooth.async_discovered_service_info API. Only devices that are still present will be in the cache.

from homeassistant.components import bluetooth

service_infos = bluetooth.async_discovered_service_info(hass, connectable=True)

Fetching all discovered devices and advertisement data by each Bluetooth adapter​

To access the list of previous discoveries and advertisement data received by each adapter independently, call the bluetooth.async_scanner_devices_by_address API. The call returns a list of BluetoothScannerDevice objects. The same device and advertisement data may appear multiple times, once per Bluetooth adapter that reached it.

from homeassistant.components import bluetooth

device = bluetooth.async_scanner_devices_by_address(hass, "44:44:33:11:23:42", connectable=True)
# device.ble_device is a bleak `BLEDevice`
# device.advertisement is a bleak `AdvertisementData`
# device.scanner is the scanner that found the device

Triggering rediscovery of devices​

When a configuration entry or device is removed from Home Assistant, trigger rediscovery of its address to make sure they are available to be set up without restarting Home Assistant. You can make use of the Bluetooth connection property of the device registry if your integration manages multiple devices per configuration entry.


from homeassistant.components import bluetooth

bluetooth.async_rediscover_address(hass, "44:44:33:11:23:42")

Waiting for a specific advertisement​

To wait for a specific advertisement, call the bluetooth.async_process_advertisements API.

from homeassistant.components import bluetooth

def _process_more_advertisements(
    service_info: BluetoothServiceInfoBleak,
) -> bool:
    """Wait for an advertisement with 323 in the manufacturer_data."""
    return 323 in service_info.manufacturer_data

service_info = await bluetooth.async_process_advertisements(
    hass,
    _process_more_advertisements,
    {"address": discovery_info.address, "connectable": False},
    BluetoothScanningMode.ACTIVE,
    ADDITIONAL_DISCOVERY_TIMEOUT
)

Registering an external scanner​

Integrations that provide a Bluetooth adapter should add bluetooth in dependencies in their manifest.json and be added to after_dependencies to the bluetooth_adapters integration.

To register an external scanner, call the bluetooth.async_register_scanner API. The scanner must inherit from BaseHaScanner.

If the scanner needs connection slot management to avoid overloading the adapter, pass the number of connection slots as an integer value via the connection_slots argument.

from homeassistant.components import bluetooth

cancel = bluetooth.async_register_scanner(hass, scanner, connection_slots=slots)

The scanner will need to feed advertisement data to the central Bluetooth manager in the form of BluetoothServiceInfoBleak objects. The callback needed to send the data to the central manager can be obtained with the bluetooth.async_get_advertisement_callback API.

callback = bluetooth.async_get_advertisement_callback(hass)

callback(BluetoothServiceInfoBleak(...))