Merge pull request #936 from google/gbg/usb-transport-packet-splitter

usb transport packet splitter

apps/bench.py

@@ -489,7 +489,7 @@ class Sender:
                         flags=(
                             Packet.PacketFlags.LAST
                             if tx_i == self.tx_packet_count - 1
-                            else 0
+                            else Packet.PacketFlags(0)
                         ),
                         sequence=tx_i,
                         timestamp=int((time.time() - self.start_time) * 1000000),

apps/controller_info.py

@@ -45,8 +45,10 @@ from bumble.hci import (
     HCI_Read_Local_Supported_Codecs_Command,
     HCI_Read_Local_Supported_Codecs_V2_Command,
     HCI_Read_Local_Version_Information_Command,
+    HCI_Read_Voice_Setting_Command,
     LeFeature,
     SpecificationVersion,
+    VoiceSetting,
     map_null_terminated_utf8_string,
 )
 from bumble.host import Host
@@ -214,6 +216,16 @@ async def get_codecs_info(host: Host) -> None:
         if not response2.vendor_specific_codec_ids:
             print('  No Vendor-specific codecs')
 
+    if host.supports_command(HCI_Read_Voice_Setting_Command.op_code):
+        response3 = await host.send_sync_command(HCI_Read_Voice_Setting_Command())
+        voice_setting = VoiceSetting.from_int(response3.voice_setting)
+        print(color('Voice Setting:', 'yellow'))
+        print(f'  Air Coding Format:       {voice_setting.air_coding_format.name}')
+        print(f'  Linear PCM Bit Position: {voice_setting.linear_pcm_bit_position}')
+        print(f'  Input Sample Size:       {voice_setting.input_sample_size.name}')
+        print(f'  Input Data Format:       {voice_setting.input_data_format.name}')
+        print(f'  Input Coding Format:     {voice_setting.input_coding_format.name}')
+
 
 # -----------------------------------------------------------------------------
 async def async_main(

apps/controller_loopback.py

@@ -16,6 +16,8 @@
 # Imports
 # -----------------------------------------------------------------------------
 import asyncio
+import statistics
+import struct
 import time
 
 import click
@@ -25,7 +27,9 @@ from bumble.colors import color
 from bumble.hci import (
     HCI_READ_LOOPBACK_MODE_COMMAND,
     HCI_WRITE_LOOPBACK_MODE_COMMAND,
+    Address,
     HCI_Read_Loopback_Mode_Command,
+    HCI_SynchronousDataPacket,
     HCI_Write_Loopback_Mode_Command,
     LoopbackMode,
 )
@@ -36,55 +40,121 @@ from bumble.transport import open_transport
 class Loopback:
     """Send and receive ACL data packets in local loopback mode"""
 
-    def __init__(self, packet_size: int, packet_count: int, transport: str):
+    def __init__(
+        self,
+        packet_size: int,
+        packet_count: int,
+        connection_type: str,
+        mode: str,
+        interval: int,
+        transport: str,
+    ):
         self.transport = transport
         self.packet_size = packet_size
         self.packet_count = packet_count
         self.connection_handle: int | None = None
+        self.connection_type = connection_type
         self.connection_event = asyncio.Event()
+        self.mode = mode
+        self.interval = interval
         self.done = asyncio.Event()
-        self.expected_cid = 0
+        self.expected_counter = 0
         self.bytes_received = 0
         self.start_timestamp = 0.0
         self.last_timestamp = 0.0
+        self.send_timestamps: list[float] = []
+        self.rtts: list[float] = []
 
     def on_connection(self, connection_handle: int, *args):
         """Retrieve connection handle from new connection event"""
         if not self.connection_event.is_set():
-            # save first connection handle for ACL
+            # The first connection handle is of type ACL,
-            # subsequent connections are SCO
+            # subsequent connections are of type SCO
+            if self.connection_type == "sco" and self.connection_handle is None:
+                self.connection_handle = connection_handle
+                return
+
             self.connection_handle = connection_handle
             self.connection_event.set()
 
-    def on_l2cap_pdu(self, connection_handle: int, cid: int, pdu: bytes):
+    def on_sco_connection(
+        self,
+        address: Address,
+        connection_handle: int,
+        link_type,
+        rx_packet_length: int,
+        tx_packet_length: int,
+        air_mode: int,
+    ) -> None:
+        self.on_connection(connection_handle)
+
+    def on_packet(self, connection_handle: int, packet: bytes):
         """Calculate packet receive speed"""
         now = time.time()
-        print(f'<<< Received packet {cid}: {len(pdu)} bytes')
+        (counter,) = struct.unpack_from("H", packet, 0)
+        rtt = now - self.send_timestamps[counter]
+        self.rtts.append(rtt)
+        print(f'<<< Received packet {counter}: {len(packet)} bytes, RTT={rtt:.4f}')
         assert connection_handle == self.connection_handle
-        assert cid == self.expected_cid
+        assert counter == self.expected_counter
-        self.expected_cid += 1
+        self.expected_counter += 1
-        if cid == 0:
+        if counter == 0:
             self.start_timestamp = now
         else:
             elapsed_since_start = now - self.start_timestamp
             elapsed_since_last = now - self.last_timestamp
-            self.bytes_received += len(pdu)
+            self.bytes_received += len(packet)
-            instant_rx_speed = len(pdu) / elapsed_since_last
+            instant_rx_speed = len(packet) / elapsed_since_last
             average_rx_speed = self.bytes_received / elapsed_since_start
+            if self.mode == 'throughput':
                 print(
                     color(
                         f'@@@ RX speed: instant={instant_rx_speed:.4f},'
-                    f' average={average_rx_speed:.4f}',
+                        f' average={average_rx_speed:.4f},',
                         'cyan',
                     )
                 )
 
         self.last_timestamp = now
 
-        if self.expected_cid == self.packet_count:
+        if self.expected_counter == self.packet_count:
             print(color('@@@ Received last packet', 'green'))
             self.done.set()
 
+    def on_l2cap_pdu(self, connection_handle: int, cid: int, pdu: bytes):
+        self.on_packet(connection_handle, pdu)
+
+    def on_sco_packet(self, connection_handle: int, packet) -> None:
+        self.on_packet(connection_handle, packet)
+
+    async def send_acl_packet(self, host: Host, packet: bytes) -> None:
+        assert self.connection_handle
+        host.send_l2cap_pdu(self.connection_handle, 0, packet)
+
+    async def send_sco_packet(self, host: Host, packet: bytes) -> None:
+        assert self.connection_handle
+        host.send_hci_packet(
+            HCI_SynchronousDataPacket(
+                connection_handle=self.connection_handle,
+                packet_status=HCI_SynchronousDataPacket.Status.CORRECTLY_RECEIVED_DATA,
+                data_total_length=len(packet),
+                data=packet,
+            )
+        )
+
+    async def send_loop(self, host: Host, sender) -> None:
+        for counter in range(0, self.packet_count):
+            print(
+                color(
+                    f'>>> Sending {self.connection_type.upper()} '
+                    f'packet {counter}: {self.packet_size} bytes',
+                    'yellow',
+                )
+            )
+            self.send_timestamps.append(time.time())
+            await sender(host, struct.pack("H", counter) + bytes(self.packet_size - 2))
+            await asyncio.sleep(self.interval / 1000 if self.mode == "rtt" else 0)
+
     async def run(self) -> None:
         """Run a loopback throughput test"""
         print(color('>>> Connecting to HCI...', 'green'))
@@ -126,8 +196,11 @@ class Loopback:
                 return
 
             # set event callbacks
-            host.on('connection', self.on_connection)
+            host.on('classic_connection', self.on_connection)
+            host.on('le_connection', self.on_connection)
+            host.on('sco_connection', self.on_sco_connection)
             host.on('l2cap_pdu', self.on_l2cap_pdu)
+            host.on('sco_packet', self.on_sco_packet)
 
             loopback_mode = LoopbackMode.LOCAL
 
@@ -148,32 +221,37 @@ class Loopback:
 
             print(color('=== Start sending', 'magenta'))
             start_time = time.time()
-            bytes_sent = 0
+            if self.connection_type == "acl":
-            for cid in range(0, self.packet_count):
+                sender = self.send_acl_packet
-                # using the cid as an incremental index
+            elif self.connection_type == "sco":
-                host.send_l2cap_pdu(
+                sender = self.send_sco_packet
-                    self.connection_handle, cid, bytes(self.packet_size)
+            else:
-                )
+                raise ValueError(f'Unknown connection type: {self.connection_type}')
-                print(
+            await self.send_loop(host, sender)
-                    color(
-                        f'>>> Sending packet {cid}: {self.packet_size} bytes', 'yellow'
-                    )
-                )
-                bytes_sent += self.packet_size  # don't count L2CAP or HCI header sizes
-                await asyncio.sleep(0)  # yield to allow packet receive
 
             await self.done.wait()
             print(color('=== Done!', 'magenta'))
 
+            bytes_sent = self.packet_size * self.packet_count
             elapsed = time.time() - start_time
             average_tx_speed = bytes_sent / elapsed
+            if self.mode == 'throughput':
                 print(
                     color(
-                    f'@@@ TX speed: average={average_tx_speed:.4f} ({bytes_sent} bytes'
+                        f'@@@ TX speed: average={average_tx_speed:.4f} '
-                    f' in {elapsed:.2f} seconds)',
+                        f'({bytes_sent} bytes in {elapsed:.2f} seconds)',
                         'green',
                     )
                 )
+            if self.mode == 'rtt':
+                print(
+                    color(
+                        f'RTTs: min={min(self.rtts):.4f}, '
+                        f'max={max(self.rtts):.4f}, '
+                        f'avg={statistics.mean(self.rtts):.4f}',
+                        'blue',
+                    )
+                )
 
 
 # -----------------------------------------------------------------------------
@@ -194,11 +272,43 @@ class Loopback:
     default=10,
     help='Packet count',
 )
+@click.option(
+    '--connection-type',
+    '-t',
+    metavar='TYPE',
+    type=click.Choice(['acl', 'sco']),
+    default='acl',
+    help='Connection type',
+)
+@click.option(
+    '--mode',
+    '-m',
+    metavar='MODE',
+    type=click.Choice(['throughput', 'rtt']),
+    default='throughput',
+    help='Test mode',
+)
+@click.option(
+    '--interval',
+    type=int,
+    default=100,
+    help='Inter-packet interval (ms) [RTT mode only]',
+)
 @click.argument('transport')
-def main(packet_size, packet_count, transport):
+def main(packet_size, packet_count, connection_type, mode, interval, transport):
     bumble.logging.setup_basic_logging()
-    loopback = Loopback(packet_size, packet_count, transport)
+
-    asyncio.run(loopback.run())
+    if connection_type == "sco" and packet_size > 255:
+        print("ERROR: the maximum packet size for SCO is 255")
+        return
+
+    async def run():
+        loopback = Loopback(
+            packet_size, packet_count, connection_type, mode, interval, transport
+        )
+        await loopback.run()
+
+    asyncio.run(run())
 
 
 # -----------------------------------------------------------------------------

apps/usb_probe.py

@@ -111,9 +111,14 @@ def show_device_details(device):
                         if (endpoint.getAddress() & USB_ENDPOINT_IN == 0)
                         else 'IN'
                     )
+                    endpoint_details = (
+                        f', Max Packet Size = {endpoint.getMaxPacketSize()}'
+                        if endpoint_type == 'ISOCHRONOUS'
+                        else ''
+                    )
                     print(
                         f'        Endpoint 0x{endpoint.getAddress():02X}: '
-                        f'{endpoint_type} {endpoint_direction}'
+                        f'{endpoint_type} {endpoint_direction}{endpoint_details}'
                     )
 
 

bumble/device.py

@@ -1423,6 +1423,9 @@ class ScoLink(utils.CompositeEventEmitter):
     acl_connection: Connection
     handle: int
     link_type: int
+    rx_packet_length: int
+    tx_packet_length: int
+    air_mode: hci.CodecID
     sink: Callable[[hci.HCI_SynchronousDataPacket], Any] | None = None
 
     EVENT_DISCONNECTION: ClassVar[str] = "disconnection"
@@ -6049,7 +6052,7 @@ class Device(utils.CompositeEventEmitter):
     def on_connection_request(
         self, bd_addr: hci.Address, class_of_device: int, link_type: int
     ):
-        logger.debug(f'*** Connection request: {bd_addr}')
+        logger.debug(f'*** Connection request: {bd_addr} link_type={link_type}')
 
         # Handle SCO request.
         if link_type in (
@@ -6059,6 +6062,7 @@ class Device(utils.CompositeEventEmitter):
             if connection := self.find_connection_by_bd_addr(
                 bd_addr, transport=PhysicalTransport.BR_EDR
             ):
+                connection.emit(self.EVENT_SCO_REQUEST, link_type)
                 self.emit(self.EVENT_SCO_REQUEST, connection, link_type)
             else:
                 logger.error(f'SCO request from a non-connected device {bd_addr}')
@@ -6418,7 +6422,6 @@ class Device(utils.CompositeEventEmitter):
             logger.warning('peer name is not valid UTF-8')
             if connection:
                 connection.emit(connection.EVENT_REMOTE_NAME_FAILURE, error)
-            else:
             self.emit(self.EVENT_REMOTE_NAME_FAILURE, address, error)
 
     # [Classic only]
@@ -6436,7 +6439,13 @@ class Device(utils.CompositeEventEmitter):
     @with_connection_from_address
     @utils.experimental('Only for testing.')
     def on_sco_connection(
-        self, acl_connection: Connection, sco_handle: int, link_type: int
+        self,
+        acl_connection: Connection,
+        sco_handle: int,
+        link_type: int,
+        rx_packet_length: int,
+        tx_packet_length: int,
+        air_mode: int,
     ) -> None:
         logger.debug(
             f'*** SCO connected: {acl_connection.peer_address}, '
@@ -6448,7 +6457,11 @@ class Device(utils.CompositeEventEmitter):
             acl_connection=acl_connection,
             handle=sco_handle,
             link_type=link_type,
+            rx_packet_length=rx_packet_length,
+            tx_packet_length=tx_packet_length,
+            air_mode=hci.CodecID(air_mode),
         )
+        acl_connection.emit(self.EVENT_SCO_CONNECTION, sco_link)
         self.emit(self.EVENT_SCO_CONNECTION, sco_link)
 
     # [Classic only]
@@ -6459,7 +6472,8 @@ class Device(utils.CompositeEventEmitter):
         self, acl_connection: Connection, status: int
     ) -> None:
         logger.debug(f'*** SCO connection failure: {acl_connection.peer_address}***')
-        self.emit(self.EVENT_SCO_CONNECTION_FAILURE)
+        acl_connection.emit(self.EVENT_SCO_CONNECTION_FAILURE, status)
+        self.emit(self.EVENT_SCO_CONNECTION_FAILURE, status)
 
     # [Classic only]
     @host_event_handler
@@ -6922,15 +6936,18 @@ class Device(utils.CompositeEventEmitter):
     @with_connection_from_address
     def on_classic_pairing(self, connection: Connection) -> None:
         connection.emit(connection.EVENT_CLASSIC_PAIRING)
+        self.emit(connection.EVENT_CLASSIC_PAIRING, connection)
 
     # [Classic only]
     @host_event_handler
     @with_connection_from_address
     def on_classic_pairing_failure(self, connection: Connection, status: int) -> None:
         connection.emit(connection.EVENT_CLASSIC_PAIRING_FAILURE, status)
+        self.emit(connection.EVENT_CLASSIC_PAIRING_FAILURE, connection, status)
 
     def on_pairing_start(self, connection: Connection) -> None:
         connection.emit(connection.EVENT_PAIRING_START)
+        self.emit(connection.EVENT_PAIRING_START, connection)
 
     def on_pairing(
         self,

bumble/hci.py

@@ -1721,6 +1721,15 @@ class CodecID(SpecableEnum):
     VENDOR_SPECIFIC = 0xFF
 
 
+# From Bluetooth Assigned Numbers, 2.10 PCM_Data_Format
+class PcmDataFormat(SpecableEnum):
+    NA = 0x00
+    ONES_COMPLEMENT = 0x01
+    TWOS_COMPLEMENT = 0x02
+    SIGN_MAGNITUDE = 0x03
+    UNSIGNED = 0x04
+
+
 @dataclasses.dataclass(frozen=True)
 class CodingFormat:
     codec_id: CodecID
@@ -1729,7 +1738,7 @@ class CodingFormat:
 
     @classmethod
     def parse_from_bytes(cls, data: bytes, offset: int) -> tuple[int, CodingFormat]:
-        (codec_id, company_id, vendor_specific_codec_id) = struct.unpack_from(
+        codec_id, company_id, vendor_specific_codec_id = struct.unpack_from(
             '<BHH', data, offset
         )
         return offset + 5, cls(
@@ -1748,6 +1757,61 @@ class CodingFormat:
         )
 
 
+@dataclasses.dataclass(frozen=True)
+class VoiceSetting:
+    class AirCodingFormat(enum.IntEnum):
+        CVSD = 0
+        U_LAW = 1
+        A_LAW = 2
+        TRANSPARENT_DATA = 3
+
+    class InputSampleSize(enum.IntEnum):
+        SIZE_8_BITS = 0
+        SIZE_16_BITS = 1
+
+    class InputDataFormat(enum.IntEnum):
+        ONES_COMPLEMENT = 0
+        TWOS_COMPLEMENT = 1
+        SIGN_AND_MAGNITUDE = 2
+        UNSIGNED = 3
+
+    class InputCodingFormat(enum.IntEnum):
+        LINEAR = 0
+        U_LAW = 1
+        A_LAW = 2
+        RESERVED = 3
+
+    air_coding_format: AirCodingFormat = AirCodingFormat.CVSD
+    linear_pcm_bit_position: int = 0
+    input_sample_size: InputSampleSize = InputSampleSize.SIZE_8_BITS
+    input_data_format: InputDataFormat = InputDataFormat.ONES_COMPLEMENT
+    input_coding_format: InputCodingFormat = InputCodingFormat.LINEAR
+
+    @classmethod
+    def from_int(cls, value: int) -> VoiceSetting:
+        air_coding_format = cls.AirCodingFormat(value & 0b11)
+        linear_pcm_bit_position = (value >> 2) & 0b111
+        input_sample_size = cls.InputSampleSize((value >> 5) & 0b1)
+        input_data_format = cls.InputDataFormat((value >> 6) & 0b11)
+        input_coding_format = cls.InputCodingFormat((value >> 8) & 0b11)
+        return cls(
+            air_coding_format=air_coding_format,
+            linear_pcm_bit_position=linear_pcm_bit_position,
+            input_sample_size=input_sample_size,
+            input_data_format=input_data_format,
+            input_coding_format=input_coding_format,
+        )
+
+    def __int__(self) -> int:
+        return (
+            self.air_coding_format
+            | (self.linear_pcm_bit_position << 2)
+            | (self.input_sample_size << 5)
+            | (self.input_data_format << 6)
+            | (self.input_coding_format << 8)
+        )
+
+
 # -----------------------------------------------------------------------------
 class HCI_Constant:
     @staticmethod
@@ -2008,7 +2072,7 @@ class HCI_Object:
                 )
                 continue
 
-            (field_name, field_type) = object_field
+            field_name, field_type = object_field
             result += HCI_Object.serialize_field(hci_object[field_name], field_type)
 
         return bytes(result)
@@ -2886,6 +2950,23 @@ class HCI_Read_Clock_Offset_Command(HCI_AsyncCommand):
     connection_handle: int = field(metadata=metadata(2))
 
 
+# -----------------------------------------------------------------------------
+@HCI_Command.command
+@dataclasses.dataclass
+class HCI_Accept_Synchronous_Connection_Request_Command(HCI_AsyncCommand):
+    '''
+    See Bluetooth spec @ 7.1.27 Accept Synchronous Connection Request Command
+    '''
+
+    bd_addr: Address = field(metadata=metadata(Address.parse_address))
+    transmit_bandwidth: int = field(metadata=metadata(4))
+    receive_bandwidth: int = field(metadata=metadata(4))
+    max_latency: int = field(metadata=metadata(2))
+    voice_setting: int = field(metadata=metadata(2))
+    retransmission_effort: int = field(metadata=metadata(1))
+    packet_type: int = field(metadata=metadata(2))
+
+
 # -----------------------------------------------------------------------------
 @HCI_Command.command
 @dataclasses.dataclass
@@ -3034,8 +3115,8 @@ class HCI_Enhanced_Setup_Synchronous_Connection_Command(HCI_AsyncCommand):
     output_coding_format: int = field(metadata=metadata(CodingFormat.parse_from_bytes))
     input_coded_data_size: int = field(metadata=metadata(2))
     output_coded_data_size: int = field(metadata=metadata(2))
-    input_pcm_data_format: int = field(metadata=metadata(1))
+    input_pcm_data_format: int = field(metadata=PcmDataFormat.type_metadata(1))
-    output_pcm_data_format: int = field(metadata=metadata(1))
+    output_pcm_data_format: int = field(metadata=PcmDataFormat.type_metadata(1))
     input_pcm_sample_payload_msb_position: int = field(metadata=metadata(1))
     output_pcm_sample_payload_msb_position: int = field(metadata=metadata(1))
     input_data_path: int = field(metadata=metadata(1))
@@ -3046,13 +3127,6 @@ class HCI_Enhanced_Setup_Synchronous_Connection_Command(HCI_AsyncCommand):
     packet_type: int = field(metadata=metadata(2))
     retransmission_effort: int = field(metadata=metadata(1))
 
-    class PcmDataFormat(SpecableEnum):
-        NA = 0x00
-        ONES_COMPLEMENT = 0x01
-        TWOS_COMPLEMENT = 0x02
-        SIGN_MAGNITUDE = 0x03
-        UNSIGNED = 0x04
-
     class DataPath(SpecableEnum):
         HCI = 0x00
         PCM = 0x01
@@ -3099,8 +3173,8 @@ class HCI_Enhanced_Accept_Synchronous_Connection_Request_Command(HCI_AsyncComman
     output_coding_format: int = field(metadata=metadata(CodingFormat.parse_from_bytes))
     input_coded_data_size: int = field(metadata=metadata(2))
     output_coded_data_size: int = field(metadata=metadata(2))
-    input_pcm_data_format: int = field(metadata=metadata(1))
+    input_pcm_data_format: int = field(metadata=PcmDataFormat.type_metadata(1))
-    output_pcm_data_format: int = field(metadata=metadata(1))
+    output_pcm_data_format: int = field(metadata=PcmDataFormat.type_metadata(1))
     input_pcm_sample_payload_msb_position: int = field(metadata=metadata(1))
     output_pcm_sample_payload_msb_position: int = field(metadata=metadata(1))
     input_data_path: int = field(metadata=metadata(1))
@@ -3944,6 +4018,23 @@ class HCI_Read_Local_OOB_Extended_Data_Command(
     '''
 
 
+# -----------------------------------------------------------------------------
+@HCI_SyncCommand.sync_command(HCI_StatusReturnParameters)
+@dataclasses.dataclass
+class HCI_Configure_Data_Path_Command(HCI_SyncCommand[HCI_StatusReturnParameters]):
+    '''
+    See Bluetooth spec @ 7.3.101 Configure Data Path Command
+    '''
+
+    class DataPathDirection(SpecableEnum):
+        INPUT = 0x00
+        OUTPUT = 0x01
+
+    data_path_direction: DataPathDirection = field(metadata=metadata(1))
+    data_path_id: int = field(metadata=metadata(1))
+    vendor_specific_config: bytes = field(metadata=metadata('*'))
+
+
 # -----------------------------------------------------------------------------
 @dataclasses.dataclass
 class HCI_Read_Local_Version_Information_ReturnParameters(HCI_StatusReturnParameters):
@@ -7334,7 +7425,7 @@ class HCI_Connection_Complete_Event(HCI_Event):
     status: int = field(metadata=metadata(STATUS_SPEC))
     connection_handle: int = field(metadata=metadata(2))
     bd_addr: Address = field(metadata=metadata(Address.parse_address))
-    link_type: int = field(metadata=LinkType.type_metadata(1))
+    link_type: LinkType = field(metadata=LinkType.type_metadata(1))
     encryption_enabled: int = field(metadata=metadata(1))
 
 
@@ -7730,12 +7821,6 @@ class HCI_Synchronous_Connection_Complete_Event(HCI_Event):
         SCO = 0x00
         ESCO = 0x02
 
-    class AirMode(SpecableEnum):
-        U_LAW_LOG = 0x00
-        A_LAW_LOG_AIR_MORE = 0x01
-        CVSD = 0x02
-        TRANSPARENT_DATA = 0x03
-
     status: int = field(metadata=metadata(STATUS_SPEC))
     connection_handle: int = field(metadata=metadata(2))
     bd_addr: Address = field(metadata=metadata(Address.parse_address))
@@ -7744,7 +7829,7 @@ class HCI_Synchronous_Connection_Complete_Event(HCI_Event):
     retransmission_window: int = field(metadata=metadata(1))
     rx_packet_length: int = field(metadata=metadata(2))
     tx_packet_length: int = field(metadata=metadata(2))
-    air_mode: int = field(metadata=AirMode.type_metadata(1))
+    air_mode: int = field(metadata=CodecID.type_metadata(1))
 
 
 # -----------------------------------------------------------------------------
@@ -7976,7 +8061,9 @@ class HCI_AclDataPacket(HCI_Packet):
         bc_flag = (h >> 14) & 3
         data = packet[5:]
         if len(data) != data_total_length:
-            raise InvalidPacketError('invalid packet length')
+            raise InvalidPacketError(
+                f'invalid packet length {len(data)} != {data_total_length}'
+            )
         return cls(
             connection_handle=connection_handle,
             pb_flag=pb_flag,
@@ -8009,10 +8096,16 @@ class HCI_SynchronousDataPacket(HCI_Packet):
     See Bluetooth spec @ 5.4.3 HCI SCO Data Packets
     '''
 
+    class Status(enum.IntEnum):
+        CORRECTLY_RECEIVED_DATA = 0b00
+        POSSIBLY_INVALID_DATA = 0b01
+        NO_DATA = 0b10
+        DATA_PARTIALLY_LOST = 0b11
+
     hci_packet_type = HCI_SYNCHRONOUS_DATA_PACKET
 
     connection_handle: int
-    packet_status: int
+    packet_status: Status
     data_total_length: int
     data: bytes
 
@@ -8021,7 +8114,7 @@ class HCI_SynchronousDataPacket(HCI_Packet):
         # Read the header
         h, data_total_length = struct.unpack_from('<HB', packet, 1)
         connection_handle = h & 0xFFF
-        packet_status = (h >> 12) & 0b11
+        packet_status = cls.Status((h >> 12) & 0b11)
         data = packet[4:]
         if len(data) != data_total_length:
             raise InvalidPacketError(
@@ -8045,7 +8138,7 @@ class HCI_SynchronousDataPacket(HCI_Packet):
         return (
             f'{color("SCO", "blue")}: '
             f'handle=0x{self.connection_handle:04x}, '
-            f'ps={self.packet_status}, '
+            f'ps={self.packet_status.name}, '
             f'data_total_length={self.data_total_length}, '
             f'data={self.data.hex()}'
         )
@@ -8073,8 +8166,8 @@ class HCI_IsoDataPacket(HCI_Packet):
     def __post_init__(self) -> None:
         self.ts_flag = self.time_stamp is not None
 
-    @staticmethod
+    @classmethod
-    def from_bytes(packet: bytes) -> HCI_IsoDataPacket:
+    def from_bytes(cls, packet: bytes) -> HCI_IsoDataPacket:
         time_stamp: int | None = None
         packet_sequence_number: int | None = None
         iso_sdu_length: int | None = None
@@ -8103,7 +8196,7 @@ class HCI_IsoDataPacket(HCI_Packet):
             pos += 4
 
         iso_sdu_fragment = packet[pos:]
-        return HCI_IsoDataPacket(
+        return cls(
             connection_handle=connection_handle,
             pb_flag=pb_flag,
             ts_flag=ts_flag,

bumble/hfp.py

@@ -44,6 +44,7 @@ from bumble.hci import (
     CodecID,
     CodingFormat,
     HCI_Enhanced_Setup_Synchronous_Connection_Command,
+    PcmDataFormat,
 )
 
 # -----------------------------------------------------------------------------
@@ -177,7 +178,7 @@ class AgFeature(enum.IntFlag):
     VOICE_RECOGNITION_TEXT = 0x2000
 
 
-class AudioCodec(enum.IntEnum):
+class AudioCodec(utils.OpenIntEnum):
     """
     Audio Codec IDs (normative).
 
@@ -189,7 +190,7 @@ class AudioCodec(enum.IntEnum):
     LC3_SWB = 0x03  # Support for LC3-SWB audio codec
 
 
-class HfIndicator(enum.IntEnum):
+class HfIndicator(utils.OpenIntEnum):
     """
     HF Indicators (normative).
 
@@ -218,7 +219,7 @@ class CallHoldOperation(enum.Enum):
     )
 
 
-class ResponseHoldStatus(enum.IntEnum):
+class ResponseHoldStatus(utils.OpenIntEnum):
     """
     Response Hold status (normative).
 
@@ -246,7 +247,7 @@ class AgIndicator(enum.Enum):
     BATTERY_CHARGE = 'battchg'
 
 
-class CallSetupAgIndicator(enum.IntEnum):
+class CallSetupAgIndicator(utils.OpenIntEnum):
     """
     Values for the Call Setup AG indicator (normative).
 
@@ -259,7 +260,7 @@ class CallSetupAgIndicator(enum.IntEnum):
     REMOTE_ALERTED = 3  # Remote party alerted in an outgoing call
 
 
-class CallHeldAgIndicator(enum.IntEnum):
+class CallHeldAgIndicator(utils.OpenIntEnum):
     """
     Values for the Call Held AG indicator (normative).
 
@@ -273,7 +274,7 @@ class CallHeldAgIndicator(enum.IntEnum):
     CALL_ON_HOLD_NO_ACTIVE_CALL = 2  # Call on hold, no active call
 
 
-class CallInfoDirection(enum.IntEnum):
+class CallInfoDirection(utils.OpenIntEnum):
     """
     Call Info direction (normative).
 
@@ -284,7 +285,7 @@ class CallInfoDirection(enum.IntEnum):
     MOBILE_TERMINATED_CALL = 1
 
 
-class CallInfoStatus(enum.IntEnum):
+class CallInfoStatus(utils.OpenIntEnum):
     """
     Call Info status (normative).
 
@@ -299,7 +300,7 @@ class CallInfoStatus(enum.IntEnum):
     WAITING = 5
 
 
-class CallInfoMode(enum.IntEnum):
+class CallInfoMode(utils.OpenIntEnum):
     """
     Call Info mode (normative).
 
@@ -312,7 +313,7 @@ class CallInfoMode(enum.IntEnum):
     UNKNOWN = 9
 
 
-class CallInfoMultiParty(enum.IntEnum):
+class CallInfoMultiParty(utils.OpenIntEnum):
     """
     Call Info Multi-Party state (normative).
 
@@ -399,7 +400,7 @@ class CallLineIdentification:
         )
 
 
-class VoiceRecognitionState(enum.IntEnum):
+class VoiceRecognitionState(utils.OpenIntEnum):
     """
     vrec values provided in AT+BVRA command.
 
@@ -412,7 +413,7 @@ class VoiceRecognitionState(enum.IntEnum):
     ENHANCED_READY = 2
 
 
-class CmeError(enum.IntEnum):
+class CmeError(utils.OpenIntEnum):
     """
     CME ERROR codes (partial listed).
 
@@ -1606,7 +1607,7 @@ class AgProtocol(utils.EventEmitter):
 # -----------------------------------------------------------------------------
 
 
-class ProfileVersion(enum.IntEnum):
+class ProfileVersion(utils.OpenIntEnum):
     """
     Profile version (normative).
 
@@ -1954,12 +1955,8 @@ class EscoParameters:
     output_coding_format: CodingFormat = CodingFormat(CodecID.LINEAR_PCM)
     input_coded_data_size: int = 16
     output_coded_data_size: int = 16
-    input_pcm_data_format: (
+    input_pcm_data_format: PcmDataFormat = PcmDataFormat.TWOS_COMPLEMENT
-        HCI_Enhanced_Setup_Synchronous_Connection_Command.PcmDataFormat
+    output_pcm_data_format: PcmDataFormat = PcmDataFormat.TWOS_COMPLEMENT
-    ) = HCI_Enhanced_Setup_Synchronous_Connection_Command.PcmDataFormat.TWOS_COMPLEMENT
-    output_pcm_data_format: (
-        HCI_Enhanced_Setup_Synchronous_Connection_Command.PcmDataFormat
-    ) = HCI_Enhanced_Setup_Synchronous_Connection_Command.PcmDataFormat.TWOS_COMPLEMENT
     input_pcm_sample_payload_msb_position: int = 0
     output_pcm_sample_payload_msb_position: int = 0
     input_data_path: HCI_Enhanced_Setup_Synchronous_Connection_Command.DataPath = (
@@ -2058,6 +2055,7 @@ _ESCO_PARAMETERS_MSBC_T1 = EscoParameters(
     max_latency=0x0008,
     packet_type=(
         HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.EV3
+        | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_2_EV3
         | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_3_EV3
         | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_2_EV5
         | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_3_EV5
@@ -2073,7 +2071,6 @@ _ESCO_PARAMETERS_MSBC_T2 = EscoParameters(
     max_latency=0x000D,
     packet_type=(
         HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.EV3
-        | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_2_EV3
         | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_3_EV3
         | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_2_EV5
         | HCI_Enhanced_Setup_Synchronous_Connection_Command.PacketType.NO_3_EV5

bumble/host.py

@@ -247,6 +247,7 @@ class Host(utils.EventEmitter):
     bis_links: dict[int, IsoLink]
     sco_links: dict[int, ScoLink]
     bigs: dict[int, set[int]]
+    link_ts_flags: dict[int, int]
     acl_packet_queue: DataPacketQueue | None = None
     le_acl_packet_queue: DataPacketQueue | None = None
     iso_packet_queue: DataPacketQueue | None = None
@@ -269,6 +270,7 @@ class Host(utils.EventEmitter):
         self.bis_links = {}  # BIS links, by connection handle
         self.sco_links = {}  # SCO links, by connection handle
         self.bigs = {}  # BIG Handle to BIS Handles
+        self.link_ts_flags = {}  # TS_Flag for ISO links, by handle
         self.pending_command: hci.HCI_SyncCommand | hci.HCI_AsyncCommand | None = None
         self.pending_response: (
             asyncio.Future[
@@ -486,6 +488,7 @@ class Host(utils.EventEmitter):
                     hci.HCI_LE_PHY_UPDATE_COMPLETE_EVENT,
                     hci.HCI_LE_EXTENDED_ADVERTISING_REPORT_EVENT,
                     hci.HCI_LE_PERIODIC_ADVERTISING_SYNC_ESTABLISHED_EVENT,
+                    hci.HCI_LE_PERIODIC_ADVERTISING_SYNC_ESTABLISHED_V2_EVENT,
                     hci.HCI_LE_PERIODIC_ADVERTISING_REPORT_EVENT,
                     hci.HCI_LE_PERIODIC_ADVERTISING_SYNC_LOST_EVENT,
                     hci.HCI_LE_SCAN_TIMEOUT_EVENT,
@@ -686,6 +689,8 @@ class Host(utils.EventEmitter):
                 self.pending_response, timeout=response_timeout
             )
             return response
+        except asyncio.TimeoutError:
+            raise
         except Exception:
             logger.exception(color("!!! Exception while sending command:", "red"))
             raise
@@ -864,7 +869,7 @@ class Host(utils.EventEmitter):
         self.send_hci_packet(
             hci.HCI_SynchronousDataPacket(
                 connection_handle=connection_handle,
-                packet_status=0,
+                packet_status=hci.HCI_SynchronousDataPacket.Status.CORRECTLY_RECEIVED_DATA,
                 data_total_length=len(sdu),
                 data=sdu,
             )
@@ -1026,6 +1031,82 @@ class Host(utils.EventEmitter):
         # Look for the connection to which this data belongs
         if connection := self.connections.get(packet.connection_handle):
             connection.on_hci_acl_data_packet(packet)
+            return
+
+        # WORKAROUND: Some controllers (e.g. Intel BE200) send ISO data wrapped in ACL packets
+        # using the CIS handle.
+        is_cis = packet.connection_handle in self.cis_links
+        is_bis = packet.connection_handle in self.bis_links
+
+        if is_cis or is_bis:
+            logger.debug(
+                f"Received ISO data wrapped in ACL packet for handle 0x{packet.connection_handle:04X}"
+            )
+            payload = packet.data
+
+            ts_flag = self.link_ts_flags.get(packet.connection_handle)
+            if ts_flag is None:
+                # Learn TS flag from the first packet on this link
+                if is_bis:
+                    # BIS packets always have Timestamp according to spec
+                    ts_flag = 1
+                elif len(payload) < 8:
+                    # Too short to have 8-byte header (TS), must be No TS
+                    ts_flag = 0
+                else:
+                    psn_no_ts = int.from_bytes(payload[0:2], 'little')
+                    psn_has_ts = int.from_bytes(payload[4:6], 'little')
+                    if psn_has_ts == 0:
+                        ts_flag = 1
+                    elif psn_no_ts == 0:
+                        ts_flag = 0
+                    else:
+                        # Fallback heuristic
+                        ts_flag = 1 if psn_has_ts < psn_no_ts else 0
+                self.link_ts_flags[packet.connection_handle] = ts_flag
+                logger.info(
+                    f"Learned TS_Flag = {ts_flag} for handle 0x{packet.connection_handle:04X}"
+                )
+
+            if ts_flag:
+                header_size = 8
+                sdu_length_offset = 6
+            else:
+                header_size = 4
+                sdu_length_offset = 2
+
+            pb_flag = 0b10
+            if len(payload) >= header_size:
+                sdu_length = int.from_bytes(
+                    payload[sdu_length_offset : sdu_length_offset + 2], 'little'
+                )
+                if sdu_length == len(payload) - header_size:
+                    pb_flag = 0b10  # Complete SDU
+                else:
+                    pb_flag = 0b00  # First fragment
+            else:
+                pb_flag = 0b01  # Continuation
+                ts_flag = 0
+
+            # Reconstruct the raw ISO packet (excluding packet indicator 0x05)
+            pdu_info = packet.connection_handle | (pb_flag << 12) | (ts_flag << 14)
+            header = bytes(
+                [
+                    pdu_info & 0xFF,
+                    (pdu_info >> 8) & 0xFF,
+                    len(payload) & 0xFF,
+                    (len(payload) >> 8) & 0xFF,
+                ]
+            )
+            raw_iso_packet = header + payload
+
+            try:
+                iso_packet = hci.HCI_IsoDataPacket.from_bytes(
+                    bytes([hci.HCI_ISO_DATA_PACKET]) + raw_iso_packet
+                )
+                self.on_hci_iso_data_packet(iso_packet)
+            except Exception as e:
+                logger.warning(f"Failed to reconstruct ISO packet from ACL: {e}")
 
     def on_hci_sco_data_packet(self, packet: hci.HCI_SynchronousDataPacket) -> None:
         # Experimental
@@ -1176,11 +1257,28 @@ class Host(utils.EventEmitter):
     def on_hci_connection_complete_event(
         self, event: hci.HCI_Connection_Complete_Event
     ):
+        if event.link_type == hci.HCI_Connection_Complete_Event.LinkType.SCO:
+            # Pass this on to the synchronous connection handler
+            forwarded_event = hci.HCI_Synchronous_Connection_Complete_Event(
+                status=event.status,
+                connection_handle=event.connection_handle,
+                bd_addr=event.bd_addr,
+                link_type=event.link_type,
+                transmission_interval=0,
+                retransmission_window=0,
+                rx_packet_length=0,
+                tx_packet_length=0,
+                air_mode=0,
+            )
+            self.on_hci_synchronous_connection_complete_event(forwarded_event)
+            return
+
         if event.status == hci.HCI_SUCCESS:
             # Create/update the connection
             logger.debug(
-                f'### BR/EDR CONNECTION: [0x{event.connection_handle:04X}] '
+                f'### BR/EDR ACL CONNECTION: [0x{event.connection_handle:04X}] '
                 f'{event.bd_addr} '
+                f'{event.link_type.name}'
             )
 
             connection = self.connections.get(event.connection_handle)
@@ -1232,6 +1330,7 @@ class Host(utils.EventEmitter):
             self.emit('disconnection', handle, event.reason)
 
             # Remove the handle reference
+            self.link_ts_flags.pop(handle, None)
             _ = (
                 self.connections.pop(handle, 0)
                 or self.cis_links.pop(handle, 0)
@@ -1352,6 +1451,20 @@ class Host(utils.EventEmitter):
             event.advertiser_clock_accuracy,
         )
 
+    def on_hci_le_periodic_advertising_sync_established_v2_event(
+        self, event: hci.HCI_LE_Periodic_Advertising_Sync_Established_V2_Event
+    ):
+        self.emit(
+            'periodic_advertising_sync_establishment',
+            event.status,
+            event.sync_handle,
+            event.advertising_sid,
+            event.advertiser_address,
+            event.advertiser_phy,
+            event.periodic_advertising_interval,
+            event.advertiser_clock_accuracy,
+        )
+
     def on_hci_le_periodic_advertising_sync_lost_event(
         self, event: hci.HCI_LE_Periodic_Advertising_Sync_Lost_Event
     ):
@@ -1580,6 +1693,9 @@ class Host(utils.EventEmitter):
                 event.bd_addr,
                 event.connection_handle,
                 event.link_type,
+                event.rx_packet_length,
+                event.tx_packet_length,
+                event.air_mode,
             )
         else:
             logger.debug(f'### SCO CONNECTION FAILED: {event.status}')

bumble/rfcomm.py

@@ -110,7 +110,7 @@ RFCOMM_DEFAULT_L2CAP_MTU        = 2048
 RFCOMM_DEFAULT_INITIAL_CREDITS  = 7
 RFCOMM_DEFAULT_MAX_CREDITS      = 32
 RFCOMM_DEFAULT_CREDIT_THRESHOLD = RFCOMM_DEFAULT_MAX_CREDITS // 2
-RFCOMM_DEFAULT_MAX_FRAME_SIZE   = 2000
+RFCOMM_DEFAULT_MAX_FRAME_SIZE   = 1000
 
 RFCOMM_DYNAMIC_CHANNEL_NUMBER_START = 1
 RFCOMM_DYNAMIC_CHANNEL_NUMBER_END   = 30

bumble/transport/pyusb.py

@@ -104,6 +104,9 @@ async def open_pyusb_transport(spec: str) -> Transport:
                         0,
                         packet[1:],
                     )
+                elif packet_type == hci.HCI_ISO_DATA_PACKET:
+                    # Workaround: Send ISO packets over Bulk Out
+                    self.device.write(USB_ENDPOINT_ACL_OUT, packet[1:])
                 else:
                     logger.warning(
                         color(f'unsupported packet type {packet_type}', 'red')

bumble/transport/usb.py

@@ -22,6 +22,8 @@ import ctypes
 import logging
 import platform
 import threading
+from collections.abc import Callable
+from typing import Any
 
 import usb1
 
@@ -35,6 +37,32 @@ from bumble.transport.common import BaseSource, Transport, TransportInitError
 logger = logging.getLogger(__name__)
 
 
+# -----------------------------------------------------------------------------
+# Constants
+# -----------------------------------------------------------------------------
+# pylint: disable=invalid-name
+USB_RECIPIENT_DEVICE = 0x00
+USB_REQUEST_TYPE_CLASS = 0x01 << 5
+USB_DEVICE_CLASS_DEVICE = 0x00
+USB_DEVICE_CLASS_WIRELESS_CONTROLLER = 0xE0
+USB_DEVICE_SUBCLASS_RF_CONTROLLER = 0x01
+USB_DEVICE_PROTOCOL_BLUETOOTH_PRIMARY_CONTROLLER = 0x01
+USB_ENDPOINT_TRANSFER_TYPE_ISOCHRONOUS = 0x01
+USB_ENDPOINT_TRANSFER_TYPE_BULK = 0x02
+USB_ENDPOINT_TRANSFER_TYPE_INTERRUPT = 0x03
+USB_ENDPOINT_IN = 0x80
+
+USB_BT_HCI_CLASS_TUPLE = (
+    USB_DEVICE_CLASS_WIRELESS_CONTROLLER,
+    USB_DEVICE_SUBCLASS_RF_CONTROLLER,
+    USB_DEVICE_PROTOCOL_BLUETOOTH_PRIMARY_CONTROLLER,
+)
+
+MAX_SCO_PACKET_SIZE = 1024
+MAX_SCO_IN_PACKETS = 128
+NUMBER_OF_SCO_IN_TRANSFERS = 2
+
+
 # -----------------------------------------------------------------------------
 def load_libusb():
     '''
@@ -60,65 +88,166 @@ def load_libusb():
             usb1.loadLibrary(libusb_dll)
 
 
-async def open_usb_transport(spec: str) -> Transport:
+def find_endpoints(device, forced_mode, sco_alternate=None):
-    '''
+    '''Look for the interfaces with the right class and endpoints'''
-    Open a USB transport.
+    # pylint: disable-next=too-many-nested-blocks
-    The moniker string has this syntax:
+    for configuration_index, configuration in enumerate(device):
-    either <index> or
+        # Select the interface and endpoints for ACL
-    <vendor>:<product> or
+        acl_interface = None
-    <vendor>:<product>/<serial-number>] or
+        bulk_in = None
-    <vendor>:<product>#<index>
+        bulk_out = None
-    With <index> as the 0-based index to select amongst all the devices that appear
+        interrupt_in = None
-    to be supporting Bluetooth HCI (0 being the first one), or
+        for interface in configuration:
-    Where <vendor> and <product> are the vendor ID and product ID in hexadecimal. The
+            for setting in interface:
-    /<serial-number> suffix or #<index> suffix max be specified when more than one
+                if acl_interface is not None:
-    device with the same vendor and product identifiers are present.
+                    continue
 
-    In addition, if the moniker ends with the symbol "!", the device will be used in
+                if (
-    "forced" mode:
+                    not forced_mode
-    the first USB interface of the device will be used, regardless of the interface
+                    and (
-    class/subclass.
+                        setting.getClass(),
-    This may be useful for some devices that use a custom class/subclass but may
+                        setting.getSubClass(),
-    nonetheless work as-is.
+                        setting.getProtocol(),
+                    )
+                    != USB_BT_HCI_CLASS_TUPLE
+                ):
+                    continue
 
-    Examples:
+                for endpoint in setting:
-    0 --> the first BT USB dongle
+                    attributes = endpoint.getAttributes()
-    04b4:f901 --> the BT USB dongle with vendor=04b4 and product=f901
+                    address = endpoint.getAddress()
-    04b4:f901#2 --> the third USB device with vendor=04b4 and product=f901
+                    if attributes & 0x03 == USB_ENDPOINT_TRANSFER_TYPE_BULK:
-    04b4:f901/00E04C239987 --> the BT USB dongle with vendor=04b4 and product=f901 and
+                        if address & USB_ENDPOINT_IN:
-    serial number 00E04C239987
+                            if bulk_in is None:
-    usb:0B05:17CB! --> the BT USB dongle vendor=0B05 and product=17CB, in "forced" mode.
+                                bulk_in = endpoint
-    '''
+                        else:
+                            if bulk_out is None:
+                                bulk_out = endpoint
+                    elif attributes & 0x03 == USB_ENDPOINT_TRANSFER_TYPE_INTERRUPT:
+                        if address & USB_ENDPOINT_IN and interrupt_in is None:
+                            interrupt_in = endpoint
 
-    # pylint: disable=invalid-name
+                # Only keep complete sets (endpoints that should be under the
-    USB_RECIPIENT_DEVICE = 0x00
+                # same interface)
-    USB_REQUEST_TYPE_CLASS = 0x01 << 5
+                if (
-    USB_DEVICE_CLASS_DEVICE = 0x00
+                    bulk_in is not None
-    USB_DEVICE_CLASS_WIRELESS_CONTROLLER = 0xE0
+                    and bulk_out is not None
-    USB_DEVICE_SUBCLASS_RF_CONTROLLER = 0x01
+                    and interrupt_in is not None
-    USB_DEVICE_PROTOCOL_BLUETOOTH_PRIMARY_CONTROLLER = 0x01
+                ):
-    USB_ENDPOINT_TRANSFER_TYPE_BULK = 0x02
+                    acl_interface = setting
-    USB_ENDPOINT_TRANSFER_TYPE_INTERRUPT = 0x03
-    USB_ENDPOINT_IN = 0x80
 
-    USB_BT_HCI_CLASS_TUPLE = (
+        # Select the interface and endpoints for SCO
-        USB_DEVICE_CLASS_WIRELESS_CONTROLLER,
+        sco_interface = None
-        USB_DEVICE_SUBCLASS_RF_CONTROLLER,
+        max_packet_size = (0, 0)
-        USB_DEVICE_PROTOCOL_BLUETOOTH_PRIMARY_CONTROLLER,
+        isochronous_in = None
+        isochronous_out = None
+
+        for interface in configuration:
+            if sco_interface is not None:
+                continue
+
+            if sco_alternate is None:
+                continue
+
+            for setting in interface:
+                if (
+                    not forced_mode
+                    and (
+                        setting.getClass(),
+                        setting.getSubClass(),
+                        setting.getProtocol(),
+                    )
+                    != USB_BT_HCI_CLASS_TUPLE
+                ):
+                    continue
+
+                if (
+                    sco_alternate != 0
+                    and setting.getAlternateSetting() != sco_alternate
+                ):
+                    continue
+
+                isochronous_in = None
+                isochronous_out = None
+
+                for endpoint in setting:
+                    if (
+                        endpoint.getAttributes() & 0x03
+                        == USB_ENDPOINT_TRANSFER_TYPE_ISOCHRONOUS
+                    ):
+                        if endpoint.getMaxPacketSize() > 0:
+                            if endpoint.getAddress() & USB_ENDPOINT_IN:
+                                if (
+                                    isochronous_in is None
+                                    or endpoint.getMaxPacketSize()
+                                    > (isochronous_in.getMaxPacketSize())
+                                ):
+                                    isochronous_in = endpoint
+                            else:
+                                if (
+                                    isochronous_out is None
+                                    or endpoint.getMaxPacketSize()
+                                    > (isochronous_out.getMaxPacketSize())
+                                ):
+                                    isochronous_out = endpoint
+
+                if isochronous_in is not None and isochronous_out is not None:
+                    if (
+                        sco_interface is None
+                        or sco_alternate == 0
+                        and (
+                            isochronous_in.getMaxPacketSize(),
+                            isochronous_out.getMaxPacketSize(),
+                        )
+                        > max_packet_size
+                    ):
+                        sco_interface = setting
+                        max_packet_size = (
+                            isochronous_in.getMaxPacketSize(),
+                            isochronous_out.getMaxPacketSize(),
                         )
 
-    READ_SIZE = 4096
+        # Return if we found at least a compatible ACL interface
+        if acl_interface is not None:
+            return (
+                configuration_index + 1,
+                acl_interface,
+                sco_interface,
+                interrupt_in,
+                bulk_in,
+                isochronous_in,
+                bulk_out,
+                isochronous_out,
+            )
+
+        logger.debug(f'skipping configuration {configuration_index + 1}')
+
+    return None
+
 
 class UsbPacketSink:
-        def __init__(self, device, acl_out):
+    def __init__(self, device, bulk_out, isochronous_out) -> None:
         self.device = device
-            self.acl_out = acl_out
+        self.bulk_out = bulk_out
-            self.acl_out_transfer = device.getTransfer()
+        self.isochronous_out = isochronous_out
-            self.acl_out_transfer_ready = asyncio.Semaphore(1)
+        self.bulk_or_control_out_transfer = device.getTransfer()
-            self.packets = asyncio.Queue[bytes]()  # Queue of packets waiting to be sent
+        self.isochronous_out_transfer = (
+            device.getTransfer(
+                iso_packets=(
+                    MAX_SCO_PACKET_SIZE // isochronous_out.getMaxPacketSize()
+                    if isochronous_out.getMaxPacketSize()
+                    else 1
+                )
+            )
+            if isochronous_out is not None
+            else None
+        )
+        self.out_transfer_ready = asyncio.Semaphore(1)
+        self.packets: asyncio.Queue[bytes] = (
+            asyncio.Queue()
+        )  # Queue of packets waiting to be sent
         self.loop = asyncio.get_running_loop()
         self.queue_task = None
-            self.cancel_done = self.loop.create_future()
         self.closed = False
 
     def start(self):
@@ -137,13 +266,10 @@ async def open_usb_transport(spec: str) -> Transport:
         self.packets.put_nowait(packet)
 
     def transfer_callback(self, transfer):
-            self.loop.call_soon_threadsafe(self.acl_out_transfer_ready.release)
+        self.loop.call_soon_threadsafe(self.out_transfer_ready.release)
         status = transfer.getStatus()
 
-            # pylint: disable=no-member
+        logger.debug(f"OUT CALLBACK: {status}")
-            if status == usb1.TRANSFER_CANCELLED:
-                self.loop.call_soon_threadsafe(self.cancel_done.set_result, None)
-                return
 
         if status != usb1.TRANSFER_COMPLETED:
             logger.warning(
@@ -154,106 +280,263 @@ async def open_usb_transport(spec: str) -> Transport:
             )
 
     async def process_queue(self):
-            while True:
+        while not self.closed:
             # Wait for a packet to transfer.
             packet = await self.packets.get()
 
             # Wait until we can start a transfer.
-                await self.acl_out_transfer_ready.acquire()
+            await self.out_transfer_ready.acquire()
 
             # Transfer the packet.
             packet_type = packet[0]
+            packet_payload = packet[1:]
+            submitted = False
+            try:
                 if packet_type == hci.HCI_ACL_DATA_PACKET:
-                    self.acl_out_transfer.setBulk(
+                    self.bulk_or_control_out_transfer.setBulk(
-                        self.acl_out, packet[1:], callback=self.transfer_callback
+                        self.bulk_out.getAddress(),
+                        packet_payload,
+                        callback=self.transfer_callback,
                     )
-                    self.acl_out_transfer.submit()
+                    self.bulk_or_control_out_transfer.submit()
+                    submitted = True
                 elif packet_type == hci.HCI_COMMAND_PACKET:
-                    self.acl_out_transfer.setControl(
+                    self.bulk_or_control_out_transfer.setControl(
                         USB_RECIPIENT_DEVICE | USB_REQUEST_TYPE_CLASS,
                         0,
                         0,
                         0,
-                        packet[1:],
+                        packet_payload,
                         callback=self.transfer_callback,
                     )
-                    self.acl_out_transfer.submit()
+                    self.bulk_or_control_out_transfer.submit()
+                    submitted = True
+                elif packet_type == hci.HCI_SYNCHRONOUS_DATA_PACKET:
+                    if self.isochronous_out_transfer is None:
+                        logger.warning(
+                            color('isochronous packets not supported', 'red')
+                        )
+                        self.out_transfer_ready.release()
+                        continue
+
+                    # Setup a list of packet lengths, each up to the max packet size
+                    iso_max_packet_size = self.isochronous_out.getMaxPacketSize()
+                    iso_packet_count = (
+                        len(packet_payload) + iso_max_packet_size - 1
+                    ) // iso_max_packet_size
+                    iso_packet_lengths = [iso_max_packet_size] * (iso_packet_count - 1)
+                    iso_packet_lengths.append(
+                        len(packet_payload) - sum(iso_packet_lengths)
+                    )
+
+                    # Set up and submit the isochronous transfer
+                    self.isochronous_out_transfer.setIsochronous(
+                        self.isochronous_out.getAddress(),
+                        packet_payload,
+                        callback=self.transfer_callback,
+                        iso_transfer_length_list=iso_packet_lengths,
+                    )
+                    self.isochronous_out_transfer.submit()
+                    submitted = True
+                elif packet_type == hci.HCI_ISO_DATA_PACKET:
+                    if self.isochronous_out_transfer is None:
+                        # Workaround: Send ISO packets over Bulk Out when Isochronous endpoints are not enabled
+                        self.bulk_or_control_out_transfer.setBulk(
+                            self.bulk_out.getAddress(),
+                            packet_payload,
+                            callback=self.transfer_callback,
+                        )
+                        self.bulk_or_control_out_transfer.submit()
+                        submitted = True
+                    else:
+                        logger.warning(
+                            color(
+                                'ISO packets over Isochronous endpoints not supported yet',
+                                'red',
+                            )
+                        )
+                        self.out_transfer_ready.release()
+                        continue
                 else:
                     logger.warning(
                         color(f'unsupported packet type {packet_type}', 'red')
                     )
+            except Exception as error:
+                logger.warning(f'!!! exception while submitting transfer: {error}')
+
+            if not submitted:
+                self.out_transfer_ready.release()
 
     def close(self):
         self.closed = True
-            if self.queue_task:
-                self.queue_task.cancel()
 
     async def terminate(self):
-            if not self.closed:
         self.close()
 
+        if self.queue_task:
+            self.queue_task.cancel()
+
         # Empty the packet queue so that we don't send any more data
         while not self.packets.empty():
             self.packets.get_nowait()
 
-            # If we have a transfer in flight, cancel it
+        # If we have transfers in flight, cancel them
-            if self.acl_out_transfer.isSubmitted():
+        for transfer in (
+            self.bulk_or_control_out_transfer,
+            self.isochronous_out_transfer,
+        ):
+            if transfer is None:
+                continue
+
+            if transfer.isSubmitted():
                 # Try to cancel the transfer, but that may fail because it may have
                 # already completed
                 try:
-                    self.acl_out_transfer.cancel()
+                    transfer.cancel()
 
                     logger.debug('waiting for OUT transfer cancellation to be done...')
-                    await self.cancel_done
+                    await self.out_transfer_ready.acquire()
                     logger.debug('OUT transfer cancellation done')
-                except usb1.USBError:
+                except usb1.USBError as error:
-                    logger.debug('OUT transfer likely already completed')
+                    logger.debug(f'OUT transfer likely already completed ({error})')
+
+            try:
+                transfer.close()
+            except usb1.USBError as error:
+                logger.warning(f'failed to close transfer ({error})')
+
+
+READ_SIZE = 4096
+
+
+class PacketSplitter:
+    """Splitter than can parse a byte stream and extract packets that consist of a
+    header and a body, where the header includes an n-byte 'length' field at a
+    certain offset.
+    Extracted packets are emitted by calling a function passed to the constructor,
+    with the full packet (header + body) as argument.
+    """
+
+    def __init__(
+        self, length_offset: int, length_size: int, emit: Callable[[bytes], Any]
+    ) -> None:
+        self.emit = emit
+        self.packet = b''
+        self.length_offset = length_offset
+        self.length_size = length_size
+        self.header_size = length_offset + length_size
+
+    def feed(self, data: bytes) -> None:
+        while data:
+            # Accumulate until we have a complete header
+            if (bytes_needed := self.header_size - len(self.packet)) > 0:
+                self.packet += data[:bytes_needed]
+                data = data[bytes_needed:]
+                if len(self.packet) < self.header_size:
+                    continue
+
+            packet_length = self.header_size + int.from_bytes(
+                self.packet[self.length_offset : self.length_offset + self.length_size],
+                'little',
+            )
+            bytes_needed = packet_length - len(self.packet)
+            self.packet += data[:bytes_needed]
+            data = data[bytes_needed:]
+            if len(self.packet) == packet_length:
+                # Packet complete
+                self.emit(self.packet)
+                self.packet = b''
+
+
+class ScoPacketSplitter(PacketSplitter):
+    def __init__(self, emit: Callable[[bytes], Any]) -> None:
+        # The length field is 1 byte at offset 2 in the HCI SCO packet header
+        super().__init__(length_offset=2, length_size=1, emit=emit)
+
+
+class EventPacketSplitter(PacketSplitter):
+    def __init__(self, emit: Callable[[bytes], Any]) -> None:
+        # The length field is 1 byte at offset 1 in the HCI Event packet header
+        super().__init__(length_offset=1, length_size=1, emit=emit)
+
+
+class AclPacketSplitter(PacketSplitter):
+    def __init__(self, emit: Callable[[bytes], Any]) -> None:
+        # The length field is 2 bytes at offset 2 in the HCI ACL packet header
+        super().__init__(length_offset=2, length_size=2, emit=emit)
+
 
 class UsbPacketSource(asyncio.Protocol, BaseSource):
-        def __init__(self, device, metadata, acl_in, events_in):
+    def __init__(self, device, metadata, interrupt_in, bulk_in, isochronous_in):
         super().__init__()
         self.device = device
         self.metadata = metadata
-            self.acl_in = acl_in
+        self.interrupt_in = interrupt_in
-            self.acl_in_transfer = None
+        self.interrupt_in_transfer = None
-            self.events_in = events_in
+        self.bulk_in = bulk_in
-            self.events_in_transfer = None
+        self.bulk_in_transfer = None
+        self.isochronous_in = isochronous_in
+        self.isochronous_in_transfers = []
         self.loop = asyncio.get_running_loop()
         self.queue = asyncio.Queue()
         self.dequeue_task = None
-            self.cancel_done = {
+        self.done = {}
-                hci.HCI_EVENT_PACKET: self.loop.create_future(),
+        self.splitters = {
-                hci.HCI_ACL_DATA_PACKET: self.loop.create_future(),
+            hci.HCI_EVENT_PACKET: EventPacketSplitter(
+                lambda packet: self.queue_packet(hci.HCI_EVENT_PACKET, packet)
+            ),
+            hci.HCI_ACL_DATA_PACKET: AclPacketSplitter(
+                lambda packet: self.queue_packet(hci.HCI_ACL_DATA_PACKET, packet)
+            ),
+            hci.HCI_SYNCHRONOUS_DATA_PACKET: ScoPacketSplitter(
+                lambda packet: self.queue_packet(
+                    hci.HCI_SYNCHRONOUS_DATA_PACKET, packet
+                )
+            ),
         }
         self.closed = False
+        self.lock = threading.Lock()
 
     def start(self):
         # Set up transfer objects for input
-            self.events_in_transfer = device.getTransfer()
+        self.interrupt_in_transfer = self.device.getTransfer()
-            self.events_in_transfer.setInterrupt(
+        self.interrupt_in_transfer.setInterrupt(
-                self.events_in,
+            self.interrupt_in.getAddress(),
             READ_SIZE,
             callback=self.transfer_callback,
             user_data=hci.HCI_EVENT_PACKET,
         )
-            self.events_in_transfer.submit()
+        self.done[self.interrupt_in_transfer] = asyncio.Event()
+        self.interrupt_in_transfer.submit()
 
-            self.acl_in_transfer = device.getTransfer()
+        self.bulk_in_transfer = self.device.getTransfer()
-            self.acl_in_transfer.setBulk(
+        self.bulk_in_transfer.setBulk(
-                self.acl_in,
+            self.bulk_in.getAddress(),
             READ_SIZE,
             callback=self.transfer_callback,
             user_data=hci.HCI_ACL_DATA_PACKET,
         )
-            self.acl_in_transfer.submit()
+        self.done[self.bulk_in_transfer] = asyncio.Event()
+        self.bulk_in_transfer.submit()
+
+        if self.isochronous_in is not None:
+            for _ in range(NUMBER_OF_SCO_IN_TRANSFERS):
+                transfer = self.device.getTransfer(iso_packets=MAX_SCO_IN_PACKETS)
+                transfer.setIsochronous(
+                    self.isochronous_in.getAddress(),
+                    MAX_SCO_IN_PACKETS * self.isochronous_in.getMaxPacketSize(),
+                    callback=self.transfer_callback,
+                    user_data=hci.HCI_SYNCHRONOUS_DATA_PACKET,
+                )
+                self.isochronous_in_transfers.append(transfer)
+                self.done[transfer] = asyncio.Event()
+                transfer.submit()
 
         self.dequeue_task = self.loop.create_task(self.dequeue())
 
-        @property
+    def queue_packet(self, packet_type: int, packet_data: bytes) -> None:
-        def usb_transfer_submitted(self):
+        self.loop.call_soon_threadsafe(
-            return (
+            self.queue.put_nowait, bytes([packet_type]) + packet_data
-                self.events_in_transfer.isSubmitted()
-                or self.acl_in_transfer.isSubmitted()
         )
 
     def transfer_callback(self, transfer):
@@ -261,26 +544,53 @@ async def open_usb_transport(spec: str) -> Transport:
         status = transfer.getStatus()
 
         # pylint: disable=no-member
-            if status == usb1.TRANSFER_COMPLETED:
+        if (
-                packet = (
+            packet_type != hci.HCI_SYNCHRONOUS_DATA_PACKET
-                    bytes([packet_type])
+            or transfer.getActualLength()
-                    + transfer.getBuffer()[: transfer.getActualLength()]
+            or status != usb1.TRANSFER_COMPLETED
+        ):
+            logger.debug(
+                f"IN[{packet_type}] CALLBACK: status={status}, length={transfer.getActualLength()}"
+            )
+        if status == usb1.TRANSFER_COMPLETED:
+            with self.lock:
+                if self.closed:
+                    logger.debug("packet source closed, discarding transfer")
+                elif (splitter := self.splitters.get(packet_type)) is None:
+                    logger.warning(f'no splitter for packet type {packet_type}')
+                else:
+                    if packet_type == hci.HCI_SYNCHRONOUS_DATA_PACKET:
+                        for iso_status, iso_buffer in transfer.iterISO():
+                            if not iso_buffer:
+                                continue
+                            if iso_status:
+                                logger.warning(f"ISO packet status error: {iso_status}")
+                                continue
+                            logger.debug(
+                                "### SCO packet: %d %s",
+                                len(iso_buffer),
+                                iso_buffer.hex(),
+                            )
+                            splitter.feed(iso_buffer)
+                    else:
+                        splitter.feed(
+                            transfer.getBuffer()[: transfer.getActualLength()]
                         )
-                self.loop.call_soon_threadsafe(self.queue.put_nowait, packet)
 
                     # Re-submit the transfer so we can receive more data
+                    try:
                         transfer.submit()
+                    except usb1.USBError as error:
+                        logger.warning(f"Failed to re-submit transfer: {error}")
+                        self.loop.call_soon_threadsafe(self.on_transport_lost)
         elif status == usb1.TRANSFER_CANCELLED:
-                self.loop.call_soon_threadsafe(
+            logger.debug(f"IN[{packet_type}] transfer canceled")
-                    self.cancel_done[packet_type].set_result, None
+            self.loop.call_soon_threadsafe(self.done[transfer].set)
-                )
         else:
             logger.warning(
-                    color(
+                color(f'!!! IN[{packet_type}] transfer not completed', 'red')
-                        f'!!! IN[{packet_type}] transfer not completed: status={status}',
-                        'red',
-                    )
             )
+            self.loop.call_soon_threadsafe(self.done[transfer].set)
             self.loop.call_soon_threadsafe(self.on_transport_lost)
 
     async def dequeue(self):
@@ -293,72 +603,107 @@ async def open_usb_transport(spec: str) -> Transport:
                 try:
                     self.sink.on_packet(packet)
                 except Exception:
-                        logger.exception(
+                    logger.exception(color('!!! Exception in sink.on_packet', 'red'))
-                            color('!!! Exception in sink.on_packet', 'red')
-                        )
 
     def close(self):
+        with self.lock:
             self.closed = True
 
     async def terminate(self):
-            if not self.closed:
         self.close()
 
+        if self.dequeue_task:
             self.dequeue_task.cancel()
 
         # Cancel the transfers
-            for transfer in (self.events_in_transfer, self.acl_in_transfer):
+        for transfer in (
+            self.interrupt_in_transfer,
+            self.bulk_in_transfer,
+            *self.isochronous_in_transfers,
+        ):
+            if transfer is None:
+                continue
+
             if transfer.isSubmitted():
-                    # Try to cancel the transfer, but that may fail because it may have
+                # Try to cancel the transfer, but that may fail because it may
-                    # already completed
+                # have already completed
                 packet_type = transfer.getUserData()
+                assert isinstance(packet_type, int)
                 try:
                     transfer.cancel()
                     logger.debug(
                         f'waiting for IN[{packet_type}] transfer cancellation '
                         'to be done...'
                     )
-                        await self.cancel_done[packet_type]
+                    await self.done[transfer].wait()
                     logger.debug(f'IN[{packet_type}] transfer cancellation done')
-                    except usb1.USBError:
+                except usb1.USBError as error:
                     logger.debug(
                         f'IN[{packet_type}] transfer likely already completed '
+                        f'({error})'
                     )
 
+
 class UsbTransport(Transport):
-        def __init__(self, context, device, interface, setting, source, sink):
+    def __init__(self, context, device, acl_interface, sco_interface, source, sink):
         super().__init__(source, sink)
         self.context = context
         self.device = device
-            self.interface = interface
+        self.acl_interface = acl_interface
+        self.sco_interface = sco_interface
         self.loop = asyncio.get_running_loop()
         self.event_loop_done = self.loop.create_future()
+        self.event_loop_should_exit = False
+        self.lock = threading.Lock()
 
         # Get exclusive access
-            device.claimInterface(interface)
+        device.claimInterface(acl_interface.getNumber())
+        if sco_interface is not None:
+            device.claimInterface(sco_interface.getNumber())
 
         # Set the alternate setting if not the default
-            if setting != 0:
+        if acl_interface.getAlternateSetting() != 0:
-                device.setInterfaceAltSetting(interface, setting)
+            logger.debug(
+                f'setting ACL interface {acl_interface.getNumber()} '
+                f'altsetting {acl_interface.getAlternateSetting()}'
+            )
+            device.setInterfaceAltSetting(
+                acl_interface.getNumber(), acl_interface.getAlternateSetting()
+            )
+        if sco_interface is not None and sco_interface.getAlternateSetting() != 0:
+            logger.debug(
+                f'setting SCO interface {sco_interface.getNumber()} '
+                f'altsetting {sco_interface.getAlternateSetting()}'
+            )
+            device.setInterfaceAltSetting(
+                sco_interface.getNumber(), sco_interface.getAlternateSetting()
+            )
 
         # The source and sink can now start
         source.start()
         sink.start()
 
         # Create a thread to process events
-            self.event_thread = threading.Thread(target=self.run)
+        self.event_thread = threading.Thread(target=self.run, daemon=True)
         self.event_thread.start()
 
     def run(self):
         logger.debug('starting USB event loop')
-            while self.source.usb_transfer_submitted:
+        while True:
+            with self.lock:
+                if self.event_loop_should_exit:
+                    logger.debug("USB event loop exit requested")
+                    break
+
             # pylint: disable=no-member
             try:
                 self.context.handleEvents()
             except usb1.USBErrorInterrupted:
                 pass
+            except Exception as error:
+                logger.warning(f'!!! Exception while handling events: {error}')
 
-            logger.debug('USB event loop done')
+        logger.debug('ending USB event loop')
         self.loop.call_soon_threadsafe(self.event_loop_done.set_result, None)
 
     async def close(self):
@@ -366,12 +711,60 @@ async def open_usb_transport(spec: str) -> Transport:
         self.sink.close()
         await self.source.terminate()
         await self.sink.terminate()
-            self.device.releaseInterface(self.interface)
+
+        # We no longer need the event loop to run
+        with self.lock:
+            self.event_loop_should_exit = True
+        self.context.interruptEventHandler()
+
+        self.device.releaseInterface(self.acl_interface.getNumber())
+        if self.sco_interface:
+            self.device.releaseInterface(self.sco_interface.getNumber())
         self.device.close()
         self.context.close()
 
         # Wait for the thread to terminate
+        logger.debug("waiting for USB event loop to be done...")
         await self.event_loop_done
+        logger.debug("USB event loop done")
+
+
+async def open_usb_transport(spec: str) -> Transport:
+    '''
+    Open a USB transport.
+    The moniker string has this syntax:
+    either <index> or
+    <vendor>:<product> or
+    <vendor>:<product>/<serial-number>] or
+    <vendor>:<product>#<index>
+    With <index> as the 0-based index to select amongst all the devices that appear
+    to be supporting Bluetooth HCI (0 being the first one), or
+    Where <vendor> and <product> are the vendor ID and product ID in hexadecimal. The
+    /<serial-number> suffix or #<index> suffix max be specified when more than one
+    device with the same vendor and product identifiers are present.
+
+    Opotionally, the moniker may include a +sco=<alternate> suffix to enable SCO/eSCO
+    and specify the alternate setting to use for SCO/eSCO transfers, with 0 meaning an
+    automatic selection.
+
+    In addition, if the moniker ends with the symbol "!", the device will be used in
+    "forced" mode:
+    the first USB interface of the device will be used, regardless of the interface
+    class/subclass.
+    This may be useful for some devices that use a custom class/subclass but may
+    nonetheless work as-is.
+
+    Examples:
+    0 --> the first BT USB dongle
+    04b4:f901 --> the BT USB dongle with vendor=04b4 and product=f901
+    04b4:f901#2 --> the third USB device with vendor=04b4 and product=f901
+    04b4:f901/00E04C239987 --> the BT USB dongle with vendor=04b4 and product=f901 and
+    serial number 00E04C239987
+    0B05:17CB! --> the BT USB dongle with vendor=0B05 and product=17CB, in "forced"
+    mode.
+    0+sco=0 --> the first BT USB dongle, with SCO enabled using auto-selection.
+    0+sco=5 --> the first BT USB dongle, with SCO enabled using alternate setting 5.
+    '''
 
     # Find the device according to the spec moniker
     load_libusb()
@@ -379,6 +772,7 @@ async def open_usb_transport(spec: str) -> Transport:
     context.open()
     try:
         found = None
+        device = None
 
         if spec.endswith('!'):
             spec = spec[:-1]
@@ -386,6 +780,12 @@ async def open_usb_transport(spec: str) -> Transport:
         else:
             forced_mode = False
 
+        if '+sco=' in spec:
+            spec, sco_alternate_str = spec.split('+sco=')
+            sco_alternate = int(sco_alternate_str)
+        else:
+            sco_alternate = None
+
         if ':' in spec:
             vendor_id, product_id = spec.split(':')
             serial_number = None
@@ -461,76 +861,41 @@ async def open_usb_transport(spec: str) -> Transport:
 
         logger.debug(f'USB Device: {found}')
 
-        # Look for the first interface with the right class and endpoints
+        assert device is not None
-        def find_endpoints(device):
+        endpoints = find_endpoints(device, forced_mode, sco_alternate)
-            # pylint: disable-next=too-many-nested-blocks
-            for configuration_index, configuration in enumerate(device):
-                interface = None
-                for interface in configuration:
-                    setting = None
-                    for setting in interface:
-                        if (
-                            not forced_mode
-                            and (
-                                setting.getClass(),
-                                setting.getSubClass(),
-                                setting.getProtocol(),
-                            )
-                            != USB_BT_HCI_CLASS_TUPLE
-                        ):
-                            continue
-
-                        events_in = None
-                        acl_in = None
-                        acl_out = None
-                        for endpoint in setting:
-                            attributes = endpoint.getAttributes()
-                            address = endpoint.getAddress()
-                            if attributes & 0x03 == USB_ENDPOINT_TRANSFER_TYPE_BULK:
-                                if address & USB_ENDPOINT_IN and acl_in is None:
-                                    acl_in = address
-                                elif acl_out is None:
-                                    acl_out = address
-                            elif (
-                                attributes & 0x03
-                                == USB_ENDPOINT_TRANSFER_TYPE_INTERRUPT
-                            ):
-                                if address & USB_ENDPOINT_IN and events_in is None:
-                                    events_in = address
-
-                        # Return if we found all 3 endpoints
-                        if (
-                            acl_in is not None
-                            and acl_out is not None
-                            and events_in is not None
-                        ):
-                            return (
-                                configuration_index + 1,
-                                setting.getNumber(),
-                                setting.getAlternateSetting(),
-                                acl_in,
-                                acl_out,
-                                events_in,
-                            )
-
-                        logger.debug(
-                            f'skipping configuration {configuration_index + 1} / '
-                            f'interface {setting.getNumber()}'
-                        )
-
-            return None
-
-        endpoints = find_endpoints(found)
         if endpoints is None:
             raise TransportInitError('no compatible interface found for device')
-        (configuration, interface, setting, acl_in, acl_out, events_in) = endpoints
+        (
+            configuration,
+            acl_interface,
+            sco_interface,
+            interrupt_in,
+            bulk_in,
+            isochronous_in,
+            bulk_out,
+            isochronous_out,
+        ) = endpoints
+        acl_interface_info = (
+            f'acl_interface={acl_interface.getNumber()}/'
+            f'{acl_interface.getAlternateSetting()}'
+        )
+        sco_interface_info = (
+            '<none>'
+            if sco_interface is None
+            else (
+                f'sco_interface={sco_interface.getNumber()}/'
+                f'{sco_interface.getAlternateSetting()}'
+            )
+        )
         logger.debug(
             f'selected endpoints: configuration={configuration}, '
-            f'interface={interface}, '
+            f'acl_interface={acl_interface_info}, '
-            f'setting={setting}, '
+            f'sco_interface={sco_interface_info}, '
-            f'acl_in=0x{acl_in:02X}, '
+            f'interrupt_in=0x{interrupt_in.getAddress():02X}, '
-            f'acl_out=0x{acl_out:02X}, '
+            f'bulk_in=0x{bulk_in.getAddress():02X}, '
-            f'events_in=0x{events_in:02X}, '
+            f'bulk_out=0x{bulk_out.getAddress():02X}, '
+            f'isochronous_in=0x{isochronous_in.getAddress() if isochronous_in else 0:02X}, '
+            f'isochronous_out=0x{isochronous_out.getAddress() if isochronous_out else 0:02X}'
         )
 
         device_metadata = {
@@ -562,9 +927,11 @@ async def open_usb_transport(spec: str) -> Transport:
             except usb1.USBError:
                 logger.warning('failed to set configuration')
 
-        source = UsbPacketSource(device, device_metadata, acl_in, events_in)
+        source = UsbPacketSource(
-        sink = UsbPacketSink(device, acl_out)
+            device, device_metadata, interrupt_in, bulk_in, isochronous_in
-        return UsbTransport(context, device, interface, setting, source, sink)
+        )
+        sink = UsbPacketSink(device, bulk_out, isochronous_out)
+        return UsbTransport(context, device, acl_interface, sco_interface, source, sink)
     except usb1.USBError as error:
         logger.warning(color(f'!!! failed to open USB device: {error}', 'red'))
         context.close()

examples/run_hfp_handsfree.py

@@ -20,17 +20,119 @@ import contextlib
 import functools
 import json
 import sys
+import wave
 
 import websockets.asyncio.server
 
 import bumble.logging
 from bumble import hci, hfp, rfcomm
-from bumble.device import Connection, Device
+from bumble.device import Connection, Device, ScoLink
 from bumble.hfp import HfProtocol
 from bumble.transport import open_transport
 
+# -----------------------------------------------------------------------------
 ws: websockets.asyncio.server.ServerConnection | None = None
 hf_protocol: HfProtocol | None = None
+input_wav: wave.Wave_read | None = None
+output_wav: wave.Wave_write | None = None
+
+
+# -----------------------------------------------------------------------------
+def on_audio_packet(packet: hci.HCI_SynchronousDataPacket) -> None:
+    if (
+        packet.packet_status
+        != hci.HCI_SynchronousDataPacket.Status.CORRECTLY_RECEIVED_DATA
+    ):
+        print('!!! discarding packet with status ', packet.packet_status.name)
+        return
+
+    frame_count = len(packet.data) // 2
+    print(f">>> received {frame_count} PCM samples")
+
+    if output_wav:
+        # Save the PCM audio to the output
+        output_wav.writeframes(packet.data)
+
+    if input_wav and hf_protocol:
+        # Send PCM audio from the input, same amount as what was received
+        while not (pcm_data := input_wav.readframes(frame_count)):
+            input_wav.setpos(0)  # Loop
+        print(f">>> sending {frame_count} PCM samples")
+        hf_protocol.dlc.multiplexer.l2cap_channel.connection.device.host.send_sco_sdu(
+            connection_handle=packet.connection_handle,
+            sdu=pcm_data,
+        )
+
+
+# -----------------------------------------------------------------------------
+def on_sco_connection(link: ScoLink) -> None:
+    print('### SCO connection established:', link)
+    if link.air_mode == hci.CodecID.TRANSPARENT:
+        print("@@@ The controller does not encode/decode voice")
+        return
+
+    link.sink = on_audio_packet
+
+
+# -----------------------------------------------------------------------------
+def on_sco_request(
+    link_type: int, connection: Connection, protocol: HfProtocol
+) -> None:
+    if link_type == hci.HCI_Connection_Complete_Event.LinkType.SCO:
+        esco_parameters = hfp.ESCO_PARAMETERS[hfp.DefaultCodecParameters.SCO_CVSD_D1]
+    elif protocol.active_codec == hfp.AudioCodec.MSBC:
+        esco_parameters = hfp.ESCO_PARAMETERS[hfp.DefaultCodecParameters.ESCO_MSBC_T2]
+    elif protocol.active_codec == hfp.AudioCodec.CVSD:
+        esco_parameters = hfp.ESCO_PARAMETERS[hfp.DefaultCodecParameters.ESCO_CVSD_S4]
+    else:
+        raise RuntimeError("unknown active codec")
+
+    if connection.device.host.supports_command(
+        hci.HCI_ENHANCED_ACCEPT_SYNCHRONOUS_CONNECTION_REQUEST_COMMAND
+    ):
+        connection.cancel_on_disconnection(
+            connection.device.send_async_command(
+                hci.HCI_Enhanced_Accept_Synchronous_Connection_Request_Command(
+                    bd_addr=connection.peer_address, **esco_parameters.asdict()
+                )
+            )
+        )
+    elif connection.device.host.supports_command(
+        hci.HCI_ACCEPT_SYNCHRONOUS_CONNECTION_REQUEST_COMMAND
+    ):
+        connection.cancel_on_disconnection(
+            connection.device.send_async_command(
+                hci.HCI_Accept_Synchronous_Connection_Request_Command(
+                    bd_addr=connection.peer_address,
+                    transmit_bandwidth=esco_parameters.transmit_bandwidth,
+                    receive_bandwidth=esco_parameters.receive_bandwidth,
+                    max_latency=esco_parameters.max_latency,
+                    voice_setting=int(
+                        hci.VoiceSetting(
+                            input_sample_size=hci.VoiceSetting.InputSampleSize.SIZE_16_BITS,
+                            input_data_format=hci.VoiceSetting.InputDataFormat.TWOS_COMPLEMENT,
+                        )
+                    ),
+                    retransmission_effort=esco_parameters.retransmission_effort,
+                    packet_type=esco_parameters.packet_type,
+                )
+            )
+        )
+    else:
+        print('!!! no supported command for SCO connection request')
+        return
+
+    global output_wav
+    if output_wav:
+        output_wav.setnchannels(1)
+        output_wav.setsampwidth(2)
+        match protocol.active_codec:
+            case hfp.AudioCodec.CVSD:
+                output_wav.setframerate(8000)
+            case hfp.AudioCodec.MSBC:
+                output_wav.setframerate(16000)
+
+    connection.on('sco_connection', on_sco_connection)
 
 
 # -----------------------------------------------------------------------------
@@ -40,59 +142,47 @@ def on_dlc(dlc: rfcomm.DLC, configuration: hfp.HfConfiguration):
     hf_protocol = HfProtocol(dlc, configuration)
     asyncio.create_task(hf_protocol.run())
 
-    def on_sco_request(connection: Connection, link_type: int, protocol: HfProtocol):
+    connection = dlc.multiplexer.l2cap_channel.connection
-        if connection == protocol.dlc.multiplexer.l2cap_channel.connection:
+    handler = functools.partial(
-            if link_type == hci.HCI_Connection_Complete_Event.LinkType.SCO:
+        on_sco_request,
-                esco_parameters = hfp.ESCO_PARAMETERS[
+        connection=connection,
-                    hfp.DefaultCodecParameters.SCO_CVSD_D1
+        protocol=hf_protocol,
-                ]
-            elif protocol.active_codec == hfp.AudioCodec.MSBC:
-                esco_parameters = hfp.ESCO_PARAMETERS[
-                    hfp.DefaultCodecParameters.ESCO_MSBC_T2
-                ]
-            elif protocol.active_codec == hfp.AudioCodec.CVSD:
-                esco_parameters = hfp.ESCO_PARAMETERS[
-                    hfp.DefaultCodecParameters.ESCO_CVSD_S4
-                ]
-            else:
-                raise RuntimeError("unknown active codec")
-
-            connection.cancel_on_disconnection(
-                connection.device.send_command(
-                    hci.HCI_Enhanced_Accept_Synchronous_Connection_Request_Command(
-                        bd_addr=connection.peer_address, **esco_parameters.asdict()
     )
-                )
+    connection.on('sco_request', handler)
-            )
-
-    handler = functools.partial(on_sco_request, protocol=hf_protocol)
-    dlc.multiplexer.l2cap_channel.connection.device.on('sco_request', handler)
     dlc.multiplexer.l2cap_channel.once(
         'close',
-        lambda: dlc.multiplexer.l2cap_channel.connection.device.remove_listener(
+        lambda: connection.remove_listener('sco_request', handler),
-            'sco_request', handler
-        ),
     )
 
+    hf_protocol.on('ag_indicator', on_ag_indicator)
+    hf_protocol.on('codec_negotiation', on_codec_negotiation)
+
+
+# -----------------------------------------------------------------------------
 def on_ag_indicator(indicator):
     global ws
     if ws:
         asyncio.create_task(ws.send(str(indicator)))
 
-    hf_protocol.on('ag_indicator', on_ag_indicator)
+
+# -----------------------------------------------------------------------------
+def on_codec_negotiation(codec: hfp.AudioCodec):
+    print(f'### Negotiated codec: {codec.name}')
 
 
 # -----------------------------------------------------------------------------
-async def main() -> None:
+async def run(device: Device, codec: str | None) -> None:
-    if len(sys.argv) < 3:
+    if codec is None:
-        print('Usage: run_classic_hfp.py <device-config> <transport-spec>')
+        supported_audio_codecs = [hfp.AudioCodec.CVSD, hfp.AudioCodec.MSBC]
-        print('example: run_classic_hfp.py classic2.json usb:04b4:f901')
+    else:
+        if codec == 'cvsd':
+            supported_audio_codecs = [hfp.AudioCodec.CVSD]
+        elif codec == 'msbc':
+            supported_audio_codecs = [hfp.AudioCodec.MSBC]
+        else:
+            print('Unknown codec: ', codec)
             return
 
-    print('<<< connecting to HCI...')
-    async with await open_transport(sys.argv[2]) as hci_transport:
-        print('<<< connected')
-
     # Hands-Free profile configuration.
     # TODO: load configuration from file.
     configuration = hfp.HfConfiguration(
@@ -108,18 +198,9 @@ async def main() -> None:
         supported_hf_indicators=[
             hfp.HfIndicator.BATTERY_LEVEL,
         ],
-            supported_audio_codecs=[
+        supported_audio_codecs=supported_audio_codecs,
-                hfp.AudioCodec.CVSD,
-                hfp.AudioCodec.MSBC,
-            ],
     )
 
-        # Create a device
-        device = Device.from_config_file_with_hci(
-            sys.argv[1], hci_transport.source, hci_transport.sink
-        )
-        device.classic_enabled = True
-
     # Create and register a server
     rfcomm_server = rfcomm.Server(device)
 
@@ -129,9 +210,7 @@ async def main() -> None:
 
     # Advertise the HFP RFComm channel in the SDP
     device.sdp_service_records = {
-            0x00010001: hfp.make_hf_sdp_records(
+        0x00010001: hfp.make_hf_sdp_records(0x00010001, channel_number, configuration)
-                0x00010001, channel_number, configuration
-            )
     }
 
     # Let's go!
@@ -167,7 +246,59 @@ async def main() -> None:
 
     await websockets.asyncio.server.serve(serve, 'localhost', 8989)
 
-        await hci_transport.source.terminated
+    await asyncio.get_running_loop().create_future()  # run forever
+
+
+# -----------------------------------------------------------------------------
+async def main() -> None:
+    if len(sys.argv) < 3:
+        print(
+            'Usage: run_hfp_handsfree.py <device-config> <transport-spec> '
+            '[codec] [input] [output]'
+        )
+        print('example: run_hfp_handsfree.py classic2.json usb:0')
+        return
+
+    device_config = sys.argv[1]
+    transport_spec = sys.argv[2]
+
+    codec: str | None = None
+    if len(sys.argv) >= 4:
+        codec = sys.argv[3]
+
+    input_file_name: str | None = None
+    if len(sys.argv) >= 5:
+        input_file_name = sys.argv[4]
+
+    output_file_name: str | None = None
+    if len(sys.argv) >= 6:
+        output_file_name = sys.argv[5]
+
+    global input_wav, output_wav
+    input_cm: contextlib.AbstractContextManager[wave.Wave_read | None] = (
+        wave.open(input_file_name, "rb")
+        if input_file_name
+        else contextlib.nullcontext(None)
+    )
+    output_cm: contextlib.AbstractContextManager[wave.Wave_write | None] = (
+        wave.open(output_file_name, "wb")
+        if output_file_name
+        else contextlib.nullcontext(None)
+    )
+    with input_cm as input_wav, output_cm as output_wav:
+        if input_wav and input_wav.getnchannels() != 1:
+            print("Mono input required")
+            return
+        if input_wav and input_wav.getsampwidth() != 2:
+            print("16-bit input required")
+            return
+
+        async with await open_transport(transport_spec) as transport:
+            device = Device.from_config_file_with_hci(
+                device_config, transport.source, transport.sink
+            )
+            device.classic_enabled = True
+            await run(device, codec)
 
 
 # -----------------------------------------------------------------------------

tasks.py

@@ -170,7 +170,9 @@ def format_code(ctx, check=False, diff=False):
 @task
 def check_types(ctx):
     checklist = ["apps", "bumble", "examples", "tests", "tasks.py"]
+    print(">>> Running the type checker...")
     try:
+        print("+++ Checking with mypy...")
         ctx.run(f"mypy {' '.join(checklist)}")
     except UnexpectedExit as exc:
         print("Please check your code against the mypy messages.")

tests/transport_test.py

@@ -24,7 +24,7 @@ import sys
 import pytest
 
 from bumble import controller, device, hci, link, transport
-from bumble.transport import common
+from bumble.transport import common, usb
 
 
 # -----------------------------------------------------------------------------
@@ -252,6 +252,69 @@ async def test_open_transport_with_metadata(spec):
     await controller_transport.close()
 
 
+# -----------------------------------------------------------------------------
+def test_packet_splitter_complete():
+    emitted = []
+    splitter = usb.AclPacketSplitter(emitted.append)
+    packet = bytes([0x01, 0x00, 0x04, 0x00, 0x11, 0x22, 0x33, 0x44])
+    splitter.feed(packet)
+    assert emitted == [packet]
+
+
+def test_packet_splitter_chunks():
+    emitted = []
+    splitter = usb.AclPacketSplitter(emitted.append)
+    packet = bytes([0x01, 0x00, 0x04, 0x00, 0x11, 0x22, 0x33, 0x44])
+    splitter.feed(packet[:4])
+    assert emitted == []
+    splitter.feed(packet[4:])
+    assert emitted == [packet]
+
+
+def test_packet_splitter_multiple():
+    emitted = []
+    splitter = usb.AclPacketSplitter(emitted.append)
+    packet1 = bytes([0x01, 0x00, 0x04, 0x00, 0x11, 0x22, 0x33, 0x44])
+    packet2 = bytes([0x02, 0x00, 0x02, 0x00, 0x55, 0x66])
+    splitter.feed(packet1 + packet2)
+    assert emitted == [packet1, packet2]
+
+
+def test_packet_splitter_partial():
+    emitted = []
+    splitter = usb.AclPacketSplitter(emitted.append)
+    packet1 = bytes([0x01, 0x00, 0x04, 0x00, 0x11, 0x22, 0x33, 0x44])
+    packet2 = bytes([0x02, 0x00, 0x02, 0x00, 0x55, 0x66])
+    splitter.feed(packet1 + packet2[:4])
+    assert emitted == [packet1]
+    splitter.feed(packet2[4:])
+    assert emitted == [packet1, packet2]
+
+
+def test_packet_splitter_empty_payload():
+    emitted = []
+    splitter = usb.AclPacketSplitter(emitted.append)
+    packet = bytes([0x01, 0x00, 0x00, 0x00])
+    splitter.feed(packet)
+    assert emitted == [packet]
+
+
+def test_sco_packet_splitter():
+    emitted = []
+    splitter = usb.ScoPacketSplitter(emitted.append)
+    packet = bytes([0x01, 0x00, 0x03, 0x11, 0x22, 0x33])
+    splitter.feed(packet)
+    assert emitted == [packet]
+
+
+def test_event_packet_splitter():
+    emitted = []
+    splitter = usb.EventPacketSplitter(emitted.append)
+    packet = bytes([0x04, 0x02, 0x11, 0x22])
+    splitter.feed(packet)
+    assert emitted == [packet]
+
+
 # -----------------------------------------------------------------------------
 if __name__ == '__main__':
     test_parser()

tests/usb_test.py

@@ -0,0 +1,95 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import asyncio
+from unittest import mock
+
+import pytest
+
+from bumble import hci
+from bumble.transport import usb
+
+
+@pytest.mark.asyncio
+async def test_usb_packet_sink_iso_routing():
+    # Mock usb1 device and endpoints
+    mock_device = mock.Mock()
+    mock_bulk_out = mock.Mock()
+    mock_bulk_out.getAddress.return_value = 0x02
+
+    # Scenario 1: Isochronous endpoints are not enabled (isochronous_out is None)
+    mock_transfer = mock.Mock()
+    mock_device.getTransfer.return_value = mock_transfer
+
+    sink = usb.UsbPacketSink(mock_device, mock_bulk_out, isochronous_out=None)
+    sink.start()
+
+    # Send HCI_ISO_DATA_PACKET
+    iso_packet = bytes([hci.HCI_ISO_DATA_PACKET, 0x01, 0x02, 0x03])
+    sink.on_packet(iso_packet)
+
+    # Yield control to let the queue processor run
+    await asyncio.sleep(0.01)
+
+    # Verify it was sent via bulk transfer
+    mock_transfer.setBulk.assert_called_once_with(
+        0x02,
+        bytes([0x01, 0x02, 0x03]),
+        callback=sink.transfer_callback,
+    )
+    mock_transfer.submit.assert_called_once()
+
+    if sink.queue_task:
+        sink.queue_task.cancel()
+        try:
+            await sink.queue_task
+        except asyncio.CancelledError:
+            pass
+
+
+@pytest.mark.asyncio
+async def test_usb_packet_sink_iso_routing_with_iso_endpoint():
+    # Mock usb1 device and endpoints
+    mock_device = mock.Mock()
+    mock_bulk_out = mock.Mock()
+    mock_bulk_out.getAddress.return_value = 0x02
+    mock_iso_out = mock.Mock()
+    mock_iso_out.getMaxPacketSize.return_value = 64
+
+    # Scenario 2: Isochronous endpoints are enabled
+    mock_transfer_bulk = mock.Mock()
+    mock_transfer_iso = mock.Mock()
+
+    # getTransfer is called twice: once for bulk_or_control and once for isochronous
+    mock_device.getTransfer.side_effect = [mock_transfer_bulk, mock_transfer_iso]
+
+    sink = usb.UsbPacketSink(mock_device, mock_bulk_out, isochronous_out=mock_iso_out)
+    sink.start()
+
+    # Send HCI_ISO_DATA_PACKET
+    iso_packet = bytes([hci.HCI_ISO_DATA_PACKET, 0x01, 0x02, 0x03])
+    sink.on_packet(iso_packet)
+
+    # Yield control to let the queue processor run
+    await asyncio.sleep(0.01)
+
+    # Verify it was NOT sent via bulk transfer
+    mock_transfer_bulk.setBulk.assert_not_called()
+
+    if sink.queue_task:
+        sink.queue_task.cancel()
+        try:
+            await sink.queue_task
+        except asyncio.CancelledError:
+            pass