`bluetooth` — low-level Bluetooth¶

This module provides an interface to a Bluetooth controller on a board. Currently this supports Bluetooth Low Energy (BLE) in Central, Peripheral, Broadcaster, and Observer roles, as well as GATT Server and Client and L2CAP connection-oriented-channels. A device may operate in multiple roles concurrently. Pairing (and bonding) is supported on some ports.

This API is intended to match the low-level Bluetooth protocol and provide building-blocks for higher-level abstractions such as specific device types.

Note

This module is still under development and its classes, functions, methods and constants are subject to change.

class BLE¶

Constructor¶

class bluetooth.BLE¶: Returns the singleton BLE object.

Configuration¶

BLE.active([active, ]/)¶

Optionally changes the active state of the BLE radio, and returns the current state.

The radio must be made active before using any other methods on this class.

BLE.config('param', /)¶

BLE.config(*, param=value, ...)

Get or set configuration values of the BLE interface. To get a value the parameter name should be quoted as a string, and just one parameter is queried at a time. To set values use the keyword syntax, and one ore more parameter can be set at a time.

Currently supported values are:

'mac': The current address in use, depending on the current address mode. This returns a tuple of (addr_type, addr).

See gatts_write for details about address type.

This may only be queried while the interface is currently active.
'addr_mode': Sets the address mode. Values can be:
- 0x00 - PUBLIC - Use the controller’s public address.
- 0x01 - RANDOM - Use a generated static address.
- 0x02 - RPA - Use resolvable private addresses.
- 0x03 - NRPA - Use non-resolvable private addresses.
By default the interface mode will use a PUBLIC address if available, otherwise it will use a RANDOM address.
'gap_name': Get/set the GAP device name used by service 0x1800, characteristic 0x2a00. This can be set at any time and changed multiple times.
'rxbuf': Get/set the size in bytes of the internal buffer used to store incoming events. This buffer is global to the entire BLE driver and so handles incoming data for all events, including all characteristics. Increasing this allows better handling of bursty incoming data (for example scan results) and the ability to receive larger characteristic values.
'mtu': Get/set the MTU that will be used during a ATT MTU exchange. The resulting MTU will be the minimum of this and the remote device’s MTU. ATT MTU exchange will not happen automatically (unless the remote device initiates it), and must be manually initiated with gattc_exchange_mtu. Use the _IRQ_MTU_EXCHANGED event to discover the MTU for a given connection.
'bond': Sets whether bonding will be enabled during pairing. When enabled, pairing requests will set the “bond” flag and the keys will be stored by both devices.
'mitm': Sets whether MITM-protection is required for pairing.

'io': Sets the I/O capabilities of this device.

Available options are:

_IO_CAPABILITY_DISPLAY_ONLY = const(0)
_IO_CAPABILITY_DISPLAY_YESNO = const(1)
_IO_CAPABILITY_KEYBOARD_ONLY = const(2)
_IO_CAPABILITY_NO_INPUT_OUTPUT = const(3)
_IO_CAPABILITY_KEYBOARD_DISPLAY = const(4)

'le_secure': Sets whether “LE Secure” pairing is required. Default is false (i.e. allow “Legacy Pairing”).

Event Handling¶

BLE.irq(handler, /)¶

Registers a callback for events from the BLE stack. The handler takes two arguments, event (which will be one of the codes below) and data (which is an event-specific tuple of values).

Note: As an optimisation to prevent unnecessary allocations, the addr, adv_data, char_data, notify_data, and uuid entries in the tuples are read-only memoryview instances pointing to bluetooth’s internal ringbuffer, and are only valid during the invocation of the IRQ handler function. If your program needs to save one of these values to access after the IRQ handler has returned (e.g. by saving it in a class instance or global variable), then it needs to take a copy of the data, either by using bytes() or bluetooth.UUID(), like this:

connected_addr = bytes(addr)  # equivalently: adv_data, char_data, or notify_data
matched_uuid = bluetooth.UUID(uuid)

For example, the IRQ handler for a scan result might inspect the adv_data to decide if it’s the correct device, and only then copy the address data to be used elsewhere in the program. And to print data from within the IRQ handler, print(bytes(addr)) will be needed.

An event handler showing all possible events:

def bt_irq(event, data):
    if event == _IRQ_CENTRAL_CONNECT:
        # A central has connected to this peripheral.
        conn_handle, addr_type, addr = data
    elif event == _IRQ_CENTRAL_DISCONNECT:
        # A central has disconnected from this peripheral.
        conn_handle, addr_type, addr = data
    elif event == _IRQ_GATTS_WRITE:
        # A client has written to this characteristic or descriptor.
        conn_handle, attr_handle = data
    elif event == _IRQ_GATTS_READ_REQUEST:
        # A client has issued a read. Note: this is only supported on STM32.
        # Return a non-zero integer to deny the read (see below), or zero (or None)
        # to accept the read.
        conn_handle, attr_handle = data
    elif event == _IRQ_SCAN_RESULT:
        # A single scan result.
        addr_type, addr, adv_type, rssi, adv_data = data
    elif event == _IRQ_SCAN_DONE:
        # Scan duration finished or manually stopped.
        pass
    elif event == _IRQ_PERIPHERAL_CONNECT:
        # A successful gap_connect().
        conn_handle, addr_type, addr = data
    elif event == _IRQ_PERIPHERAL_DISCONNECT:
        # Connected peripheral has disconnected.
        conn_handle, addr_type, addr = data
    elif event == _IRQ_GATTC_SERVICE_RESULT:
        # Called for each service found by gattc_discover_services().
        conn_handle, start_handle, end_handle, uuid = data
    elif event == _IRQ_GATTC_SERVICE_DONE:
        # Called once service discovery is complete.
        # Note: Status will be zero on success, implementation-specific value otherwise.
        conn_handle, status = data
    elif event == _IRQ_GATTC_CHARACTERISTIC_RESULT:
        # Called for each characteristic found by gattc_discover_services().
        conn_handle, def_handle, value_handle, properties, uuid = data
    elif event == _IRQ_GATTC_CHARACTERISTIC_DONE:
        # Called once service discovery is complete.
        # Note: Status will be zero on success, implementation-specific value otherwise.
        conn_handle, status = data
    elif event == _IRQ_GATTC_DESCRIPTOR_RESULT:
        # Called for each descriptor found by gattc_discover_descriptors().
        conn_handle, dsc_handle, uuid = data
    elif event == _IRQ_GATTC_DESCRIPTOR_DONE:
        # Called once service discovery is complete.
        # Note: Status will be zero on success, implementation-specific value otherwise.
        conn_handle, status = data
    elif event == _IRQ_GATTC_READ_RESULT:
        # A gattc_read() has completed.
        conn_handle, value_handle, char_data = data
    elif event == _IRQ_GATTC_READ_DONE:
        # A gattc_read() has completed.
        # Note: The value_handle will be zero on btstack (but present on NimBLE).
        # Note: Status will be zero on success, implementation-specific value otherwise.
        conn_handle, value_handle, status = data
    elif event == _IRQ_GATTC_WRITE_DONE:
        # A gattc_write() has completed.
        # Note: The value_handle will be zero on btstack (but present on NimBLE).
        # Note: Status will be zero on success, implementation-specific value otherwise.
        conn_handle, value_handle, status = data
    elif event == _IRQ_GATTC_NOTIFY:
        # A server has sent a notify request.
        conn_handle, value_handle, notify_data = data
    elif event == _IRQ_GATTC_INDICATE:
        # A server has sent an indicate request.
        conn_handle, value_handle, notify_data = data
    elif event == _IRQ_GATTS_INDICATE_DONE:
        # A client has acknowledged the indication.
        # Note: Status will be zero on successful acknowledgment, implementation-specific value otherwise.
        conn_handle, value_handle, status = data
    elif event == _IRQ_MTU_EXCHANGED:
        # ATT MTU exchange complete (either initiated by us or the remote device).
        conn_handle, mtu = data
    elif event == _IRQ_L2CAP_ACCEPT:
        # A new channel has been accepted.
        # Return a non-zero integer to reject the connection, or zero (or None) to accept.
        conn_handle, cid, psm, our_mtu, peer_mtu = data
    elif event == _IRQ_L2CAP_CONNECT:
        # A new channel is now connected (either as a result of connecting or accepting).
        conn_handle, cid, psm, our_mtu, peer_mtu = data
    elif event == _IRQ_L2CAP_DISCONNECT:
        # Existing channel has disconnected (status is zero), or a connection attempt failed (non-zero status).
        conn_handle, cid, psm, status = data
    elif event == _IRQ_L2CAP_RECV:
        # New data is available on the channel. Use l2cap_recvinto to read.
        conn_handle, cid = data
    elif event == _IRQ_L2CAP_SEND_READY:
        # A previous l2cap_send that returned False has now completed and the channel is ready to send again.
        # If status is non-zero, then the transmit buffer overflowed and the application should re-send the data.
        conn_handle, cid, status = data
    elif event == _IRQ_CONNECTION_UPDATE:
        # The remote device has updated connection parameters.
        conn_handle, conn_interval, conn_latency, supervision_timeout, status = data
    elif event == _IRQ_ENCRYPTION_UPDATE:
        # The encryption state has changed (likely as a result of pairing or bonding).
        conn_handle, encrypted, authenticated, bonded, key_size = data
    elif event == _IRQ_GET_SECRET:
        # Return a stored secret.
        # If key is None, return the index'th value of this sec_type.
        # Otherwise return the corresponding value for this sec_type and key.
        sec_type, index, key = data
        return value
    elif event == _IRQ_SET_SECRET:
        # Save a secret to the store for this sec_type and key.
        sec_type, key, value = data
        return True
    elif event == _IRQ_PASSKEY_ACTION:
        # Respond to a passkey request during pairing.
        # See gap_passkey() for details.
        # action will be an action that is compatible with the configured "io" config.
        # passkey will be non-zero if action is "numeric comparison".
        conn_handle, action, passkey = data

The event codes are:

from micropython import const
_IRQ_CENTRAL_CONNECT = const(1)
_IRQ_CENTRAL_DISCONNECT = const(2)
_IRQ_GATTS_WRITE = const(3)
_IRQ_GATTS_READ_REQUEST = const(4)
_IRQ_SCAN_RESULT = const(5)
_IRQ_SCAN_DONE = const(6)
_IRQ_PERIPHERAL_CONNECT = const(7)
_IRQ_PERIPHERAL_DISCONNECT = const(8)
_IRQ_GATTC_SERVICE_RESULT = const(9)
_IRQ_GATTC_SERVICE_DONE = const(10)
_IRQ_GATTC_CHARACTERISTIC_RESULT = const(11)
_IRQ_GATTC_CHARACTERISTIC_DONE = const(12)
_IRQ_GATTC_DESCRIPTOR_RESULT = const(13)
_IRQ_GATTC_DESCRIPTOR_DONE = const(14)
_IRQ_GATTC_READ_RESULT = const(15)
_IRQ_GATTC_READ_DONE = const(16)
_IRQ_GATTC_WRITE_DONE = const(17)
_IRQ_GATTC_NOTIFY = const(18)
_IRQ_GATTC_INDICATE = const(19)
_IRQ_GATTS_INDICATE_DONE = const(20)
_IRQ_MTU_EXCHANGED = const(21)
_IRQ_L2CAP_ACCEPT = const(22)
_IRQ_L2CAP_CONNECT = const(23)
_IRQ_L2CAP_DISCONNECT = const(24)
_IRQ_L2CAP_RECV = const(25)
_IRQ_L2CAP_SEND_READY = const(26)
_IRQ_CONNECTION_UPDATE = const(27)
_IRQ_ENCRYPTION_UPDATE = const(28)
_IRQ_GET_SECRET = const(29)
_IRQ_SET_SECRET = const(30)

For the _IRQ_GATTS_READ_REQUEST event, the available return codes are:

_GATTS_NO_ERROR = const(0x00)
_GATTS_ERROR_READ_NOT_PERMITTED = const(0x02)
_GATTS_ERROR_WRITE_NOT_PERMITTED = const(0x03)
_GATTS_ERROR_INSUFFICIENT_AUTHENTICATION = const(0x05)
_GATTS_ERROR_INSUFFICIENT_AUTHORIZATION = const(0x08)
_GATTS_ERROR_INSUFFICIENT_ENCRYPTION = const(0x0f)

For the _IRQ_PASSKEY_ACTION event, the available actions are:

_PASSKEY_ACTION_NONE = const(0)
_PASSKEY_ACTION_INPUT = const(2)
_PASSKEY_ACTION_DISPLAY = const(3)
_PASSKEY_ACTION_NUMERIC_COMPARISON = const(4)

In order to save space in the firmware, these constants are not included on the bluetooth module. Add the ones that you need from the list above to your program.

Broadcaster Role (Advertiser)¶

BLE.gap_advertise(interval_us, adv_data=None, *, resp_data=None, connectable=True)¶

Starts advertising at the specified interval (in microseconds). This interval will be rounded down to the nearest 625us. To stop advertising, set interval_us to None.

adv_data and resp_data can be any type that implements the buffer protocol (e.g. bytes, bytearray, str). adv_data is included in all broadcasts, and resp_data is send in reply to an active scan.

Note: if adv_data (or resp_data) is None, then the data passed to the previous call to gap_advertise will be re-used. This allows a broadcaster to resume advertising with just gap_advertise(interval_us). To clear the advertising payload pass an empty bytes, i.e. b''.

Observer Role (Scanner)¶

BLE.gap_scan(duration_ms, interval_us=1280000, window_us=11250, active=False, /)¶

Run a scan operation lasting for the specified duration (in milliseconds).

To scan indefinitely, set duration_ms to 0.

To stop scanning, set duration_ms to None.

Use interval_us and window_us to optionally configure the duty cycle. The scanner will run for window_us microseconds every interval_us microseconds for a total of duration_ms milliseconds. The default interval and window are 1.28 seconds and 11.25 milliseconds respectively (background scanning).

For each scan result the _IRQ_SCAN_RESULT event will be raised, with event data (addr_type, addr, adv_type, rssi, adv_data).

addr_type values indicate public or random addresses:

0x00 - PUBLIC
0x01 - RANDOM (either static, RPA, or NRPA, the type is encoded in the address itself)

adv_type values correspond to the Bluetooth Specification:

0x00 - ADV_IND - connectable and scannable undirected advertising

0x01 - ADV_DIRECT_IND - connectable directed advertising

0x02 - ADV_SCAN_IND - scannable undirected advertising

0x03 - ADV_NONCONN_IND - non-connectable undirected advertising

0x04 - SCAN_RSP - scan response

active can be set True if you want to receive scan responses in the results.

When scanning is stopped (either due to the duration finishing or when explicitly stopped), the _IRQ_SCAN_DONE event will be raised.

Central Role¶

A central device can connect to peripherals that it has discovered using the observer role (see gap_scan) or with a known address.

BLE.gap_connect(addr_type, addr, scan_duration_ms=2000, min_conn_interval_us=None, max_conn_interval_us=None, /)¶

Connect to a peripheral.

See gap_scan for details about address types.

To cancel an outstanding connection attempt early, call gap_connect(None).

On success, the _IRQ_PERIPHERAL_CONNECT event will be raised. If cancelling a connection attempt, the _IRQ_PERIPHERAL_DISCONNECT event will be raised.

The device will wait up to scan_duration_ms to receive an advertising payload from the device.

The connection interval can be configured in microseconds using either or both of min_conn_interval_us and max_conn_interval_us. Otherwise a default interval will be chosen, typically between 30000 and 50000 microseconds. A shorter interval will increase throughput, at the expense of power usage.

Peripheral Role¶

A peripheral device is expected to send connectable advertisements (see gap_advertise). It will usually be acting as a GATT server, having first registered services and characteristics using gatts_register_services.

When a central connects, the _IRQ_CENTRAL_CONNECT event will be raised.

Central & Peripheral Roles¶

BLE.gap_disconnect(conn_handle, /)¶

Disconnect the specified connection handle. This can either be a central that has connected to this device (if acting as a peripheral) or a peripheral that was previously connected to by this device (if acting as a central).

On success, the _IRQ_PERIPHERAL_DISCONNECT or _IRQ_CENTRAL_DISCONNECT event will be raised.

Returns False if the connection handle wasn’t connected, and True otherwise.

GATT Server¶

A GATT server has a set of registered services. Each service may contain characteristics, which each have a value. Characteristics can also contain descriptors, which themselves have values.

These values are stored locally, and are accessed by their “value handle” which is generated during service registration. They can also be read from or written to by a remote client device. Additionally, a server can “notify” a characteristic to a connected client via a connection handle.

A device in either central or peripheral roles may function as a GATT server, however in most cases it will be more common for a peripheral device to act as the server.

Characteristics and descriptors have a default maximum size of 20 bytes. Anything written to them by a client will be truncated to this length. However, any local write will increase the maximum size, so if you want to allow larger writes from a client to a given characteristic, use gatts_write after registration. e.g. gatts_write(char_handle, bytes(100)).

BLE.gatts_register_services(services_definition, /)¶

Configures the server with the specified services, replacing any existing services.

services_definition is a list of services, where each service is a two-element tuple containing a UUID and a list of characteristics.

Each characteristic is a two-or-three-element tuple containing a UUID, a flags value, and optionally a list of descriptors.

Each descriptor is a two-element tuple containing a UUID and a flags value.

The flags are a bitwise-OR combination of the flags defined below. These set both the behaviour of the characteristic (or descriptor) as well as the security and privacy requirements.

The return value is a list (one element per service) of tuples (each element is a value handle). Characteristics and descriptor handles are flattened into the same tuple, in the order that they are defined.

The following example registers two services (Heart Rate, and Nordic UART):

HR_UUID = bluetooth.UUID(0x180D)
HR_CHAR = (bluetooth.UUID(0x2A37), bluetooth.FLAG_READ | bluetooth.FLAG_NOTIFY,)
HR_SERVICE = (HR_UUID, (HR_CHAR,),)
UART_UUID = bluetooth.UUID('6E400001-B5A3-F393-E0A9-E50E24DCCA9E')
UART_TX = (bluetooth.UUID('6E400003-B5A3-F393-E0A9-E50E24DCCA9E'), bluetooth.FLAG_READ | bluetooth.FLAG_NOTIFY,)
UART_RX = (bluetooth.UUID('6E400002-B5A3-F393-E0A9-E50E24DCCA9E'), bluetooth.FLAG_WRITE,)
UART_SERVICE = (UART_UUID, (UART_TX, UART_RX,),)
SERVICES = (HR_SERVICE, UART_SERVICE,)
( (hr,), (tx, rx,), ) = bt.gatts_register_services(SERVICES)

The three value handles (hr, tx, rx) can be used with gatts_read, gatts_write, gatts_notify, and gatts_indicate.

Note: Advertising must be stopped before registering services.

Available flags for characteristics and descriptors are:

from micropython import const
_FLAG_BROADCAST = const(0x0001)
_FLAG_READ = const(0x0002)
_FLAG_WRITE_NO_RESPONSE = const(0x0004)
_FLAG_WRITE = const(0x0008)
_FLAG_NOTIFY = const(0x0010)
_FLAG_INDICATE = const(0x0020)
_FLAG_AUTHENTICATED_SIGNED_WRITE = const(0x0040)

_FLAG_AUX_WRITE = const(0x0100)
_FLAG_READ_ENCRYPTED = const(0x0200)
_FLAG_READ_AUTHENTICATED = const(0x0400)
_FLAG_READ_AUTHORIZED = const(0x0800)
_FLAG_WRITE_ENCRYPTED = const(0x1000)
_FLAG_WRITE_AUTHENTICATED = const(0x2000)
_FLAG_WRITE_AUTHORIZED = const(0x4000)

As for the IRQs above, any required constants should be added to your Python code.

BLE.gatts_read(value_handle, /)¶: Reads the local value for this handle (which has either been written by gatts_write or by a remote client).

BLE.gatts_write(value_handle, data, send_update=False, /)¶

Writes the local value for this handle, which can be read by a client.

If send_update is True, then any subscribed clients will be notified (or indicated, depending on what they’re subscribed to and which operations the characteristic supports) about this write.

BLE.gatts_notify(conn_handle, value_handle, data=None, /)¶

Sends a notification request to a connected client.

If data is not None, then that value is sent to the client as part of the notification. The local value will not be modified.

Otherwise, if data is None, then the current local value (as set with gatts_write) will be sent.

Note: The notification will be sent regardless of the subscription status of the client to this characteristic.

BLE.gatts_indicate(conn_handle, value_handle, /)¶

Sends an indication request containing the characteristic’s current value to a connected client.

On acknowledgment (or failure, e.g. timeout), the _IRQ_GATTS_INDICATE_DONE event will be raised.

Note: The indication will be sent regardless of the subscription status of the client to this characteristic.

BLE.gatts_set_buffer(value_handle, len, append=False, /)¶

Sets the internal buffer size for a value in bytes. This will limit the largest possible write that can be received. The default is 20.

Setting append to True will make all remote writes append to, rather than replace, the current value. At most len bytes can be buffered in this way. When you use gatts_read, the value will be cleared after reading. This feature is useful when implementing something like the Nordic UART Service.

GATT Client¶

A GATT client can discover and read/write characteristics on a remote GATT server.

It is more common for a central role device to act as the GATT client, however it’s also possible for a peripheral to act as a client in order to discover information about the central that has connected to it (e.g. to read the device name from the device information service).

BLE.gattc_discover_services(conn_handle, uuid=None, /)¶

Query a connected server for its services.

Optionally specify a service uuid to query for that service only.

For each service discovered, the _IRQ_GATTC_SERVICE_RESULT event will be raised, followed by _IRQ_GATTC_SERVICE_DONE on completion.

BLE.gattc_discover_characteristics(conn_handle, start_handle, end_handle, uuid=None, /)¶

Query a connected server for characteristics in the specified range.

Optionally specify a characteristic uuid to query for that characteristic only.

You can use start_handle=1, end_handle=0xffff to search for a characteristic in any service.

For each characteristic discovered, the _IRQ_GATTC_CHARACTERISTIC_RESULT event will be raised, followed by _IRQ_GATTC_CHARACTERISTIC_DONE on completion.

BLE.gattc_discover_descriptors(conn_handle, start_handle, end_handle, /)¶

Query a connected server for descriptors in the specified range.

For each descriptor discovered, the _IRQ_GATTC_DESCRIPTOR_RESULT event will be raised, followed by _IRQ_GATTC_DESCRIPTOR_DONE on completion.

BLE.gattc_read(conn_handle, value_handle, /)¶

Issue a remote read to a connected server for the specified characteristic or descriptor handle.

When a value is available, the _IRQ_GATTC_READ_RESULT event will be raised. Additionally, the _IRQ_GATTC_READ_DONE will be raised.

BLE.gattc_write(conn_handle, value_handle, data, mode=0, /)¶

Issue a remote write to a connected server for the specified characteristic or descriptor handle.

The argument mode specifies the write behaviour, with the currently supported values being:

mode=0 (default) is a write-without-response: the write will be sent to the remote server but no confirmation will be returned, and no event will be raised.

mode=1 is a write-with-response: the remote server is requested to send a response/acknowledgement that it received the data.

If a response is received from the remote server the _IRQ_GATTC_WRITE_DONE event will be raised.

BLE.gattc_exchange_mtu(conn_handle, /)¶

Initiate MTU exchange with a connected server, using the preferred MTU set using BLE.config(mtu=value).

The _IRQ_MTU_EXCHANGED event will be raised when MTU exchange completes.

Note: MTU exchange is typically initiated by the central. When using the BlueKitchen stack in the central role, it does not support a remote peripheral initiating the MTU exchange. NimBLE works for both roles.

L2CAP connection-oriented-channels¶

This feature allows for socket-like data exchange between two BLE devices. Once the devices are connected via GAP, either device can listen for the other to connect on a numeric PSM (Protocol/Service Multiplexer).

Note: This is currently only supported when using the NimBLE stack on STM32 and Unix (not ESP32). Only one L2CAP channel may be active at a given time (i.e. you cannot connect while listening).

Active L2CAP channels are identified by the connection handle that they were established on and a CID (channel ID).

Connection-oriented channels have built-in credit-based flow control. Unlike ATT, where devices negotiate a shared MTU, both the listening and connecting devices each set an independent MTU which limits the maximum amount of outstanding data that the remote device can send before it is fully consumed in l2cap_recvinto.

BLE.l2cap_listen(psm, mtu, /)¶

Start listening for incoming L2CAP channel requests on the specified psm with the local MTU set to mtu.

When a remote device initiates a connection, the _IRQ_L2CAP_ACCEPT event will be raised, which gives the listening server a chance to reject the incoming connection (by returning a non-zero integer).

Once the connection is accepted, the _IRQ_L2CAP_CONNECT event will be raised, allowing the server to obtain the channel id (CID) and the local and remote MTU.

Note: It is not currently possible to stop listening.

BLE.l2cap_connect(conn_handle, psm, mtu, /)¶

Connect to a listening peer on the specified psm with local MTU set to mtu.

On successful connection, the the _IRQ_L2CAP_CONNECT event will be raised, allowing the client to obtain the CID and the local and remote (peer) MTU.

An unsuccessful connection will raise the _IRQ_L2CAP_DISCONNECT event with a non-zero status.

BLE.l2cap_disconnect(conn_handle, cid, /)¶: Disconnect an active L2CAP channel with the specified conn_handle and cid.

BLE.l2cap_send(conn_handle, cid, buf, /)¶

Send the specified buf (which must support the buffer protocol) on the L2CAP channel identified by conn_handle and cid.

The specified buffer cannot be larger than the remote (peer) MTU, and no more than twice the size of the local MTU.

This will return False if the channel is now “stalled”, which means that l2cap_send must not be called again until the _IRQ_L2CAP_SEND_READY event is received (which will happen when the remote device grants more credits, typically after it has received and processed the data).

BLE.l2cap_recvinto(conn_handle, cid, buf, /)¶

Receive data from the specified conn_handle and cid into the provided buf (which must support the buffer protocol, e.g. bytearray or memoryview).

Returns the number of bytes read from the channel.

If buf is None, then returns the number of bytes available.

Note: After receiving the _IRQ_L2CAP_RECV event, the application should continue calling l2cap_recvinto until no more bytes are available in the receive buffer (typically up to the size of the remote (peer) MTU).

Until the receive buffer is empty, the remote device will not be granted more channel credits and will be unable to send any more data.

Pairing and bonding¶

Pairing allows a connection to be encrypted and authenticated via exchange of secrets (with optional MITM protection via passkey authentication).

Bonding is the process of storing those secrets into non-volatile storage. When bonded, a device is able to resolve a resolvable private address (RPA) from another device based on the stored identity resolving key (IRK). To support bonding, an application must implement the _IRQ_GET_SECRET and _IRQ_SET_SECRET events.

Note: This is currently only supported when using the NimBLE stack on STM32 and Unix (not ESP32).

BLE.gap_pair(conn_handle, /)¶

Initiate pairing with the remote device.

Before calling this, ensure that the io, mitm, le_secure, and bond configuration options are set (via config).

On successful pairing, the _IRQ_ENCRYPTION_UPDATE event will be raised.

BLE.gap_passkey(conn_handle, action, passkey, /)¶

Respond to a _IRQ_PASSKEY_ACTION event for the specified conn_handle and action.

The passkey is a numeric value and will depend on on the action (which will depend on what I/O capability has been set):

When the action is _PASSKEY_ACTION_INPUT, then the application should prompt the user to enter the passkey that is shown on the remote device.

When the action is _PASSKEY_ACTION_DISPLAY, then the application should generate a random 6-digit passkey and show it to the user.

When the action is _PASSKEY_ACTION_NUMERIC_COMPARISON, then the application should show the passkey that was provided in the _IRQ_PASSKEY_ACTION event and then respond with either 0 (cancel pairing), or 1 (accept pairing).

class UUID¶

Constructor¶

class bluetooth.UUID(value, /)¶

Creates a UUID instance with the specified value.

The value can be either:

A 16-bit integer. e.g. 0x2908.
A 128-bit UUID string. e.g. '6E400001-B5A3-F393-E0A9-E50E24DCCA9E'.

bluetooth — low-level Bluetooth¶

class BLE¶

Constructor¶

Configuration¶

Event Handling¶

Broadcaster Role (Advertiser)¶

Observer Role (Scanner)¶

Central Role¶

Peripheral Role¶

Central & Peripheral Roles¶

GATT Server¶

GATT Client¶

L2CAP connection-oriented-channels¶

Pairing and bonding¶

class UUID¶

Constructor¶

`bluetooth` — low-level Bluetooth¶