433 lines
18 KiB
ReStructuredText
433 lines
18 KiB
ReStructuredText
:mod:`ubluetooth` --- low-level Bluetooth
|
|
=========================================
|
|
|
|
.. module:: ubluetooth
|
|
:synopsis: Low-level Bluetooth radio functionality
|
|
|
|
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, and a device may operate in multiple
|
|
roles concurrently.
|
|
|
|
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:: BLE()
|
|
|
|
Returns the singleton BLE object.
|
|
|
|
Configuration
|
|
-------------
|
|
|
|
.. method:: 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.
|
|
|
|
.. method:: 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'``: Returns the device MAC address. If a device has a fixed address
|
|
(e.g. PYBD) then it will be returned. Otherwise (e.g. ESP32) a random
|
|
address will be generated when the BLE interface is made active.
|
|
|
|
**Note:** on some ports, accessing this value requires that the interface is
|
|
active (so that the MAC address can be queried from the controller).
|
|
|
|
- ``'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 for a central role to receive
|
|
larger characteristic values.
|
|
|
|
Event Handling
|
|
--------------
|
|
|
|
.. method:: 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:** the ``addr``, ``adv_data``, ``char_data``, ``notify_data``, and
|
|
``uuid`` entries in the tuples are references to data managed by the
|
|
:mod:`ubluetooth` module (i.e. the same instance will be re-used across
|
|
multiple calls to the event handler). If your program wants to use this
|
|
data outside of the handler, then it must copy them first, e.g. by using
|
|
``bytes(addr)`` or ``bluetooth.UUID(uuid)``.
|
|
|
|
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 central has written to this characteristic or descriptor.
|
|
conn_handle, attr_handle = data
|
|
elif event == _IRQ_GATTS_READ_REQUEST:
|
|
# A central has issued a read. Note: this is a hard IRQ.
|
|
# Return None to deny the read.
|
|
# Note: This event is not supported on ESP32.
|
|
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 peripheral has sent a notify request.
|
|
conn_handle, value_handle, notify_data = data
|
|
elif event == _IRQ_GATTC_INDICATE:
|
|
# A peripheral has sent an indicate request.
|
|
conn_handle, value_handle, notify_data = data
|
|
elif event == _IRQ_GATTS_INDICATE_DONE:
|
|
# A central has acknowledged the indication.
|
|
# Note: Status will be zero on successful acknowledgment, implementation-specific value otherwise.
|
|
conn_handle, value_handle, status = 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)
|
|
|
|
In order to save space in the firmware, these constants are not included on the
|
|
:mod:`ubluetooth` module. Add the ones that you need from the list above to your
|
|
program.
|
|
|
|
|
|
Broadcaster Role (Advertiser)
|
|
-----------------------------
|
|
|
|
.. method:: BLE.gap_advertise(interval_us, adv_data=None, resp_data=None, connectable=True)
|
|
|
|
Starts advertising at the specified interval (in **micro**\ seconds). 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)
|
|
-----------------------
|
|
|
|
.. method:: BLE.gap_scan(duration_ms, [interval_us], [window_us])
|
|
|
|
Run a scan operation lasting for the specified duration (in **milli**\ seconds).
|
|
|
|
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* **micro**\ seconds every *interval_us*
|
|
**micro**\ seconds for a total of *duration_ms* **milli**\ seconds. 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)``. ``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
|
|
|
|
When scanning is stopped (either due to the duration finishing or when
|
|
explicitly stopped), the ``_IRQ_SCAN_DONE`` event will be raised.
|
|
|
|
|
|
Peripheral Role (GATT Server)
|
|
-----------------------------
|
|
|
|
A BLE peripheral 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 central device. Additionally, a peripheral can "notify" a
|
|
characteristic to a connected central via a connection handle.
|
|
|
|
Characteristics and descriptors have a default maximum size of 20 bytes.
|
|
Anything written to them by a central 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 central to a given characteristic, use
|
|
:meth:`gatts_write<BLE.gatts_write>` after registration. e.g.
|
|
``gatts_write(char_handle, bytes(100))``.
|
|
|
|
.. method:: BLE.gatts_register_services(services_definition)
|
|
|
|
Configures the peripheral 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
|
|
:data:`ubluetooth.FLAG_READ`, :data:`ubluetooth.FLAG_WRITE` and
|
|
:data:`ubluetooth.FLAG_NOTIFY` values defined below.
|
|
|
|
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
|
|
:meth:`gatts_read <BLE.gatts_read>`, :meth:`gatts_write <BLE.gatts_write>`, :meth:`gatts_notify <BLE.gatts_notify>`, and
|
|
:meth:`gatts_indicate <BLE.gatts_indicate>`.
|
|
|
|
**Note:** Advertising must be stopped before registering services.
|
|
|
|
.. method:: BLE.gatts_read(value_handle)
|
|
|
|
Reads the local value for this handle (which has either been written by
|
|
:meth:`gatts_write <BLE.gatts_write>` or by a remote central).
|
|
|
|
.. method:: BLE.gatts_write(value_handle, data)
|
|
|
|
Writes the local value for this handle, which can be read by a central.
|
|
|
|
.. method:: BLE.gatts_notify(conn_handle, value_handle, [data])
|
|
|
|
Sends a notification request to a connected central.
|
|
|
|
If *data* is specified, then that value is sent to the central as part of
|
|
the notification. The local value will not be modified.
|
|
|
|
Otherwise, if *data* is not specified, then the current local value (as
|
|
set with :meth:`gatts_write <BLE.gatts_write>`) will be sent.
|
|
|
|
.. method:: BLE.gatts_indicate(conn_handle, value_handle)
|
|
|
|
Sends an indication request to a connected central.
|
|
|
|
**Note:** This does not currently support sending a custom value, it will
|
|
always send the current local value (as set with :meth:`gatts_write
|
|
<BLE.gatts_write>`).
|
|
|
|
On acknowledgment (or failure, e.g. timeout), the
|
|
``_IRQ_GATTS_INDICATE_DONE`` event will be raised.
|
|
|
|
.. method:: 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 :meth:`gatts_read <BLE.gatts_read>`, the value will
|
|
be cleared after reading. This feature is useful when implementing something
|
|
like the Nordic UART Service.
|
|
|
|
|
|
Central Role (GATT Client)
|
|
--------------------------
|
|
|
|
.. method:: BLE.gap_connect(addr_type, addr, scan_duration_ms=2000, /)
|
|
|
|
Connect to a peripheral.
|
|
|
|
On success, the ``_IRQ_PERIPHERAL_CONNECT`` event will be raised.
|
|
|
|
.. method:: BLE.gap_disconnect(conn_handle)
|
|
|
|
Disconnect the specified connection handle.
|
|
|
|
On success, the ``_IRQ_PERIPHERAL_DISCONNECT`` event will be raised.
|
|
|
|
Returns ``False`` if the connection handle wasn't connected, and ``True``
|
|
otherwise.
|
|
|
|
.. method:: BLE.gattc_discover_services(conn_handle, [uuid])
|
|
|
|
Query a connected peripheral 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.
|
|
|
|
.. method:: BLE.gattc_discover_characteristics(conn_handle, start_handle, end_handle, [uuid])
|
|
|
|
Query a connected peripheral 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.
|
|
|
|
.. method:: BLE.gattc_discover_descriptors(conn_handle, start_handle, end_handle)
|
|
|
|
Query a connected peripheral 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.
|
|
|
|
.. method:: BLE.gattc_read(conn_handle, value_handle)
|
|
|
|
Issue a remote read to a connected peripheral 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.
|
|
|
|
.. method:: BLE.gattc_write(conn_handle, value_handle, data, mode=0, /)
|
|
|
|
Issue a remote write to a connected peripheral 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 peripheral but no confirmation will be
|
|
returned, and no event will be raised.
|
|
* ``mode=1`` is a write-with-response: the remote peripheral is
|
|
requested to send a response/acknowledgement that it received the
|
|
data.
|
|
|
|
If a response is received from the remote peripheral the
|
|
``_IRQ_GATTC_WRITE_DONE`` event will be raised.
|
|
|
|
|
|
class UUID
|
|
----------
|
|
|
|
|
|
Constructor
|
|
-----------
|
|
|
|
.. class:: 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'``.
|
|
|
|
|
|
Constants
|
|
---------
|
|
|
|
.. data:: ubluetooth.FLAG_READ
|
|
ubluetooth.FLAG_WRITE
|
|
ubluetooth.FLAG_NOTIFY
|