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Python Bluetooth LE (Low Energy) and GATT Library

Project description

pygatt - Python Module for Bluetooth LE Generic Attribute Profile (GATT).
=========================================================================

This Module allows reading and writing to GATT descriptors on devices
such as fitness trackers, sensors, and anything implementing standard
GATT Descriptor behavior.

pygatt provides a Pythonic API by wrapping two different backends:

- BlueZ (requires Linux), using the ``gatttool`` command-line utility.
- Bluegiga's BGAPI, compatible with USB adapters like the BLED112.

Motivation
----------

Despite the popularity of BLE, we have yet to find a good programming
interface for it on desktop computers. Since most peripherals are
designed to work with smartphones, this space is neglected. One
interactive interface, BlueZ's ``gatttool``, is functional but difficult
to use programmatically. BlueZ itself obviously works, but the interface
leaves something to be desired and only works in Linux.

Requirements
------------

- Python 2.7.5 or greater, or Python 3.5 or greater

- Python 2.7.3's ``struct`` library has a bug that will break PyGATT - 2.7.5
or greater is recommended.

- BlueZ 5.18 or greater (with gatttool) - required for the gatttool
backend only.

- Tested on 5.18, 5.21, 5.35 and 5.43

- GATTToolBackend requires Linux (i.e. not Windows compatible)

Installation
------------

Install ``pygatt`` with pip from PyPI:

::

$ pip install pygatt

The BlueZ backend is not supported by default as it requires
``pexpect``, which can only be installed in a UNIX-based environment. If
you wish to use that backend, install the optional dependencies with:

::

$ pip install "pygatt[GATTTOOL]"

Install the latest development version of ``pygatt`` with pip:

::

$ pip install git+https://github.com/peplin/pygatt

Documentation
----------

The documentation for pygatt consists of:

- This README
- The code in the ``samples`` directory
- The Python docstrings in the code itself.

The ``BLEDevice`` and ``BLEBackend`` base classes are the primary interfaces for
users of the library.

Example Use
-----------

The primary API for users of this library is provided by
``pygatt.BLEBackend`` and ``pygatt.BLEDevice``. After initializing an
instance of the preferred backend (available implementations are found
in ``pygatt.backends``, use the ``BLEBackend.connect`` method to connect
to a device and get an instance of ``BLEDevice.``

.. code:: python

import pygatt

# The BGAPI backend will attempt to auto-discover the serial device name of the
# attached BGAPI-compatible USB adapter.
adapter = pygatt.BGAPIBackend()

try:
adapter.start()
device = adapter.connect('01:23:45:67:89:ab')
value = device.char_read("a1e8f5b1-696b-4e4c-87c6-69dfe0b0093b")
finally:
adapter.stop()

Note that not all backends support connecting to more than 1 device at
at time, so calling ``BLEBackend.connect`` again may terminate existing
connections.

Here's the same example using the GATTTool backend. It's identical
except for the initialization of the backend:

.. code:: python

import pygatt

adapter = pygatt.GATTToolBackend()

try:
adapter.start()
device = adapter.connect('01:23:45:67:89:ab')
value = device.char_read("a1e8f5b1-696b-4e4c-87c6-69dfe0b0093b")
finally:
adapter.stop()

Notifications Example
---------------------

This example uses the gatttool backend to connect to a device with a specific
MAC address, subscribes for notifications on a characteristic, and prints the
data returned in each notification.

.. code:: python

import pygatt
from binascii import hexlify

adapter = pygatt.GATTToolBackend()

def handle_data(handle, value):
"""
handle -- integer, characteristic read handle the data was received on
value -- bytearray, the data returned in the notification
"""
print("Received data: %s" % hexlify(value))

try:
adapter.start()
device = adapter.connect('01:23:45:67:89:ab')

device.subscribe("a1e8f5b1-696b-4e4c-87c6-69dfe0b0093b",
callback=handle_data)
finally:
adapter.stop()

Debugging
---------

While debugging software using pygatt, it is often useful to see what's
happening inside the library. You can enable debugging logging and have
it printed to your terminal with this code:

::

import pygatt
import logging

logging.basicConfig()
logging.getLogger('pygatt').setLevel(logging.DEBUG)

Can't find BGAPI device in Windows
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You may need to explicitly specify the COM port of your BGAPI-compatible
device in windows, e.g.:

::

adapter = pygatt.BGAPIBackend(serial_port='COM9')

If you provide the COM port name, but still get an error such as
``WindowsError(2, 'The system cannot find the file specified.')``, try
changing the COM port of the device to a value under 10, e.g. ``COM9``.

Authors
-------

- Jeff Rowberg @jrowberg https://github.com/jrowberg/bglib
- Greg Albrecht @ampledata https://github.com/ampledata/pygatt
- Christopher Peplin @peplin https://github.com/peplin/pygatt
- Morten Kjaergaard @mkjaergaard https://github.com/mkjaergaard/pygatt
- Michael Saunby @msaunby https://github.com/msaunby/ble-sensor-pi
- Steven Sloboda https://github.com/sloboste
- Ilya Sukhanov @IlyaSukhanov
- @dcliftreaves
- Jonathan Dan
- Ilann Adjedj
- Ralph Hempel
- Rene Jacobsen
- Marcus Georgi
- Alexandre Barachant
- Michel Rivas Hernandez
- Jean Regisser
- David Martin
- Pieter Hooimeijer
- Thomas Li Fredriksen
- Markus Proeller
- lachtanek
- Andrea Merello
- Richard Mitchell
- Daniel Santos
- Andrew Connell
- Jakub Hrabec
- John Schoenberger

Releasing to PyPI
-----------------

For the maintainers of the project, when you want to make a release:

- Merge all of the changes into ``master``.
- Update the version in ``setup.py``.
- Update the ``CHANGELOG.mkd``
- Tag the commit and push to GitHub (will need to push to a separate
branch of PR first since ``master`` is a protected branch).
- Travis CI will take care of the rest - it will build and deploy
tagged commits to PyPI automatically.

License
-------

Copyright 2015 Stratos Inc. and Orion Labs

Apache License, Version 2.0 and MIT License. See LICENSE.


.. :changelog:

Release History
================

V4.0.1
------

* Improvement: Wait longer for characteristics discovery with BGAPI backend (#201)
* Fix: Protect against invalid BGAPI packets
* Fix: Fix parsing fields from BGAPI connection status
* Fix: Robust to non-UTF8 characters in hcitool scan results
* Fix: Log correct connection flags from BGAPI response

V4.0.0
------

* Feature: Add ``char_read_long`` for reading characteristics longer than a
single packet (#206, #177)
* Feature: Add command to change MTU (GATTTool only) (#182)
* Feature: Allow registering callbacks for device discovery events. (#176)
* Feature: Support fetching BLE device MAC address (#150)
* Improvement: Add better serial port error handling for BGAPI. (#162)
* Improvement: Expand and allow overriding pexpect search buffer for gatttool
output to support devices with many characteristics without negatively
impacting performance (#209)
* Improvement: Wait before re-opening BGAPI serial port to improve detection on
Windows. (#162)
* Improvement: Add support for Python 3.7
* Fix: Use ATT write (not command) by default for char_write
* Fix: Wait longer for ATT write according to BlueGiga spec
* Fix: Fix BGAPI device detection (#154)
* Fix: Stop leaking file descriptors when erasing BLE bonds with GATTTool
backend (#188)
* Fix: Typos (#173)
* Drop official support for Python 3.4, 3.5 and 3.6.

V3.2.1
------

- Improvement: Officially support Python 3.6.
- Improvement: Permit use of non-standard characteristics in reserved range (#140)

V3.2.0
------

- Fix: Reliably auto-reconnect after restarting BGAPI device. Fixes a bug in
first attempt at auto-reconnection, only worked in some environments. (#144)
- Fix: Remove spurious "no handler for logger" warnings (#143)
- Fix: Use enum-compat instead of enum34, to fix installation in Python 3.4+
- Feature: Limit search window size for GATTTool backend, to avoid high CPU
usage for long running connections. (#123)
- Feature: Add support for write commands to BGAPIBackend (#115)

V3.1.1
------

- Improvement: Convert documentation to RST for better PyPI integration.

V3.1.0
------

- Fix: Support platforms without ``termios`` (Windows)
- Feature: Add ``char_read_handle`` to GATTTool backend.
- Improvement: Warn if ``hcitool`` requires a sudo authentication.
- Improvement: Allow BGAPI device more time to reboot for more reliable
discovery.
- Improvement: Interpret "invalid file descriptor" as a disconnect
event.
- Fix: Correctly handle service class UUIDs that aren't 16 bytes.
- Improvement: Support BLE devices with any UTF8 character.
- Improvement: Make gatttol prompt timeout configurable.
- Improvement: Gracefully stop ``lescan`` to avoid leaving the adapter
in a bad state.
- Improvement: Allow custom timeout for discovery on GATTTool backend.
- Fix: Make sure responses to char reads on BGAPI backend are from the
requested handle.
- Improvement: Raise and exception if trying to instantiate the
GATTTool backend in Windows.
- Improvement: If no BGAPI device attached, abort immediately.
- Fix: Use user's configured HCI device for connection and scanning in
GATTTool backend.

V3.0.0
------

- [API Change] The BGAPIBackend.connect method now takes the same
``address_type`` argument as the GATTTool backend [BGAPI].
- [API Change] The ``address_type`` argument on both backends now
requires a value from a new enum, ``pygatt.BLEAddressType``, instead
of a string.
- Made Python 3 support a priority for both GATTTOOL and BGAPI
backends.
- Improve reliability of BGAPI backend by re-setting device for each
connection.

V2.1.0
------

- Added all standard GATT characteristics. [BGAPI]
- Move gatttool monitor to a background thread for increased
performance. [GATTTOOL]

V2.0.1
------

- Feature: Allow unsubscribing from notifications.
- Improvement: Allow more time to discover characteristics. [GATTTOOL]
- Improvement: Allow using gatttol backend without root. [GATTTOOL]
- Improvement: Standardize type of UUID so comparison always works (str
vs unicode)
- Fix: Fix packaging so the version on PyPI can be installed.
- Fix: Fix Python 3 compatibility.

Thanks to Ilya Sukhanov and Alexey Roslyakov for the changes in this
release!

v2.0.0
------

- New API with support for multiple BLE adapters.

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