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=====
Usage
=====
.. note::
A Bluetooth peripheral may have several characteristics with the same UUID, so
the means of specifying characteristics by UUID or string representation of it
might not always work in bleak version > 0.7.0. One can now also use the characteristic's
handle or even the ``BleakGATTCharacteristic`` object itself in
``read_gatt_char``, ``write_gatt_char``, ``start_notify``, and ``stop_notify``.
One can use the ``BleakClient`` to connect to a Bluetooth device and read its model number
via the asynchronous context manager like this:
.. code-block:: python
import asyncio
from bleak import BleakClient
address = "24:71:89:cc:09:05"
MODEL_NBR_UUID = "2A24"
async def main(address):
async with BleakClient(address) as client:
model_number = await client.read_gatt_char(MODEL_NBR_UUID)
print("Model Number: {0}".format("".join(map(chr, model_number))))
asyncio.run(main(address))
or one can do it without the context manager like this:
.. code-block:: python
import asyncio
from bleak import BleakClient
address = "24:71:89:cc:09:05"
MODEL_NBR_UUID = "2A24"
async def main(address):
client = BleakClient(address)
try:
await client.connect()
model_number = await client.read_gatt_char(MODEL_NBR_UUID)
print("Model Number: {0}".format("".join(map(chr, model_number))))
except Exception as e:
print(e)
finally:
await client.disconnect()
asyncio.run(main(address))
.. warning:: Do not name your script ``bleak.py``! It will cause a circular import error.
Make sure you always get to call the disconnect method for a client before discarding it;
the Bluetooth stack on the OS might need to be cleared of residual data which is cached in the
``BleakClient``.
See `examples <https://github.com/hbldh/bleak/tree/master/examples>`_ folder for more code, e.g. on how
to keep a connection alive over a longer duration of time.
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