usage.rst

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:

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:

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 folder for more code, e.g. on how to keep a connection alive over a longer duration of time.