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"""
Example showing how to use BleakClient.mtu_size
"""
import asyncio
from bleak import BleakBackend, BleakClient, BleakScanner
from bleak.backends.scanner import AdvertisementData, BLEDevice
# replace with real characteristic UUID
CHAR_UUID = "00000000-0000-0000-0000-000000000000"
async def main() -> None:
queue: asyncio.Queue[BLEDevice] = asyncio.Queue()
def callback(device: BLEDevice, adv: AdvertisementData) -> None:
# can use advertising data to filter here
queue.put_nowait(device)
async with BleakScanner(callback):
# get the first matching device
device = await queue.get()
async with BleakClient(device) as client:
# BlueZ doesn't have a proper way to get the MTU, so we have this hack.
# If this doesn't work for you, you can set the client._mtu_size attribute
# to override the value instead.
if client.backend_id == BleakBackend.BLUEZ_DBUS:
await client._backend._acquire_mtu() # type: ignore
print("MTU:", client.mtu_size)
# Write without response is limited to MTU - 3 bytes
data = bytes(1000) # replace with real data
chunk_size = client.mtu_size - 3
for chunk in (
data[i : i + chunk_size] for i in range(0, len(data), chunk_size)
):
await client.write_gatt_char(CHAR_UUID, chunk, response=False)
if __name__ == "__main__":
asyncio.run(main())
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