espressif: Fails every time with Nimble "not connected" error on `_bleio.Connection..discover_remote_services()`

[o-murphy]

CircuitPython version and board name

LILYGO T-Display S3, ESP32S3

Code/REPL

async def _discover_services_task(self):
        if hasattr(self._connection, "_bleio_connection"):
            bleio_conn = self._connection._bleio_connection
            if hasattr(bleio_conn, "discover_remote_services"):

                await asyncio.sleep(1.0)
                try:
                    await asyncio.sleep(1)
                    return bleio_conn.discover_remote_services()
                except Exception as e:
                    raise BleakError(f"Failed to discover remote services: {e}")
        raise BleakError("Discover remote services not available")

Behavior

1368.945: DEBUG - Connected to BLE device @ 55:26:5e:02:d3:6b
1368.949: DEBUG - Retrieving services from BLE device @ 55:26:5e:02:d3:6b
Traceback (most recent call last):
  File "/lib/bleak/backends/circuitpython/client.py", line 114, in _discover_services_task
_bleio.BluetoothError: Unknown BLE error: 7

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 38, in <module>
  File "asyncio/core.py", line 346, in run
  File "asyncio/core.py", line 299, in run_until_complete
  File "asyncio/core.py", line 283, in run_until_complete
  File "asyncio/funcs.py", line 181, in gather
  File "asyncio/core.py", line 283, in run_until_complete
  File "<stdin>", line 22, in main
  File "/lib/bleak/__init__.py", line 565, in __aenter__
  File "/lib/bleak/__init__.py", line 587, in connect
  File "/lib/bleak/backends/circuitpython/client.py", line 79, in connect
  File "asyncio/core.py", line 283, in run_until_complete
  File "/lib/bleak/backends/circuitpython/client.py", line 116, in _discover_services_task
BleakError: Failed to discover remote services: Unknown BLE error: 7

Description

I'm trying to make bleak-compatible backend for CircuitPython, for now every time I wanna discover all services for peripheral i got _bleio.BluetoothError 7 HCI TIMEOUT

Additional information

No response

[dhalbert]

Could you show a complete simple example to reproduce?

Where are you getting HCI TIMEOUT from? ESP32-S3 has native BLE and does not use HCI. But there are multiple LILYGO Display boards, both ESP32 and ESP32-S3. What is the exact name of the .uf2 or .bin file you're loading onto the LILYGO? I want to confirm it is the S3 Lilygo.

[dhalbert]

Could you give an example that is not using your bleak layer, but just _bleio or adafruit_ble?

[o-murphy]

Could you give an example that is not using your bleak layer, but just _bleio or adafruit_ble?

Yes, simply

from _bleio import UUID
from adafruit_ble import BLERadio
from adafruit_ble.advertising import Advertisement
from adafruit_ble.advertising.standard import (
    ProvideServicesAdvertisement,
    SolicitServicesAdvertisement,
)

radio = BLERadio()


scan_results = radio.start_scan(
    Advertisement,
    ProvideServicesAdvertisement,
    SolicitServicesAdvertisement,
    active=True,
    timeout=20
)

lookup_service = UUID("f47b5e2d-4a9e-4c5a-9b3f-8e1d2c3a4b5c")

found_adv = None
for adv in scan_results:
    if isinstance(adv, ProvideServicesAdvertisement):
        for srv in adv.services:
            if srv == lookup_service:
                found_adv = adv
                radio.stop_scan()
                break
    
if found_adv:
    connection = radio.connect(found_adv.address)
    is_connected = connection.connected
    print("Is connected:", is_connected)
    if is_connected:
        discovered_services = connection._bleio_connection.discover_remote_services()
        print(discovered_services)
else:
    print("Not found")

Is connected: True
Traceback (most recent call last):
  File "<stdin>", line 36, in <module>
_bleio.BluetoothError: Unknown BLE error: 7

[o-murphy]

Could you show a complete simple example to reproduce?

Where are you getting HCI TIMEOUT from? ESP32-S3 has native BLE and does not use HCI. But there are multiple LILYGO Display boards, both ESP32 and ESP32-S3. What is the exact name of the .uf2 or .bin file you're loading onto the LILYGO? I want to confirm it is the S3 Lilygo.

Possibly i'm wrong, but i found that: A Bluetooth error 0x07 indicates that a device is out of range or Memory Capacity Exceeded

[o-murphy]

Could you show a complete simple example to reproduce?

Where are you getting HCI TIMEOUT from? ESP32-S3 has native BLE and does not use HCI. But there are multiple LILYGO Display boards, both ESP32 and ESP32-S3. What is the exact name of the .uf2 or .bin file you're loading onto the LILYGO? I want to confirm it is the S3 Lilygo.

The latest one from https://circuitpython.org/board/lilygo_tdisplay_s3/
v9.2.8, same happen on 9.2.6

Adafruit CircuitPython 9.2.8 on 2025-05-28; LILYGO T-DISPLAY S3 v1.2 with ESP32S3

sys.platform=Espressif, os.uname()=(sysname='ESP32S3', nodename='ESP32S3', release='9.2.8', version='9.2.8 on 2025-05-28', machine='LILYGO T-DISPLAY S3 v1.2 with ESP32S3')
sys.version=3.4.0; CircuitPython 9.2.8 on 2025-05-28
sys.implementation=(name='circuitpython', version=(9, 2, 8, ''), _machine='LILYGO T-DISPLAY S3 v1.2 with ESP32S3', _mpy=774)

[o-murphy]

You can try it with bitchat app. I used it to simulate ble device with my iphone/android

[dhalbert]

The unknown error 7 here is a Nimble "not connected" error. I'm not sure why you became disconnected. Can you try it with something other than the bitchat app, like some simple BLE peripheral?

Normally one wouldn't call connection._bleio_connection.discover_remote_services() directly, but instead use the adafruit_ble API. Some examples are in https://github.com/adafruit/Adafruit_CircuitPython_BLE/blob/main/examples. For instance ble_uart_echo_client.py does scanning, and ble_uart_echo_test.py acts as a peripheral. Do you have another board to act as a peripheral?

Which bitchat app are you using? I am finding several iOS apps.

[o-murphy]

The unknown error 7 here is a Nimble "not connected" error. I'm not sure why you became disconnected. Can you try it with something other than the bitchat app, like some simple BLE peripheral?

Normally one wouldn't call connection._bleio_connection.discover_remote_services() directly, but instead use the adafruit_ble API. Some examples are in https://github.com/adafruit/Adafruit_CircuitPython_BLE/blob/main/examples. For instance ble_uart_echo_client.py does scanning, and ble_uart_echo_test.py acts as a peripheral. Do you have another board to act as a peripheral?

Which bitchat app are you using? I am finding several iOS apps.

The adafruit_ble API has not direct method to discover all possible services. It allows just discover with specified machlist. So that's because I use protected inner API. Also the call with machlist returns same error. I also have no problems with connection and discovering services with same peripheral over the bleak on my PC.

[o-murphy]

@dhalbert where can I get valid error codes description? Can't find it in docs

[dhalbert]

It's not in the docs, because the "unknoown" errors are unexpected, and there are a lot of them. So they would be looked up in the source code. In this case, it is ports/espressif/esp-idf/components/bt/host/nimble/nimble/nimble/host/include/host/ble_hs.h.

[o-murphy]

It's not in the docs, because the "unknoown" errors are unexpected, and there are a lot of them. So they would be looked up in the source code. In this case, it is ports/espressif/esp-idf/components/bt/host/nimble/nimble/nimble/host/include/host/ble_hs.h.

I have no something like a beacon, but I have Mi Band 6 that advertise the generic heartbeat and battery sensor services. And there same thing happen when I try to connect to it from esp32-s3.

I have not same problem when connecting to it with bleak from my PC or even with self-written bleak backend from iOS. Also I have no issues with connection between bitchat clients on different platforms. So it seems like the problem specific for the esp32-s3 with circuitpython