[Bug] Connecting to Pybricks Code after connecting Xbox Controller sends pairing request to PC

[laurensvalk]

Describe the bug
In certain cases, the Technic Hub will send a pairing request to the host when it shouldn't.

To reproduce

• Connect to the Xbox Controller. The hub disconnects from Pybricks Code.
• Stop the program, which disconnects the controller.
• Connect the hub to Pybricks Code.

On the PC, you will now get a pairing request.

This is known behavior, but it would not happen in practice since we used to always reset Bluetooth after running a program while disconnected.

However, we no longer do that. So we should unset this setting manually at runtime.

Expected behavior
Not get a pairing request on the PC. It is only intended for the Xbox Controller.

[laurensvalk]

Well, unsetting works, but then setting it again does not. It never ends with this chip 😆.

Edit: that second part might not be due to Pybricks Code, though. It just doesn't seem to want a second connection in general. So maybe we do need to reset bonding in between runs as we used to do. We could do it prior to a new connection that requires bonding. Edit: That doesn't work either. By comparison, using 3.6.1 with stay_connected=True it was possible to connect a second time, even if this did not reset the chip.

So it seems that the second connection is an unrelated problem, i.e. a bad notification handler.

[BertLindeman]

Sorry for the long post 😄

I think I saw this "connect to pc" yesterday: tried to pair xbox controller to a technichub.
Running on windows 11.

The controller was not paired to this technichub as that moment.
The connect did not succeed, but my (android) phone woke-up.
Had to set bluetooth off on my phone to get connected.
I think I had stay_connected set to False.

With Pybricks MicroPython ci-build-4554-v4.0.0b3-41-gd92d07d0 on 2025-12-23; LEGO Technic Hub with STM32L431RC
I got a fast blinking led if I try to stop this program:

from pybricks import version
from pybricks.iodevices import XboxController
from pybricks.tools import wait
waittime = 1  # was 10
print(f"Waiting {waittime} seconds")
wait(waittime * 1000)
print(f"Waited {waittime} seconds now try to connect")
ctrl = XboxController(stay_connected=True)

The program seemed to never get past the wait, but that may be due to the print not coming over to the pc in time.

Trying this commit 7bd9b96

Firmware: Pybricks MicroPython ci-build-4567-v4.0.0b3-60-g7bd9b965 on 2025-12-30; LEGO Technic Hub with STM32L431RC

With stay_connected=True I get a timeout and
with stay_connected=False the connection comes up OK.

Long press of the hub button in both cases simply stops the program.

[laurensvalk]

The pairing request is fixed by pybricks/pybricks-micropython@134683a

A few other peripheral issues are being fixed in #2521.

Thanks!