NRF52832 does not disconnect to phone

[xtian]

Hi,

currently having problem connecting a second device to my BLE device after disconnecting the first device. upon further checking, i noticed that the first device is still connected based on the bluetooth list in settings of my phone. i am using nrf52832 with SDK 17.1 and nrf Connect for mobile (iOS).

[Edvin]

Hello,

Can you please show me what it looks like in the settings on your phone?

Do you use bonding/pairing in your application? 

Did you disconnect the first device? Did you turn it off, or disconnect it in any other ways?

Best regards,

Edvin

[Adam Varga]

Not sure if this is helpful or not, but I'm experiencing a similar issue. (Latest iOS, iPhone 14 Pro Max, nRF52840, SDK 17.1.0)

The correlation that I was able to make so far is that if I have a HID service running on the nRF and bonding is disabled, and I connect to my device through the nRF Connect iOS app, then iOS doesn't disconnect when I tap on the disconnect button in the nRF. The app behaves as if the disconnect happened successfully, but I can still see my device under the bluetooth device list in the settings.

When I remove the HID service AND change the device's MAC address (!!!!!!!), then the disconnect works properly. Maybe I'm on the wrong track, but I feel that iOS cashes the device parameters (even if bonding is disabled), that's why I need the MAC address change. I guess this also means, that the service changed service is not properly implemented on my side....

[Edvin]

Hello,

I see. Perhaps the bonding is not properly disabled in the nRF application?

What could happen is that if they are bonded, and you disconnect by pressing disconnect in the nRF Connect for iOS app, then the device will go back to advertising, and since the device is bonded, it will reconnect very quickly. 

However, if you power the nRF device off completely, there is no way that it is still connected (after 4 seconds). If you still see it in your phone's settings, then that is not the list of active connections, but bonded devices. If you press the little (i) next to the nRF's name, you should be able to select (forget device), which should make it forget about it, and stop trying to connect to it. Hence, you should also not need to change the MAC address.

If this isn't correct, I am happy to test what you are seeing. If possible, please upload an application that can reproduce the issue, then I can give it a test run, to see what's going on.

Best regards,

Edvin