Problems with nRFDK not disconnecting from iPhone running nRF Connect App

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

Mike Austin (LPI) — Tue, 05 Apr 2022 22:52:13 GMT

If I use the nRF Connect for Desktop on my Windows machine, everything works as expected, and I can get the Peripheral to respond to a disconnect command from the Central when they are paired and bonded - which is the behaviour I would expect.

Must be something about the App, or iOS devices that prevents this functionality, because I see it on both the nRF Connect App and the LightBlue App. I'm using an iOS device, so not sure if the same behaviour occurs on an Android device

Cheers,

Mike

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

Charlie — Tue, 05 Apr 2022 12:19:53 GMT

Hi Mike,

Again, I guess this is some limitation decided by the iOS or Android system. I do not have a better answer from the BLE peripheral perspective.

Best regards,

Charlie

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

Mike Austin (LPI) — Mon, 04 Apr 2022 22:43:19 GMT

Hi Charlie,

Thanks for the confirmation. It only seems to be an issue when the Central and Peripheral are bonded. Why is that?

If there is a non-bonded connection, the Central can issue the disconnect command and the Peripheral will acknowledge and disconnect.

But if the connection is bonded, this doesn't occur. Is this an intentional design feature for bonded connections? Just trying to understand the "why" even though I've got a solution to the problem

Cheers,

Mike

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

Charlie — Mon, 04 Apr 2022 14:41:13 GMT

Hi Mike,

Yes, the app itself doe not have access to disconnect Bluetooth Device, you need either go to Settings->Bluetooth->Forget this device on iOS system level or disconnect from periperial.

Best regards,

Charlie

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

Mike Austin (LPI) — Sun, 03 Apr 2022 22:09:32 GMT

Had a bit more of a look into this over the weekend. Seems there are plenty of references to this behaviour on the Nordic DevZone, but all are related to Android devices as the Central, not iOS devices. And no-one appears to have provided a reason/solution, beyond forcing the disconnection from the Peripheral side. Seems a bit counter-intuitive for a Peripheral to be severing the connection that a Central has requested though.

So, I had a play around with that approach and putting in a call to:

bt_conn_disconnect(cts_c->conn, BT_HCI_ERR_REMOTE_USER_TERM_CONN);

once the Peripheral had successfully grabbed the current time. This appears to work.

Seems like a cludgy work-around to me though. Surely a Peripheral should respond to a disconnect request from a Central, regardless of whether they are bonded or not?

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

leox — Fri, 01 Apr 2022 08:22:42 GMT

Same to me, only affects the bonded devices.

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

Mike Austin (LPI) — Fri, 01 Apr 2022 07:59:32 GMT

No, they’re not. Maybe that’s the issue?

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

leox — Fri, 01 Apr 2022 07:47:44 GMT

Are other examples bonded with iOS?

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

Mike Austin (LPI) — Fri, 01 Apr 2022 07:44:38 GMT

Weird thing is, any of the other BLE examples work fine with the iOS nRF Connect App. I can get them to connect and disconnect ok using the App.

And if I use another BLE App (eg: LightBlue) I see the same behavior where the App wants to disconnect but my code stays connected.

I can’t I understand why it’s an issue with this example code and not with any other BLE examples I’ve tried

RE: Problems with nRFDK not disconnecting from iPhone running nRF Connect App

leox — Fri, 01 Apr 2022 07:31:56 GMT

Hi Mike,

I got the same with a iOS device after BLE bonded with the iOS. Android phone is ok. It looks like a issue with the nRF connect app with iOS.

The peripherial_uart working ok without bonding. please run the following and see if works at your side.

1: connect the DK to PC, and run command 'nrfjprog --recover' in a terminal // to remove the bonding.

2: compile example 'peripherial_uart' and flash it to DK.

3: try to connect with nRF connect app on mobile, and disconnect. And see if ok to disconnect.