Reconnect aftter turn off and turn on BT while connected with device

[TAEYOUNG]

Hello

*Environment

- LG V30 (Android 9)

- nRF52832, 15.3.0 SDK, S132

- nRF5340 ( I can't find SDK version)

I have some issue.

LG V30 Mobile can't reconnect after turn oof and turn on BT while connected with device.

If i wanna reconnect, I should scan again and connect to found device on scanning.

But, Samsung Galaxy Note8 (Android 9), Note 9 (Android 10) is going to reconnect.

How can I solve this problem?

Thanks.

this is demo video site.

https://cafe.naver.com/kindplayer/5667

[Sigurd]

Hi,

Looking at the first video, it seems like the phone is actually trying to connect to the device, but it failed to connect. 

Does the log show any error codes? You can bring up the log If you swipe from left to right when in the device tab, or by clicking on the "3 dots button" and click "Show log".

[TAEYOUNG]

I wrote logs on this site.

log content

-[Recconect Success] Ti Product on LG V30 (Android 9)

-[Recconect Fail] nRF5340 Product on LG V30 (Android 9) : BLE code is \zephyr\samples\bluetooth\peripheral

-[Recconect Fail] nRF52832 Product on LG V30 (Android 9)

-[Recconect Success] nRF52832 Product on Samsung Galaxy Note9 (Android 10)

https://blog.naver.com/92-theo/221953267916

[Sigurd]

From the log you uploaded we have this:

V 10:14:48.558 Connecting to DE:CF:F2:4A:CE:8C...

D 10:14:48.559 gatt = device.connectGatt(autoConnect = false, TRANSPORT_LE, preferred PHY = LE 1M)

D 10:15:18.566 [Callback] Connection state changed with status: 133 and new state: DISCONNECTED (0)

E 10:15:18.575 Error 133 (0x85): GATT ERROR

I 10:15:18.575 Disconnected

It happens in different occasions. We have observed it on:

1) packet collision
2) CONNECT_REQ missed by the target
3) timeout (30 or 20 seconds after connection was initiated)
4) in general, an expected packet wasn't received or an unexpected was.

It used to be much more common in old days, now we see it less and less with the new phones, but the low-end devices still have a lot of problems with them. Very often it is enough to repeat the last operation, for example the connection request from the phone and it should work. Maybe you could also try to change the advertising interval on the nRF5x, and see if that makes any difference.

[TAEYOUNG]

Okay.

For reference

I tried to test that " BLE Connected -> BT Off -> BT On -> BLE Connecting ->  Failed connect" on LG V50.

I guess the same issue occurs with LG phones.

Thanks.