Nordic controller is not receveing the ble disconnect event from the ble android application som times if i kill the app?reproducability 1 out of 20.

[ramakrishna]

I am using nrf52832 peripheral and ble central with some android application .if an app opens it we get ble disconnect event and if we kill the app ble_disconect will come to the nordic board.it is working normally in most cases.if we forcefully kill the application when app was getting opened for n number of times the nordic controller  some times not receiving the ble disconnect event and controller board is still in connected state.Now if i kill the app since nordic is in  connected state and the peripheral is not visible to the android application. The nordic is coming out of connection state only after bluetooth was turn off.(android is throwing ble disconnect event when disconnect but which is blocking its reach to nordic board or it is problem with nordic internal code)

[Kenneth]

When a device disconnect the link, there will be disconnect packet sent from the device to the peer, and the peer  will acknowledge this packet, now the link is considered disconnected on both sides of the link.

If there is noise in the environment, the acknowledge from the peer may be lost, in such case only the peer will disconnect, while the device will remain in a connection until supervisor timeout occurs. This is according to Bluetooth spec.

[ramakrishna]

android is not sending disconnect .here in this case i have verified with bluetooth snooping log

[Kenneth]

Then the issues is likely a issue with Android, not much the nRF52832 softdevice can do if it doesn't receive a disconnect packet.

[ramakrishna]

In my case nordic  was in connected state even if app was killed reason is i have not received a ble_disconnect event. and now if off the bluetooth only then only we are able to connect again to the tablet.

I am using hrs rtos code.

why the nordic is not disconnecting even they are not exchanging the data means even after after time out of 4 sec.

what exactly the role of the supervisor time out?

[Kenneth]

Hi, the intention of the supervisor timeout is to handle cases like this, to ensure that the link is eventually disconnected if for instance the device and peer are out or range or battery is empty. The supervisor timeout is part of the connection request packet and can be updated using connection parameter update request during link is active. In this case it seems the android in some cases does not send a disconnect packet, thereby the peer will wait until supervisor timeout before link is disconnected.