ble_advertising: connection formed before initialization

[michaelchiasson]

Hello,

I find that after I DFU a new application (using the nRF Connect Mobile App), my device boots into that new application and reconnects to the App, as expected.  Then, weirdly, I find that if I disconnect from the app, my device does not start advertising again until after a reboot.

I traced this down to the fact that the ble_advertising module initializes a variable called `current_slave_link_conn_handle` to `BLE_CONN_HANDLE_INVALID` (occurs inside `ble_advertising_init`).  If a connection forms before the module is initialized, that variable will get overwritten during initialization, losing the conn handle.  Then, when `on_disconnected` is called, it checks that variable before restarting advertising, but since it has been overwritten during initialization, advertising never restarts.  I find this happens very consistently for me when the App is trying to reconnect following a successful DFU.

I ultimately resolved the issue by moving the initializing of `current_slave_link_conn_handle` to the `BLE_ADVERTISING_DEF` macro definition in ble_advertising.h.  This ensures that member is initialized at compile-time rather than run-time.

The most confusing part of all this is that I don't use `NRF_SDH_DISPATCH_MODEL_INTERRUPT` as my `NRF_SDH_DISPATCH_MODEL`, I use `NRF_SDH_DISPATCH_MODEL_POLLING`, and importantly, I don't call `nrf_sdh_evts_poll` until after I initialize the ble_advertising module. So I don't fully understand how `on_connected` is called to set `current_slave_link_conn_handle` before the ble_advertising module is initialized.  Am I missing something here?

I don't know what I'm looking for here... maybe just help someone who's running into the same issue.

Thanks,

Michael

P.S. some more information about my setup:

• nRF52840
• SDK v15.2.0
• FreeRTOS

[Kenneth]

Not heard of this problem before no.

If a connection forms before the module is initialized, that variable will get overwritten during initialization, losing the conn handle.

I would likely looked into the sequence here. Do you need to advertise and thereby potentially connecting before the ble_advertising module is initialized? 

[michaelchiasson]

Kenneth,

Thanks for your response, I figured out my issue just now typing a response to you. The issue ultimately stems from the fact that I'm inadvertently calling ble_advertising_init multiple times, once before I start polling for softdevice events, and again after I start polling. 

Thanks again for your help,

Michael