Bluetooth RPC Stack Hangs When Running a Second BLE Scan

Question

Hello,

I am working on developing an application on the NRF5340 development kit which scans for nearby BLE beacons. I am using the Bluetooth RPC Stack for communication between the network core and the application core. Scanning works completely as expected the first time it happens, however if I stop a scan and start a new one, both cores hang. I turned on debug logging on the BLE and RPC stacks and this is what each core says before they hang:

Application Core:

[00:00:23.227,142] <dbg> NRF_RPC: cmd_ctx_alloc: Command context 0 allocated
[00:00:23.227,142] <dbg> NRF_RPC: nrf_rpc_cmd_common: Sending command 0x2A from group 0x00
[00:00:23.227,203] <dbg> NRF_RPC: wait_for_response: Waiting for a response

Network Core:

[00:00:23.227,233] <dbg> NRF_RPC: receive_handler: Received 5 bytes packet from 0 to 255, type 0x80, cmd/evt/cnt 0x2A, grp 0 (bt_rpc)
[00:00:23.227,325] <dbg> NRF_RPC: cmd_ctx_alloc: Command context 0 allocated
[00:00:23.227,325] <dbg> NRF_RPC: parse_incoming_packet: Executing command 0x2A from group 0x00
[00:00:23.227,416] <dbg> NRF_RPC: nrf_rpc_rsp: Sending response

Is this a known issue with the RPC stack? Is there a workaround I can use to allow the application to work?

Thanks,

Amr

Amr Moussa · Accepted Answer

After inspecting your code I was able to resolve the issue. The problem is that I was calling bt_le_scan_stop() in a timer handler thread. If my understanding is correct, timer handlers are "interrupt threads" which do not get to live for very long, and it seems not long enough to properly shut down BLE scanning. I moved my bt_le_scan_stop() call into a work queue job that is submitted to the queue from the timer handler and that resolved the issue. Thank you for your help!

Bluetooth RPC Stack Hangs When Running a Second BLE Scan

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