connectless CTE TX/RX problem

[loquat]

I am testing connectless CTE RX/TX.
A strange behavior is occurring.
Please advice me.

・connectless CTE TX
     nRF52833-DK + nRF Connect SDK + connectless CTE TX (almost same as sample)
・connectless CTE RX
   nRF52833-DK + nRF Connect SDK + My Application (customised connectless CTE RX)
   Scan doesn't stop after sync_create().

1. CTE is received normally for several tens of minutes.
2. Suddenly reception on the connectless CTE RX side stops. (stop scan)
3. If you start advertising while reception is stopped, you will be able to receive it.
4. When advertising stops, reception also stops. (stop scan)
5. If the connectless CTE TX is operating (transmitting) while advertising is running, reception will not stop even if advertising stops.

Is there anything we can investigate?

[Simonr]

Hi

CONFIG_BT_CTLR_SCAN_ENABLE_STRICT enforces returning HCI error commands on enabling/disabling already enabled/disabled scanning, which is what the hypothesis of what's happening currently is.

Best regards,

Simon

[loquat]

sorry. My understanding is lacking.
What I need to do is
Just to confirm that this bug no longer occurs after setting "CONFIG_BT_CTLR_SCAN_ENABLE_STRICT=y"?
Or do I need to do something more than that?

[Simonr]

Try setting CONFIG_BT_CTLR_SCAN_ENABLE_STRICT=y and see if you still see the bt_le_scan_stop() being triggered if/when this issue occurs. I don't think it will fix the issue entirely, but you should be able to see a bt_le_scan_stop() trigger when the scanner actually stops, and likely glean some information from what exactly called this scan_stop() function.

Best regards,

Simon

[loquat]

I try it.

bt_le_scan_stop() symbol is not found.(No one calls bt_le_scan_stop())
I set a break-point on "set_le_ext_scan_enable()".
but, not be called.

[Simonr]

And you're still able to reproduce the scanner stopping altogether, correct? Note that you should also enable logging if you haven't to see error codes that are returned from function calls.

Best regards,

Simon

[loquat]

I don't quite understand it.
"returned from function calls."
What function is this returning from?
bt_le_scan_stop() is never called by anyone.
But the scan stops.

[Simonr]

But can you try calling bt_le_scan_stop() when the scan "just stops" here and see if you're able to stop the scan or if it returns an error?

Best regards,

Simon

[loquat]

OK.

I tested it.
1. add "CONFIG_BT_CTLR_SCAN_ENABLE_STRICT=y" to RX side
2. Add button press->scan_stop() processing to RX side
3. Run the test until reception on the RX side stops
4. After stopping reception, press the button
5. Check the return value of scan__stop()
result is zero.