nrf5340 reports BLE is active when running samples and viewed via RTT, but the device is not visible from any BLE scanner

Question

Heyyy guys!

It is possible that I'm doing something wrong, but i'm confused as this was definitely not an issue at some point while i've been working with the 5340.

I'm an app developer so I don't often dive too deeply into this kind of thing, and other people around me are equally unsure.

However everything seems correct in this case, and it's easily reproducible, so maybe it's something straightforward?

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Basically - when I flash some sample to my 5340dk (using VSCode, or West), everything goes well, the board restarts, the LEDs flicker, and I see this in RTT:

00> [00:00:00.485,168] <inf> bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)
00> [00:00:00.485,198] <inf> bt_hci_core: HW Variant: nRF53x (0x0003)
00> [00:00:00.485,229] <inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 51.10872 Build 1643454488
00> [00:00:00.489,379] <inf> bt_hci_core: Identity: F3:42:9B:11:89:0B (random)
00> [00:00:00.489,410] <inf> bt_hci_core: HCI: version 5.3 (0x0c) revision 0x2136, manufacturer 0x0059
00> [00:00:00.489,410] <inf> bt_hci_core: LMP: version 5.3 (0x0c) subver 0x2136

But the device is not visible when I check for devices around me.

If there are some things I am missing here, or perhaps some links you can point me to to figure this out, that would be great!

As for my env - I'm on a Mac OS 12.5, using west v0.13.1, and i've so far tried the following on the nrf toolchains 1.9.1, 2.0.0 and 2.0.2

Steps to recreate:

'open terminal' from nrf connect toolchain
cd <toolchain>/zephyr/samples/bluetooth/peripheral_hr
west build -b nrf5340dk_nrf5340_cpuapp
west flash --recover

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Some additional notes:

I can remember at one stage that I was able to flash (from VS Code, using the nrf plugin) some application core sample like peripheral_hr that I edited, and then afterwards flash an hci_rpmsg image to netcore, and it worked correctly on my 5340 then, although I've updated one thing or another now and that doesn't work anymore. The same issue was happening before I "re-flashed" hci_rpmsg, whereby I could see in an RTT Viewer that advertising was started, but I was unable to actually detect the device, until re-flashing - but I'm not remotely sure if that's related.

We do have another board that I connect to via my 5340dk to run samples on, and this works correctly for most (but not all) samples, making me think there is some particular issue with my own board, however I tried another team members' 5340dk today, and same issue was happening as with me. That could suggest it is my environment, but it's hard to be sure.

When my Nrf Connect for Desktop Programmer App (3.0.3) is able to connect to my device (it frequently fails due to readback protection issue, and I have to try to reconnect until it reads successfully) I am actually able to flash hex files for the hci_open_amp.hex and peripheral_hr.hex and this works, but I want to be able to deploy myself

Any other info I can provide to help, I shall do!

Thanks for your time guys! :)

acaskey · Accepted Answer

Hellloooo Simon! 
 Sorry I have had an incredibly busy week. One thing I should start by saying is that we eventually found that some of the 5340DKs we had around did indeed "just work", when deploying samples from our envs, the same that weren't working on the other boards. So the problem must be related to our own boards, and not env or toolchain etc! 
 And although there was no visible cuts to my board, it transpired that some of the boards had indeed been modified throughout their lifetime there, some more than others. We eventually found some that worked, and what seems to be the case is that the older/first iteration DKs that we were using were having the issues, whereas the newer ones were not - we were speculating lots of reasons (many of them way over my head) but in the end we just decided to take this into account and that we are not crazy, and it's just possible that someone broke something etc. 
 Anyway from my perspective the project has just wrapped up, and I hear they even solved the other issue we had with the network core, so I am finished for now, but thanks for your time, patience and help Simon! Hopefully I can find some excuse to come back in future :D 
 Sincere cheers! 
 Alex