No bluetooth signal detected from nRF5340-DK

[David Pletcher]

I received an nRF5340-DK last week. Today I got the zephyr toolchain configured and working under Linux, and hooked everything up. The "blinky" sample app works fine. The USB cable is connected to the programmer port and the power switch is at the central setting (the one that turns on the green LED next to the JLink chip).

Using the current nRF Connect app on Android (Pixel 4A), I am unable to detect any BT signal from my nRF5340-DK after compiling and flashing any of several bluetooth sample apps, e.g.:

* samples/bluetooth/beacon
* samples/bluetooth/scan_adv
* samples/bluetooth/periodic_adv
* samples/bluetooth/peripheral_hr

I have attempted to flash each of these sample applications, in succession, to each of the following board targets:

* nrf5340dk_nrf5340_cpuapp
* nrf5340dk_nrf5340_cpuappns
* nrf5340dk_nrf5340_cpunet

[Aside: the "getting started" documentation could be a bit clearer about which board target to use, and when, for the audience of people first getting to know the nRF5340 via sample applications. I'm still fuzzy about the deployment considerations and interactions between these targets.]

I have also used the west --recover and west --eraseall options a couple times to unstick the development process.

Conversely, flashing the "samples/bluetooth/periodic_adv" app to my nRF52382-DK via the nrf52dk_nrf52832 board target works fine; I see the bluetooth signal perfectly on my phone.

I have reviewed the online DK specifications and it doesn't seem like there's any DIP switch that disables RF, so I'm stumped. Do I have a defective unit? Is there some other magic required to make bluetooth goodness happen?

Thank you for sharing your diagnostic wisdom!

[Amanda Hsieh]

Hi David, 

Do you use SES to build and load the application? If so, you also need to program the network sample from ses.

-Amanda H.

[David Pletcher]

Wrapping this up, I am unable to get any Bluetooth sample app working properly (e.g. detectably advertising) on my nRF5340-DK. I discern that there are toolchain and documentation obstacles:

* The private label Nordic SES package is many versions behind what's available from Segger, and does not contain board support for the nRF53 family.

* The latest release of SES from Segger's site is not installable on Debian Linux with XFCE because of X compatibility problems (a longstanding problem)

* ARM gdb / west debug is not usable with Debian Linux (absent dangerous and tedious workarounds) because of the unexpected dynamic linking dependency on Python 3.8; this has been discussed in bug reports but doesn't seem to be a priority for the developers

* Available build tools and processes warn that 5340 support is preliminary, not for production use

* Clear documentation (especially a walkthrough) of the west/zephyr build+deployment process for the asymmetric dual core 5340 seems to be a pending opportunity

The nRF52832 is adequate for my current needs, and the development toolchain is working fine for that platform. I am going to pause my investigation of the 5340 for a while, with cautious optimism that the relevant tooling and knowledge base will progress over time. It's also possible that I just have a defective board, in which case time is unlikely to cure the problem. :-) Amanda, if you will please pass along the word, I'll be grateful--nay, thrilled!--if Nordic will put together a detailed walkthrough of the CLI-based deployment process, using west/zephyr and ARM-gcc, that starts with a fully-erased nRF5340-DK and ends with a flashed device that's happily broadcasting advertising packets (and bonus points if it has multi-platform Win+Mac+Linux guidance, like on some of the other Nordic tutorial pages.)

I get the sense that Windows toolchain support is more mature and robust than Linux. If I need to proceed with the 5340 in the nearer future, I'll reluctantly consider provisioning a Windows development environment. I prefer to keep Windows machines off of my network for security reasons.

Kind regards and thank you for your attention. I appreciate the excellent expertise and assistance that Nordic staff contribute on this forum.

[Amanda Hsieh]

Hi David, 

Sorry for the delay. 

What version of NCS are you using? Is it v1.5.1?

David Pletcher said:

I tried targeting nrf5340dk_nrf5340_cpuapp, then nrf5340dk_nrf5340_cpunet (a much larger image, encouragingly), and flashing each, and later flashed periodic_adv to the app processor, but I still don't see any BT activity.

We see the same issue with periodic_adv on nRF5340DK and investigate it now. 

Are you able to build other sample like samples/bluetooth/peripheral_hr with west build -b nrf5340dk_nrf5340_cpuapp && west flash --recover and see the nRF5340DK advertise as "Zephyr Heartrate Sensor" on nRF Connect mobile app?

-Amanda H.

[David Pletcher]

Thank you, that clue reveals the crux of the problem. The documentation I was following guided me to install open-source Zephyr, not NCS Zephyr.

I tried locating that installation guide page again but couldn't find it. The first Nordic intro page I originally looked at scared me away; it said it only applied to the nRF52 or the (obsolete) nRF53 PDK, and I continued hunting around the site for more current information.

The peripheral_hr device works when deployed with NCS zephyr v1.5.1. It does not work when compiled and flashed with open-source zephyr:

https://pastebin.com/5dsPHZ1u

Thank you for your help with figuring this out.

I commend the ongoing effort of Nordic tech writers to consolidate redundant, dated installation guides and documentation.

[Amanda Hsieh]

Hi David,

David Pletcher said:

The first Nordic intro page I originally looked at scared me away; it said it only applied to the nRF52 or the (obsolete) nRF53 PDK, and I continued hunting around the site for more current information.

Which installation guide did you use? You should refer to Getting started with nRF Connect SDK (nRF53 Series) which will guide you to Install the nRF Connect SDK.

David Pletcher said:

The peripheral_hr device works when deployed with NCS zephyr v1.5.1. It does not work when compiled and flashed with open-source zephyr:

Unfortunately, we only provide support to nRF Connect SDK (NCS). 

-Amanda H.