Unexpected board reboot during LTE connection on custom boards (nrf9151)

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

HoovinSchoovin — Thu, 04 Sep 2025 14:58:55 GMT

We believe this is the cause of the issue - thanks for help Øyvind Mariano Goluboff

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

HoovinSchoovin — Thu, 28 Aug 2025 23:10:33 GMT

Hi Øyvind , apologies for taking some time to get back to you.
We are retrieving the problematic device from the field to test so will be able to get you data this weekend.

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

Øyvind — Thu, 28 Aug 2025 12:20:48 GMT

HoovinSchoovin any updates on this? Has this been resolved? Did you try probing VDD and verify >3V at all times?

Kind regards,
Øyvind

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

Mariano Goluboff — Wed, 20 Aug 2025 12:47:49 GMT

Are you able to probe VDD and make sure that it stays above 3V at all times, even when there's a transmit current peak?

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

Øyvind — Fri, 15 Aug 2025 07:42:29 GMT

Just to verify, does the same application and SIM work on a nRF9151DK?

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

HoovinSchoovin — Wed, 13 Aug 2025 15:17:17 GMT

Thanks Oyvind,

That would be handy to know, if there are any suggestions internally please let me know.

I am in Boston, USA.

Upon further analysis, I think i can rule out Emnify as the cause since it also happens on Hologram sims (i assume when it attempts connection o AT&T, but don't know since the trace seems to stop prior to connection).

I did a test: hologram sim in the "bad board". When at home, it works as expected. When i walk down a couple streets, it goes into the board reset loop. When i come back, it works. To me that suggests it could be network or tower dependent?

We've also identified that the hardware has something to do with it. Ie we have the bad board with another board both with hologram sims. One goes into the issue while the other does not. On the bad board, we can easily replicate the issue by changing to AT&T or traveling around.

Here is the hologram trace of it happening. Also note here i did not block any networks (hopefully that will be able to rule that out as the cause of PLMN not allowed.

devzone.nordicsemi.com/.../hologram_5F00_issue_5F00_trace.bin

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

Øyvind — Wed, 13 Aug 2025 07:53:58 GMT

Thanks for elaborating.

[quote user="HoovinSchoovin"]I am worried that the PLMN not allowed may be a byproduct of blocking tmobile on the emnify portal to replicate the issue i was experiencing specifically with AT&T. Is this what you may expect if a network was blocked on the network side?[/quote]

I don't think this should give this error, but I will need to discuss internally.

Where in the world are you testing this?

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

HoovinSchoovin — Tue, 12 Aug 2025 14:26:15 GMT

Hi Oyvind,

Thanks for getting back to me.

Resets occur at "buzzer: Initializing buzzer" in the logs. There are no logs near reset that give any clue as to why it is happening, the last log is event_handler_list_dispatch.

I am worried that the PLMN not allowed may be a byproduct of blocking tmobile on the emnify portal to replicate the issue i was experiencing specifically with AT&T. Is this what you may expect if a network was blocked on the network side?

Emnify sims have been working with AT&T in some cases, which makes me believe that there are agreements in place but your suggestion will prompt me to reach out and confirm with them too.

Thanks for sending over the traces.

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

Øyvind — Tue, 12 Aug 2025 06:47:16 GMT

Forgot to ask, but exactly where are you seeing this issue? And where in the logs are the resets?

Thanks.
-Øyvind

RE: Unexpected board reboot during LTE connection on custom boards (nrf9151)

Øyvind — Tue, 12 Aug 2025 06:38:49 GMT

Hello,

The initial issue I see from the application log is that you device is rejected by the network with EMM cause 11, which according to 3GPP TS 24.301 Annex A (Cause related to subscription options) means:

Cause #11 – PLMN not allowed
This EMM cause is sent to the UE if it requests service, or if the network initiates a detach request, in a PLMN
where the UE, by subscription or due to operator determined barring, is not allowed to operate.

[quote user=""]We are using emnify sims[/quote]

What networks does these have an agreement with?

Will forward the modem traces and have our team analyze.

Kind regards,
Øyvind