[NRF9151] Modem does not connect after SIM deactivate/reactivate

[Mlgr]

Hi,

I’m using the Thingy:91X board with the nRF9151 chip, modem firmware version 2.0.2, and SDK version 2.9.0.

We’re encountering a serious issue: the modem does not reconnect after the SIM has been deactivated and then reactivated.

I’ve tried:

• sys_reboot(SYS_REBOOT_COLD)

• Placing the modem offline (lte_lc_offline())

• Shutting down the modem library (nrf_modem_lib_shutdown())

• Forcing a hard reboot via the watchdog

None of these approaches has worked.

Do you have any suggestions for resolving this issue?

The only workaround so far (which isn’t acceptable) is to manually power the device off and on.

Regards,
Mathieu

[Achim Kraus]

Not sure, how you really tested that.

There may be two pitfalls:

- the reactivation of the SIM may take some time (in some cases more minutes, even longer, especially, if you deactivate and reactivate multiple times in just a few minutes)

- some rejection cause are treated "sticky" by the modem. That requires usually to wait some time or do a "lte_lc_power_off/lte_lc_normal" cycle (but I didn't retest that for a nRF9151)

So, let me propose, that you try to wait a minute or so after reactivate the SIM until you test to connect the modem again. If that results in rejected registrations, then try a "lte_lc_power_off/lte_lc_normal" cycle.

[Mlgr]

Hello Achim,

I let the card run for a few days, but it never reconnected to the network. However, I have a watchdog that reboots the card after “x” minutes without data. Should I disable it? Could it be causing a conflict with the modem in the new version?

I already tried the lte_lc_power_off/lte_lc_normal cycle, but it didn’t work (the watchdog still rebooted the card after a few minutes).

Best regards,
Mathieu

[dejans]

Hi,

Can you show how you enable tracing over UART and RTT?
You can read more about modem tracing and modem trace module in the documentation.

Best regards,
Dejan

[Achim Kraus]

I don't know, how Mathieu enabled the modem trace, in my test I did it with the snippets "west build -S nrf91-modem-trace-uart ..." and "west build -S nrf91-modem-trace-rtt ...".

With the UART it works, with RTT I wasn't able to get the trace and got only warnings in the logging console instead.

NCS 2.9.2, nRF9151-DK, mfw 2.0.2. 

Ubuntu, JLinkRTTLogger V8.18

nrfjprog --reset && JLinkRTTLogger -Device NRF9151_XXCA -If SWD -Speed 50000  modemtracesrtt.bin

(As already mentioned above.)

But the modem trace is rather a side issue.

[dejans]

Hi Mathieu,

Have you made some progress?

Have you been able to capture modem trace, possibly following Achim's suggestion using modem trace snippet?

Which mobile network operator does your device connect to?

Due to frequent rebooting via watchdog, it could be that reset loop restriction was triggered.

Best regards,
Dejan

[Jon]

Hi !

We were not really able to make some progress. 

We were not able to get modem traces. I was not able to do it with UART1, since the uart1 is used for other purposes, and the connectivy_bridge is not used anymore. That's why we redirect all our app uart to RTT.

So, i tried to use the RTT modem trace snippet. 
I also get the -63 error.



By the way, i get nothing on channel 2, about modem traces. It remains empty

Here is the command i used to build

of course, i used the link given for the snippet.

Well, it seems i won't be able to get some modem traces :)

About the operator, i tried with a Onomondo sim until now.   My device connects to Bouygues Telecom Network (by using onomondo or Tele2).

Tomorrow, i will check with some TELE2 sim, and a brand new Thingy91X. I'll give you more infos then.

[dejans]

Hi,

For additional information about capturing modem traces, you can refer to these links in documentation
modem tracing and capturing modem trace using Cellular Monitor.

Jon said:

Tomorrow, i will check with some TELE2 sim, and a brand new Thingy91X. I'll give you more infos then.

I am looking forward to your update.

Best regards,
Dejan