nRF9131 modem Init failure

[Emmett Tagliere]

Hi, having a little of an issue and would appreciate your support:

When bringing up a board which has the nRF9131 and the nPM6000 I'm getting the following error when doing nrf_modem_lib_init();      

 Modem fault! PC: 0x001299C2, Reason: 0x010 - ASSERT

[00:00:07.263,732] <err> nrf_modem: Modem library initialization failed, err -5
[00:00:07.263,763] <dbg> nrf_modem: nrf_modem_lib_init: Modem init callback: 0xdc7d
[00:00:07.263,763] <err> nrf_modem: Modem library did not initialize: -5
nrf_modem_lib_init failed, err: -5

I tried:

Changing the modem firmware to different versions,

testing on different boards,

re-assembly and probing for any shorts,

adding capacitors near the nPM6000 Vin,

Changing the TCXO to a different model.

still got the same error

Any tips on how to solve this would be much appreciated

Thanks!!

[Emmett Tagliere]

Hi, 

Modem FW: mfw_nrf91x1_2.0.4.zip

NCS version: v3.1.0

Thanks

[Michal]

Thank you for the information.

Best regards,

Michal

[Michal]

I have a feeling it may be possibly be a footprint or soldering issue with some of the internal modem connections being shorted, causing error in communicating with the modem.

Errno -5 is EIO, which would make sense, if the application core is unable to contact the modem because of that.

But that's just my intuition.

Best regards,

Michal

[Emmett Tagliere]

ok, I hope thats the case.

I'll try re-soldering again, while also sending the design files for review in a new private ticket.

Best regards and thanks

[Emmett Tagliere]

Hi, I re-assembled the board a few times and tried again, still same issue, and I'm pretty sure there weren't shorts in all those times of re-assembly. (it was on fresh new boards each time). 

Also, important to note, I dont get that error on the modem firmware that came on the chip, so if I just plug the board in and start the application, nrf_modem_lib_init(); returns successfully. Only after doing a modem firmware upgrade the -5 error happens. 

So I wonder if there is something with the modem firmware / NCS / nrf9131 / nPM6000 versions that mismatch, which is causing the updated firmware to fail.

Looking forward to your insights.

Thanks

[Emmett Tagliere]

Also, I'm using softSIM, if that can also cause an issue. 

Regards

[Emmett Tagliere]

Hi, sorry for the ongoing messages, but wanted to updated:

I tried to switch between my nRF9131 and the nRF9131 that's on the EK I had around, and now everything works perfectly. so its not a short or hardware, I think there may be something wrong with the specific revision I have. 

The chip that works (the one I took from the EK):

AO

2346AH

The chips that don't work (at least the 5 I tested):

AO

2402G7

Would love your help on how to make the chips I have to work like the EK version does, since we already bought a big quantity of them.

Thanks!

[Øyvind]

Hello, 

Michal is currently out of office and I've been asked to follow-up this ticket. If OK with you, can we continue the discussion in ticket #358011?

Kind regards,
Øyvind

[Emmett Tagliere]

Hi, 

Yes lets continue in ticket #358011

Best regards