nRF9160DK AT commands don't work

[Collin Moore]

Hi,

I have an nRF9160DK board, and I seem to have broken the modem.

I can't get any demo apps to work, and when I use LTE Link monitor, all AT commands time out.

I have a Thingy91 that works fine. I have looked at similar-sounding questions on here, but they didn't help.

Is there a "bricked" state of modem FW? Is there a way to get out of such a state?

How can I debug the modem when AT commands don't work?

I did notice that my dev board is PCA10090 0.8.2, from 2018.49, and that I have updated to MFW 1.3.1 in nRF Connect Desktop's Programmer.

Could this be the problem? I have since uploaded mfw1.3.3, and Programmer says it completed successfully in ~46 seconds.

I have not tried downgrading, due to the warning against that in the downloads section for the nRF9160DK. I'm sure I have the first rev SiP.

[Charlie]

Hi Collin,

Did you run through Updating the DK firmware?

When you test with AT client sample, does any printing appear on LTE Link Monitor?

What if you test with zephyr hello world or blinky samples? 

Best regards,

Charlie

[Collin Moore]

Charlie,

Yes, I can update the application FW to anything. To elaborate more, all the Asset Tracker apps bootloop. The AT Client is the only one that doesn't bootloop, but AT commands all time out.

I just tried  full erase, update modem to, 1.3.3:

then re-flash of Asset Tracker v2 from img_app_bl/nrf9160dk_asset_tracker_v2_2022-12-08_188a1603.hex

This is what LTE Link Monitor shows (note the scroll bar on the right, that is so small because it is bootlooping:

When I flash AT_Client, it doesn't bootloop, but no AT commands work:

The first AT command was sent automatically when I opened Link Monitor. Then I pressed the Reset button on the DK, and it printed all the blue text. Then I clicked the AT+CFUN? button and got the timeout message.

That is my issue.

Now, the zephyr hello world as compiled from v2.2.0 SDK seems to have a somewhat different issue. I select New Freestanding project based on zephyr/hello_world, then this build config builds.

Then I flash and get no output on Link Monitor, which used to work. If I debug, it never gets to a breakpoint that I put in main(), and if I pause, it is stuck here:

I think that I am having some issue with TP-M or some other security feature, and that this is an unrelated issue, as I also have it on the Thingy91 with my VSCode projects, but the Thingy runs the Asset Tracker just fine.

Can you help me get the modem on this nRF9160DK working again?

[Collin Moore]

I got an email from Gene Rittenhouse, my local region sales rep, and he said my DK from 2018 is not worth messing around with. So I do not need to get the modem up and running. My only problem now is getting code working in the debugger. That problem is shared by both this old DK and my Thingy:91. I'll start a new thread on that issue and mark this one as closed, since I'm not going to try and fix the modem on my nRF9160DK that is so old.