NRF9160 NB-IOT disconnecting (+CEREG registration = 0) after period of stable connection.

RE: NRF9160 NB-IOT disconnecting (+CEREG registration = 0) after period of stable connection.

Didrik Rokhaug — Fri, 06 May 2022 11:37:33 GMT

Great to hear that you found the cause!

In modem fw version 1.2.x, you can use the %XVBAT, %XVBATLVL, %XVBATLOWLVL and %XPOFWARN to monitor the voltage level. You can also use +CGEREP to subscribe to +CGEV events (which can give you much of the same information as %MDMEV).

Best regards,

Didrik

RE: NRF9160 NB-IOT disconnecting (+CEREG registration = 0) after period of stable connection.

narrowerband — Fri, 06 May 2022 10:39:27 GMT

Hi Didrik,

It seems that I've fixed my issue. It was related to a hardware issue where the power supply was not able to deliver the current needed for the modem, so the voltage dipped to a point that it did not trigger a brownout, but did trigger a network disconnect.

RE: NRF9160 NB-IOT disconnecting (+CEREG registration = 0) after period of stable connection.

narrowerband — Mon, 02 May 2022 19:14:01 GMT

Hi Didrik,

I am using modem firmware 1.2.7 (because our devices are the NRF9160 SiP revision 1 (B0)) which is to our understanding the highest modem firmware that the B0 can safely run.

I will update a development kit to 1.3.0 to see what comes from the modem events.

RE: NRF9160 NB-IOT disconnecting (+CEREG registration = 0) after period of stable connection.

Didrik Rokhaug — Mon, 02 May 2022 11:16:37 GMT

Hi,

What modem firmware version are you using?

If you are using 1.3.0 or newer, could you subscribe to modem events (AT%MDMEV=1), and see if that reports anything?

Best regards,

Didrik