nRF9160 connected yet not connected

RE: nRF9160 connected yet not connected

Kazi Afroza Sultana — Wed, 03 Nov 2021 14:06:01 GMT

Hello Lukas,

Its good to hear that your main problem is fixed.

Here are the answers of your remaining questions:-

* Which queries do You recommend to find out connection quality?

For finding out connection quality you can use AT+CSCQ command (Nordic Semiconductor Infocenter) which shows the Reference Signal Received Quality (RSRQ) and Reference Signal Received Power (RSRP).

* What can I query to try to renew the connection, change operator or somehow get a connection?

You can write AT+COPS selects a Public Land Mobile Network(PLMN) manually. It reads and searches the current mobile network (Nordic Semiconductor Infocenter). We recommend to left it on automatic selection.

Regarding Debug print : I think it may not be an error as you are trying to read a field in a struct that isn't used, and thinking the invalid value in the unused field is a problem. struct lte_lc_evt is used only in the tac fields and id fields in the cell struct. Therefore, when you get the CELL-UPDATE event only these two parameter are set with value. Others are zero. (See again- number 4 line of your debug log). You can look at this link : https://github.com/nrfconnect/sdk-nrf/blob/main/include/modem/lte_lc.h#L179

Hope it helps.

Kazi Afroza Sultana

RE: nRF9160 connected yet not connected

Lukas Kuhs — Tue, 02 Nov 2021 12:07:45 GMT

Hmm... There are two problems.

"Yesterday" (refereing to ticket creation) there was a bad connection. "Today" (refereing to ticket creation) there was a software bug that led to the server rejecting some of the packets, but connection seemed to have been OK "today". So my main problem is fixed. Thank You for helping with this!

Questions remaining to be able to cope with bad connection situations better in the future:

* Why is the debug print incorrect (showing mcc=mnc=0)? This is misleading...

* Which queries do You recommend to find out connection quality?

* What can I query to try to renew the connection, change operator or somehow get a connection?

Best regards

Lukas

RE: nRF9160 connected yet not connected

Lukas Kuhs — Tue, 02 Nov 2021 09:55:19 GMT

Yes, I already wrote so in my initial question, that it is only in some of the queries.

This is the code for printing (omitting the other cases):

static void lte_handler(const struct lte_lc_evt *const evt)
{
	switch (evt->type) {
	case LTE_LC_EVT_CELL_UPDATE:
		printk("LTE cell changed: mcc=%d, mnc=%d, id=%d, tac=%d, earfcn=%d, timing_advance=%d, measurement_time=%lld, phys_cell_id=%d, rsrp=%d, rsrq=%d\n", 
                          evt->cell.mcc,
                          evt->cell.mnc,
                          evt->cell.id,
                          evt->cell.tac,
                          evt->cell.earfcn,
                          evt->cell.timing_advance,
                          evt->cell.measurement_time,
                          evt->cell.phys_cell_id,
                          evt->cell.rsrp,
                          evt->cell.rsrq);
		break;
	}
}

The handler is registered like so:

lte_lc_connect_async(lte_handler);

And this works fine. And I'm quite sure that it always had worked well.

RE: nRF9160 connected yet not connected

Kazi Afroza Sultana — Tue, 02 Nov 2021 09:42:19 GMT

Hello Lukas,

I can see from the log file that it (LTE_LC_EVT_CELL_UPDATE: LTE cell changed: mcc=0, mnc=0.....) shows mcc and mnc zero but from the command AT%XMONITOR, it's not zero. You can see the PLMN id 26201 which is MccMnc.

AT%XMONITOR: 5,"","","26201","67B9",7,3,"01DE9703",333,1444,27,25,"","11100000","00000110","01001001" => Registered, roaming === mcc=262 mnc=1

Could you please tell where did you print MccMnc in your source code? I mean where it is printed, and from where it gets the mcc and mnc.

Best Regards,

Kazi Afroza Sultana

RE: nRF9160 connected yet not connected

Lukas Kuhs — Tue, 02 Nov 2021 07:03:09 GMT

Hello Kazi,

thank Your for looking into it.

I updated to 1.3.1. Problem still persists. Hardware version is 1.0.0 PCA10090 (2021.6) Application is taken from UDP sample and then extended to use MQTT-SN. So no certificates involved.

I'm wondering what

mcc=0, mnc=0

means. How could the device do DNS and send some packets successfully without a valid connection?

Best regards,

Lukas Kuhs

RE: nRF9160 connected yet not connected

Kazi Afroza Sultana — Mon, 01 Nov 2021 12:49:50 GMT

Hello Lukas,

Thanks for your query. Sorry, It is a bit late reply because this ticket arrived in weekend.

Our technical team has looked at the modem trace file and they can not find anything immediately wrong in the modem trace. The device connects to the network, performs a successful DNS lookup, sends a UDP packet to the server, get a reply, then sends 4 more packets without getting a reply from the server.

**What else should I do to find out the problem?

What can I query to make the connection good again?**

Is it possible to download the latest version of nRF9160-DK application and modem firmware since it shows AT+CGMR command that version is old one (mfw_nrf9160_1.3.0)? Could you also please tell us which hardware (version no) you are using and what application (for example asset tracker or at-client etc) running on it? You may have to update the nRF for Cloud certificates from nRF cloud.

Please try this and let us know if still same problem continues.

Best Regards,

Kazi Afroza Sultana