AT_LTE socket hanging

RE: AT_LTE socket hanging

Martin Lesund — Thu, 15 Oct 2020 11:44:40 GMT

Hi Mike,
Are you connected to the same network at your home?
Is it possible to get the modemtrace when the device is working as well to compare?

Br,
Martin L.

RE: AT_LTE socket hanging

miked531 — Mon, 12 Oct 2020 17:53:04 GMT

I've left the customer site and have not yet been able to reproduce the issue here at home. Building with NCS v1.3 is going to take some time to get it working due to the zephr api changes so I'll try 1.2.1 when I can duplicate the hang.

RE: AT_LTE socket hanging

Martin Lesund — Fri, 09 Oct 2020 12:06:43 GMT

Hi Mike,

Sorry for the delay, I have not managed to analyze the modem traces yet.
I will get back to you on this next week.

In the meantime could you build your project based on NCS v1.3.1 to see if an updated bsdlib etc. could have a positive effect to this?

(or v1.2.1)

Br;
martin L.

RE: AT_LTE socket hanging

Martin Lesund — Wed, 07 Oct 2020 14:08:38 GMT

Hi Mike,

We will analyze the modemtrace and see if we can find out what is going on.
Most likely I can share the information tomorrow.

BR,
Martin L.

RE: AT_LTE socket hanging

miked531 — Tue, 06 Oct 2020 14:17:16 GMT

Thanks for the quick response. I am using NCS 1.2.0 and mfw 1.2.1 (saw the same problem with mfw 1.2.0). The message is a bit misleading--it *will* try nb-iot the next time, but I haven't got around to it yet. The code is attempting to issue AT+CFUN=4 when I experience the hang. I open an additional socket to issue that AT command. I will set the XSYSTEMMODE after the modem shuts down.

I am less concerned as to why I am not connecting but more about the reason socket() is hanging. I am not using lte_lc as I have my own modem access routines (lte_lc wasn't mature enough when I started the project).

RE: AT_LTE socket hanging

Martin Lesund — Tue, 06 Oct 2020 13:49:02 GMT

Hi Mike,
Which NCS version is this code based of?
From what I see in the modemtrace the basestation in your customers area does not support LTE-M.

However I do suspect that you may not switch to NB-IoT gracefully.

When you do:
"[00:02:00.796,997] <inf> boss: next LTE connection will use NB-IoT"
Do you make sure that the modem is fully in offline mode ("AT+CFUN=4") before changing the mode ("AT%XSYSTEMMODE=0,1,0,0") ?
Are you using the lte_lc to handle this?