nrf9160 LTE modem documentation

RE: nrf9160 LTE modem documentation

Hadrien Kohl — Tue, 11 Aug 2020 12:36:49 GMT

Sure thing. I created https://devzone.nordicsemi.com/f/nordic-q-a/64713/how-to-recover-9160-modem-after-enetdown-errors

RE: nrf9160 LTE modem documentation

Håkon Alseth — Tue, 11 Aug 2020 12:27:32 GMT

Hi,

Thanks, so the modem should respond to those AT commands.

Could you create a new thread on your issue? I am afraid it falls a bit out of scope for this one.

Kind regards,

Håkon

RE: nrf9160 LTE modem documentation

Hadrien Kohl — Tue, 11 Aug 2020 12:25:21 GMT

I am using the modem version 1.2.0

RE: nrf9160 LTE modem documentation

Håkon Alseth — Tue, 11 Aug 2020 12:12:08 GMT

Which modem fw are you using?

Kind regards,

Håkon

RE: nrf9160 LTE modem documentation

Hadrien Kohl — Tue, 11 Aug 2020 11:48:47 GMT

I Håkon, I wasn't clear. I have a situation where I am getting ENETDOWN on socket operations after some time. This is a new thing that I did not experienced with a prior version of our application.

What I am wondering is how do I reset the modem to a correct state. I have tried to send AT+CFUN=4 and AT+CFUN=0 via lte_lc_offline() and lte_lc_power_off() methods but it hangs from there.

[00:10:32.730,407] <dbg> at_cmd.at_write: Sending command AT+CFUN=4
[00:10:32.731,109] <dbg> at_cmd.at_write: Awaiting response for AT+CFUN=4

Regards,

Hadrien

RE: nrf9160 LTE modem documentation

Håkon Alseth — Mon, 10 Aug 2020 10:41:58 GMT

Check the network connection status (using AT+CEREG), as per the former comment. In that case, it can be that you're out of range. You can for instance try to connect via NB1 (if former mode was M1). It all depends on your wanted application behavior.

Kind regards,

Håkon

RE: nrf9160 LTE modem documentation

Hadrien Kohl — Mon, 10 Aug 2020 08:49:33 GMT

I see. What should one do when getting ENETDOWN?

RE: nrf9160 LTE modem documentation

Håkon Alseth — Mon, 09 Mar 2020 07:18:16 GMT

[quote user="Hadrien Kohl"]What errno/err should one expect to see if the modem connection went down? And what would be the appropriate recovery actions to take?[/quote]

The errno depends on the socket call, please see the independent manual for each socket call (like "man setsockopt"). A common one is ENETDOWN if the network is down, and ENOTCONN if the socket was closed. I would still recommend that you parse the CEREG status to see the LTE network status.

[quote user="Hadrien Kohl"]Alternatively, is there a way to query the modem for it's state (connected/disconnected) before using it?[/quote]

AT+CEREG shall give you the network status, and you can check the signal strength RSRP with AT+CESQ (or subscribe to it via AT%CESQ)

RE: nrf9160 LTE modem documentation

Hadrien Kohl — Sun, 08 Mar 2020 15:26:28 GMT

What errno/err should one expect to see if the modem connection went down? And what would be the appropriate recovery actions to take?

Alternatively, is there a way to query the modem for it's state (connected/disconnected) before using it?

RE: nrf9160 LTE modem documentation

Håkon Alseth — Tue, 11 Feb 2020 10:09:03 GMT

Hi,

AT+CEREG? gives you the network status:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/nw_service/cereg_read.html?cp=2_1_6_9_1

The <stat> field will be either 1 or 5 when you're connected, depending on what type of SIM card you have. Since you're using iBasis, it returns roaming (5)

AT+CESQ will give you the signal quality and strength, as described here: https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/mob_termination_ctrl_status/cesq_set.html?cp=2_1_3_4_0

For the RSRP, you normally want 40 or higher (ie: -100 dBm or better), which you seem to get.

For the connection over IP, the socket operations will return an errno/err if the connection over LTE has gone down.

Kind regards,

Håkon