Check if 9160 LTE-M Connection has Become Unavailable

RE: Check if 9160 LTE-M Connection has Become Unavailable

user104389 — Tue, 07 Jun 2022 17:05:23 GMT

Okay that's everything I needed, thanks so much!

RE: Check if 9160 LTE-M Connection has Become Unavailable

user2115 — Tue, 07 Jun 2022 07:02:23 GMT

Hi,

You will normally see _SEACHING (ie. AT+CEREG stat field = 2) first, and if there's no cell towers within range, you'll see _UNKNOWN (stat=4), and eventually it will go into NOT_REGISTERED state (stat=0).

However, you can also get a _REGISTRATION_DENIED in cases where you try to roam to a network provider that does not accept your SIM card.

[quote user="jake11212"]Will it automatically try to reconnect if this happens or does this need to be handled directly? [/quote]

Yes, it will try to reconnect to a network.

[quote user="jake11212"]Is there a way to simulate the LTE-M network going down? I'm not sure how to test the behavior.[/quote]

A Faraday cage can be used for such testing to see how your application handles this specific scenario.

Kind regards,

Håkon

RE: Check if 9160 LTE-M Connection has Become Unavailable

user104389 — Fri, 03 Jun 2022 19:41:08 GMT

Thanks for the response that's really helpful!

So if the network goes out or connection is lost I assume it would change the

LTE_LC_EVT_NW_REG_STATUS to

LTE_LC_NW_REG_SEARCHING correct?

Will it automatically try to reconnect if this happens or does this need to be handled directly?

Is there a way to simulate the LTE-M network going down? I'm not sure how to test the behavior.

RE: Check if 9160 LTE-M Connection has Become Unavailable

user2115 — Fri, 03 Jun 2022 13:10:12 GMT

Hi,

If you are using lte_lc already, you should get a event if the AT+CEREG notification is signaled (ie. the state has changed). This is through this event:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.6.0/nrf/include/modem/lte_lc.html#c.lte_lc_evt_type.LTE_LC_EVT_NW_REG_STATUS

Where the response is not "1" (LTE_LC_NW_REG_REGISTERED_HOME) or "5" (LTE_LC_NW_REG_REGISTERED_ROAMING)

The above logic in lte_lc directly reflects the value of <stat> field that is reported through the AT+CEREG at command:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/nw_service/cereg.html?cp=2_1_7_6

Kind regards,

Håkon