lte link control outside coverage

RE: lte link control outside coverage

Didrik Rokhaug — Fri, 12 Mar 2021 14:40:41 GMT

The LTE link controller (lte_lc) library now (NCS v1.5.0; I have not checked earlier versions) has a configurable timeout.

The default value is 10 minutes, but you can change it by setting CONFIG_LTE_NETWORK_TIMEOUT to the desired value (in seconds).

The LTE link controller library has also been expanded to include an asyncrounous API, which is more flexible than the old blocking API.

Best regards,

Didrik

RE: lte link control outside coverage

chouquette_fr — Thu, 11 Mar 2021 13:48:00 GMT

Hello, is it possible to do this in my own application without changing the library code ?

RE: lte link control outside coverage

Didrik Rokhaug — Fri, 26 Jul 2019 11:36:52 GMT

Hi.

The lte_lc_init_and_connect function waits indefinitely for a semaphore which is signaled when the modem establishes a connection. The function not returning when there is no coverage is therefore intended behavior.

If you do not want it to potentially wait forever you can change the timeout argument in the k_sem_take call on line 123 in ncs/nrf/drivers/lte_link_control/lte_lc.c.

E.g. if you change it from

k_sem_take(&link, K_FOREVER);

if (k_sem_take(&link, K_MINUTES(5)) != 0) {
    return -EAGAIN;
}

lte_lc_init_and_connect will return -EAGAIN if it were unable to connect within 5 minutes. I have not tested it properly so there might be unintended consequences. As we do not do anything with the modem it will still be active, but the application will not be notified if we establish a connection.

Best regards,

Didrik