NRF9160 w_lte_lc_init_and_connect throws __usage_fault after at_cmd(at_socket_fd, subscribe...)

Question

Hi, 
 I have the latest 0.4.0 tag, flashed the latest modem firmware 0.7.0-29.alpha, and debugging the asset_tracker app under nrf9160_pca10090ns. 
 When I debug the app it throws a __usage_fault sometime after at_cmd(at_socket_fd, subscribe, AT_CMD_SIZE(subscribe)); within w_lte_lc_init_and_connect 
 Any idea what is asyncronously happening behind the scenes that is throwing the __usage_fault? 
 Thx!

Martin Lesund · Accepted Answer

Hi GJSea, As you have found out this is a classic stack overflow issue. 
 The solution would be to find out which stacks that overflows with the help of the thread ID and zephyr.map, and then increase the size of these. 
 
 Typically it will be to increase the size of these two from 512 to 1024: 
 - https://github.com/NordicPlayground/fw-nrfconnect-nrf/blob/master/lib/at_host/at_host.c#L27 
 - https://github.com/NordicPlayground/fw-nrfconnect-nrf/blob/master/lib/modem_info/modem_info.c#L21 
 
 Best regards, Martin L.

GJSea · Answer

Yes increasing these stack size values solved the overflow problem. Thanks!!! The code might want to check for CONFIG_NO_OPTIMIZATIONS and have a #ifdef for the values there.

NRF9160 w_lte_lc_init_and_connect throws __usage_fault after at_cmd(at_socket_fd, subscribe...)

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