First boot after modem FOTA results in at_cmd error

[Jack Panetta]

I'm currently working on integrating modem FOTA updates into my application. I have the FOTA working at the moment, I'm able to go to and from a FOTA-TEST version with the differential images.

However, I have been noticing that during the first boot after the update, I get at_cmd errors and I'm unable to send any AT commands to the modem. Once the FOTA download process has finished, I do a system reboot via sys_reboot(0). On the very next boot I'll get this error when my application starts up:

SPM: prepare to jump to Non-Secure image.
***** Booting Zephyr OS build v2.0.99-ncs1 *****
[00:00:06.240,081] <err> at_cmd: Failed to open AT socket (err:-12)
[00:00:06.260,711] <err> at_cmd: Failed to send AT command (err:1)

These errors go away if I reset one more time. I have tested this many times and the same behavior happens every single time.

Is there any way to resolve this issue? Otherwise, is there a way to handle this error? For example, If I could catch the event where the AT socket fails to open, I could then initiate another system reset.

- Jack

[Hakon]

Hey,

You try implementing any of the fixes mentioned here. I don't know what you are doing in your code specifically, but the post I linked to seemed to have the same error as yours.

[Jack Panetta]

Hey Hakon,

The link you referenced doesn't seem to be working. I'm getting a browser error (tried with both Chrome and Firefox):

ERR_TOO_MANY_REDIRECTS

- Jack

[Hakon]

My bad, it was from another private ticket. Here's an excerpt;

"There has been an update in NCS on handling modem FOTA.  

Have a look at the main file of http_application_update, the switch case is based on the return code from bsdlib_init(), however, this should be changed to bsdlib_get_init_ret. 

The system needs to be rebooted twice after downloading the modem FOTA, and changing the above should solve the issue. Let me know how that works for you."

[Siyou]

Hi 

I am facing the same issue(need reboot modem twice after its FOTA), and the bsdlib_get_init_ret() always returned -1, why? I have defined CONFIG_BSD_LIBRARY=y

If -1 indicated fatal error, what operations are required before invoking bsdlib_init()?