FOTA with NB-IoT failing

[zhaw-moss]

Hi community

I'm trying to evaluate the possibilities of an application update over the air via NB-Iot. According to this post this should be possible.

I'm using the application_update example with the nRF9160-DK (B1).

The example works fine with LTE-M and is able to download the update.

In the prj.conf I changed the defaults for the fragment size (2048 B) and the network mode (LTE-M) to 512 B and NB-IoT by adding the following lines:

CONFIG_DOWNLOAD_CLIENT_HTTP_FRAG_SIZE_512=y
CONFIG_LTE_NETWORK_MODE_NBIOT=y

The code compiles and the LTE Link does connect. It also connects to the server but then it fails with the error 116, see below:

*** Booting Zephyr OS build v2.6.99-ncs1  ***
HTTP application update sample started
LTE Link Connecting ...
LTE Link Connected!
Press Button 1 to perform application firmware update
I: Configuring socket timeout (30 s)
I: Connecting to hidden-url.com
I: Downloading: FOTA/app_update.bin [0]
E: Error in recv(), errno 116
E: Download client error
Received error from fota_download

Does anyone have an idea whats wrong here?

Thanks!

Simon

[zhaw-moss]

Hi Charlie,

thanks for your answer.

No, I'm not using the default iBasis SIM card. We have Swisscom IoT simcards running with both LTE-M and NB-IoT enabled.

Best wishes,

Simon

[Charlie]

Hi Simon,

Ok, have you tested the NB-IoT connection before? You can use nRF9160: Serial LTE modem or nRF9160: AT Client.

If you can confirm there is no issue with the NB-IoT connection, please record the modem trace and share it with us for further analysis. 

Best regards,

Charlie

[zhaw-moss]

Hi Charlie

Yes, I tested the NB-IoT connection before, but I doublechecked it with the AT Client sample and it works.

I recorded the trace of two attempts. In the first attempt it failed before the download started. In the second attempt it failed after it downloaded the first two fragments. Log below:

*** FIRST ATTEMPT ***

*** Booting Zephyr OS build v2.6.99-ncs1  ***
HTTP application update sample started
LTE Link Connecting ...
LTE Link Connected!
Press Button 1 to perform application firmware update
I: Configuring socket timeout (30 s)
I: Connecting to hidden-domain.com
I: Downloading: FOTA/app_update.bin [0]
E: Error in recv(), errno 116
E: Download client error
Received error from fota_download


*** SECOND ATTEMPT ***

*** Booting Zephyr OS build v2.6.99-ncs1  ***
HTTP application update sample started
LTE Link Connecting ...
LTE Link Connected!
Press Button 1 to perform application firmware update
I: Configuring socket timeout (30 s)
I: Connecting to hidden-domain.com
I: Downloading: FOTA/app_update.bin [0]
I: Downloaded 512/167219 bytes (0%)
I: Downloaded 1024/167219 bytes (0%)
E: Error in recv(), errno 116
E: Download client error
I: MCUBoot image upgrade aborted.
Received error from fota_download

trace-2021-10-14T11-24-14.754Z.bin

Thanks and best regards,

Simon