nRF Connect SDK Modem Firmware compatibility

[Norbert Braun]

Hi,

We are in the process of upgrading device firmware (using Nordic nRF9160) from nRF Connect SDK 2.4.2 to nRF Connect SDK 3.4.0 LTS. A number of devices to be upgraded are already deployed in the field.

The devices in the field have modem firmware 1.3.4 installed. We would prefer to not upgrade the modem firmware of the devices in the field unless necessary.

Looking at the compatibility matrix at docs.nordicsemi.com/.../nrf9160_modem_fw.html, it seems that nRF Connect SDK versions >= 3.0.0 require modem firmware 1.3.7.

We did our own (limited) testing, and the new device firmware (based on nRF Connect SDK 3.4.0 LTS) seems to actually work with modem firmware 1.3.4, although we did notice some (non-critical) differences in behavior (compared to modem firmware 1.3.7).

Two questions:

1. Is there a technical reason why nRF Connect SDK 3.4.0 LTS cannot work with modem firmware 1.3.4, or is it something that "should work" and just has not been tested?

2. If we do decide to update the modem firmware, do we have to do multiple delta updates (i.e. 1.3.4 -> 1.3.5 -> 1.3.6 -> 1.3.7) or is there a way (for Nordic or for us) to generate a delta update that goes directly from 1.3.4 to 1.3.7? (I understand the limitation imposed by the modem DFU area size, I would just like to reconfirm that this particular combination indeed does not fit.)

Thank you for any insights!

Best regards,

Norbert

[Øyvind]

Hello Norbert,

1. Is there a technical reason why nRF Connect SDK 3.4.0 LTS cannot work with modem firmware 1.3.4, or is it something that "should work" and just has not been tested?

We recommend updating the modem FW as well due to bug fixes introduced in mfw 1.3.7. nRF Connect SDK v3.4.0 LTS has not been tested with mfw 1.3.4 and thus cannot confirm if it works or not. That said, there should not be a reason for it to not work. I would recommend testing with a unit or two first. Most likely it's fine, it's just not verified (hence support might be limited in case of compatbility-related issues) and some new features are not be supported.

2. If we do decide to update the modem firmware, do we have to do multiple delta updates (i.e. 1.3.4 -> 1.3.5 -> 1.3.6 -> 1.3.7) or is there a way (for Nordic or for us) to generate a delta update that goes directly from 1.3.4 to 1.3.7? (I understand the limitation imposed by the modem DFU area size, I would just like to reconfirm that this particular combination indeed does not fit.)

It is possible to update to 1.3.7, however there are no delta updates directly. The following .bin files are found in the modem FW package downloadable from the nRF9160 product page

mfw_nrf9160_update_from_1.3.4_to_1.3.5.bin (220 kB)

mfw_nrf9160_update_from_1.3.5_to_1.3.6.bin (210 kB)

mfw_nrf9160_update_from_1.3.6_to_1.3.7.bin (142 kB)

Let me know how that works for you!

Kind regards,
Øyvind