firmware update of nrf9160 through UART

[Amol_Chor]

Hi,

In the link (https://infocenter.nordicsemi.com/topic/nwp_037/WP/nwp_037/external_flash.html) it mentions that nrf9160 need minimum 4 MB external memory for firmware upgrade.

But the modem firmware "mfw_nrf9160_1.3.4.zip" is of size 5831KB~ (6MB), how it will perform firmware upgrade with the 4MB external memory?

[Didrik Rokhaug]

Hi,

As the whitepaper says, that requirement is for full modem upgrades. If you follow the "DFU target full modem update" link, you will see that you shall use the .cbor file (inside the mfw .zip) for full modem updates, not the whole zip folder.

Best regards,

Didrik

[Amol_Chor]

Thanks you for your reply !!

I can see in the latest firmware zip there is 2001KB of .cbor file.

could you please confirm, what will be the maximum file size (.cbor) so that I can connect external memory accordingly?

also I have one question regarding application update (serial lte modem application) in this case the application bin file will going to write in external memory then update or directly it will store in internal memory?

[Didrik Rokhaug]

Amol_Chor said:

could you please confirm, what will be the maximum file size (.cbor) so that I can connect external memory accordingly?

As the documentation states, you should reserve 4MB for full modem updates over the air.

It is also possible to update the modem over UART. In that case, you don't need an external flash, as long as the external host is able to hold the entire modem update.

See this sample for more details: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/cellular/fmfu_smp_svr/README.html

Amol_Chor said:

also I have one question regarding application update (serial lte modem application) in this case the application bin file will going to write in external memory then update or directly it will store in internal memory?

This depends on how you set up your flash partitions. The new image will be written to the MCUBoot secondary slot. This partition might be in the internal flash, or it can be in external flash.

For more details on how to use MCUBoot with the secondary slot in external flash, see here: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/config_and_build/bootloaders_and_dfu/bootloader_external_flash.html#ug-bootloader-external-flash