What is the maximum expected file size of the modem update file for the 9160 LTE modem?

[blake-bit]

What is the maximum file size of the LTE Modem firmware update we can expect on the 9160 platform?
I am trying to plan out our external flash size and partitions.

The current update is around 244KB from file serial_lte_modem_2021-06-25_7a076c22.bin

The documentation recommends a minimum 4MB partition of external flash to store a full update.
What is the reasoning behind this large size requirement?

[Albrecht Markus Schellenberger]

Hello Blake,

my apologies for the late reply! It took me some time to confirm the facts.

The documentation recommends a minimum 4MB partition of external flash to store a full update.
What is the reasoning behind this large size requirement?

Maximum expected modem firmware image size is around 3MB. Next available memory size is 4MB, so what is stated in the HTTP full modem update documentation is correct. However, modem firmware delta image updates can be managed with the internal nRF9160 memory.

The current update is around 244KB from file serial_lte_modem_2021-06-25_7a076c22.bin

The file you are referring to is the Serial LTE modem application firmware image, which is not the modem firmware image. The full modem firmware update image file is called “../mfw_nrf9160_1.3.0.zip/ firmware.update.image.cbor” and is currently around 2MB in size.

I hope this answers your question!

Regards,

Markus