.. _lib_fmfu_fdev:

Full modem firmware update from flash device
############################################

.. contents::
   :local:
   :depth: 2

The fmfu_fdev library provides an API for applying a full modem firmware update from a flash device.

Functionality
*************

The modem firmware and metadata stored in the flash device must conform to a specific serialization format.
For more information, see :ref:`lib_dfu_target_full_modem_update`.

The serialized modem firmware contains the hash of the firmware and a signature.
These fields are used to pre-validate the modem firmware before it is programmed to the modem, ensuring that the data about to be written corresponds to the data that have been signed.
Once the modem firmware is pre-validated, it is written to the modem using the :file:`nrf_modem_bootloader.h` API.

.. _lib_fmfu_fdev_serialization:

Serialization
*************

The modem firmware is serialized using the following CDDL scheme.

.. literalinclude:: ../../../../../../subsys/dfu/fmfu_fdev/cddl/modem_update.cddl
    :language: none

The resulting serialized firmware file uses the :file:`.cbor` extension.
A generated decoder, :file:`modem_update_decode.c`, is used for parsing the data serialized with this format.

Prerequisites
*************

* The serialized modem firmware must be stored in the flash device.
* The modem library must be initialized in DFU mode.

API documentation
*****************

| Header file: :file:`include/dfu/fmfu_fdev.h`
| Source files: :file:`subsys/dfu/fmfu_fdev/src/`

.. doxygengroup:: fmfu_fdev
   :project: nrf
   :members: