Pre-load files into flash for custom firmware.

[SomeSpaceNerd]

I was creating a custom firmware and need to load 3 files within a directory into flash memory as soon as the board gets flashed, is there a place to put this directory where it would get copied into flash, or do I have to do it afterwards by accessing the Filesystem? Also, I would like more clarification on where or how to put main.py into a custom firmware as well, as some of the documentation and discussions I found are outdated or not useful.

[Walkline80]

It seems to me that this is a port-related issue, some ports, such as esp32 and rp2, they have their own modules folder for containing initialization files and/or user files compiled to firmware, while some ports don't.

[robert-hh]

If you build your own firmware, then you can use the manifest scheme to tell the place and names of the files to be included. There is one hiccup with main.py and boot.py. They cannot be frozen into the firmware and have to be loaded into the final board.
You could however as a workaround create them in _boot.py. _boot.py is frozen in the firmware, as it usually mounts the file system. There you can add code to create a default main.py and eventually boot.py if they do not exist.

[SomeSpaceNerd]

My code that I would like to load is a OTA updater/bootloader, so replacing/appending _boot.py with it would be what I’m looking for. But the manifest system may not work for the types of files I need to load. Thank you for the answer!

[robert-hh]

There was a suggestion by @peterhinch to embed non-python files into a python script, which would be extracted on import of the script. Peter, do you still have the link?

[peterhinch]

It's data-to-py. However freezefs (below) is a major superset.

Those interested in these capabilities may also be interested in romfs. This is a line of development with huge potential.

[bixb922]

This may help for what you need:

https://github.com/bixb922/freezefs

Install with pip install freezefs. Put all your files and subfolders in a folder called (for example) myfolder and run python -m freezefs myfolder frozen_myfolder.py . This archives the files to frozen_myfolder.py and aooebds the needed driver.

Add frozen_myfolder.py to the manifest.py and generate a Micropython image.

In boot.py or main.py add import frozen_myfolder

The files now will appear as a readonly folder /myfolder as a virtual file system.

(edit)
Other excellent and related options are:

#8191 (see status in the PR, it seems this will soon be in standard Micropython, and officially supported)
https://github.com/Josverl/vfs_merge
https://github.com/peterhinch/micropython-samples/blob/master/data_to_py/data_to_py.py
https://github.com/glenn20/micropython-esp32-ota
https://github.com/glenn20/mp-image-tool-esp32

[Josverl]

Good collection of options, which I suggest would be good to add to the wiki

[andrewleech]

For reference I compiled some of these notes here: https://github.com/micropython/micropython/wiki/Bundling-and-deploying-application-code-and-files which is linked from the wiki tips and tricks page