This implementaion of file system is developed by ELM Chan
https://elm-chan.org/fsw/ff/.  

This is based on FAT file system specification.  It provides
an interface to physical storage management through its disk io
API in diskio.c. The disk io interfaces are updated to interface
with Zephyr flash memory management.

Current revision in the tree is 0.16

URL to current version: https://elm-chan.org/fsw/ff/arc/ff16.zip
SHA256 20b07c8047b4976118f6488e9cd8c4b1126e0525479828986adca69bb31047d1