The Petit FatFS module contains a write function with some restrictions, in order to
minimize the required memory. These restrictions include:
- Files cannot be created; only an
existing file can be written to
- Files cannot be expanded in
size
- The time stamp of a file cannot
be updated
- A write operation will only start
and stop on a sector boundary
- A read-only file attribute will
not block a write operation
This means that in order to write to a file, it must already exist on the SDC/MMC,
and have the required size allocated.