FAT12 was not choosen, because it's virtually no longer in use
(allows volume sizes up to 32 MB, only) and would increase
binary size by another 248 bytes.
Measured sizes are in a comment in pff_conf.h, where one can also
enable or disable support for these variants.
Part 1 is, implement
- M20: List SD card.
- M21: Initialize SD card (has to be done before listing).
- M22: Release SD card.
Do all this in one chunk, splitting this up wouldn't allow to test
the result.
This is all the commands to read from and write to SPI,
initializing the card, read in blocks and so on. This should
make Petit FatFs actually usable.
So far read-only and no M-codes to let end users play with
this stuff.
The demonstration code was changed to list the SD card's
top level directory over and over again.
Some modifications to avoid file name conflicts with other parts and
make it compile. As the glue code to the hardware (spi.c/.h) is
still missing, there are a few warnings, of course.
Changes to this library are tracked in pff.c.
Markus Hitter
Michael Moon