Posted on March 24, 2018 at 01:00I think the code I provided was the ST code refactored so it handled blocks properly without a lot of stupid/unnecessary transforms. Earlier ST code was also limited to SD/MMC cards, mostly 2GB and below. They used to ship EVAL kits with 128MB cards, then later with 2GB cards.
Most of the cards 4GB and greater fall into the SDHC/SDXC category and have different read/write block commands. There are some 4GB card using the older SD/MMC category, these seem to target people using old navigation hardware (car info-tainment system) to hold large map files.
You want FAT32 for media >2GB, you want EXFAT for media >=32GB.
I seem to recall FAT32 having a 2GB FILE SIZE issue, at least in some target systems in prevalent use at the time, I used to span things across multiple files (datasets holding 4.7GB or 8.5GB), NTFS supported much larger files, things might have changed in the decade or so since I was deep into that, but things around 4GB are always going to give people used to 32-bit machines headaches, you really need to be 64-bit portable, you need a different mindset and refactor a lot of code.
The ceiling for the SDHC/XC cards is likely 2TB, I've used 128GB and 200GB cards on most current 0.12c and 0.13 FatFs.
A 400GB MicroSD card runs about $199
http://users.ece.utexas.edu/~valvano/EE345M/SD_Physical_Layer_Spec.pdf
