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General • Re: What percentage of MicroSD card supports SPI and FatFS

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It is clearly stated in SD Specifications Physical Layer Simplified Specification and other documents that SDUC cards larger than 2 TB do not support SPI mode.
My PDF reader seems to not support their documents so I can't check what it says, but I thought all SD Cards had to support SPI for initial access and configuration. Maybe it's 'doesn't need to, and shouldn't, support SPI after that'. Otherwise it's how to see how a host could support more and less than 2 TB on the same socket, but maybe there's some 'if it doesn't respond' approach.
It is because the >2TB cards need 38-bit LBA to address all of it. SPI mode can only do 32-bit LBA. SD assoc considers SPI mode to be legacy so it wasn't extended.

Statistics: Posted by trejan — Wed Jul 10, 2024 12:45 pm



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