Messages in this thread | | | Date | Tue, 15 Apr 2008 19:23:16 -0400 (EDT) | From | Daniel Barkalow <> | Subject | Re: Problem: non-SDHC 2GB SD cards are unreadable |
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On Mon, 14 Apr 2008, H. Peter Anvin wrote:
> Arnd Bergmann wrote: > > > > On the contrary, the USB card readers go through a lot of effort to > > make the card look like a SCSI device, and many of these implementations > > are buggy in some way. SD cards are defined to have 512 byte sectors, while > > USB mass storage can theoretically have a different sector size. Of course > > any other size than 512 bytes is likely to break some code, which you have > > experienced. > > > > Actually, I believe 2 GB (non-SDHC) *only* have 1024 byte sectors.
The most easily available SD documentation is the SanDisk product manual (1.9) and the cards it documents only support 512-byte blocks ("The default block length is as specified in the CSD (512 bytes). A set block length of less than 512 bytes will cause a write error. The only valid set block length is 512 bytes. CMD16 is not manditory if the default is accepted.")
Somewhat unsurprisingly, not all manufacturers took into account the possibility that a card would use a different block size than what all of the cards of the time used.
-Daniel *This .sig left intentionally blank*
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