On Wed, Mar 25, 2009 at 08:09:02AM -0400, Jim Donelson wrote: > -If we are talking about regular SD cards, there is no internal wear > leveling. > It is up to the driver to do that.
Well it's up to the controller to do that perhaps. Given that most people seem t use usb adapters for SD cards, the OS simply sees a USB storage device and runs FAT or some other filesystem on it. Certainly no wear leveling done in software. Perhaps the usb adapter does it. > -It take can take up to something like 40ms to write a single sector, as an > entire block must be erased and re-written.For a given card, it is indeed > specified. Cards have different speeds, but that that is available from the > internal config data of the card and the mfg specs - which are published. > The card indicated via status when it is done (of course only the driver is > going to see that) > > -As for "low level formatting", huh? Unlike a hard drive, a sector is a > sector. While writing a stand alone driver, I scrambled the data plenty of > times, and reformatting with windows "format" never failed to work. You > might be assuming it is like CF, which does emulate a hard drive. Certainly CF cards do have to do any wear leveling in the card since they present IDE to the host system. > You should get the spec from the SD people for 1.1 and read (parts of) it. I > think your issues are with the the OS/Driver and the way you are doing > things. Used correctly, SD cards will work fine. > Unless you have many files open, it should complete quickly. Well there might be some really bad SD cards out there too. -- Len Sorensen _______________________________________________ uClinux-dev mailing list [email protected] http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by [email protected] To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
