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SD Card Chip/Emulator

Discussion in 'Datasheets, Manuals and Component Identification' started by KeithM, Apr 21, 2016.

  1. KeithM

    KeithM

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    Nov 3, 2015
    Hi,

    I'm wonder if anyone knows if such an IC exists that is basically the chip inside an SD card?

    So basically by using it on a board, you could replace an SD card slot with it, since it's essentially an SD card.

    I have a unique project idea in mind where I would use something like this, but I wasn't able to find anything by Googling.

    Thanks for the help!
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    The memory chip inside is a FLASH memory (NAND FLASH to be precise).
    Plus a controler to provide the necessary interface.

    It may be easier to build a complete SD card into your device and use the SD-card's SPI interface for reading and writing data into the card's file system.
     
    KeithM likes this.
  3. KeithM

    KeithM

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    Nov 3, 2015
    Thanks, I wasn't sure what was in them before :)

    Do you know what I should search for to get more information on SD controller chips? I've been googling and searching on digikey with no avail, I just keep getting get normal SD cards, not the chips inside them.

    I've been looking on the SD card association's site, but I can't find anything there on the technology either https://www.sdcard.org/index.html
     
    Last edited: Apr 21, 2016
  4. Alec_t

    Alec_t

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    Jul 7, 2015
    I'm not surprised. Isn't the tech proprietary?
     
  5. KeithM

    KeithM

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    Nov 3, 2015
    From what I've read it sounds like it is, but I'd be surprised if there isn't an IC somewhere that's compatable
     
    Last edited: Apr 21, 2016
  6. Harald Kapp

    Harald Kapp Moderator Moderator

    9,303
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    Nov 17, 2011
    As far as I know you ned to signa a nondisclosure agreement for getting access to the full SD card specification. The one things that is comparatively freely available is the spec of the SPI interface. This is comaratively slow. Whether you can use it depends on your application.
    If you need to access data fast, you'd have to sign that agreement (which surely isn't for free either) or use another technology.
    You can use a bare FLASH chip, but then you'll have to manage the programing and in the case of NAND FLASh the so called wear leveling yourself. Or use NOR FLASH, not so much capacity and higher price, but much more reliable than NAND FLASH. Typically wear leveling is not absolutely required with NOR FLASH, stil you need to manage the programing algorithm(s) yourself.

    Or use a CompactFlash (cf) card. These come at not so high capacity as SD cards, but are probably easier to handle. Specs still come at 100$, but you can find instructions on using a cf card on e.g. PICs and AVRs on the internet.

    Perhaps it were helpful if you didn't ask specificaly for the sd card, but if you were to show us the application problem you want to solve. We might have other ideas ;)
     
  7. Solidus

    Solidus

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    Jun 19, 2011
    Here you can see a full-size SD card with discrete flash and controllers. Maybe that part number is a start?

    Seeing as microSD cards have really taken ground in the past few years, it's probable (to say the least) that the controller that provides glue logic and wear leveling for microSDs is on-die (that is, integrated on silicon) with the FGMOS data area. Vendors are likely to "roll their own" here; while the SD specs are available, the specifics of those implementations are not and probably vary. The controller is designed so that the SD data interface is the only means to interact with it; I've seen potential security vulnerabilities talked about that are created from potentially subverting that controller's firmware. Those sorts of implications make it much more unlikely that a manufacturer will disclose internal behaviors of their controllers.

    This bodes well for you, though, because it means you wouldn't need the information on a specific implementation; if you designed a small microcontroller to handle wear leveling and flash access via either the SD or SPI protocols, you will have effectively designed the proper SD controller. This is a sort of "duck test"-style argument - if it implements flash, the SD or SD/SPI protocols, and performs the proper data manipulations, then it is an SD controller.

    As an expansion on Harald's notes toward CompactFlash above, original Type-I and Type-II CF cards use a large subset of the original (P)ATA/IDE data protocol, which makes them for the most part identical from an electrical and software interface perspective to non-SATA hard disks (in fact, many adapters exist to allow fitting of a CF card as a small hard disk). Current capacities are up to 512GB for CF cards, and the ATA specs are freely available (ATA-6 here).
     
  8. KeithM

    KeithM

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    Nov 3, 2015
    I think I have all the information now I need to get a started on my project :) Thanks guys!

    I'm probably going to just go with an SD card in a socket, I was mainly asking this because I wanted to see if I could save space and cost on my design by putting the actual SD card electronics on the board instead of an actual card ;)
     
  9. Solidus

    Solidus

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    Jun 19, 2011
    Look for Micron or Spansion serial NOR flash modules. These are available in SOP, BGA, or DFN SMT footprints and so are usually smaller than microSD cards. The density is less (256MB is the maximum for Micron parts, haven't checked Spansion), but if you're looking for storage of information that needs to "stay with the board" so to speak, they're probably worth a look.

    Depending on your needs (type of data stored), you might not require any sort of wear leveling provisions and the container format that stores the data on the flash could range in complexity from a simple C struct to a full filesystem.
     
    KeithM likes this.
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