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SD card's and Micro SD card connections — Parallax Forums

SD card's and Micro SD card connections

James LongJames Long Posts: 1,181
edited 2009-03-06 17:32 in General Discussion
Just because I botched the first try, I figured I would get some guru's to converse the issue of connecting a Micro SD card to the propeller.

I tried with a PCB and the result was less than optimum.

Anyone want to discuss the correct connection of a Micro SD card?

Thanks,

James L

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James L
Partner/Designer

Lil Brother SMT Assembly Services

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-03-03 05:18
    I used the SparkFun breakout board for the micro-SD card socket. The connections are the same as that for the standard SD card except that there's only DO, Gnd, Clk, Vcc, DI, and CS. There's also a CD (card detect), but I don't use it.
  • James LongJames Long Posts: 1,181
    edited 2009-03-03 05:24
    Mike,

    The pin out for a micro SD card is somewhat different than with a regular size SD card. The Micro card only has 8 pins, where a standard one has 9. The locations for the different items (vdd, vss, etc) are a little different.

    That is the root of the confusion.

    James L

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    James L
    Partner/Designer

    Lil Brother SMT Assembly Services
  • James LongJames Long Posts: 1,181
    edited 2009-03-03 05:29
    Mike,

    But the schematic at Spark Fun does solve the problem.

    Thanks for the reference.

    James L

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    James L
    Partner/Designer

    Lil Brother SMT Assembly Services
  • QuattroRS4QuattroRS4 Posts: 916
    edited 2009-03-03 10:32
    not all microSD cards support SPI mode ..This caught me out for a bit ..

    see here
    en.wikipedia.org/wiki/Secure_Digital_card

    Regards,
    John Twomey

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  • Cluso99Cluso99 Posts: 18,066
    edited 2009-03-04 10:39
    QuattroRS4: I have noticed this too, but from what I have been able to determine, the manufacturers seem to always support this anyway. So which ones didn't work please?

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  • QuattroRS4QuattroRS4 Posts: 916
    edited 2009-03-04 18:32
    Cluso99,
    Unfortunately it was an unbranded 4GB cheapie - FAT16 formatted - worked fine on PC .. but not using SPI. I'll see if I can find it and take a photo and check if it has any defining markings at all. I then bought a 4GB sandisk and it worked flawlessly .. It was only after the 'cheapie' that I researched reasons as to why it didn't work and found that many others had similar issues - and usually with unbranded cheapies!. I believe that most manufactures still support it (in the smaller memory units anyway).

    Regards,
    John

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    'Necessity is the mother of invention'

    Those who can, do.Those who can’t, teach.
  • Mike GreenMike Green Posts: 23,101
    edited 2009-03-04 19:15
    FAT16 doesn't reliably support storage media larger than 2GB.· I would stay away from 4GB cards.· I don't remember whether Rokicki's routines work with 4GB media.· Some older Windows, Linux,·and MacOS versions don't support it.
  • QuattroRS4QuattroRS4 Posts: 916
    edited 2009-03-04 21:18
    Mike,
    That is true but they can be partitioned .. As Tomas Rokiki's Routines work up to 2GB

    Regards,
    John
    Tomas Rokiki's - 'Readme' File said...
    The following table shows the range of cluster sizes you can select in
    XP when formatting in order to guarantee a FAT16 volume. The number
    of clusters will be the size of the card divided by the cluster size
    (approximately).

    min max
    4M 512 512
    8M 512 1K
    16M 512 2K
    32M 512 4K
    64M 1K 8K
    128M 2K 16K
    256M 4K 32K
    512M 8K 32K
    1G 16K 32K
    2G 32K 32K

    If you do not select the right cluster size, your volume may be formatted
    in FAT12 or FAT32, neither of which is supported by this code.

    FAT16 does not support volumes greater than 4G. If you must use a 4G
    card, you will have to ensure the first volume is 2G or less, and this
    code will only mount that first volume. In reality this is not much of
    an issue, because this code only supports the SD protocol, and cards
    of 4G or larger require the new SDHC protocol. (I have no way at this
    time to know if an SDHC card will default to the SD protocol for the
    first portion of the card.)
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    'Necessity is the mother of invention'

    Those who can, do.Those who can’t, teach.

    Post Edited (QuattroRS4) : 3/4/2009 9:29:06 PM GMT
  • JavalinJavalin Posts: 892
    edited 2009-03-06 17:32
    above 2GB you get the SHDC cards which don't work with SPI / SD card protocol's so I am told.
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