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microSD Card Reader & P8X32A — Parallax Forums

microSD Card Reader & P8X32A

megaionstormmegaionstorm Posts: 178
edited 2011-08-24 05:55 in Propeller 1
I have the following microSD Card Reader.
http://www.komputer.de/zen/index.php?main_page=product_info&cPath=22&products_id=122

How must i connect it to a breadboard P8X32A for spi ?

Comments

  • RaymanRayman Posts: 14,998
    edited 2011-08-10 11:43
    It's not any different from a regular, full size SD card interface. If you look in OBEX, you can find a few drivers there. I believe the driver files show how to connect things...

    Look for "FRSW" in OBEX and there's also a driver from from Kye there too.

    You could also take a look at the GadgetGangster.com "Propeller Platform USB" and see how they hooked it up...
  • megaionstormmegaionstorm Posts: 178
    edited 2011-08-10 12:24
    My sd card reader has no CD connection.

    Is this a problem ?
  • Bob Lawrence (VE1RLL)Bob Lawrence (VE1RLL) Posts: 1,720
    edited 2011-08-10 13:48
    Try the this (the required pinouts are shown)

    Tutorial: Writing to SD Cards
    http://gadgetgangster.com/tutorials.html

    Reading SD Cards
    http://gadgetgangster.com/tutorials/414
  • Cluso99Cluso99 Posts: 18,069
    edited 2011-08-10 14:32
    A number of the software drivers in the obex have the pinout connections shown at the beginning of the source. You will need to view them in PropTool to see the schematic due to the special font used. The connection is simple, 4 pins and at least a 10K pullup on -CS, plus you should have a decoupling/bulk capacitor on the connector power pins.
  • prof_brainoprof_braino Posts: 4,313
    edited 2011-08-10 15:01
    This page
    http://code.google.com/p/propforth/wiki/PropToSDconnection
    has some information for the physical connection for SD to the prop.

    If you use a microSD and micro to full size SD adapter, you solder to the adapter and use it as the SD slot

    Though the page is in the context of propforth, it should apply to any SD card connection, just change the pin numbers per your configuration
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2011-08-10 23:46
    As I recall, CD is connected to the metal case of the card holder. Ideally, it is grounded to provide static shielding. I think the Parallax micro SD card reader even has a 10,000 ohm pull up provided for it as an alternative. But that seems a bit odd to me.

    Take a look at the Parallax document for comparison to yours. Various vendors have different ideas about the need for pullups.f

    Connecting CD may be trivial.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2011-08-10 23:58
    Correction about CD, it isn't a ground.

    CD stands for Card Detect. You can get by without it, but you might have to adapt your SPIN code.

    This is NOT for the Lock on the card to make it Read Only (I've corrected this post).

    The feature is not critical to use SDcards.

    On the other hand, some very large size SDcard have CD/DATA3 - a shared function. That may be a problem. But since smaller SDCards (less than 2Gbytes) are really all you need for the Propeller, using small cards would avoid further issues.

    Parallax's Micro SD card reader includes ALL the lines and provides ALL the pullup resistors. So it is a better option.
  • ejwongejwong Posts: 21
    edited 2011-08-24 03:23
    sorry for the bump, saw this thread...

    what would you need to do if you needed to use >4gb micro SD cards? well i`ll leave the details as to why i`d need such a big storage.
  • caskazcaskaz Posts: 957
    edited 2011-08-24 04:53
    Hi.

    Please see attached photo.
    This microSD card adaptor has 10pin.
    I installed it to protoboard. I re-used card-reader(junk parts).
    Every microSD card adaptor terminal is same.
    But some parts has no CD-terminal.
    Signal direction
    P0 --> microSD
    P1 --> microSD
    P2 --> microSD
    P3 <-- microSD

    microSD adaptor terminal
    From upward;
    DAT1/IRQ
    Not Used
    DAT0/DO
    P3(Green wire) with pull-up resistor(10kohm)
    Vss
    Gnd(Gray wire)
    CLK
    P2(Blue wire) with pull-up resistor(10kohm)
    Vdd
    3.3V(Red wire)
    CMD/DI
    P1(White wire) with pull-up resistor(10kohm)
    DAT3/CS
    P0((Black wire) with pull-up resistor(10kohm)
    DAT2
    Not Used
    CD(Card Detect)
    Not Used
    CD(Card Detect)
    Not Used
    dscn8879.jpg
    1024 x 768 - 96K
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2011-08-24 05:55
    From my experience with SD cards for many years now I know to use the CS line without a pull-up as that is the method used to detect a card. Essentially the SD card itself has a pull-up on this line and by simply driving the line low and releasing it back to an input you can tell if a card is connected. I've tracked it down in the spec just to prove it too and you will find it hiding in the SD Bus Mode Pad Definition which is the power-up condition of the card. At power-up the CS pin is actually the "Card Detect/Data Line [Bit 3]".
    3) After power up, this line is input with 50Kohm(+/-20Kohm) pull-up (can be used for card detection or SPI mode selection). The pull-up may be disconnected by the user, during regular data transfer, with SET_CLR_CARD_DETECT (ACMD42) command.
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