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Launchpad and SD card

A D
Intellectual 400 points
Other Parts Discussed in Thread: CC3200

It doesn't look like the Launchpad as made the SD/MMC host interface available.

I've seen http://doc.43oh.com/The_Card_Reader_SDCard_BoosterPack, but that BoosterPack seems to take a different approach (SPI).

Is it possible to use but a Micro SD breakout board with the Launchpad?

  • 0
    Intellectual 400 points

    The SD Card BoosterPack isn't available anymore.

    I've bought a Micro SD Card breakout board.

    Can someone please enlighten me on how to connect it to the CC3200 LaunchPad?

  • 0 in reply to A D
    TI__Expert 6700 points

    Hi,

    Apologies for delayed response. Where you able to make you setup up and working ?

    You need to make the connections as shown in docs/examples/CC32xx SDHost.pdf.

    Can you post here which Micro SD Breakout board you are using?

    Thanks and Regards,

    Praveen

  • 0 in reply to Praveen Kumar N
    Intellectual 400 points

    Thank you for replying.

    I would tend to try this prototype board. But I can't find MOSI/MISO on the LaunchPad. How would I connect the two?

    I'm not a hardware guy, so I wouldn't know of any resistor/capacitor to apply. I would just connect both boards directly. Would that be a problem?

    I don't want to consult hardware designers for the prototype because it would be too expensive to hire them at this stage. (I'll consult them later when it comes to production, however.)

    Your answer is very much appreciated. Perhaps it'll help others facing the same challenge, too.

  • 0 in reply to A D
    TI__Expert 6700 points

    Hi,

    SD Cards support two mode SPI and SD mode and the card pin are multi-functional. The marking your board are for SPI mode.


    I have expanded the table given in the pdf to have the SPI signal names also (other signals you can ignore). You can connect it as shown below

    LP Pin

    SD Card Pin

    Signal Name

    SPI Signal Names

    P2.3

    2

    CMD

    MOSI

    P3.2

    3

    GND/Vss

    GND

    P1.1

    4

    Vcc/Vdd

    Vcc

    P2.6

    5

    CLK

    SCLK

    P2.1

    6

    Vss

    GND

    P2.7

    7

    DAT0

    MISO

    You need to make sure all your connection are firm (no loose connections) and also keep the connecting wires as short as possible to ensure stable operation.

    Thanks and Regards,

    Praveen

  • 0 in reply to Praveen Kumar N
    Intellectual 400 points

    Excellent!

    Thank you Praveen. You've been a great help!

  • 0 in reply to A D
    Intellectual 400 points

    After examining the table you have given I'm not sure whether the information is correct.

    According to your table, P2.6 is CLK, but according to the CC3200 LaunchPad user's guide, P2.6 is SPI_DOUT.

    Can you please verify?

    Your answer is appreciated.

  • 0 in reply to A D
    TI__Expert 6700 points

    Hi,

    On CC3200, most of the pins can have multiple functionality (or modes). Pin 7 (P2.6 on header ) is one such pin. It can be SPI_DOUT or SDHOST_CLK based on software configurable internal muxes. The above image just shows one set of such possible configuration.

    To see the complete list of pins and their modes please refer to Table 16-7. Pin Multiplexing in TRM.

    Thanks and Regards,

    Praveen

  • 0 in reply to Praveen Kumar N
    Intellectual 400 points

    OK ... I'm a bit baffled now.

    So if I wanted to connect other SPI devices, too, wouldn't I need to repetitively switch modes in order to address the SD card and the SPI devices then?

    There is no chip select (SS) pin on the SD Card connector. How would I disambiguate? Would I connect one of the LaunchPad's GPIOs to Vcc of the SD card connector in order to emulate SS?

  • 0 in reply to A D
    TI__Expert 6700 points

    Hi,

    No you don't need to repetitively switch pin modes. First you need to decide on what functionality you need on which set of pins. For e.g. you need SPI along with SDHost interface

    There are some recommended pin combinations given in the TRM. Please refer to Table 16-9. Pin Groups for SPI and Table 16-10. Pin Groups for SD-Card I/F


    Lets say we choose first group for SPI i.e Pins 5(CLK), 6(MISO), 7(MOSI) and 8(CS).

    Now from second table for SD Card, again we have two potions but we can't use Group #2 as some of the pins we have assigned to SPI. So we will choose Group #1 i.e. 1(CLK), 2(CMD) and 64(DATA)


    Now you have exclusive set of pins for both SPI and SDHost interface.

    You can download the TI pin mux tool for CC3200 to help you out with choosing the pins and generate the pinconfig.c file.


    Regarding SS for SD Card, you shouldn't use GPIOs to power SD Card, the power to the card should be kept stable.

    Note : Based on the set of pins you assign to each interface you might have to edit the SDK examples to make them work on your setup.

    Does this answers your question ?

    Thanks and Regards,

    Praveen

  • 0 in reply to Praveen Kumar N
    Intellectual 400 points

    Thank you, Praveen, for your valuable help.

    I begin to apprehend. But it still seems a long learing courve to climb to me.

    Thanks,
    Axel