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SD Card example design using standalone?

Former Member

Hello folks,

Quick question:  Is it possible to do read/writes to an SD card using standalone (bare-metal) OS? 

I tried building a Zynq-based SDK project with a standalone BSP + xilfatfs.  However when I do so I get this error in SDK:

ERROR:EDK:3900 - issued from TCL procedure "::sw_xilfatfs_v1_00_a::xilfatfs_drc"
   line 15
   xilfatfs () - Sysace HW module not present or not accessible from this
   processor. FATfs cannot be used without this module

So my guess is, standalone OS doesn't have libraries for SD/MMC support...

I know the typical flow is to use U-boot/Linux, but my application will be *dumb* simple and U-boot/Linux would be unnecessary overhead. 

The application will simply move a file from SD card over to memory, and buffer the data via GPIOs to an external device.

Thanks,

Eddie

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  • 0

    Hi all,

    In a related post, SDIO for Windows 7 (http://www.zedboard.org/comment/3291) Kenny successfully used the SPI protocol to access the SD card on the Zedboard. Unfortunately, the link to his personal implementation seems to be dead.

    Therefore I created a sample project which implements the generic FatFs file system on the Zedboard. It is available at https://dl.dropbox.com/s/7i4ioinjkn3a7am/zynq_spi_sdc.zip. The adaptation is largely based on the files and documentation of ChaN's FatFS - Generic FAT File system http://elm-chan.org/fsw/ff/00index_e.html, in particular the AVR sample project.


    The configuration uses the Zynq GPIO pins and the Xilinx GPIO driver functions.

    Hardware configuration

    In the ZYNQ7 processing system the MIO pins 40-45 are connected to the SD card interface.
    Since these pins are programmed using the GPIO interface, it is mandatory that the SD0 peripheral in the Zynq Block Design (accessing the same pins) is not selected. On the other hand, the GPIO peripheral needs to be selected.

    Programming

    The software has been tested using Vivado 2013.2, SDK build 14.6. The sample project main.c writes a file "newfile.txt" onto the SD card and checks the result. The FatFs API-functions are described on the FatFs website http://elm-chan.org/fsw/ff/00index_e.html.

    Date and time stamps

    Since a bare metal application has no time-of-day function, the timestamp is derived from the user supplied get_fattime function. In the absence of a real-time clock, the user may specify the date and time using the FILDAT and FILTIM strings, e.g.
    #define FILDAT "20140514"
    #define FILTIM "123500"t

    Erik



  • 0 in reply to Former Member

    Hi Erik,

    Just one question!? Where to find libraries usbdisk.h, atadrive.h, sdcard.h which are used in diskio.c!? Also the function platform_init() in the main faile is not in any of the header files given!?

    Any help would be appreciated.

    Jet

  • 0 in reply to Former Member

    Hi Jet,

    Basically, you have to generate a block design containing a Zynq processor system in "Vivado". Then you export the implemented design to "Xilinx SDK". During the export a directory hw_platform_0 is created. Next you generate a new application project, e.g. hello_world. Using the defaults this will create a "hello world" program as well as a "hello_world.bsp" board support package which includes the initialization of the platform, init_platform() in the file platform.c. Next, you right-click on the source folder hello_world/src and select import -> General -> File System -> From directory. Here you select the directory with the SD card source files and import all *.h and *.c files. Remove the file helloworld.c and recompile, e.g. using Project -> Build all. From there on you can program the FPGA and run the main() program in main.c. This writes to the SB card.

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  • 0 in reply to Former Member

    Hi Jet,

    Basically, you have to generate a block design containing a Zynq processor system in "Vivado". Then you export the implemented design to "Xilinx SDK". During the export a directory hw_platform_0 is created. Next you generate a new application project, e.g. hello_world. Using the defaults this will create a "hello world" program as well as a "hello_world.bsp" board support package which includes the initialization of the platform, init_platform() in the file platform.c. Next, you right-click on the source folder hello_world/src and select import -> General -> File System -> From directory. Here you select the directory with the SD card source files and import all *.h and *.c files. Remove the file helloworld.c and recompile, e.g. using Project -> Build all. From there on you can program the FPGA and run the main() program in main.c. This writes to the SB card.

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