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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

    I was working on this topic for the last week and I have a solution. Not perfect, but Iu2019m able to write and read from SD card and use the FATFS. Since I'm working on proprietary firmware I can't simply give you the code, but I can help:
    The FSBL app from Xilinx implements Chanu2019s FAT FS in readonly mode. This is good start point.
    You will have to update ffconf to fill your needs.
    Update mmm.c :
    u2022tadd definitions for CMD24 (single write) and CMD25 (multiwrite)
    u2022tIn the make_command  function update CMD24 & CMD25 (both R1 resposes and remember, you are sending DATA)
    u2022tIn send_cmd only CMD18 is implemented. Change if/else to switch and add CMD24/25 cases. Take a look on ug585/appendix b.27. Transfer command register is explained in detail.
    u2022tThere is a bug in disk_status function. Write_Protect_Switch is 0 when write protected, not 1! Change it. Take a look on ug585/b.27 Present_State register, if you donu2019t understand.
    u2022tChange disk_ioctl. STM32F4xx_SDIO_Example was great help.
    u2022tCreate disk_write function. Again STM32F4xx_SDIO_Example shows how to do it.
    Guys Iu2019m sorry, but I simply canu2019t give you codes. Hope that this helps.

  • 0 in reply to Former Member

    Hi thank you for your step by step instructions.
    Could you give me maybe a keyword or an additional hint what to look at in STM32F4xx_SDIO_Example.

    I used the FSBL template as a start. After removing most of the code and include files ADMA2 file transfer suddenly stopped working.

    After a while I figured that I have to call the InitPcap(void) function in order to fix the problem.

    int InitPcap(void)
    {
    tXDcfg_Config *ConfigPtr;
    tint Status = XST_SUCCESS;
    tDcfgInstPtr = &DcfgInstance;

    t/*
    t * Initialize the Device Configuration Interface driver.
    t */
    tConfigPtr = XDcfg_LookupConfig(DCFG_DEVICE_ID);

    tStatus = XDcfg_CfgInitialize(DcfgInstPtr, ConfigPtr,
    tttttConfigPtr->BaseAddr);
    tif (Status != XST_SUCCESS) {
    ttreturn XST_FAILURE;
    t}

    treturn XST_SUCCESS;
    }

    Can someone please explain why this is needed? The communication/configuration to and from the card worked fine (responses in accordance with sdc physical spec etc.) but the ADMA2 transfer did not.

    Thanks in advance

    regards,
    Christian

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  • 0 in reply to Former Member

    Hi thank you for your step by step instructions.
    Could you give me maybe a keyword or an additional hint what to look at in STM32F4xx_SDIO_Example.

    I used the FSBL template as a start. After removing most of the code and include files ADMA2 file transfer suddenly stopped working.

    After a while I figured that I have to call the InitPcap(void) function in order to fix the problem.

    int InitPcap(void)
    {
    tXDcfg_Config *ConfigPtr;
    tint Status = XST_SUCCESS;
    tDcfgInstPtr = &DcfgInstance;

    t/*
    t * Initialize the Device Configuration Interface driver.
    t */
    tConfigPtr = XDcfg_LookupConfig(DCFG_DEVICE_ID);

    tStatus = XDcfg_CfgInitialize(DcfgInstPtr, ConfigPtr,
    tttttConfigPtr->BaseAddr);
    tif (Status != XST_SUCCESS) {
    ttreturn XST_FAILURE;
    t}

    treturn XST_SUCCESS;
    }

    Can someone please explain why this is needed? The communication/configuration to and from the card worked fine (responses in accordance with sdc physical spec etc.) but the ADMA2 transfer did not.

    Thanks in advance

    regards,
    Christian

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