SD Card example design using standalone?

Eddie,

Here is a great thread from the Xilinx forums talking about doing exactly what you would like to do (except on a MicroBlaze processor, however the flow will be very similar).

http://forums.xilinx.com/t5/EDK-and-Platform-Studio/XPS-SPI-Core-and-SD-Card/td-p/173580

Let me know if that helps, and if not we can go through it step by step.

Hi Eddie,

Tim makes a great suggestion above.

I just wanted to add that using only U-Boot may also be an option to look at as well.  There are mechanisms built into U-Boot for reading FAT file systems.

Another option to look at, if your code is compact enough, is the FSBL.  There are mechanisms in FSBL BSP for reading from the SD card FAT file system.  Plus you have the source code available to you for modification.

Going to either of these routes will give you some nice APIs to work with but still keep you at a very low level of complexity when it comes to writing into the PL hardware address space.

Regards,

-Kevin

Thank you both folks.  I'll review and get back to the thread with my findings.  Thanks again!

Eddie

I'm currently working on SDCard access for my real-time operating system, which is based on FreeRTOS. Unfortunately there seems to be little to no support from Xilinx for doing this.

The other problem is that there really isn't much useful information for handling SD cards using the SDIO protocol. (SPI mode there is a lot of documentation from hobbyists etc, as seen from the provided link).

There are the SDHCI simplified specs, which are useful, but don't seem to provide all the information you need.

Anyway, fortunately there are a few reference drivers you can look at for help.

Obviously there's linux, which provides the most fully featured driver possible, and its pretty complex. As mentioned earlier I'd avoid this unless you have to.

Also the raspberrypi is using an SDHCI controller, similar to that in Zynq.

See:
https://github.com/jameswalmsley/rpi-boot/blob/master/emmc.c

They seem to have full read access to the card, and from that write access should be trivial.

In anycase, I shall have my fully featured driver ready in 2/3 weeks from now (hopefully). So checkout:
https://github.com/jameswalmsley/bitthunder/

The source will be found under: drivers/mmc/host/sdhci.c

Hope this helps someone.

James

Hi Guys,

I mentioned I was working on an SDCard driver.. Well its now working.

See http://github.com/jameswalmsley/bitthunder/
Look under drivers/mmc/sdcard.c and drivers/mmc/host/sdhci.c

Also the Xilinx FSBL provides a rather primitive driver example, but
should help anyone trying to write their own driver.

Hope this helps,

James

Hi James. I saw your website, it looks great.
I am using a V707 Virtex 7 board with Xilinx's XPS with an AXI bus, and I'm attempting to access the SD card.
Do you know if your code would work with my project, and if so, how I might go about implementing this?
My partner and I are both new to XPS/FPGA development, and our research professor assigned us this project, but we're pretty much clueless :P.
Chase

Hi all! I'm working on SD driver for eCos and have problems with write operation. I've created this topic on Xilinx forum, but still didn't get any reasonable answer

http://forums.xilinx.com/t5/Embedded-Development-Tools/Zynq-SD-write-operation/m-p/314123

I investigate your version of SD driver, but didn't find write operation too(( I just found return 0. Did you work on SD write op for Zynq ?

I am also working on the SD write, do you have already find the solutions for this? Thanks!

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.

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