pcie dma sdram

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Re: pcie dma sdram

Post by support »

Hi,

The programming guides explain the principles behind the sample C programs. Needless to say, working with Xillybus requires mastering C programming and FPGA design at some level, so if there are some gaps to fill, maybe start with that.

Regards,
Eli

Re: pcie dma sdram

Post by Guest »

Hi eli
Thank you for your reply~I will try to learn more form the documentation.
I still don't quite understand the differences of those 6 files (eg. memread.c streamread.c fifo.c)
If I want to realize my function ,then which file should I connect?
I don't know if you could understand me...
By Colin

Re: pcie dma sdram

Post by support »

Hi,

The issue with mem_8 is that it's a synchronous interface, and it has 8 bits width. That makes it slow.

I suggest that you'll take a look at the documentation and also try to interact with Xillybus with your own logic. FPGA design is not a simple field, and it looks like there's a quite a way for you to go. At a minimum, you should be able to master synchronous RTL design, and understand how to interact with a standard FIFO. Once you'll master FPGA design at a reasonable level, it will be quite clear to you how to get on.

Regards,
Eli

Re: pcie dma sdram

Post by Guest »

Hi~
Thank you for your reply
I'm sorry to ask such a low-level issues :D
You say that the mem_8 interface is slow~Then if I want to read from SDRAM or send DATA from SDRAM to the PC'mem.
What part should I modify?Do you have any suggestion?
This problem have trouble me monthes.
By Colin

Re: pcie dma sdram

Post by support »

Hi,

It took me some time to figure out what happened there. Please don't click hexdump.exe and type the text. Rather, open a DOS window and type the hexdump command line. What you did was feeding the hexdump program with the string you typed in, so it returns the ASCII representation of what you typed (as 16 bit words). Xillybus was never involved here.

And by the way, don't type the ">" sign. It's shown in the docs to represent the DOS prompt.

Regards,
Eli

Re: pcie dma sdram

Post by Guest »

Hi
I click the hexdump.exe in the unixutils package and type the command > hexdump -C -v -n 32 \\.\xillybus_mem_8
the result is
------------------------------------------------------------------
0000000 203e 6568 6478 6d75 2070 432d 2d20 2076
0000010 6e2d 3320 2032 5c5c 5c2e 6978 6c6c 6279
------------------------------------------------------------------
then in the SDK I type the command > memwrite \\.\xillybus_mem_8 3 170
After that I opened a new hexdump.exe and type > hexdump -C -v -n 32 \\.\xillybus_mem_8
But it come out the same result as before. I can't see any change like the example.
And I don't know the command about the hexdump.
By the way if the xillybus_mem_8 is too slow what other method could I use?
Colin

Re: pcie dma sdram

Post by support »

Hi,

Could you please detail the session you had? What exactly went wrong?

Besides, I'd like to point out that the mem_8 interface is very slow, and is intended for setting up registers etc. Since your original intention was to read from SDRAM, I doubt if you'll find it very useful anyhow.

Regards,
Eli

Re: pcie dma sdram

Post by Guest »

Hi eli,
Thank you for your reply~You mean the xillybus have package the dma operation,right?
Today I try the project on my board (V5lx85t) and It works well~ :D
The computer(win 7) could check the device and I install the driver successful.
However I have meet another question~
when I use the > streamread \\.\xillybus_read_8 or > streamwrite \\.\xillybus_read_8command It word just
like the DOC said.
But when I use the > hexdump -C -v -n 32 \\.\xillybus_mem_8 I meet a problem
the data doesn't change to aa when I type the command > memwrite \\.\xillybus_mem_8 3 170
Is there a detail step about what command I should use in what tool?
Thanks in advance~

Re: pcie dma sdram

Post by support »

Hi,

OK, I now understand what you asked. Xillybus puts an extra layer around the DMA operation, to make it easier to use. To the user, a simple stream of data between the FPGA and a computer program is presented.

So if you need the communication itself, Xillybus can be handy for you. If you want to learn how DMA works from this, I doubt if it will help you: Xillybus hides all those details, and presents a friendlier interface instead.

Regards,
Eli

Re: pcie dma sdram

Post by Guest »

Hi ~
Have you ever see the XAPP1052 or XAPP859 provided by XILINX.
In the XAPP1052 we can see the DMA HDL code.But in this demo I didn't find any thing to operate or start the DMA .
there are only two fifo and a IP core . I have see the IP core ,It is just like the pcie core generate by the ISE.
I am a new to this...maybe I am wrong in understanding the pcie and the demo.
I will try it tomorrow on my board.
Thank you for your quick reply.You are really nice~I hope I can learn more about pcie from you~ :D
Sorry for my bad english since I'm a student from Chine.
Good wishes.
By Colin.

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