pcie dma sdram

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pcie dma sdram

Postby Guest » Tue Apr 29, 2014 4:24 pm

hello ,I have read your artical about pcie
and I want to use the pcie to send data FROM sdram TO cpu mem.
Does there has some demo?
Please help me~Thanks in advance
Guest
 

Re: pcie dma sdram

Postby support » Tue Apr 29, 2014 4:42 pm

Hello,

It's not clear exactly what you mean, but I suppose you meant that you want to send data from an SDRAM on the FPGA to the host.

I don't know about a demo project that does exactly that. Besides, there's always an issue of drivers that needs to be taken care of. The PCie interface needs configuration, DMA buffers need to be set up etc.

If your host runs Linux or Windows, you may want to consider Xillybus as a solution for transporting the data between the FPGA and the CPU.

Regards,
Eli
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Re: pcie dma sdram

Postby Guest » Sat May 03, 2014 3:48 am

Hello ,
Thank you for your reply.
Yes you are right,I want to send data form a sdram on FPGA to the host.
Since I'm a new to Hardware! I think it is to hard for me.My host runs windows and the FPGA is Xilinx v5lx85t.
Could you give me a link or an detailed example .Then I can use is and modify it~
Looking forword to your reply.
Guest
 

Re: pcie dma sdram

Postby support » Sat May 03, 2014 5:31 am

Hi,

As I mentioned before, I don't think there is an example design doing exactly what you want. But you could download the demo bundle for Virtex 5 at http://xillybus.com/ which will get you the PCIe communication part up and running, at least.

Regards,
Eli
support
 
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Re: pcie dma sdram

Postby Guest » Sat May 03, 2014 3:35 pm

Hello ~
Thank you for your reply again~
Now I have another question.Does the demo implement the Bus Master DMA?
Or Does the demo have a DMA?
By Colin
Guest
 

Re: pcie dma sdram

Postby support » Sat May 03, 2014 3:43 pm

Hi,

I didn't quite understand that question. Xillybus works with DMA, and hence functions as a PCIe bus master. The IP core generates TLP packets that request read and write operations on the bus -- this is how DMA is done on PCIe. So it's not clear what you meant with "implement the DMA" vs. "have DMA".

I suggest downloading the demo bundle and try it out. It's really simple.

Regards,
Eli
support
 
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Joined: Tue Apr 24, 2012 3:46 pm

Re: pcie dma sdram

Postby Guest » Sat May 03, 2014 4:01 pm

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.
Guest
 

Re: pcie dma sdram

Postby support » Sat May 03, 2014 4:15 pm

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
support
 
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Joined: Tue Apr 24, 2012 3:46 pm

Re: pcie dma sdram

Postby Guest » Sun May 04, 2014 9:32 am

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~
Guest
 

Re: pcie dma sdram

Postby support » Sun May 04, 2014 10:46 am

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
support
 
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Joined: Tue Apr 24, 2012 3:46 pm

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