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Re: from PCI framegrabber to PCI raid
At 06:03 AM 4/4/00 , you wrote:
>Hello,
>
>I have an IDE RAID which is connected via the PCI bus.
>I have also 2 framegrabbers. I'd like to capture real time video (2 x
>27Mb/s) to my RAID (max transferrate ~ 70 MB/s).
>
>I haven't tried it yet. But I suppose it should work.
>
>Is it however possible to move the video stream directly to the raid
>without passing the system memory ?
>Because if you use the PCI bus to pass the RAM and vice versa than the
>bandwith of the PCI bus is divided in half.
>
>
>Best Regards,
>
>Geert
I worked on exactly this problem a year or two ago. One advantage we had
was that we designed our own input/output board and could modify operation
to suit the bus and RAID board.
First, the best way for you to reach your speed requirements is to transfer
directly from the framegrabber board to the RAID board. You can never reach
the full 133 MB/s and trying to get 54 is a lot harder than 27 MB/s. Keep
your burst sizes up as much as you can, but that will be controlled by the
bus master (PCI RAID controller).
What RAID adaptor are you using? We used one from DPT but I can't tell you
what model it was. We did have to make quite a few adjustments to get our
board to work with it since, even though we were paying NRE to have the
RAID controller ported to the compact PCI bus, DPT would not change the way
it operated. They did not have much insight into the embedded world at that
time. A quick look at their website shows some standard compact PCI
products. So maybe that has changed some.
I would be happy to discuss this further with you either in the PCI
maillist or by email. I don't know how interesting this is to the rest of
the group. Let me know.
Rick Collins
rick.collins@arius.com
Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design
Arius http://www.arius.com
4 King Ave 301-682-7772 Voice
Frederick, MD 21701-3110 301-682-7666 FAX