Re: [Discuss-gnuradio] The coming deluge of CPU cycles

[Alex Gross]

The cost for the Xilinx PCI Express LogiCORE was $25,000, the last time 
I looked. It may have dropped to $20,000. It can be used on a Virtex 2P 
(for x1 and x4) or a Virtex 4 (for x1, x4, x8) operation.

The alternative is to use a PCIe PHY chip and then supply a PCIe Link 
Layer / Transaction Layer softcore. Xilinx offers this solution for x1, 
using a Philips PHY. I am not sure of the cost, but it's probably in the 
neighborhood of $5k.

While PCI Express is desirable for bandwidth, it is cost-prohibitive and 
somewhat difficult to implement for both PCB layout and FPGA code 
generation. It is preferable to PCI-X, however, since it is compatible 
with a wide variety of new systems.

Since software radio is often used in embedded environments, it seems to 
me that the interface chosen must support the most common interfaces 
available today. Thus, a 10/100/1000 Ethernet interface would enable to 
software radio to be plugged in to a variety of systems, including 
laptops, embedded systems, and legacy systems.

Remember that if you want the bandwidth of PCI Express, you can always 
use multiple SDRs, a Gigabit Ethernet switch, and multiple NICs in the 
host PC. This would still be significantly cheaper than the cost 
associated with a PCI Express license. Of course, this same argument can 
be applied to USB.

--Alex



Daniel O'Connor wrote:
> I dunno how much PCI-e soft cores cost, but it looks like one of the "easier" 
> routes to doing PCI-e :( You need an interface chip (BGA..) unless you're 
> using a Virtex-4 though (dunno what that translates to in Altera-land)