Re: [Discuss-gnuradio] re: Low cost hardware option

[Marcus D. Leech]

On 01/12/2011 10:01 PM, Brian Padalino wrote:
>
> Altera Cyclone IV EP4CGX15 FPGA, Analog Devices AD9861 MxFE, USB2
> microcontroller (for reprogramming the FPGA) in an ExpressCard/34
> format.  The FPGA has a hard PCIe 1.1 x1 lane with a hard IP core for
> PCIe connectivity.  The PCIe interface has an extremely low latency
> and pretty high throughput - ~200MB/sec full duplex (after overhead
> and whatnot).  The FPGA would be mostly empty since the PCIe core is
> hard.  If the F169 package is used, it should be compatible with up to
> a EP4CGX30 which would give 80 18x18 multipliers and over 1Mbit of
> embedded memory.  The ExpressCard format can fit into desktop PC's
> with simple and cheap adapters, or into laptops which have ExpressCard
> slots.
>
> ExpressCard has both an x1 PCIe connection as well as a USB 2.0
> connection.  I imagine a small USB 2.0 micro used for FPGA
> configuration and, possibly, a secondary way for samples to enter/exit
> the FPGA for different use cases (similar to the original USRP).  But
> the main purpose would be for reconfiguration of the FPGA.
>
> Frequency synthesis can be an optional part of the assembly.  I
> imagine a relatively inexpensive VCTCXO (2ppm accuracy?) along with an
> Si5338 clock synthesis chip.  The idea, though, is to be completely
> optional for those who really want it.  Otherwise, the FPGA PLL's can
> probably be good enough for most people.
>
>
>   
There are a couple of downsides to a PCIe implementation that I can
think of:

  o not all host platforms are going to have PCIe slots
  o it's noisy in there!

The upside, as you point out, is that it'd be high bandwidth into the host.

-- 
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org