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

From: Jamie Morken
Subject: Re: [Discuss-gnuradio] re: Low cost hardware option
Date: Wed, 12 Jan 2011 21:17:12 -0800

> On Wed, Jan 12, 2011 at 8:36 PM, Jamie Morken
> <address@hidden> wrote:
> >
> > Hi,
> >
> > I am interested in helping out with making some new gnuradio
> hardware that is compatible with the USRP daughterboards.  I
> worked with Matt doing CAD on the original gnuradio project
> hardware and have since then made lots more boards including a
> cyclone 3 board.
> >
> > Here is a possible hardware configuration:
> > USB 3.0 transceiver IC or USB 3.0 microcontroller
> > Altera Cyclone3 FPGA
> > highspeed DAC/ADC
> >
> > If we use just a single channel ADC and DAC (ie half a USRP
> v1) then we can get away with a smaller/cheaper FPGA and have a
> cheaper/simpler board that can be paralleled if needed (ie. two
> boards hooked up to USB 3.0)
> The idea of USB3 is nice for the future, but I don't think there are
> enough peripherals out there yet to make a good board.  I
> can't really
> find anything that's not completely preliminary and somewhat cheap.
> I'd like to propose what I think may be a good compromise.
> 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
> latencyand 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
> completelyoptional for those who really want it. 
> Otherwise, the FPGA PLL's can
> probably be good enough for most people.
> For connectors, 2 HDMI (commodity and cheap, twisted pair, shielded
> and rated to relatively high frequencies) - one for analog/baseband
> signals, one for digital I2C/SPI comms.  Goes to a daughterboard
> carrier which can hold the daughterboard and a digital IO port
> expander for controlling the RX/TX IO [0:15] pins for the db
> connectors.
> I think the high bandwidth, low latency, and low CPU utilization of
> PCIe is very attractive.  The main downside to the parts
> are the BGA
> components which can be daunting for hobbyists, but toaster
> ovens with
> PID controllers can really do a pretty amazing job.  I'm
> not sure if
> this is a dealbreaker or not.
> I'm very interested to hear other people's opinions as to proposed
> interfaces, platforms, architectures, and connectivity.
> Jamie, I hope you don't see this as a hijacking of your original
> e-mail.  I am particularly interested in your response.

Hi Brian,

That sounds like a pretty good system.  I should say right off the bat that if I am involved to make this I would want to add a clause in the open source hardware license to not allow the hardware to be used for military applications.  I think it is important to state this at the start before I would get involved working on a new gnu radio board.  If people can live with that requirement I am happy to do the layout work.


> Brian
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