[time-nuts] XRPU hardware on the current marketplace

Magnus Danielson magnus at rubidium.dyndns.org
Sun Dec 30 13:22:34 EST 2007


From: Bo Granlund <bgran at tiq.fi>
Subject: Re: [time-nuts] XRPU hardware on the current marketplace
Date: Sun, 30 Dec 2007 18:08:33 +0200
Message-ID: <4777C281.80300 at tiq.fi>

Hej Bo!

> > I'm very interested in this area, but haven't actually done anything beyond 
> > surf the web looking for something that fits my budget and interests.
> >
> > I think a major part of the problem is that bleeding edge silicon technology 
> > as used by up-to-date FPGAs doesn't fit with 5V PCI.  (The specs call for 11V 
> > spikes when the reflections are out to get you.)
> >
> > Most PCs have 5V PCI slots because most PCI add in cards are keyed for 5V 
> > slots.  I haven't seen any motherboards with 3V only PCI slots, but maybe I'm 
> > not looking in the right place.  In any case, I haven't seen any Xilinx 
> > development boards setup for 3V only.

Most boards use front-end chips. See below.

> I'm not entirely familiar with the power consumption characteristics of 
> a FPGA, the ones I've dealt with have an power supply, and I haven't 
> even cared to look at them more deeply to find out what they eat in 
> essence. I'm not terribly experienced in the area of HDL 
> implementations, or even using the system as sone kind of time source. 
> I've found a company http://www.digilentinc.com/, that sells for a very 
> decent price FPGA development boards. You get just about everything but 
> the kitchen and sick with one of their products, for a very lucrative 
> price, but I'm quite unsure howto connect the development board to a PC. 

Have a look at MTE (http://www.mte-india.com) who has three boards for the PCI
bus, all three use Xilinx FPGAs and have various amounts of goodies. I think
the "General Purpose PCI board" fits your needs fairly well, with some
additional interface hardware which should not too hard to acheive.

The MTE boards do as suspected, use a PCI chip, they use PLX chips, which is
fairly industry standard.

> They have somekind of bus architecture as far as I can tell, but I have 
> no idea howto use it, my HDL skills are not that developed yet. And to 
> interface with the PCI bus is maybe a little bit out of the scope of my 
> personal knowledge, and the scope of this project I want to undertake. 

There are PCI blocks to pick up, or use a PCI frontend chip like the PLX and
run of that local bus. The PCI bus is complex enought to be confusing unless
you spend quality time with the PCI spec and the PCI book.

> A Spartan-3 is perhaps a little bit too complicated for the particular 
> project I'm looking at. If I'm to understand correctly, PHK did his 
> thing on a much smaller FPGA. But I can't find the specifications of the 
> HOT-I board anywhere. I kindof hope that some of the wizards comes 
> around and enlightens us with his foresight.

The thing is, the Spartan-3 is at the dirty cheap level so you will certainly
get a very big bang for the buck, and almost any attempt for such a board will
be a nice little field-trip on the level of offending the chip with the task.

> I'm sorry for just babbling about things in general, but even a newbie 
> has to start somewhere and learn the ropes.
> 
> warm regards, and have a happy new year,
> Bo Granlund

Happy New welltimed Year!
Magnus



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