Topic: Minimalist Spartan6-LX150 board - page 5. (Read 49903 times)

I would if I owned a (tens-of-thousands-of-dollars) pick-and-place machine.  Unfortunately trying to do those by hand is painful and unreliable.  I just can't justify it on an eyestrain/benefit basis.

You have a good point.  But to flip that around, on the GPU side it's taken as a given that you're going to buy your hardware from a company (ATI) that does not provide the mining software (or even admit it knows what bitcoin is).  But I understand that while gamers have seen GPUs before, most bitcoiners are encountering FPGAs for the first time.  They aren't scary; they're just obscenely flexible... "enough rope to hang yourself with."

I could, perhaps, put together a turn-key solution, although it would involve a lot of effort.  My two major concerns are:

1. HDL developer guilt.  It makes me slightly ill to see posts like ngzhang's "hey you lazy-ass HDL developers make your code faster so I can make MOAR PROFITZ!!!".  I'd feel queasy about selling a "solution" that bundled in somebody else's hard work.  I don't know the exact details of the fpgaminer/ztex dispute, but I can certainly empathize with the initial reaction from fpgaminer.  It would make me really happy to be providing low-cost boards to people who are interested in tweaking/tuning/improving the HDL code, but I think I've figured out now that there aren't as many of those people as I'd thought.

2. Support.  I'm happy to help out here in a casual message-board-member way.  But I'm kinda worried about lazy users buying a "turn-key" solution from me and then demanding that I hand-hold them through the whole process of configuring Xilinx's crapware drivers on their Windows host box (I haven't used Windows in almost a decade) under threat of posting negative reviews of my product ("did not work for me").  I definitely can't sell the boards for $250 if I have to budget in my own time spent on extensive tech support work.

Anyways.  Looks like the first run will be small personal-use-only, but there may be another batch of boards in November after I've figured out if it's worth taking this to the next level.

Please consider SMD ceramics..

-rph

hehehehehehe I soooo want to add a "see also: emachines.com" or maybe foxconn to the end of that article for no reason and see if anyone notices   Didn't know they named it btw.  I've seen at least a dozen myself with my small PC repair business.  One time I even saw one out in the middle of nowhere on the board bulge and fail causing the onboard graphics to distort and fail to initialize almost 100% of the time and it wasn't exposed to much heat.  So don't get cheap caps either apparently I'm sure there are plenty of high failure rate solid capacitor knock offs out there given their current reputation as being awesome.

That's actually a pretty good idea and won't even require a PCB change.  Spending an extra buck or two on something non-electrolytic is probably worthwhile insurance against capacitor plague.  Thanks for the suggestion!

You raise an important point, although you can always crank the JTAG clock rate down to something ridiculous like 0.25Mhz.  Sure, it will take a full minute or two to load the bitstream, but once that's done you've still got an order of magnitude more bandwidth than you need for loading getwork's and reading back nonces.

So, yes, signal integrity is an issue here and I fully expect that the JTAG clock rate will need to be reduced when all six slots are full.  Once I have another four boards built I will know this for sure.  But the reduced clock rate will not affect mining throughput at all -- just "boot up" time.

I think there would be more customers if you translated some of this info from electronics expert into computer expert I have about enough electronics experience to know about electricity and ummm...well, that looks an awful lot like 3 liquid looking caps in your pic which are going to explode over the not-so-long long term if they're exposed to heat constantly You know, like cheap liquid caps that some uncaring manufacturer like HP mounts a quarter inch from an old Pentium 4 that leak after 1 years of significant enough dust build up as opposed to modern solid capacitors on ASUS boards that you could basically run in an oven for 10 years.  Get some of those 50,000 MTBF Japanese ones

That concern aside, everyone keeps making models and potential products and asking for preorders without ever explaining to us computer people the process outside the board that we're familiar with.  In other words, what's the hookup style (USB?), who wrote a driver if anyone, what versions of windows would it operate correctly on, and what mining software recognizes it as a processing device and can send and receive data for mining?  I bet you'd get 10x the interest if you made a quick post outlining all that.

Well, with the price drop, the payoff for GPUs is bleak already.
A completely DIY 6s150 should pay for itself faster than the "best" ATI option,
if you agree with the Bitminer math.

The exact #s are endlessly debatable of course (and not everybody will DIY).
[And some people live directly next to a hydro dam, or get free power through
various legal and illegal ways..]

Still I think FPGAs have already overtaken GPUs for the guys with real $$$$
to invest in mining. And, if not, at least they will very soon.

-rph

These situation will or not come to truth depends on YOU HDL programmers and custom FPGA board venders.
My DUAL spartan6-SLX150 board for development will small-lot on offer in 1week. I think a 400MH/s perboard(200 per FPGA, and certainly MUST with yours MAGIC bitstream) hashing speed with a price less than 600$ will attract more people turn to FPGA mining.

Once miners start posting success stories and pics of stable, large, $1-2/MH FPGA rigs,
the demand will follow. Anybody buying today would be a super-early-adopter.
(Which I guess makes ArtForz a super-super-super-early adopter...)

It's a huge PITA to build and cool a 100 GPU rig, but a 200-300+ FPGA rig is no problem in a tiny apartment.
Without dummy monitor plugs, $500 of molex<->PCI-e cables, 50 ATX power supplies, and all the other non-wife-approved stuff.

Once there are enough FPGAs on the network, difficulty will increase and GPUs will become unprofitable or barely
profitable for anyone paying for cooling + electricity [probably most people with more than 4-5 GPUs]. It's a self-fulfilling prophesy.
Live or die, make your choice 

-rph

I am with these guys..  I am no electrical engineer..  but I can plug in a psu

Hmm, I disagree... Anyway, your design works, so that's good! It just might not be as immune to noise as it would be with 0402s. It's not a mortal sin to disobey the datasheet, just risky.

This is phenomenal that you could get the cost down so low. My only complaint was going to be the JTAG interface. But, since you've accounted for daisy-chaining 6 of them... that complaint is gone. Hopefully your JTAG signal integrity holds up from daisy-chaining 6 boards. It's touchy.

Give the bitcoin community some time to warm up to your idea. There've been enough scams going around, so it's no surprise they don't jump on the bandwagon right away.

About fpgaminer's open-source code and ztex's "borrowing" of it-- the issue wasn't that ztex borrowed a few bits and pieces. It is open-source after all. I think the issue was lack of acknowledgement.

agree this

Well for people like me (carpenter) all this technical things are a bit hard to understand. The prize is one thing but for me it's more important to understand first how it works. I need a kit i can plug in and mine. The total package. When you can offer that (with enough hash rate), i'm sure that people will buy.

Perhaps.  My point is that even this price point is not low enough, so you guys might want to hold off on high-volume production until you can go even lower.  Apparently neither of us is at a low enough price point.


Yes, I read it many times... did you?  There's no prohibition against through-hole caps and they explicitly say that it's okay to have the 0.47uF's outside the footprint as long as they're within half an inch of the device outline.

It makes me happy to see more designs out there. Competition is a good thing! Especially, if others are developing different designs that will suit different needs. This backplane concept looks very nice.

That said, I don't think the cost advantage of your board over, say, ours is as large as it might appear. Our boards have the -3 speed grade by default, so we should compare the $270 price. Fully assembled with 6 boards, your system costs 6*270+160+20 = $1800. Our boards cost $610, so an equivalent system (3*X6500) would be $1830 (plus three USB cables). Also, do your boards include heatsinks?

As for the design, those through-hole capacitors are troubling. Take a look at UG393. They spend pages stressing the importance of capacitor package size and placement, even taking the time to explain a lot of fundamental PCB design concepts. Definitely worth a read.

i'm quite interested in buying some boards..

Could you provide a link to the cable?  Might be nice if you offered the cable you use for an additional fee..

Well, seems like quite a lot of people are interested in this thread, but so far only one posting from somebody who actually mentions being interested in buying a board.

Looks like I will only be ordering enough PCBs for my own personal use.

This isn't a big deal for me because I designed the boards mainly for myself, figuring the ability to sell them would be neat if it worked out -- but not depending on it.

However, for anybody out there thinking of designing/building/marketing a Spartan6 board for mining purposes, it looks like the market isn't interested unless the fully-assembled cost is below $250 per chip.  Probably an important data point to have before you make any plans for large-scale production!