Topic: FPGA -- DIY @ Low Cost - page 2. (Read 8488 times)

From my limited knowledge on this topic, I expect the hardest part to be getting the prices down. Granted, part of that would be in optimizing FPGA code. But getting the code initially may be as easy as using what has already been developed for open use (if any). There is an open Python code I think that you can analyze to see how the algorithm is used. But I would personally start with some block diagram level stuff first. I've yet to find any such diagrams though.

My thinking is that any low cost DIY will [probably] incorporate Spartan 6s150 chips. However, I don't want to be tunnel visioned and/or dogmatic about that idea. Also, I'd like to take time to think outside the chip    It may be that the best low cost solution would require buying more parts than a minimalist board. Perhaps, any ASICS to do the SHA256 hashing? Maybe, use the FPGA's to do whatever else needs to be done.

Brainstorm:
From some cursory reading, I would expect any dedicated SHA256 ASICs to do the hashing part of the overall algorithm about 3 to 4 times faster than an FPGA (i.e. pound for pound). If a such a dedicated ASIC could be used for this, then for each hashing routine the ASIC would perform, let's say we can free up say three hashing routines from the FPGA. And I anticipate this to be a large part of the FPGA code. Anyway, the FPGA would use any such free space to process output from (or for) the ASIC as needed.
From there, figure out the right ratio of FPGA's to ASIC's to utilize every ounce of logic circuitry. This MIGHT work to increase MH/$ (MH => MH/s) if the ASIC work:cost alone would translate into a higher MH/$ value.

Another thought might be to consider how a GPU can work with FPGA's.

...

Back to 'normal' thinking:
Anyone got any idea on what a minimalist board might cost? Assume the FPGA can be programmed to achieve about 150Mh/s. Already we are at a disadvantage in MH/$. Such a chip might cost about $170 (not sure if that is accurate). Anyway, if that is the case, you start out with 150MH/s/$170 or  .88MH/s ... not counting the printed circuit board and any minor components (capacitors, resistors, connectors).  Just from that alone, I would decide to go with whoever is the bext retail FPGA. But I wouldn't want to give up so easily.


||bit.out

Miners SHA256 hash a string until the hash is lower than a target value. You can read a fairly accessible article on it here.

Both these threads have gone a little quite but there's some info in there. One of the projects has a Dropbox.

https://bitcointalksearch.org/topic/modular-fpga-miner-hardware-design-development-22426
https://bitcointalk.org/index.php?topic=9047.560

Is not easy to do this lol.
I can easily make a board but what's impossible is coding it to work properly. I don't even know how bitcoin works. I think miner "decrypt" the string and returns it's value, but how do the miner "decrypt" these strings?

Thanks.

On the usual boards, many other components are SMT as well, and I have no idea whether they could be redesigned with through-hole parts. My guess is that they probably could, and the daughterboard idea might work, but I don't know how well it would work in practice.

Thanks for your thoughts.

For DIY, what would you suggest to accommodate this problem? A premounted FPGA chip on a daughter board? Akin to one RPH seemed to use here: https://bitcointalksearch.org/topic/ultra-low-cost-diy-fpga-miner-175mhs-1mh-44891

BTW: RPH seemed to pull off something like that at his home: https://bitcointalksearch.org/topic/m.536983

Thoughts?

Reflow soldering without the right components is very easy to mess up and get wrong. I don't think there would be many users that would be successful with a kit. I don't think it would be possible to create a board that isn't reflow soldered.

And it must be low cost, i.e. it must be competitive with two of the top three FPGA boards in MHash/$.
Otherwise, it's just fiscal sense to just do the retail option. BFL, ZTEX, et. al.

I think DIY would have the advantage, since you automatically cut out the profit aspect. However, there are some disadvantages of DIY  -- e.g. individuals have a higher hurdle to receive any bulk discounts (which might be able to be met by pooling DIY'ers purchases), or any special or costly equipment needs.

That sounds good too. Though, I'm even curious about the potential for a DIY PCB. What necessary PCB complexity is there to accommodate to an FPGA chip. One thread I read seemed to indicate a 4 layer PCB would be a minimum. If-so, then yeah, I don't see that happening easily in a DIY venue. Which would mean having the PCB made professionally. But that may be the one thing that needs to be bought in bulk. And if it is as simple as RPH's boards seem, then it shouldn't be that costly at all.

BTW: I am pretty sure RPH soldered his own FPGA to a BGA board. That was part of his excitement in using a skillet or hot-plate to do so. It appears this is the BGA board he used:
http://www.xilinx.com/support/documentation/package_specs/fg484.pdf

So, a professional outside PCB source seems to have been his approach as well. There may not be any practical alternative for DIY.


||bit.out

 

Yep,all we need is the board design & a parts list

Something simple,maybe around 200+ mh/s.

I have a guy that can assemble boards in his home  

I would be willing to kick some BTC towards this IF it'll work.

Someone really needs to release a board design and sell plain pcbs. As soon as you can just buy a board and your own components and then solder it all together, this becomes far more feasible for the DIY hobbyist.  Especially with something like rph's approach where you could buy the fpga already soldered on a daughter board.

I'm glad to see some initial interest in this. Though, it isn't much of a surprise having seen the other DIY FPGA threads.

I'd personally like to bypass all the fun of designing one, and use someone else's already made DIY plans. My expertise is as an electronics technician, not an engineer. In the meantime, I might go with Butterfly Labs products.

....

There are good ideas already posted and well commented, but nothing finalized. I personally like the thread started by RPH here: https://bitcointalksearch.org/topic/ultra-low-cost-diy-fpga-miner-175mhs-1mh-44891

RPH's o/p reads "Ultra-Low-Cost DIY FPGA Miner - 175MH/s @ $1/MH". i.e. 1MH/$

If his design path actually would yield 1MH/$, then that DIY approach seems quite worthwhile...b/c BFL Singles is the best at about 1.38MHash/$. The next best two found here (https://en.bitcoin.it/wiki/Mining_hardware_comparison#FPGA_Devices) are 0.82-0.5 MH/$ made by ZTEX (but the best rate there requires a bulk purchase), and the very comparable 'X6500 Rev 3' at .71MH/$.

So, 1MH/$ seems very nice for DIY...even considering some of the new stuff that seems ready to come out. Furthermore, the MHash/$ might possibly be improved more with some creative thought.


Any thoughts?

Maybe go to this thread for some other insights to consider:

"Minimalist Spartan6-LX150 board"
https://bitcointalksearch.org/topic/m.543312

...

I'll see what kind of responses we get, and if anyone wants to contribute, I can certainly think of plenty of questions to ask.

||bit out.

I'm really interested in helping out with something like this. I would be doing as much learning as contributing, but this would be really fun.

I haven't seen anything successful from those threads either; let's be the first!

Using retail or bulk-purchased components: Has anyone here developed any actual low cost do-it-yourself FPGA boards that have competitive or better-than competitive hash/$ rates?
If-so: Is that person willing to share or sell the design plan?

I've seen a few threads attempt to tackle this topic, but I have yet to see anything actually come from them. It seems the thread authors drop out or decide to develop the idea for their own use after some progress.

If not: Is anyone here willing to collaborate on developing such a board? And not just an FPGA board that will hash, it MUST be competitive in price...if this is even possible. It seems, so far, the best hash/$ rate is BFL's products. But if a board could be developed to be at least as good as the next best hash/$ rates, it might be worth it. Especially considering the slow product shipping time of Butterfly Labs.