Minimalist Spartan6-LX150 board

[eldentyrell]

Any prices for shipping to the UK if it's available?

I'm flexible on that; any insured service is fine.  By default I guess I'd just use the US Postal Service (which, I assume, does a handoff to the UK postal service somewhere before delivery).

However, buyer must pay any/all customs charges imposed by the receiving country.  You probably ought to fill out the customs form yourself and email it to me so I don't screw it up.  I'll set up a mechanism for doing this if there is enough interest to warrant a large run of PCB's.

[1714036085]

1714036085

[1714036085]

1714036085

[Dargo]

Also, the advantage of the $160 back plane is entirely cosmetic (i.e. to nicely hold several boards in a compact way)?  

The backplane has the 48W DC-DC power supply on it.  You won't be able to do much without a power supply!  That's why there's the option to get a smaller 12W version soldered directly on to the spartan card -- you need that option if you don't get the backplane.

I understand that, but $160/6 = $26.67 per board vs $15 for the 12W supply directly on the board. So I'm wondering if there is any advantage to the back plane to justify the higher cost, aside from the cosmetic point of having six boards neatly mounted on the back plane. Also, is 48W enough for six boards? That's only 8W per board.

Edit: Sorry, didn't see Big Chip's (added?) reply about JTAG connections - that answers my question.

[eldentyrell]

Also, is 48W enough for six boards? That's only 8W per board.

That's a good point.

Fortunately ArtForz pointed out a 72W (60A @ 1.2V) power supply that is schematic-compatible (though not pin-compatible) with the 48W one I've been using.  It's very likely that I'll switch.  This may increase the cost of the backplane by about $10.  Unfortunately they have different pinouts, so I can't offer a choice of one or the other.

One of the other reasons for choosing the backplane design is uncertainty about power requirements.  I have a hunch that FPGA mining will continue to increase the mhashes-per-lut, but from this point forward the increases will require increased power consumption (though still nothing close to GPUs).  So I'm trying to future-proof things a bit by separating the expensive chip from the power supply.

If some magical bitstream falls out of the sky that gives us twice the hashpower for twice the wattage, people can just leave half the slots on the backplane empty.  Sure those empty slots "cost" you $26 per board, but it's a lot better than having the power supply welded on to the board and being left out of the game completely!

[rph]

If some magical bitstream falls out of the sky that gives us twice the hashpower for twice the wattage

Heh, there's no way 6s150 will reach 300MH/s, even if you take several
months to hand-place and hand-route every LUT...

-rph

[Turbor]

Interested 

[eldentyrell]

If some magical bitstream falls out of the sky that gives us twice the hashpower for twice the wattage

Heh, there's no way 6s150 will reach 300MH/s, even if you take several
months to hand-place and hand-route every LUT...

-rph

Ah, you are underestimating the power of <blink>magical</blink> bitstreams!!!!

No seriously, the point is there will undoubtedly be ways to get (1+X)% the performance for (1+Y)% of the power, and I don't think anybody knows for sure right now what the X/Y values will be.

You're right that nobody's going to fit two whole copies of the current (6s150-sized) fpga miners on a 6s150 at any point in the future.  But there are less efficient mining cores that are much more flexibly routed and come at a much finer granularity.  This has been the course I've been pursuing lately with my own designs: find an inefficient-yet-better-than-nothing use for the idle LUTs left behind after PARing the ordinary design.

[ultraimports]

I am veeerrry interested, pausing my own FPGA purchase to see where this goes....keep me updated (sub'd).

[nelisky]

How much power would the 6 boards + backplane take? Expecting 900MHs out of it, and if you sell these plug & mine, I'll almost certainly be in for on full backplane for testing!

[322i0n]

How much power would the 6 boards + backplane take? Expecting 900MHs out of it, and if you sell these plug & mine, I'll almost certainly be in for on full backplane for testing!

Me too.

[Philj]

I'm interested.

What would be required to get one device connected to a standard PC? The base device($250), plus a single 12w power suply ($15)? Are you including any connector/cable to get I/O to/from the PC, or would an additional cable (jtag to usb???) be required?

Just trying to get an idea of just how much would be needed to attach this to a basic PC. I don't want to budget for $265 per card then find out that each card also needs a $50 cable or something like that to make it actually work.

[dovewing2000]

notified - though i'm still wondering what the speed will be like...

[eldentyrell]

How much power would the 6 boards + backplane take?

That depends on what bitstream you use.

Most of the posts I've seen on this site quote under 7W per board, but like I've said before I believe that will go up in future designs.  Anyways, power consumption is determined by the chip and the bitstream (unless the board designer did something really stupid) so you can assume this board's power consumption will be pretty much the same as any other.

[eldentyrell]

What would be required to get one device connected to a standard PC? The base device($250), plus a single 12w power suply ($15)? Are you including any connector/cable to get I/O to/from the PC, or would an additional cable (jtag to usb???) be required?

Just trying to get an idea of just how much would be needed to attach this to a basic PC. I don't want to budget for $265 per card then find out that each card also needs a $50 cable or something like that to make it actually work.

You need a USB-to-JTAG cable.  One of the important features of the backplane is that it lets you use ONE cable for six boards, so you get to split the cost of the cable six ways.

Some bitstreams require that you use Xilinx's lame IMPACT software and an IMPACT-compatible JTAG cable (they tend to be more expensive).

I personally use urjtag in my own (unreleased) designs, and there are $20 cables that work with it.  But I don't think the "fpgaminer" and "ztex" designs work with them.

[teek]

What would be required to get one device connected to a standard PC? The base device($250), plus a single 12w power suply ($15)? Are you including any connector/cable to get I/O to/from the PC, or would an additional cable (jtag to usb???) be required?

Just trying to get an idea of just how much would be needed to attach this to a basic PC. I don't want to budget for $265 per card then find out that each card also needs a $50 cable or something like that to make it actually work.

You need a USB-to-JTAG cable.  One of the important features of the backplane is that it lets you use ONE cable for six boards, so you get to split the cost of the cable six ways.

Some bitstreams require that you use Xilinx's lame IMPACT software and an IMPACT-compatible JTAG cable (they tend to be more expensive).

I personally use urjtag in my own (unreleased) designs, and there are $20 cables that work with it.  But I don't think the "fpgaminer" and "ztex" designs work with them.

Are you selling the cable with the units? 

[eldentyrell]

Are you selling the cable with the units? 

No.

[eldentyrell]

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!

[teek]

Are you selling the cable with the units? 

No.

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

[teek]

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!

i'm quite interested in buying some boards..

[fizzisist]

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!

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.

[eldentyrell]

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!

That said, I don't think the cost advantage of your board over, say, ours is as large as it might appear.

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.

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.

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.