Free 4xSpartan 6 DIY design and schematics!!! - page 3.

TheSeven

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FPGA Mining LLC

Quote from: BTC-engineer on March 09, 2012, 03:47:49 PM

You mentioned to choose the FT232,

Not really a good choice...

Quote from: BTC-engineer on March 09, 2012, 03:47:49 PM

because it will already be used in other FPGA miner designs, so you expect to be compatible with the other bitstreams.
Unfortunately I also haven't looked how it will be done in the X6500 design, so maybe my worries are stupid, but did you check that the wiring between the FT232 and the FPGA's is exactly the same?

It isn't. And the X6500 will move away from using the FT232 soon, because that's really awful from a software point of view.

Quote from: BTC-engineer on March 09, 2012, 03:47:49 PM

From your signal names it looks like you would like to use the JTAG pins of the FPGA's for communication. Is this how the X6500 design is doing the communication?

Yes.

Quote from: BTC-engineer on March 09, 2012, 03:47:49 PM

Are you sure it doesn't matter for the existing mining-software/bitstream if there are 1,2 or 4 or even more FPGA's in the chain?

The current software for the X6500 only supports one setup: 2 FPGAs, hooked up to one set of JTAG pins each. Multiple devices in a chain aren't supported, and there is no reason to add support for that because that whole interface will be redesigned.

Quote from: BTC-engineer on March 09, 2012, 03:47:49 PM

I don't know how you wire the daughter boards with the FPGA on board, but from your backplane I can see that the TDO (output) of one daughter board is not going to the TDI (input) of the next board and so on (JTAG chain). All TDO's/TDI's are on the same pinnumber. I don't understand this kind of wiring.

That looks just broken.

BTC-engineer

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Hi stcupp thanks for sharing your DIY design with the community.

I'm a hw-engineer, and also quite experienced with EAGLE. I did not yet look longer time on your design. Maybe I will find some time this weekend.

But a few thinks directly came into my mind.

You mentioned to choose the FT232, because it will already be used in other FPGA miner designs, so you expect to be compatible with the other bitstreams.
Unfortunately I also haven't looked how it will be done in the X6500 design, so maybe my worries are stupid, but did you check that the wiring between the FT232 and the FPGA's is exactly the same?
From your signal names it looks like you would like to use the JTAG pins of the FPGA's for communication. Is this how the X6500 design is doing the communication? Are you sure it doesn't matter for the existing mining-software/bitstream if there are 1,2 or 4 or even more FPGA's in the chain? I don't know how you wire the daughter boards with the FPGA on board, but from your backplane I can see that the TDO (output) of one daughter board is not going to the TDI (input) of the next board and so on (JTAG chain). All TDO's/TDI's are on the same pinnumber. I don't understand this kind of wiring.

dropt

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Quote from: DeathAndTaxes on March 09, 2012, 02:06:40 PM

Quote from: stcupp on March 09, 2012, 02:03:43 PM

Just wondering..... Why would I want to hook up fan headers to my converter thats running at 1.2v and put more load oon it when there is perfectly good 12v and 5v lines coming from a PC power supply?

This. All that is needed is a 2pin male fan connector and a trace to the 12V input. Nothing more complicated than that is necessary.

You're both completely right, brain fart as I wrote the reply in a rush.

I'm partial to using PSpice, but that's just because it's what I was taught.

DeathAndTaxes

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Gerald Davis

Quote from: stcupp on March 09, 2012, 02:03:43 PM

Just wondering..... Why would I want to hook up fan headers to my converter thats running at 1.2v and put more load oon it when there is perfectly good 12v and 5v lines coming from a PC power supply?

This. All that is needed is a 2pin male fan connector and a trace to the 12V input. Nothing more complicated than that is necessary.

stcupp

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Quote from: dropt on March 09, 2012, 12:57:33 PM

If I find some time in the next couple of days I'll take a gander at the data sheets and your design.

Just curious, have you done any circuit analysis on this yet?

I think glasswalker covered the off-the-top of my head concerns. It'd be nice if you could isolate the VCC input for each core.

I might also think about using two 30 amp DC-DC converters instead of the single. Doing so would give you some head room to add a header at each core location for a fan if ever there was a desire for it. At 33.3/40 amps you're not leaving yourself a lot of room for other losses in the circuit(s) as well as a the converter dies you don't lose the whole board.

Non-EE note: Holes for heat sinks on each core daughter card.

No I haven't done any circuit analysis on it... can you recommend a program?

Just wondering..... Why would I want to hook up fan headers to my converter thats running at 1.2v and put more load oon it when there is perfectly good 12v and 5v lines coming from a PC power supply?

dropt

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If I find some time in the next couple of days I'll take a gander at the data sheets and your design.

Just curious, have you done any circuit analysis on this yet?

I think glasswalker covered the off-the-top of my head concerns. It'd be nice if you could isolate the VCC input for each core.

I might also think about using two 30 amp DC-DC converters instead of the single. ~~Doing so would give you some head room to add a header at each core location for a fan if ever there was a desire for it.~~ At 33.3/40 amps you're not leaving yourself a lot of room for other losses in the circuit(s) as well as a the converter dies you don't lose the whole board.

Non-EE note: Holes for heat sinks on each core daughter card.

dropt

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Quote from: rjk on March 09, 2012, 12:21:21 PM

Quote from: dropt on March 09, 2012, 12:17:22 PM

Quote from: stcupp on March 09, 2012, 10:00:39 AM

errr..... well it depends on what gauge the wiring is im not sure what is normally used on molex

18 awg for a standard good quality molex.

Are you talking about 4-pin HDD molexes, or 6/8 pin PCIe connectors? My PCIe 6-pins are all 16AWG from a PSU I have here.

The 4 pin molex, since that was what the OP has on his render. 16 awg is used as well for high-end PSU's (Primarily used for PCI-E and the 24-pin ATX connector.) That said, IIRC 18 is standard fair, but 16 allows greater wire length without a noticeable increase in resistance.

I've seen "shitty" adapters use fine strand 20awg, and if you see threads where adapters have burned out, this is usually the culprit from what I've seen.

rjk

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1ngldh

Quote from: dropt on March 09, 2012, 12:17:22 PM

Quote from: stcupp on March 09, 2012, 10:00:39 AM

errr..... well it depends on what gauge the wiring is im not sure what is normally used on molex

18 awg for a standard good quality molex.

Are you talking about 4-pin HDD molexes, or 6/8 pin PCIe connectors? My PCIe 6-pins are all 16AWG from a PSU I have here.

dropt

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Quote from: stcupp on March 09, 2012, 10:00:39 AM

errr..... well it depends on what gauge the wiring is im not sure what is normally used on molex

18 awg for a standard good quality molex.

stcupp

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so heres a rough estimate:

50 female connectors 137.75
50 male connectors 114.57
6 psu 250.56
3 FT232R     12
50 330uf     22.33
3 5x12 pcb     60
3 pcie connectors     3
rand caps & res 5
fuses         3
anything im forgetting??? 10

            618.1033
618.1033/3 = 206.0344333333333

However I didn't factor in the power supplies for VCCIO bc im not sure what exactly youd need for 14 chips =p but id expect it to be a extra $20-$30 per board

nebulus

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... it only gets better...

Watchin

stcupp

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Quote from: DeathAndTaxes on March 09, 2012, 10:42:02 AM

Nice. Yeah 14 daughter boards. Drool.

Got a guesstimate on what just the backplane would cost w/ 14 connectors. $80? $200?

It all depends on how many youd want to make......

stuff is ALOT cheaper in bulk..... you would also prob need around a 12 x 5 PCB which could be pretty expensive in small qty even these connectors are over $1 cheaper a peice if you buy like 50

I'll do a rough estimate for 3 boards for you

DeathAndTaxes

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Gerald Davis

Nice. Yeah 14 daughter boards. Drool.

Got a guesstimate on what just the backplane would cost w/ 14 connectors. $80? $200?

stcupp

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Quote from: DeathAndTaxes on March 09, 2012, 10:25:57 AM

Quote from: stcupp on March 09, 2012, 10:21:28 AM

I see lol I thought you meant like a couple per board.... when I started designing this I was thinking of using a cheap $25 300 watt single rail PSU

Yeah maybe Molex would be fine. I guess one could use a custom PCIe 6pin to Molex adapter. For a large backplane though might need to do some testing to see how much amperage most PSU can push on a single wire. Sure the wire and connector can handle it but most PSU may not be designed for such a high load on a single wire.

Maybe they are and the whole thing is just academic.

Check this out

http://search.digikey.com/us/en/products/D12S300-1%20C/941-1046-ND/2501318

you could throw 2 of those on a board and have enough power for 14 spartan 6's

and its only about $10 more than the regulator i got on this small board

DeathAndTaxes

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Gerald Davis

Quote from: stcupp on March 09, 2012, 10:21:28 AM

I see lol I thought you meant like a couple per board.... when I started designing this I was thinking of using a cheap $25 300 watt single rail PSU

Yeah maybe Molex would be fine. I guess one could use a custom PCIe 6pin to Molex adapter. For a large backplane though might need to do some testing to see how much amperage most PSU can push on a single wire. Sure the wire and connector can handle it but most PSU may not be designed for such a high load on a single wire.

Maybe they are and the whole thing is just academic.

stcupp

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Quote from: DeathAndTaxes on March 09, 2012, 10:06:07 AM

Quote from: stcupp on March 09, 2012, 10:00:39 AM

Well actually I don't think a whole bunch of pcie connectors are needed...... my model here should only be pulling about 3.5 amps at 40 watts on the 12v line normal molex connectors like im using should be able to go up to around 35-40 amps max on the 12v line as long as the power supply can handle it. although I wouldn't recommend that as you would be pulling like 400 watts off one wire

Well it isn't a "whole bunch" just 1 PCIe connector per backplane (12 boards).

The reason to use PCIe connector instead of Molex is simply a practical matter instead of a technical limit.

Most PSU are designed to give full amperage of a rail to a pair of PCIe connectors. On the other hand all the Molex connectors and likely either ATX24 connector and/or 8pin MB supplemental connector are usually all crammed on the same rail.

Even in single rail designs "virtual rails" are often used to limit current on one "set of wires". So as a practical matter it is pretty easy to push 900W to 1200W over 6 PCIe connectors (1 per backplane). If you had the same 1200W PSU and tried to pull 900W from the Molex connectors you would find the PSU would trip off.

Maybe not all PSU would but a lot would. Trying to find the "right" PSU then becomes difficulty. Using PCIe connector is simply a "practical solution". If a PSU had 4 PCIe connectors it likely can power 4 boards, 6 connectors = 6 boards. Doesn't take a lot of trying (and failure). Just plug and go.

I understand Molex connector can handle a lot of amperage but most PSU aren't setup to deliver max amperage on Molex connectors. In modern computer almost nothing uses them anymore except fans.

I see lol I thought you meant like a couple per board.... when I started designing this I was thinking of using a cheap $25 300 watt single rail PSU

DeathAndTaxes

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Gerald Davis

Quote from: stcupp on March 09, 2012, 10:00:39 AM

Well actually I don't think a whole bunch of pcie connectors are needed...... my model here should only be pulling about 3.5 amps at 40 watts on the 12v line normal molex connectors like im using should be able to go up to around 35-40 amps max on the 12v line as long as the power supply can handle it. although I wouldn't recommend that as you would be pulling like 400 watts off one wire

Well it isn't a "whole bunch" just 1 PCIe connector per backplane (12 boards).

The reason to use PCIe connector instead of Molex is simply a practical matter instead of a technical limit.

Most PSU are designed to give full amperage of a rail to a pair of PCIe connectors. On the other hand all the Molex connectors and likely either ATX24 connector and/or 8pin MB supplemental connector are usually all crammed on the same rail.

Even in single rail designs "virtual rails" are often used to limit current on one "set of wires". So as a practical matter it is pretty easy to push 900W to 1200W over 6 PCIe connectors (1 per backplane). If you had the same 1200W PSU and tried to pull 900W from the Molex connectors you would find the PSU would trip off.

Maybe not all PSU would but a lot would. Trying to find the "right" PSU then becomes difficulty. Using PCIe connector is simply a "practical solution". If a PSU had 4 PCIe connectors it likely can power 4 boards, 6 connectors = 6 boards. Doesn't take a lot of trying (and failure). Just plug and go.

I understand Molex connector can handle a lot of amperage but most PSU aren't setup to deliver max amperage on Molex connectors. In modern computer almost nothing uses them anymore except fans.

nelisky

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Watching closely...

stcupp

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Quote from: DeathAndTaxes on March 09, 2012, 09:35:41 AM

I love it but honestly I would like to see a "bigger one".

PCIe 6/8 pin connector is good for 150W. I would love to see a backplane which gets power from a PCIe 8 pin "socket" (and can work with either 6 pin or 8 pin connector, usb controller for connection to a host, and a 120W 12VDC to 1.2VDC supply and 12 (yes 12) connectors.

Each board would have only a heatsink no fan and you could put 2x 140mm fans along the "long side of the board to blow cool air across all the heatsinsk. The board could have L brackets (or just screw holes) to mount the fans and 2x 3pin fan headers to power the fans.

210 MH/s * 12 = ~2.5 GH/s fully loaded and user could add daughter cards incrementally. An 900 to 1200W PSU w/ 6 PCIe power connectors could power 6 boards or 12.5 GH/s. It could be a "poor mans" Rig Box. Start small w/ one backplane and 4 or 6 FPGA and build as you go.

Well actually I don't think a whole bunch of pcie connectors are needed...... my model here should only be pulling about 3.5 amps at 40 watts on the 12v line normal molex connectors like im using should be able to go up to around 35-40 amps max on the 12v line as long as the power supply can handle it. although I wouldn't recommend that as you would be pulling like 400 watts off one wire

EDIT:
errr..... well it depends on what gauge the wiring is im not sure what is normally used on molex

DeathAndTaxes

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Gerald Davis

I love it but honestly I would like to see a "bigger one".

PCIe 6/8 pin connector is good for 150W. I would love to see a backplane which gets power from a PCIe 8 pin "socket" (and can work with either 6 pin or 8 pin connector, usb controller for connection to a host, and a 120W 12VDC to 1.2VDC supply and 12 (yes 12) connectors.

Each board would have only a heatsink no fan and you could put 2x 140mm fans along the "long side of the board to blow cool air across all the heatsinsk. The board could have L brackets (or just screw holes) to mount the fans and 2x 3pin fan headers to power the fans.

210 MH/s * 12 = ~2.5 GH/s fully loaded and user could add daughter cards incrementally. An 900 to 1200W PSU w/ 6 PCIe power connectors could power 6 boards or 12.5 GH/s. It could be a "poor mans" Rig Box. Start small w/ one backplane and 4 or 6 FPGA and build as you go.

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