Author Topic: SQRL Acorn as an interesting Artix-7 board?  (Read 6329 times)

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Offline Fred27

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SQRL Acorn as an interesting Artix-7 board?
« on: April 14, 2020, 11:04:35 am »
I keep seeing SQRL Acorn CLE-215 boards appearing on eBay. From what I can tell they were intended for crypto mining, but didn't go down well due to the necessary software not appearing. Cue a lot of angry people and boards being sold on eBay.

Considering it's an Artix-7 and it has a M.2 interface plus a JTAG header, I was wondering if this would make an interesting board to play around with. I'm very much a beginner with FPGAs and have played with Spartan-7 and Zynq. My gut feel is that any PCIe work is probably advanced stuff and that it would end up gathering dust, especially without a schematic. Just thought I'd ask and maybe put others onto a good deal - at eBay prices that is, not the original selling price.

Link to manufacturer: http://squirrelsresearch.com/acorn-cle-215/
eBay example: https://www.ebay.com/itm/Used-SQRL-Acorn-CLE-215-Artix-7-FPGA-w-Powered-Carrier/184251132237

Anyone have an opinion?
« Last Edit: April 14, 2020, 11:06:23 am by Fred27 »
 

Offline SiliconWizard

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #1 on: April 14, 2020, 05:11:12 pm »
My gut feel is that any PCIe work is probably advanced stuff and that it would end up gathering dust, especially without a schematic.

You're quite right about that.
The board has nothing but the FPGA, power supply stuff, heatsinking and a PCIe interface. There's no access to any other IOs as far as I can see. So the only use case would be to implement some kind of accelerator for a computer. If that's of any interest to you. Then you'd need to learn about implementing a PCIe interface. And writing the appropriate driver for the OS. And... And.

Yes it's going to gather dust in a drawer unless you have already done all of the above. Or you have a few years available.
 

Offline mark03

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #2 on: April 14, 2020, 07:57:23 pm »
Presumably, all of those pins on the M.2 connector can be used just as well for generic I/O, and M.2 connectors are cheap, so it may not matter that it was designed for PCIe... you could always use it differently.  No schematics [that I could find in two minutes] may be a more serious problem, however!
 

Offline hamster_nz

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #3 on: April 14, 2020, 09:03:53 pm »
Presumably, all of those pins on the M.2 connector can be used just as well for generic I/O, and M.2 connectors are cheap, so it may not matter that it was designed for PCIe... you could always use it differently.  No schematics [that I could find in two minutes] may be a more serious problem, however!

If they were running PCIe over those pins then they will be the high speed transceivers, and not generic low-speed fabric pins.
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Online asmi

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #4 on: April 15, 2020, 12:35:33 am »
Yes it's going to gather dust in a drawer unless you have already done all of the above. Or you have a few years available.
Well it's not that bad - Xilinx provides free PCIE IP so you can put together some working design relatively quickly, and they also provide drivers for Linux for that IP, but without available GPIO utility of such board would be severely limited.

Online asmi

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #5 on: April 15, 2020, 12:36:21 am »
Presumably, all of those pins on the M.2 connector can be used just as well for generic I/O, and M.2 connectors are cheap, so it may not matter that it was designed for PCIe... you could always use it differently.
You might want to read up on what exactly M.2 connector is, and what kind of signals are available there...

Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #6 on: April 15, 2020, 12:38:52 am »
It'll probably end up in a drawer, but I bought one. I have experience with the hardware side of the PCIe, but not the drivers... Anyway we'll see in a few days how much additional I/O is available. Thanks for the tip Fred27!
 

Online Someone

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #7 on: April 15, 2020, 07:36:17 am »
The board has nothing but the FPGA, power supply stuff, heatsinking and a PCIe interface. There's no access to any other IOs as far as I can see. So the only use case would be to implement some kind of accelerator for a computer. If that's of any interest to you. Then you'd need to learn about implementing a PCIe interface. And writing the appropriate driver for the OS. And... And.
There are some acceleration/compute tasks that have a low enough data bandwidth that it can all be done over JTAG so it could be easily repurposed there, but still very niche.
 

Offline Wiljan

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #8 on: April 15, 2020, 08:14:18 am »
Do we know which Artix-7 part are on the board?
The name CLE-215 could indicate 215K macrobocks = XC7A200T?  (It's just a guess)

After some search
Quote
Xilinx Artix-7 series: XC7A100T in "CLE-101" acorn, XC7A200T in "CLE-215" acorn.
https://bitcointalk.org/index.php?topic=4391318.1100

As far as I can see the Vivado WebPack should support the Artix®-7 (XC7A15T, XC7A35T, XC7A50T, XC7A75T, XC7A100T, XC7A200T)

So the challenge would be to power the board correctly and to hook up the JTAG correct, I only found some high res images of the CLE-215+ and on that board you have a JTAG connector (Different shape than normal) and another connector called I/O witch might contains some I/O's  ;) and then there are 4 leds where I would  expect you could could us as I/O

It might sure be a nice board, special it you want to use it for some algo or so where you do not need high I/O as long the M2 are not documented

For sure it sound like people want's to get rid of those boards in respect to mining

 

Offline Fred27

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #9 on: April 15, 2020, 08:23:19 am »
I was thinking that the ideal use would be to use for something like an accelerator project - i.e. hand data to it over PCIe, do something and get it back. I assume that's basically what the mining was doing. I had spotted that there is some Xilinx PCIe IP and I suppose I hoped it would be reasonably easy to get something working passing data back and forth.

I'm OK on the PC side of things. However, my experience working with Vivado means I suspect that SiliconWizard is right and it would require a huge amount of time and effort to get to that point. Being able to pass data from a PC to the FPGA fabric and back would be a great tool to have in the mental toolbox but it is far more likely to be a dust collector. (I suppose Zynq is a much easier way to do this sort of thing anyway.)

Good luck with it, miken. Keep us posted. I don't think there will be much IO, but that's not really what it's for.
 

Offline SiliconWizard

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #10 on: April 15, 2020, 02:49:12 pm »
Presumably, all of those pins on the M.2 connector can be used just as well for generic I/O, and M.2 connectors are cheap, so it may not matter that it was designed for PCIe... you could always use it differently.
You might want to read up on what exactly M.2 connector is, and what kind of signals are available there...

Yup. And their number is pretty limited too (so that would be very limited for all-purpose IOs anyway.)

You'd also have to use an M2 female connector, which implies designing a small PCB if you want to use this board outside of a computer motherboard. (Soldering tiny wires on the connector instead would be crap probably, would be problematic for high-speed stuff, and would be also problematic for the power supply lines. This thing likely draws a lot of current.)

If you want a generic dev board with an Artix-7, go look elsewhere IMHO. QMTECH for instance.

Now of course for those interested in exactly this - a PCIe solution - that should be fun, but without the schematic, probably close to unusable (where are the PCIe signals themselves on the FPGA? a lot of possibilities AFAIK.)

And then, even though XIlinx provides IPs and driver stuff for PCIe development, if you've never done it before, I wouldn't call this easy. A reality check tells me that it WILL end up in a drawer.

But if anyone manages to do anything useful with this board, please report back, that should be interesting!
 

Online asmi

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #11 on: April 15, 2020, 04:38:02 pm »
(where are the PCIe signals themselves on the FPGA? a lot of possibilities AFAIK.)
Actually not a lot because in Artix PCIE hard block can only be connected to quads which are on the same side of die as the block itself. This is not the case in Kintex for example, because there MGT quads are arranged in a column - which is why it's possible to support x8 PCIE connection.
This is actually interesting because you'd think you would need 2 PCIE hard blocks - one as endpoint to connect to PC, and another one as a root port to connect M.2. Which means that at least one of those connections use soft PCIE IP block. That is unless they intend to use SATA M.2 drive, in which case they will only need a single transceiver. But since MGTs come in quads, I'd connect all 4 to M.2 socket anyway even if I would only intend to use SATA protocol through a single MGT.

Offline mark03

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #12 on: April 15, 2020, 04:48:52 pm »
Presumably, all of those pins on the M.2 connector can be used just as well for generic I/O, and M.2 connectors are cheap, so it may not matter that it was designed for PCIe... you could always use it differently.
You might want to read up on what exactly M.2 connector is, and what kind of signals are available there...

Yup. And their number is pretty limited too (so that would be very limited for all-purpose IOs anyway.)

In my defense, this was a thought experiment, not a suggestion.  The proposal was that this board (at ~ $25) could be a cheap substitute for something like the Digilent Arty series.  The M.2 connector has many more pins than the PMODs provided on boards like that, and because it's designed for differential signaling, IMO it wouldn't be a bad connector choice for a cheap hobbyist dev board if you were designing one.  Not my first choice, but not bad.

The flaw in my reasoning was pointed out (as usual, thanks :-[) by @hamster_nz.  Never having worked with high-speed transceivers and PCIe, I didn't realize that those FPGA pins were dedicated and unavailable for other (non-transceiver) uses.  All of the other objections are just... weird.
 

Offline hamster_nz

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #13 on: April 15, 2020, 09:50:24 pm »
Oh, and for a final nail in the coffin... how much power does an Artix 7 200T need?

IIRC an M.2. slot has a 8.25 W limit.

My Nexys Video (with a XC7A200T-1SBG484C) needs a 36W PSU, and has a tall heat sink.

So I suspect you wouldn't be able to use most of the useful logic (eg. all the DSP blocks)


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Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #14 on: April 16, 2020, 03:15:25 am »
Yeah the hard PCIe block goes to one particular quad, and a soft IP encapsulates it. Now Xilinx does something weird inside the soft IP where the lanes are numbered backwards from what you'd expect them to be, but the lane reversal feature works as far as I know.

What I didn't think about before buying: tracing the SDRAM routing. Hopefully they didn't use any fancy board technology.

I doubt an Artix-200 can provide much useful co-processing for an up-to-date computer. For now it's just a cheap fun thing to play with. What's crazy is that the SQRL guys went on to make a board with a VU33P with HBM... For under $1K at eBay, that's a hell of a deal, and potentially a huge headache ;)
 

Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #15 on: April 18, 2020, 11:34:06 pm »
OK, so the bad news is that the board uses blind and possibly buried vias, since it's fairly high density. There may be enough traces on the back to guess where the memory traces are going and apply a process of elimination, but that would come later.

The good news is that there's a high-density connector hidden underneath the fan. Could it possibly be I/O? I don't recognize the connector type though. I need to measure the pitch of that connector and the JTAG.
 

Offline Fred27

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #16 on: April 19, 2020, 09:22:10 am »
As far as tracing pins goes would it be possible to create some simple HDL to toggle lots of them and probe output? Our would it be easier to use JTAG for it's original purpose as a test protocol? Obviously this wouldn't work for checking connections to the RAM.

That power connector may be there to supply more power than m.2 can.

I decided not to go for one, partly because I realised it wouldn't physically fit in my desktop PC. I'll be interested to see how you get on though.
 

Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #17 on: April 19, 2020, 10:29:33 pm »
I'm thinking something like a bunch of divide-by-2s and running them out to pins. Somehow I've gotten by without ever having to use JTAG Boundary Scan features but that would work too.

The big 12V connector on the carrier board goes to a 3.3V switcher to supply the M.2. There is a footprint for a diode coming from the PCIe slot 3.3V@3A, so slot-powered is a possibility. But they probably exceeded that power envelope too. Small form factors mean a lot of tradeoffs; they fit it in a 2280 board-wise but then they slap a heatpipe cooler on it. With the carrier board it takes up two slots at least, but leaves a lot of empty space that's not doing anything useful for cooling.

I think the JTAG and I/O connectors are Molex Pico-EZMate. Thankfully premade jumper cables are available, so I can initially cut them in half for pigtails.
  • Molex 0781715006, connector, 6 circuits
  • Molex 0369200603, 300 mm jumper cable
The mysterious J1 connector seems to be about 0.8 mm pitch. At this point I think it's a Hirose DF52, 20 positions. Unfortunately I haven't been able to find premade cables for this one, and crimping these tiny contacts is not going to be fun, I'm sure.
  • Hirose DF52-20P-0.8C, connector plug body
  • Hirose DF52-20S-0.8H(21)‎, connector socket SMT
  • Hirose ‎DF52-2832PCF‎, crimp terminal
Again, these are just guesses for now, will hopefully confirm in a few days.
 
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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #18 on: April 20, 2020, 02:54:46 am »
Have you determined what specific Artix-7 part it has?
 

Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #19 on: April 20, 2020, 05:50:24 am »
I don't think I'll be able to confirm until I hook up the Xilinx pod, but I expect it to be an XC7A200T. It looks like the FBG484 package, flip-chip bare die. Unfortunately it appears to be bonded to the heatsink, so I'm not going to pull it off to see the markings at least for now. There is no way to read the speed grade from inside the FPGA as far as I know.
 

Offline Fred27

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #20 on: April 20, 2020, 08:12:09 am »
I found a YouTube video where someone successfully pulls the heatsink off to add water cooling. It's possible but probably not a great idea. However, you can see it's an XC7A200T under there. Try not to shout at the screen when he describes it as "the world's most powerful FPGA".
« Last Edit: April 20, 2020, 08:19:56 am by Fred27 »
 

Offline richardbb

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #21 on: April 20, 2020, 01:43:28 pm »
The board looks very similiar to https://github.com/RHSResearchLLC/NiteFury maybe the pinout is the same
 
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Offline Wiljan

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #22 on: April 20, 2020, 02:29:04 pm »
The board looks very similiar to https://github.com/RHSResearchLLC/NiteFury maybe the pinout is the same
On the phote the "VRM" (as he call it the video) with the small heatsink (1.0V 12A are on the other side than the FPGA but pretty close and a great find  :-+
Sold as NiteFury https://www.crowdsupply.com/rhs-research/nitefury
« Last Edit: April 20, 2020, 02:37:04 pm by Wiljan »
 

Offline SiliconWizard

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #23 on: April 20, 2020, 02:55:59 pm »
The board looks very similiar to https://github.com/RHSResearchLLC/NiteFury maybe the pinout is the same

Nice find. Sold for $359.

A $25 "clone"? Yeah.
 

Offline Fred27

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #24 on: April 20, 2020, 03:33:34 pm »
It seems quite likely that SQRL ripped off the open source NiteFury. Maybe the NiteFury schematic will help! (No surprise that I had no reply from SQRL regarding a schematic.)

The original selling price for the Acorn 215 was $329. It's only selling cheap on eBay because it was a failure for cryptomining.
 


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