Author Topic: SQRL Acorn as an interesting Artix-7 board?  (Read 6354 times)

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Offline MattSR

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #75 on: July 14, 2020, 03:34:53 am »
This has to be the cheapest way to get an Artix-7-200T FPGA dev board.
 

Online NiHaoMike

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #76 on: July 15, 2020, 04:32:15 am »
How easy is it to get the board communicating via PCIe to some userspace program on the PC connected to it? If I understand correctly, the differential inputs could be connected as a HDMI input using a cheap HDMI "repeater" as a buffer, even if it doesn't actually use HDMI protocol. Could be a way to get a cheap 4K HDMI capture card (not counting the cost of development time, of course) that can also work to accept all sorts of high speed data streams, with plenty of its own memory for buffering and logic for offloading some processing from the PC.

Too bad there aren't any fast ADCs that I'm aware of that will be able to interface with the limited number of I/Os available, could make a really nice SDR coprocessor otherwise.
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Offline james_s

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #77 on: July 15, 2020, 05:01:11 am »
It would sure be nice if the designers of boards like this would bring out a bunch of the extra IO to pads on the PCB. The added cost of manufacture would be essentially zero and it would enable the board to be repurposed into something far more useful when it inevitably becomes obsolete for the original intended purpose.
 
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Online Fred27

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #78 on: July 15, 2020, 07:00:43 am »
PCIe is the feature that makes this board interesting. I've been trying to get Project-0 PCIe
example from the NiteFury repo working. I'm struggling with the Xilinx xdma driver side of things. I've even gone as far as downgrading the Linux kernel on Ubuntu 18.04. Has anyone got this working or have any tips to do so?
 

Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #79 on: July 17, 2020, 07:18:59 am »
Getting PCIe register peek-poke is fairly straightforward, it's DMA where you have to get into trouble with (sometimes proprietary) cores and drivers. I am more interested in the LiteX ecosystem's DMA solution rather than messing with Xilinx XDMA. Maybe in a few weeks I'll have more time to work on it.

The FPGA has a temperature sensor, and the temp sensor in the power controller is connected to one of the ADC channels on the FPGA. To read the internal temp and any external analog signals, you use this block called the XADC, which I think you can either instantiate as an IP or write a sort of wrapper around (see UG480).

This family of FPGA doesn't have an auto temp shutdown so I would be careful running without a fan. You can also see the temperature through the Hardware Manager if you have a dongle.

 

Offline MattSR

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #80 on: July 21, 2020, 01:00:04 am »
So basically, it's possible to burn one out by driving it too hard with inadequate cooling?

This family of FPGA doesn't have an auto temp shutdown so I would be careful running without a fan.
 

Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #81 on: July 21, 2020, 05:49:27 am »
It's possible though admittedly you'd need to have a fair amount of stuff ticking away.  Just do your due diligence ;)
 

Offline conmega

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #82 on: July 26, 2020, 06:10:34 am »
Ordered up boards for my SQRL root complex use case.
Will let everyone know:
A) How JLCs 4 layer process comes out
B) If I am competent enough to have a working board

Hopefully there aren't too many delays in getting all the parts and boards in.
 
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Online NiHaoMike

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #83 on: July 27, 2020, 12:03:44 am »
Could LVDS encoders/decoders be an easy workaround to the limited I/O problem?
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Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #84 on: July 27, 2020, 06:55:56 am »
Looks neat conmega, good luck with the build  :-+

Could LVDS encoders/decoders be an easy workaround to the limited I/O problem?

Of course, but it all depends on your application. (Ignoring the gigabit transceivers) If you're aiming for the high end, a -3 grade LVDS pair can handle 1250 Megabits/sec, so 6x that is the hard limit as far as data transfer goes. Plus your downstream device would need to be able to handle that kind of rate. You could even slap on another FPGA, but at some point add-ons eclipse the original in terms of complexity and you might as well start over from scratch...

Maybe an iCE40 breakout would be useful for people who need more I/O, but don't have large bandwidth requirements.
 

Online NiHaoMike

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #85 on: July 27, 2020, 01:54:54 pm »
I was thinking use a LVDS encoder to connect a fast ADC so that the board could be used as a SDR.
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Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #86 on: July 29, 2020, 09:19:55 am »
Do you have any parts in mind? I took a look around Digikey and saw mostly display link serializers.

I think though that for the price of a few serializers, you could get a small Spartan-7 or similar and have that manage the interface.
 

Offline dmendesf

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #87 on: July 29, 2020, 12:47:41 pm »
There are fast ADCs with LVDS outputs, for example ADS6149.
 

Online NiHaoMike

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #88 on: July 29, 2020, 01:15:22 pm »
There are fast ADCs with LVDS outputs, for example ADS6149.
Except it has more LVDS pairs than the Acorn has available.
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Offline dmendesf

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #89 on: July 29, 2020, 01:45:51 pm »
How many LVDS pairs are available? I also bought one of these boards... Not planning to do SDR but fast data aquisition for other purposes, but I'm still searching for a suitable mini-itx board. Maybe I'll wait for Ryzen 4000 APUs broad deployment.
 

Offline dmendesf

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #90 on: July 29, 2020, 02:07:04 pm »
LTC2387-18 is a 18bit, 15MSPS with single LVDS lane output. Still need to connect conv, clock, etc but maybe these can be output as single ended and then converted to differential. I Know that 18 bits is not interesting for SDR (12 bits at 30MSPS would be better) but for now that's what I found for a single lane. There's also the JESD output converters...
 

Online NiHaoMike

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #91 on: July 29, 2020, 10:58:01 pm »
How many LVDS pairs are available? I also bought one of these boards... Not planning to do SDR but fast data aquisition for other purposes, but I'm still searching for a suitable mini-itx board. Maybe I'll wait for Ryzen 4000 APUs broad deployment.
4 pairs specifically marked as LVDS plus another 2 that are shared with the auxiliary header. (Why they didn't dedicate another 4 pins to the header is strange, there's so many extra pins...)

Then there are up to 3 more TX pairs and 3 more RX pairs (all of them really fast) if you're willing to downgrade the PCIe to a x1. Might actually do that by modifying one of my cheap PCIe extenders, x1 is the best those really cheap extenders can do anyways.
LTC2387-18 is a 18bit, 15MSPS with single LVDS lane output. Still need to connect conv, clock, etc but maybe these can be output as single ended and then converted to differential. I Know that 18 bits is not interesting for SDR (12 bits at 30MSPS would be better) but for now that's what I found for a single lane. There's also the JESD output converters...
Not sure about you but if I were to go through the effort to use a PCIe connected FPGA, I would like far more bandwidth than what a super cheap FX2 based solution can do.
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Online NiHaoMike

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #92 on: July 30, 2020, 11:31:50 pm »
A quick search finds this LVDS serializer/deserializer:
https://www.ti.com/product/DS92LV16
As well as this one that has a pair of serializers, but in a not so hobbyist friendly BGA package:
https://www.ti.com/product/SCAN921821

Looking through the datasheets, they just seem to be super fast UARTs.
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Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #93 on: August 02, 2020, 08:27:54 am »
The SCAN921821 is interesting since you could do 18 bit I+Q at up to 62.5 MHz with just one chip. Doesn't seem available in small quantities from anywhere except direct from TI though. It's also LVCMOS/TTL in, but that's fine.

The real challenge is doing the receive side. You'd have to build the "DES" part of a SERDES in the FPGA. The PLL in the Rx side needs to track the PLL in the Tx side well enough for the data to come through. I don't know if that's a realistic goal. The first trouble is getting the ADC clock into the FPGA. The bank where the 4 LVDS are doesn't have the clock-capable pins broken out. The bank with the 2 LVDS does, but those are attached to the LEDs. So you'd need to see if the clocking is feasible and/or realistic.

I actually didn't know that splitting up the GTs in a quad was possible. Using the GTs might perhaps be simpler but due to shared resources there are restrictions per AR62267. The quad doesn't have the second refclk input broken out so we might be restricted to the PCIe refclk (100 MHz).
 

Online NiHaoMike

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #94 on: August 20, 2020, 03:31:44 am »
Just thought of this, could the PCIe interface act as a x2 device and x2 host simultaneously? Might make a cheap PCIe analyzer. I also wonder if it could be possible to implement USB 2.0 device on the aux header for connection to another PC that's hosting the UI.
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Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline denger

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #95 on: September 17, 2020, 10:09:41 pm »
I managed to build the demo FPGA-A200T-3 project included in the NiteFury git repo. Took a bit tinkering with latest vivado. Loaded it on the CLE-215+, and it's recognized by the driver. It even passes XDMA tests, sometimes. About every 6th test returns bad data. It's usually in the 18th bit, which gets flipped.
I suspect the clocking of memory is at fault. Initially project sets the clock at 1850ps, which is outside the range that the IP wizard dialog wants.
I have tried 3077ps (So I can get exactly 200Mhz input)  and it does much better as far as error rate, but still not perfect. With that setting I get about 1 in 20 tests fail, same failure mode.
Anyone managed to get the XDMA tests to reliably pass? Would you kindly share the parameters for the mig_7series core you made to run?
 

Offline miken

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #96 on: September 20, 2020, 08:33:34 pm »
I managed to build the demo FPGA-A200T-3 project included in the NiteFury git repo.
You may actually be the farthest along ;)

I haven't looked at the XDMA project. Try something slow like 2:1 mode, 2500 ps.
 

Offline fanoush

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #97 on: September 21, 2020, 10:58:26 am »
Hello anyone got more of those molex  Pico-EZmate  jtag cables and could ship one inside EU in a letter/envelope and accept paypal? Sadly mouser/digikey/arrow has quite expensive (>$20) shipping for this ~$3 item.
 

Online Fred27

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #98 on: September 22, 2020, 09:16:00 am »
I've got a spare. PM me your address an I'll send you one.
 

Offline fanoush

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Re: SQRL Acorn as an interesting Artix-7 board?
« Reply #99 on: Yesterday at 06:52:48 am »
Great, thank you very much,  so with the cable on a way to me I've ordered one from here https://www.ebay.com/itm/Acorn-CLE-215-Artix-7-FPGA/193672183164 The prices are not that low anymore but this one still looks good to me, seen it for 70EUR few weeks ago. And it is the 215+ !

Wanted to try LiteX on it but now I see someone already got it working :-) https://spoolqueue.com/new-design/fpga/migen/litex/2020/08/11/acorn-cle-215.html  https://twitter.com/enjoy_digital/status/1257985111469015040
 


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