high speed data acquisition

Sub forum for Parallella daughter cards and accessories

Moderator: Folknology

Re: high speed data acquisition

Postby willf » Wed Sep 03, 2014 3:11 pm

Thank you Fred for your comments on the TI serialised-LVDS and high-speed connectors. I've also been looking at Linear Technology serial LVDS ADCS.
I've received my new Parallella (embedded) board today, very excited about that. I've ordered some ADC evaluation boards as well so looking forward to trying to get all of this to work together.

Another questiuon I have is how easy would it be to interface the parallella board to a mini-itx board? I've come across that article "My Name is Brian and I Build Supercomputers in My Spare Time", I'm sure you've read it too, where he mentions "since they (i.e. parallella boards) have relatively limited storage and memory, I added two Intel NUCs. Each NUC has 1x Intel i3, 16GB RAM, 120GB SSD". For my data acqusition application I would like to continuously stream data from the ADCs to the FPGA and from theere to host memory and to a disk array (e.g. RAID0). I've been looking at a Kontron mini-itx board (http://www.kontron.com/products/boards- ... cification). Do you reckon it would be possible to interface the parallela to the mini-itx board (Brian has done this with his application and the NUCs but don't know how he has done it) and if so how?

Thank you in advance Fred.

Will.
willf
 
Posts: 11
Joined: Mon Jul 28, 2014 2:49 pm

Re: high speed data acquisition

Postby 9600 » Thu Sep 04, 2014 9:27 am

willf wrote:(Brian has done this with his application and the NUCs but don't know how he has done it) and if so how?


Using Ethernet and this is by far the simplest solution. If you had another host with an FPGA you could implement an Epiphany Link (eLink) and connect this to the Parallella's PEC_NORTH or PEC_SOUTH. Of course, you could also implement some other interface in the Zynq PL and connect via PEC_FPGA to the other host.

Regards,

Andrew
Andrew Back (a.k.a. 9600 / carrierdetect)
User avatar
9600
 
Posts: 997
Joined: Mon Dec 17, 2012 3:25 am

Re: high speed data acquisition

Postby willf » Thu Sep 04, 2014 1:21 pm

Thank you for your reply Andrew.

I would like ideally to have several Parallella (embedded) boards, with for example a 4 channel high speed ADC board connected to each one. I could then I guess have these and the mini-itx board connected to a GbE network switch. I would like to somehow have the mini-itx board control the parallella boards, when to start the data acqusition etc. and to also handle and store the data streamed from the PArallella boards.

Any thoughts you have on this would be welcome.

Thanks in advance.

Regards,
Will.
willf
 
Posts: 11
Joined: Mon Jul 28, 2014 2:49 pm

Re: high speed data acquisition

Postby 9600 » Thu Sep 04, 2014 7:12 pm

willf wrote:I would like to somehow have the mini-itx board control the parallella boards, when to start the data acqusition etc. and to also handle and store the data streamed from the PArallella boards.


For storage you could have the Mini-ITX board provide network storage such as NFS or iSCSI, which the Parallella boards mount. Or the former could run some sort of server process that the latter streams data to. There are likely many different ways you could do this and which is the best will depend on the application and requirements.

For the control part it again depends on specific requirements and there are a great many different ways you could do this. For example, you could simply use rexec, rsh or SSH, or if your apps were written in Java you could use RMI, and other languages will have their own methods. Or you could use Linux clustering and remote job scheduling tools.

Neither of these things are Parallella-specific and I'd probably look into clustering and associated software.

Regards,

Andrew
Andrew Back (a.k.a. 9600 / carrierdetect)
User avatar
9600
 
Posts: 997
Joined: Mon Dec 17, 2012 3:25 am

Re: high speed data acquisition

Postby willf » Thu Sep 04, 2014 10:37 pm

Thanks Andrew for those ideas.

How easy would it be to link multiple parallella boards together?
One of the data acquisition ideas I have is for multiple channel triggering. It may be necessary to have for example three ot more parallela boards each with a 4 channel ADC board. So if I have a total of 12 channels (i.e. 3 parallella boards each with a 4-ch ADC board) and wanted to trigger on for example any of the 12 channels (whether it's triggering on a single channel or on multiple channels) all the channels (FPGAs) would somehow need to be linked even though they are on seperate boards.
Is there a way to do this? I've come across on one of the parallella forums a discussion about the elink cables. Is this the solution? How would it physically work between multiple (3 or more) boards?

Thanks in advance.
Regards,
Will.
willf
 
Posts: 11
Joined: Mon Jul 28, 2014 2:49 pm

Re: high speed data acquisition

Postby 9600 » Fri Sep 05, 2014 7:19 am

willf wrote:How easy would it be to link multiple parallella boards together?


See my previous reply.

all the channels (FPGAs) would somehow need to be linked even though they are on seperate boards.


I'd suggest a "backplane" PCB that routes PEC_FPGA pins from one board to another.

Is there a way to do this? I've come across on one of the parallella forums a discussion about the elink cables. Is this the solution? How would it physically work between multiple (3 or more) boards?


Cables turned out to be too stiff and risked putting excessive force on connectors/boards.

As I say, I would suggest a backplane PCB, which could connect from FPGA->FPGA if you need to do some sort of low latency sync/trigger, and the same board could also route PEC_NORTH/PEC_SOUTH from one board to another for Epiphany->Epiphany communications — as I previously suggested.

Since Parallella is an open source design (board and FPGA RTL) you should be able to work out a solution for your particular requirement by studying the documentation, design and HDL source.

Regards,

Andrew
Andrew Back (a.k.a. 9600 / carrierdetect)
User avatar
9600
 
Posts: 997
Joined: Mon Dec 17, 2012 3:25 am

Re: high speed data acquisition

Postby kaklik » Tue Sep 09, 2014 7:02 pm

Hello,

I have explored high speed connection of various ADCs to Parallella in my diploma thesis http://www.mlab.cz/Designs/HAM%20Constructions/SDRX02B/DOC/2014-05-12KakonaDiplThesisCTU-Prague.pdf few months ago. It seems to be the best solution to use SATA or SAS cables and differential signaling. SATA connectors may be connected to Parallella via an adapter board similar to Porcupine, but optimized for differential signaling. The adapter board even allows mounting of Parallella board to the MLAB's http://wiki.mlab.cz/ base board.
Such design allows use different number of ADC channels (optimized for experiment) and even various ADC types. I have tested this idea on LTC2271 and LTC2190 ADCs with combination of ML605 FPGA development board (Parallella board was not available in time in which I was writing the thesis).
kaklik
 
Posts: 3
Joined: Tue Sep 09, 2014 12:36 pm

Re: high speed data acquisition

Postby G4GUO » Tue Nov 11, 2014 10:23 pm

Hi,
Some time ago I bought an ADC evaluation card from Analog Devices
http://www.analog.com/en/analog-to-digital-converters/ad-converters/ad9253/products/EVAL-AD9253/eb.html
with the idea of making a 4 channel diversity receiver. Initially I tried a low en Xilinx FPGA board with FMC connector.
(The interposer board has to be modified to work with the Xilinx dev boards). While I had no problem getting data into the
dev board I ran out of resources.

With the arrival of the Parallella board I thought I would revisit this again. So at the moment I am in the process of deciding
the best way to connect the two. The PEC GPIO has enough differential IO on it to do the job. The board requires 2 lanes per
ADC channel a Data clock and a Frame clock plus some I2S.

Digikey stock the 80 pin TE Connectivity 2065769-1 used on the ADC board (they are very expensive at $20 each).
I think consuming all 4 channels will be a bit too much for a single Parallella board (8 GBits/s) so my current thinking
is to split the data and use 4 Parallella boards (eventually interlinked). I will however try to get it to work with
just one board before I waste more time and money on it.

I have not fully decided the topology of the system but I am leaning towards splitting the output of the ADC
on a custom board to 4 HDMI connectors, then another small custom board with HDMI and Samtec connectors.
Then using 4 HDMI cables to connect each of the Parallella boards. The cables will be the shortest ones I can
find to cut down on cable mismatching / losses. The Parallella boards would do some pre-processing
(DDC) then output that to a PC using 4 x 1 Gigabit Ethernet links where further processing would be done using
NVIDIA CUDA

This is a very long term project but I will follow this thread with interest. I am sure someone will come up with a
"I wish I had thought of that" idea. the system needs to be expandable so I can add more receivers (as cash allows).

Something like this looks interesting to do (click on overview)
http://dxatlas.com/dxmath/emvs/

- Charles
G4GUO
 
Posts: 6
Joined: Tue Nov 11, 2014 3:05 pm

Re: high speed data acquisition

Postby voyager » Wed Sep 16, 2015 8:37 pm

Hi
Sorry guys if I post wrong place please somebody help me I want to connect an adc chip with 14 pairs lvds port but my parallella has only 12 pairs! I need just two pairs more :D and embedded version price is high! how could we manage this problem? Any suggestion would be appreciated!
tnx
voyager
 
Posts: 8
Joined: Wed Sep 16, 2015 8:01 pm

Previous

Return to Daughter Cards & Accessories

Who is online

Users browsing this forum: No registered users and 2 guests

cron