high speed data acquisition

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high speed data acquisition

Postby willf » Mon Jul 28, 2014 2:59 pm

Hello,
I'm interested in developing a multi-channel high speed data acqusition system for material science, rock mechnics applications etc. I'm wondering how easy would it be to interface a high speed ADC (for example a quad or Octal input ADC suchas for example Analog Devices AD9259 ADC, continuously sampling at for e.g. 40 MSPS or higher on all channels, Serial LVDS output) to a parallela board? Having got the data into the FPGA I would then like to do some real-time (or pseudo real-time processing of the data) and stream the data over the network to be stored on a server or store it locally on a hard disk array (e.g. 2 x SSDs in RAID0 configuration).

Any thoughts on the above would be welcome.

Thanks in advance,
Regards,
Will.
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Re: high speed data acquisition

Postby FHuettig » Mon Jul 28, 2014 5:17 pm

Hi Will,

The Parallella board has a high-speed Samtec connector with up to 48 GPIO pins that can be configured as LVDS pairs. If you look at the current product list here, you'll see that the "Microserver" does not have this connector, the "Desktop" has 24 pins (12 pairs) to a Zynq 7010, and the "Embedded" system provides 48 pins (24 pairs) to a larger 7020 FPGA.

-Fred
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Re: high speed data acquisition

Postby willf » Tue Jul 29, 2014 8:28 am

Thank you Fred for your comments.

In terms of interfacing an ADC to the Parallela board, it would if I'm not mistaken involve using the PEC connectors. Ideally it would be great to use an off the shelf high speed ADC module, most of which use the LPC FMC connector. Having such a connector on the board or perhaps as seperate board/daughter card with an FMC connector that could intreface to the exisitng connectors on the parallella board would be very useful. The only option I guess at this stage is to design an ADC board that has a PEC connector to interface to that on the Parallella. That's something I have no experience with.

Regards,

Will.
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Re: high speed data acquisition

Postby FHuettig » Tue Jul 29, 2014 3:03 pm

The idea of a PEC-to-FMC board has come up before, but since we only have 24 (or 12) pairs available we'd have to be careful about which pins we use on the FMC and the risk is it wouldn't be very general. Just for my curiousity, can you list a few FMC modules you'd like to connect to?

BTW: PEC = "Parallella Expansion Connector" = What I referred to as "Samtec" which is the manufacturer.
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Re: high speed data acquisition

Postby willf » Tue Jul 29, 2014 8:58 pm

Thanks for your comments again Fred.

The FMC ADC modules I've been looking at are from 4DSP. E.g a 4 channel, (14 bit resolution, 250 MSPS sampling rate) module http://www.4dsp.com/fmc.php?id=FMC104
There may be other equivalent/suitable ones out there.

Regards,

Will.
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Re: high speed data acquisition

Postby FHuettig » Tue Jul 29, 2014 9:35 pm

willf wrote:The FMC ADC modules I've been looking at are from 4DSP. E.g a 4 channel, (14 bit resolution, 250 MSPS sampling rate) module http://www.4dsp.com/fmc.php?id=FMC104

It's a problem of pin count. I think that FMC takes 14 pins (7 pairs) per channel, DDR, so that's 56 pins just for data and we only have 48 available. Add to that some clocks and a serial interface for control, and you'd have to give up a few bits per channel (or one or two channels) to make it work. Any FMC adapter we could make would not be LPC but "VLPC" (very low pin count), the challenge would be figuring out which pins to skip to make the board work with as many daughtercards as possible.
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Re: high speed data acquisition

Postby willf » Tue Aug 26, 2014 10:12 pm

Dear Fred.

I've been looking again at ways to interface high speed ADCs (e.g. quad and/or octal input) to the Parallella board. As I previously mentioned I was looking at FMC based ADCs but realise the difficulty in trying to interface this. Alternatively I've been looking at ADC evaluation boards from TI (e.g. ADS5294 an Octal Channel 14-Bit, 80MSPS, evaluation kit ADS5294EVM and the AS5263 a Quad Channel 16-Bit, 100-MSPS, evaluation kit ADS5263EVM). These eval boards do have Samtec high speed connectors (QTH-060-01-L-D-A) on them but are not compatible with the Samtec connectors (BSH-030-01-F-D-A) on theParallella board. At this stage I guess it boils down to a new ADC board design for these ADCs which isn't a trivial task or possibly designing a board to somehow interface the different Samtec type connectors. For reference I am looking at using the embedded version of the Parallella board which as you previously pointed out has 48 GPIO and the larger 7020 FPGA.
I'd appreciate any thoughts, comments you have on the above.
Thanks in advance.

Will
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Re: high speed data acquisition

Postby FHuettig » Wed Aug 27, 2014 7:57 pm

willf wrote:...Alternatively I've been looking at ADC evaluation boards from TI (e.g. ADS5294 an Octal Channel 14-Bit, 80MSPS, evaluation kit ADS5294EVM and the AS5263 a Quad Channel 16-Bit, 100-MSPS, evaluation kit ADS5263EVM). These eval boards do have Samtec high speed connectors (QTH-060-01-L-D-A) on them but are not compatible with the Samtec connectors (BSH-030-01-F-D-A) on theParallella board. At this stage I guess it boils down to a new ADC board design for these ADCs which isn't a trivial task or possibly designing a board to somehow interface the different Samtec type connectors...


Any of TIs serialized-LVDS ADCs would be a good match for the Parallella, the data rate on each pin is right for the Zynq IO and the number of LVDS pairs is small enough to work. The 8xADC has only 2 pairs (4 pins) per channel plus 2 pairs for clocks and a few for SPI. The quad-channel part might even work with the 7010 boards. Making a small board to adapt the QSH pinout of an EVM to the BSH pinout of the Parallella would be pretty easy.

The more ambitious thing would be to put one of those ADCs on a board with regulators, input circuitry, and the BTH connectors. You'd have to be careful in layout, but it's entirely possible to do. Take a look at the EVM schematics and decide which features you need or don't need, and go from there. And maybe use a differential amp like the TIs THS542x if you want DC-coupled inputs.
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Re: high speed data acquisition

Postby Mon Mon » Fri Aug 29, 2014 12:58 am

Sorry, if I'm a bit off with this suggestion, I've just received my parallella and begun my adventure into FPGA and parallel risc processing, but isn't this precisely what the DSP slices on the FPGA are designed to do? Still working towards understanding the cpu/fpga/bus architecture, so any correction on my understanding would be greatly appreciated. :)
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Re: high speed data acquisition

Postby FHuettig » Fri Aug 29, 2014 3:09 am

Hi Mon^2,

Mon Mon wrote:...isn't this precisely what the DSP slices on the FPGA are designed to do? Still working towards understanding the cpu/fpga/bus architecture, so any correction on my understanding would be greatly appreciated. :)


I'm not sure what "this" you are referring to. The FPGA has some Analog-to-Digital converters, but they are not all that fast and on the Parallella we can only use one of them because of pin constraints. The FPGA's DSP slices are integer multiply-adders.
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