Embracing a New Standard

“A promising new FPGA connectivity solution is here.”

Steve Johnson, President, Digilent, Inc.

For engineers working with FPGAs (Field Programmable Gate Arrays) for high-speed control, signal processing, or test and measurement applications, a promising new FPGA connectivity solution is here. Dubbed SYZYGY (pronounced ‘Sizz-Uh-Gee’) this emerging new standard fills the need for compact yet high-performance I/O expansion direct to the FPGA.  

Until recently, prototyping or developing new FPGA-based systems has been limited by the capabilities of the two most commonly used expansion schemes. Pmods, created by Digilent and popular on many FPGA development boards, are a common and low-cost option. FPGA Mezzanine Card (FMC or VITA 57.1), is a larger and more expensive option.  The newest is SYZYGY, a high-performance open standard from Portland, Oregon’s Opal Kelly. It fits – in cost, size, and performance – somewhere between the Pmod and FMC standards. Although not much larger than many Pmods, SYZYGY-compatible modules are capable of high-bandwidth connections to an FPGA, enabling very compact and cost-effective high performance I/O.  

The SYZYGY module (or “pod”) standard describes two variants:  a “standard” pod and a “transceiver” pod. Both use a low-cost, high-density board-to-board connector with 40-pins that are 45mm or 50mm in width – about double the width of a typical Pmod but approximately half the width of an FMC module.  Both pod types include “DNA” embedded on a microcontroller to facilitate module identification, and both include single-ended and differential signaling with up to 500Mhz throughput per pin. The transceiver pod dedicates up to 8 transceiver pairs with dedicated clocks allowing 5GHz signaling.  

At Digilent, we are working on a series of new SYZYGY-compatible modules. We’re calling these new modules “Zmods”, in conformance with our existing Pmod and Cmod naming but with a nod to the “z-heavy” SYZYGY name. When paired with our new SYZYGY-compatible base boards, customers will be able to simply plug in an application-specific module that is suited for their prototyping or testing needs, utilize our getting started demos, and be up and running in hours or days, instead of weeks or months.  We have two Zmods planned for the end of 2019 and several more in development for 2020. We’re also releasing three new powerful base boards with SYZYGY expansion capability this year.

Digilent Zmods use

Engineers and scientists rely on open standards to ensure interoperability and compatibility among a large and vibrant ecosystem of vendors, with the ultimate benefit of speeding development time and improving efficiency. We are excited about the capabilities of the new SYZYGY standard – when matched with Digilent’s Xilinx FPGA board expertise, instrumentation capabilities, and software tools, the results will drastically simplify and shorten the time it takes for engineers and researchers to develop innovative and powerful new high-speed instrumentation, control and measurements systems.   


32 Comments on “Embracing a New Standard”

  1. I would like to purchase one of the SYZYGY boards when they become available. Can you put me on a email notification list?
    Thank you.
    Frank Rose

  2. Any chance of ever getting a cable or flex pcb extension? It is quite useful sometimes to be able to take the boards physically apart but still connected for diagnostics

    1. David– SYZYGY was designed with cables in mind. Samtec provides these at a pretty reasonable cost considering their capability and quality. You can buy them direct from Samtec at any quantity and made to the length you like. There are a couple available through the Opal Kelly website as well.

  3. I remember seeing these mentioned by Opal Kelly – and being less than happy.

    One of the hard things to do with PMODS is high speed data acquisition. With a struggle, and using multiple connectors, you can find ADC solutions that run at 60 MHz to 80 MHz. Beyond that, it’s very hard to make something reliable.

    So when Opal Kelly bragged about SYZYGY peripherals, I did some checking.

    DAC: 125 MSPS, 12-bit dual channel (AD9116)
    ADC: 40 MSPS, 12-bit dual channel ( LTC2264) Huh ? I can get that with PMOD…

    If you are going to use SYZYGY connectors, PLEASE produce a decent ADC board. One that lets Xilinx compete with the like of Terasic, with their ADC-SoC board.

  4. I would recommend you to consider making an FMC-to-ZMODs adapter board to broaden the adoption of a new standard by allowing existing customers to use new addon boards with baseboards they already have.
    Also the post is talking about three new baseboards, however only two are announced – Eclypse Z7 and Genesys ZU. What’s the third one?

    1. Andrey,

      You know us – we probably have something coming down the pipeline 😉

      And regarding the “third” baseboard…wouldn’t you like to know?!

      1. Yes I would, as those two boards that were announced are like “not enough” (Eclypse) or “too much” (Genesys). I would like the third one to be somewhere in between, like Kintex/Kintex US FPGA or some Kintex-based Zynq.

  5. Yeah, after reading Opal Kelly’s licensing terms, I’m going to have to say HARD NO to this. Sorry.

    If you can’t support open/libre licenses for interfaces, I’m not interested.

    “Each party that receives a copy of this Document (“Recipient”) via any means and/or in any format acknowledges and agrees that each such Recipient is only permitted to implement and/or use this Document pursuant to a separate license agreement that the Recipient has entered into with Opal Kelly (the “Specification License”). The Document may not be used without first entering into that Specification License. Unauthorized use of this Docu-ment is strictly prohibited.”

      1. Opal Kelly grants a free license to participate in the standard with only a few simple conditions: 1) you must conform to the specification, 2) you can’t modify/revise the standard without their permission, and 3) you must properly use the SYZYGY trademark and give attribution to Opal Kelly for use of trademark. There’s lots of other legalese, but all seems intended to protect the effort and investment made in the standard by Opal Kelly and the give the users of the standard some assurance that it will be reliable and stable.

        Seems reasonable to us.

    1. Hi Samuel– The license terms are actually very similar to Digilent’s PMOD license terms. The goal is to protect consumers in the marketplace so that someone can’t release a product that claims to be SYZYGY compatible and isn’t. We recognized the need and value of making this as open as possible from the beginning.

  6. I’d be interested to see the outline spec for the two zmod’s you intend to release in the next few months – as it looks like (from the picture) its a ADC and a DAC, the number of channels, sampling rate per channel, bit depth and bandwidth would be useful.

        1. Also, are you going to release faster sampling rate zmods? I’d be interested in 1-2Gs/s per channel and 2 channels. I’d also be interested in many (8+) channels sampled at 200+Ms/s (simultaneously) and 10+ bits per sample.



          1. We envision our Zmod to be similar to our Pmod line, meaning that we develop them for a wide range of applications, including a range of sampling rates.

  7. Hmm, there’s only one Z in SYZYGY – but there are three Ys. Can we call them Ymods instead?

    On a serious note – this seems like a great thing. FMC is OK, but if you have to pay for the standard, and pay for the (expensive) connector, and pay for someone to solder it (because they are definitely not hand-soldering friendly) then it’s pretty much unusable for a hobbyist. Pmod is fine for something like I2C or SPI, but it can’t cope with either wide or fast signals. Zmod (Ymod!) has enough pins to allow for things like parallel ADCs/DACs/cameras on cheap (sub-$10) PCBs.

  8. This looks like a fantastic intermediate between PMOD and FMC. My only question is, how are we supposed to pronounce “SYZYGY”? sizeguy? sizzigee? sci-zye-guy?

    1. Fun fact – SYZYGY is actually a real word, meaning (from Oxford):
      -a conjunction or opposition, especially of the moon with the sun.
      “the planets were aligned in syzygy”
      -a pair of connected or corresponding things.
      “animus and anima represent a supreme pair of opposites, the syzygy”

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