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How to use K24 Syzygy ports when the GTR pins are only mapped to PS?

glenncb

I'm trying to map the K24 IO carrier Syzygy TXR pins but I've hit an issue that I don't know how to work around and wanted to see if anyone has a suggestion.  Pins 5-13 and 15 of the Site 1 and Site 2 HSIO ports appear to map to GTR pins which are locked to the PS DisplayPort signals.  I though this was a standard SZG TXR port, but it appears to be some custom non-Syzygy port, perhaps only for use with the Avnet provided peripherals?  I'm trying to use a 3rd party Syzygy device and I don't see any way to make this work.  If there is no workaround, then the HSIO "Syzygy" ports are fairly useless on this board.

  • 0

    What are you trying to map to these ports? The K24 module does not contain PL based transceivers. Only GTR transceivers map to this MPSoC. You will be limited to implementations of the GTRs, ie PCIe, Display Port, USB3, SATA.

  • 0 in reply to iksevas

    I was trying to connect a Digilent ADC 1410 module to the site 1 port, using a custom PCB to convert from the Syzygy-TXR connector to the Syzygy-STD connector.  There were 10 pins on the port hard wired to the PS GTR pins.  The rest appear to be useable.  The chart below shows the conflicting GTR pins:

    image

    The pins in red are the conflicting ones.  To workaround the issue, I'm developing a custom PCB to remap pins from Site 1 + Site 2 to a single Syzygy-STD port by mapping those pins in conflict to non conflicting pins from Site 2.  That should give me one usable Syzygy-STD port until I can design my own custom carrier.

    image

    The trace length for the pins coming from Site2 will be substantially longer, so probably not useable for any high speed signals but should be ok for the Digilent ADC as those pins are mostly low speed controls (gain, ac coupling, etc).

    -GlennCB

  • 0 in reply to glenncb

    There are 28 I/O that make up SYZYGY STANDARD PINOUT (Not accounting for 2x clock pairs and I2C). There are 18 I/O that make up a SYZYGY TXR PINOUT (not accounting for 2x clock pairs and I2C). That converter board should be relatively simple. The NET LENGTH report for the KIT shows that the length to the two TXR sites are tuned, so you should be able to length tune the conversion from TXR to STD to maintain performance if desired.

    It's difficult to design a product to get the most available features that will work for the majority of people. That's the challenge with expansion interface specifications in general. My assumption / expectation is that people would develop their own add-on cards for quick prototyping, ie - like this converter board for you to mate to an off-the-shelf solution or a custom add-on card to bolt onto the one or both of the expansion connectors with whatever custom interface they can think of.

    An option for you could have been ZUBoard if you were targeting the STANDARD port as it has one of them on the board. This takes you away from the K24 SOM though. The K24 Development Kit was designed with ZUBoard as the form factor and there simply was not enough I/O to make a STADNARD port from.