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Explorer
Explorer
455 Views
Registered: ‎04-19-2018

AXI interface to GTH

 

I've been using the Wizard-generated GTH transceiver for demonstration and eye diagram measurements.

Now it's time to do something useful. I need to input/output data from it, I assume AXI-Stream is the logical choice.

Is there any guidance on how to do that?

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Xilinx Employee
Xilinx Employee
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Registered: ‎03-30-2016

Hello

GTH transceiver is not using AXI stream for data interface.
( Please see also UG576 Chapter3 and Chapter4 "TX/RX interface" section)

The data interface will be different, depending on your GTH configuration.
( For example 8B10B encoding vs RAW data )
You would probably want to generate GTH with your configuration , and run Example Design simulation to observe the behavior.

For GTH Example Design , please see also PG182 Chapter5/6 for a start point.


Regards
Leo

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Explorer
Explorer
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Registered: ‎04-19-2018

 

I know. That's what I want to achieve. To add an AXI-Stream interface to it. Otherwise is not much useful.

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Xilinx Employee
Xilinx Employee
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Registered: ‎10-19-2011

Hi @satguy ,

how about using an IP like Aurora?

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350 Views
Registered: ‎07-23-2019

 

@eschidl 

that's a good suggestion, unfortunately, I've been asked the 8b10b encoding to be optional. If there were a way for Aurora to send raw data (that I would encode and ensure there is no DC bias) then I would certainly ditch the GTH wizardry without tears besides those of joy. 

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Xilinx Employee
Xilinx Employee
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Registered: ‎10-19-2011

Hi @archangel-lightworks ,

okay, that reduces your options quite a bit. I guess 64b66b encoding is optional too :).

With raw data I do not know of an IP myself that would provide AXI access. Maybe you could reuse parts of Aurora there. AXI is just the outer layer there.

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Registered: ‎07-23-2019

 

I started on the AXI interface from the example. It is not a big deal, actually. It's just how long debugging it until reliable enough can be.

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Explorer
Explorer
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Registered: ‎08-14-2013

The GTH transceiver is just a serializer. It accepts new data on every clock cycle. So you could consider it as an AXI stream endpoint that always has tready = 1 and expects tvalid continuously high. In general, you'll want to have some sort of a 'shim' in between the transceiver and your AXI stream interface that can properly encode/scramble the data as well as include framing information. You could use an Ethernet PHY for this, or Aurora, or roll your own that does something similar. Presumably you would need the same thing on the other end as well to pull the data back out and get it back into an AXI stream interface.