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Visitor jimian_tw
Visitor
1,534 Views
Registered: ‎08-22-2016

How to setup GTH CDR for USB3 application

We are using GTH in the Virtex-7 FPGA to implement a USB3 PHY that can work together with our existing USB3 PCS and link layer designs, that has been verified with a conventional PHY chip.

Because there is no recommendation from Xilinx's official GTH guide on how to setup RX CDR for USB3 use case, I searched here and found the following reply from a Xilinx staff, that suggested referencing AR#53364:
https://forums.xilinx.com/t5/7-Series-FPGAs/V7-GTH-RXCDR-CFG-Settings-For-SSC/m-p/663518/highlight/true#M13894

 

So I applied the settings in AR#53364, but our PCS couldn't achieve symbol lock on the resulting Rx data from GTH.

Id like to try adjusting RXCDR_CFG myself, but without knowing how RXCDR_CFG works, it is hard to perform such experiments.

So I'd like to know where I can find assistance on solving such issues.

 

By the way, I found the GTR transceiver in UltraScale architecture can support USB3.0 officially:

https://www.xilinx.com/support/documentation/data_sheets/ds890-ultrascale-overview.pdf

I'd like to know if we can apply the RXCDR_CFG parameter for USB3.0 in GTR to GTH.

 

Thank you!

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4 Replies
Moderator
Moderator
1,500 Views
Registered: ‎05-02-2017

Re: How to setup GTH CDR for USB3 application

hi @jimian_tw,

 

officially Xilinx does not support usb  interface with the GTH transceivers , now coming down the GTR , GTR is associated with the processing system (PS)  so the PS supports the USB interface but not the programming logic(PL).

 

for PS you can interface  you refer the following link :

 

https://www.xilinx.com/Attachment/58277_Zynq_USB_Linux_Design_Examples_Nov2013.pdf

 

 Please mark the Answer as "Accept as solution" if information provided is helpful.
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Regards
Chandra sekhar
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Visitor jimian_tw
Visitor
1,488 Views
Registered: ‎08-22-2016

Re: How to setup GTH CDR for USB3 application


@csattar wrote:

hi @jimian_tw,

 

officially Xilinx does not support usb  interface with the GTH transceivers , now coming down the GTR , GTR is associated with the processing system (PS)  so the PS supports the USB interface but not the programming logic(PL).

 

for PS you can interface  you refer the following link :

 

https://www.xilinx.com/Attachment/58277_Zynq_USB_Linux_Design_Examples_Nov2013.pdf

 

 Please mark the Answer as "Accept as solution" if information provided is helpful.
Give Kudos to a post which you think is helpful and reply oriented.



Thanks!
It seems that you can program GTR PHY to USB3 mode using the Zynq's processing system (PS).
I'd like to know if we can apply a similar approach to Virtex-7's GTH? (i.e. What parameters in PHY should we change to support USB3 signals?)

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Moderator
Moderator
1,482 Views
Registered: ‎06-16-2008

Re: How to setup GTH CDR for USB3 application

PL based GTH transceivers and PS GTR are not same. GTR based USB3.0 is supported only with limited use case (channel loss and hardware) and have dedicated PHY controller designed in PS. The same can not be said to GTH.
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Visitor jimian_tw
Visitor
1,477 Views
Registered: ‎08-22-2016

Re: How to setup GTH CDR for USB3 application

We have implemented a PHY controller in our PCS IP, so we want to use GTH as a versatile USB3-compliant PHY to ease FPGA verification effort for the next generation of USB3 design.
Does GTR and GTH have similar CDR mechanism? If they do, I'd like to know if we can apply the CDR parameter for GTR USB3 to GTH in order to achieve sufficient Rx quality, which is a big issue for us.
Thanks!
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