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vhdlveri123
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Registered: ‎04-21-2021

FAR END LOOPBACK AURORA

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Hi,

I have to see the transmission between two GTH Transceivers in the same board. I need t use a loopback cable i assume with far end loopback right or should i use near end loopback mode?

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ghasemi_r
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Registered: ‎05-07-2018

take a look at this web page

https://electronics.stackexchange.com/questions/544216/difference-between-pcs-and-pma-loopback-in-transceivers#:~:text=The%20near%2Dend%20loopback%20modes,far%20end%20of%20the%20link.&text=Far%2Dend%20PCS%20loopback%3A%20full,of%20the%20link%20is%20a....

far end and near end loop back are internal loopback

so in my opinion you should not set in this two mode

Choose the "none" option, you want to communicate through cable.

your test is loop back externally, definitely it is loop back from your point of view but the board can not understand that. it is like connection between 2 boards.

of course, there is a difference, when you set link between Tx and RX of 1 board, Eye diagram has better performance than 2 different boards. 

 

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roym
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Registered: ‎07-30-2007

One of the GT's would normally be put into far end loopback to reflect data back to the other through the cables.  If you have only one GT you would use either cable loopback or Near End PMA loopback.  It is possible to have one send known data that the other is set up to receive - sending PRBS-7 for instance.  You could have them both set up to send the example design data but in that case you need to make sure the TX's are reset before the RX's so that there is good stable data coming in for the RX to reset to.  




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vhdlveri123
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Registered: ‎04-21-2021

So what u meant to say is, if i am connecting two GTs , then the data can be received by one of the GTs if its properly set up? Whats the meaning of this set up?

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ghasemi_r
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Explorer
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Registered: ‎05-07-2018

take a look at this web page

https://electronics.stackexchange.com/questions/544216/difference-between-pcs-and-pma-loopback-in-transceivers#:~:text=The%20near%2Dend%20loopback%20modes,far%20end%20of%20the%20link.&text=Far%2Dend%20PCS%20loopback%3A%20full,of%20the%20link%20is%20a....

far end and near end loop back are internal loopback

so in my opinion you should not set in this two mode

Choose the "none" option, you want to communicate through cable.

your test is loop back externally, definitely it is loop back from your point of view but the board can not understand that. it is like connection between 2 boards.

of course, there is a difference, when you set link between Tx and RX of 1 board, Eye diagram has better performance than 2 different boards. 

 

View solution in original post

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vhdlveri123
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Registered: ‎04-21-2021

So do i need to use two AUrora IP for this?

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ghasemi_r
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Explorer
381 Views
Registered: ‎05-07-2018

No 

Aroura has Tx and Rx 

and you need to have one IPcore 

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vhdlveri123
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Explorer
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Registered: ‎04-21-2021

Yes, but for far end loop back, i have to set the far end GTH to that mode, how will i do that?

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ghasemi_r
Explorer
Explorer
367 Views
Registered: ‎05-07-2018

sorry, 

don't realize what you mean.

when you use far end loopback, signal is not coming from cable.

it loopback internally