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Explorer
Explorer
4,061 Views
Registered: ‎03-31-2016

7-series GTX TXN/TXP and RXN/RXP issue

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Hello

 

I want to used 7-series transceiver IP.

 

Why does TXN/P connect RXN/RXP?

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Scholar u4223374
Scholar
7,052 Views
Registered: ‎04-26-2015

Re: 7-series GTX TXN/TXP and RXN/RXP issue

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@quincyq2003 That makes sense. You want the transmitter on one board (TXN/TXP) connected to the receiver (RXN/RXP) on the other board. That way you can transmit data from one and receive it on the other.

 

If you connected TXN/TXP on one board to TXN/TXP on the other board then they'd both be trying to drive the same lines, and damage may occur. If you connected RXN/RXP on one board to RXN/RXP on the other board then neither could drive the lines (because the receiver cannot provide an output); you wouldn't cause any damage but you also couldn't transmit any data.

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Scholar u4223374
Scholar
4,057 Views
Registered: ‎04-26-2015

Re: 7-series GTX TXN/TXP and RXN/RXP issue

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Where does TXN/P connect to RXN/P? Which document are you looking at?

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Explorer
Explorer
4,049 Views
Registered: ‎03-31-2016

Re: 7-series GTX TXN/TXP and RXN/RXP issue

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Hello @u4223374

 

In PG-168 7 Series FPGAs Transceivers Wizard v3.6 document page 129 description.

 

https://www.xilinx.com/support/documentation/ip_documentation/gtwizard/v3_6/pg168-gtwizard.pdf

 

GTX.PNG

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Scholar u4223374
Scholar
7,053 Views
Registered: ‎04-26-2015

Re: 7-series GTX TXN/TXP and RXN/RXP issue

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@quincyq2003 That makes sense. You want the transmitter on one board (TXN/TXP) connected to the receiver (RXN/RXP) on the other board. That way you can transmit data from one and receive it on the other.

 

If you connected TXN/TXP on one board to TXN/TXP on the other board then they'd both be trying to drive the same lines, and damage may occur. If you connected RXN/RXP on one board to RXN/RXP on the other board then neither could drive the lines (because the receiver cannot provide an output); you wouldn't cause any damage but you also couldn't transmit any data.

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Explorer
Explorer
4,016 Views
Registered: ‎03-31-2016

Re: 7-series GTX TXN/TXP and RXN/RXP issue

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Hello @u4223374

 

If FPGA TXN/TXP connect to FPGA  RXN/RXP, have any benefit?

 

If FPGA TXN/TXP not connect to FPGA  RXN/RXP, have any impact?

 

 

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Scholar u4223374
Scholar
4,012 Views
Registered: ‎04-26-2015

Re: 7-series GTX TXN/TXP and RXN/RXP issue

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The document you've referred to is explaining how to connect one FPGA (FPGA1) to another FPGA (FPGA2).

 

If you do connect FPGA1 TXN/TXP to FPGA1 RXN/RXP (ie one FPGA connected to itself) then you have created a loop-back, which is useful for testing signal integrity but has no practical purpose.

 

If you do connect FPGA1 TXN/TXP to FPGA2 RXN/RXP (ie one FPGA connected to another FPGA) then you can send data from FPGA1 to FPGA2.

 

If you don't connect FPGA1 TXN/TXP to FPGA1 RXN/RXP (ie one FPGA not connected to itself) then this is how a circuit would normally be designed - as above, there's no practical purpose to connecting them.

 

If you don't connect FPGA1 TXN/TXP to FPGA2 RXN/RXP (ie one FPGA not connected to another FPGA) then obviously you can't send data between them. You need to connect them if you want to send data.