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Adventurer
Adventurer
4,761 Views
Registered: ‎05-15-2014

GTX data rate

hello

 

I am trying to transmit mass data from a VC707 board to another VC707 board via GTX at 10 Gbits/sec.

 

To do so, first, I worked with a single VC707 board.

I connected the differential RX ports of GTX on SMA connectors to the differential TX ports of GTX on SMA connectors.

Using a single Transceiver IP for both transmit and receive, I observed data transfer at 10Gbits/sec without any error.

 

Then I started to use both of the VC707 boards.

I cross connected the RX ports of the boards to TX ports of the boards.

At 6.25 Gbits/sec, while sending comma characters only I observe erroneous bytes at receive sides of both boards.

However at 4 Gbits/sec, while sending comma characters only I do not observe any erroneous bytes at receive sides of both boards.

In the figures below you can find the received signal patterns measured differentially from RX ports of GTX

 

at 4Gbits/sec

1.jpg

  

at 6.25Gbits/sec

2.jpg

  

I am using 40cm RF cables of which phase latency are almost same.

The grounds of the boards are not necessarily matched since the signals are AC coupled.

Should I change any parameters while tranmitting from one board to the other?

 

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5 Replies
Xilinx Employee
Xilinx Employee
4,748 Views
Registered: ‎02-06-2013

Re: GTX data rate

Hi

 

Are you using any specific protocol for these tests or is this a custom protocol.

 

Can you try using the 10G Ethernet subystem to test your 10Gbs data rates.

Regards,

Satish

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Xilinx Employee
Xilinx Employee
4,746 Views
Registered: ‎02-14-2014

Re: GTX data rate

Hello @fatih.aydogdu,

 

Can you share .xci file to know the details about your IP customization?

Regards,
Ashish
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Adventurer
Adventurer
4,721 Views
Registered: ‎05-15-2014

Re: GTX data rate

hello

 

first of all, the problem I mentioned is not related with the protocol since the receiver does not take the comma bytes correctly.

I mean there is problem even if the transmitter sends only comma bytes not data bytes.

 

I do not use specific protocol. Instead I use simple protocol which is verified when I use single VC707 board for data transmission.

The verified simple protocol is like this.

 

state 0: send 4 bytes of comma, make read enable of data fifo 1, state<=state+1.

state 1: send 4 bytes of comma, make read enable of data fifo 0, state<=state+1.

state 2: send 4 bytes of comma, if valid data from fifo buffer 512 bit data from fifo to be send and go to state 3.

                                                    if not valid go to state 0.

state 3-17:  send 4 bytes of data, state<=state+1

state 18:  send 4 bytes of data, state<=0

 

I am also attaching the .xci file.

 

best regards

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Moderator
Moderator
4,550 Views
Registered: ‎02-16-2010

Re: GTX data rate

It seems you enabled DFE equalizer. Check by enabling LPM.
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Adventurer
Adventurer
4,431 Views
Registered: ‎05-15-2014

Re: GTX data rate

Hello

 

Actually, I was using LPM-Auto Mode for RX Equalization.

I tried to use DFE-Auto Mode for RX Equalization which increased the amount of erroneous comma values received.

Eventhough I still receive receive erroneous comma values in LPM-Auto Mode, LPM-Auto Mode is more successfull.

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