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Contributor
Contributor
638 Views
Registered: ‎07-25-2018

Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi,

I am currently working on Gigabit Transceiver and able to send & receive data between two boards(KC705(GTX) to ZC102(GTH)).
We are receiving comma character and rxcharisk in first board while programming second board and our fabric logic implemented on receiver board side  depending on COMMA character & RXCHARISK .
Is it expected ???

How to know whether comma character is detected on receiver other than Rxcharisk signal???

Thanks & Regards

Pradeep

 

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17 Replies
Xilinx Employee
Xilinx Employee
616 Views
Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

For 7 series GTX, 

rxcommadet indicates comma is detected. this is asserted earlier than the BC is presented to rxdata.

rxcharisk indicates an K character is received.

rxchariscomma indicates comma is identified by 8b10b decoder.

 

For US GTH,

rxcommadet is the same.

rxcharisk mapped to RXCTRL0

rxchariscomma mapped to RXCTRL2.

 

Thanks,

Boris

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Contributor
Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq 

Thanks for reply,

But my doubt is that both comma character and rxchariscomma shouldn't be detected in the other board (eg.,KC705) while programming the first board (ZCU102) when they are connected by SFP cable?

We observed the same behaviour while programming kc705, comma character and RXCTRL2  are getting detected in zcu102.

As suggested above in my post, we entirely depend on comma character and rxchariscomma  detection for our PL fabric logic and our functionality fails due to this false detection. Kindly let us know if this is  an expected behaviour and how to take care it.

Thanks & Regards,

Pradeep

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

this is not expected. 

does rxbyterealign assert?

how many commas did one board receive during the programming process for the other board?

maybe you can put some ILA waveforms with the following signals.

rxdata

rxdataisk

rxbyteisaligned

rxbyterealign

 

Thanks,

Boris

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Contributor
Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq ,

Thanks for reply,

I have captured ILA signal as per your suggestions

snap30.JPG

 

snap31.JPG

I have also observed that without connecting SFP cable to KC705 board  it is receiving comma character(BC) and rxchariscomma(1) as shown in above waveform.

Thanks & Regards

Pradeep

 

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Xilinx Employee
Xilinx Employee
578 Views
Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

did you check LOOPBACK[2:0] input port?

is it 000 or something else?

 

Thanks,

Boris

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Contributor
Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq 

Thanks for reply,

I checked the value of  LOOPBACK[2:0] input port  it is 000.

Thanks & Regards,

 Pradeep

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Xilinx Employee
Xilinx Employee
568 Views
Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

how did you check this?

did you open Implemented design and check the LOOPBACK ports connection?

 

Thanks,

Boris

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Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq ,

Thanks for Reply,

I didn't enable Loop back port option  in GTX IP.

So i checked gtxe2_i channel in verilog file it is connected to 000.

//----------------------------- Loopback Ports -----------------------------
.LOOPBACK (tied_to_ground_vec_i[2:0]),

Thanks for Reply,

Pradeep

 

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

after disconnecting sfp, if you assert gtrxreset and de-assert it, did you still see comma is received?

 

Thanks,

Boris

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Contributor
Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq ,

Thanks for reply,

From  board power on SFP port on KC705 Evaluation kit is left unconnected.

Now i programmed the board and tried to capture signal in  ILA  .I could observe comma is detected .

Thanks & regards,

Pradeep

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

let me clarify...

 

if SFP is unconnected, there is no connection between zcu102 and kc705 transceivers.

when you program zcu102, you can see comma is received on kc705, and vice versa?

if you don't program zcu102, there is no comma on KC705 receiver?

 

Thanks,

Boris

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Contributor
Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq 

Thanks for reply.  I think there is some confusion created. I will describe the issue in two cases:

1. Intially, I was using ZCU102 and KC705 boards for TX/Rx data through GTH-GTX SFP connection. I have observed comma character is getting detected in one board if I program either of the two boards.

2. To understand the issue while debugging, I turned off both the boards and removed  ZCU102 board from my setup along with SFP cable. Now I have only KC705 board. I turned on KC705 board with nothing connected to SFP connector, programmed the KC705 board , opened ILA hardware manager to  look at the signals rxdata, rxdataisk. I could observed that comma character is getting detected. 

Thanks & Regards,

Pradeep

 

 

 

 

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

is it possible that you observed another GTX which is not the one with SFP on KC705?

 

Thanks,

Boris

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Contributor
Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq 

Thanks for reply,

For KC705 Kit  there is  one SFP port available and i have  built only one GTX(X0Y10) for this  SFP Port. I am looking at those signals.

Thanks & Regards,

Pradeep

 

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-07-2007

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

hi @abbu_2390 

 

did you observe txdata and txcharisk?

can it match rxdata and rxcharisk exactly?

 

thanks,

Boris

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Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq 

I have observed both TXdata , Txcharisk  and RXData, Rxcharisk they are no matching .(LOOPBACK[2:0]  = 000)

Thanks & Regards,

Pradeep

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Contributor
Contributor
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Registered: ‎07-25-2018

回复: Receiving comma character while programming(ZCU102(GTH) & KC705(GTX))

Hi @borisq 

 

i have built open example project from scratch for GTX in KC705 kit in Vivado 2018.2 and observed that GTX(SFP X0Y10) is receving  comma character without any SFP connector to KC705 kit. I have attached example project and  obtain waveform results  as shown below. How to resolve it??

snap41.JPGsnap40.JPG

 

Thanks & Regards

Pradeep

 

 

 

 

.

 

 

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