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zero_china
Visitor
Visitor
8,769 Views
Registered: ‎09-15-2014

The Spartan 6 GTP for the RX Margin Analysis

Hi

I have some issues when I use the GTP of the Spartan 6 .

Here is the setup:

clock:125Mhz

connection:SATA

IC:XC6SLX25T-2Fgg484

Tools:ISE14.7

In my design , I used the RX Margin Analysis In the horizontal eye margin scan mode of the receiving end .

Now I need to shut  the  data sampler PLL of the CDR down ,but I don't know how to shut it down ,

there are two singals that I don't understand,they are  PMA_CDR_SCAN and PMA_RX_CFG,I don't know how to set them to shut down the PLL of the CDR.

 

Wait for your help 

 

Thanks in advance

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6 Replies
venkata
Moderator
Moderator
8,756 Views
Registered: ‎02-16-2010

What do you mean by shut the data sampler of the CDR down? do you want to fix the sampling point location?

In that case revert back the PMA_RX_CFG to the default setting and update PMA_CDR_SCAN [7:0] bits to the value to be fixed.
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smarell
Community Manager
Community Manager
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Registered: ‎07-23-2012

Please refer to RX Margin Analysis from http://www.xilinx.com/support/documentation/user_guides/ug386.pdf
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zero_china
Visitor
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8,738 Views
Registered: ‎09-15-2014

scan.JPG

Er,What I want to shut the data sampler of the CDR down mean that I want to keep a fixed delay from starting to receive data to the CDR out , In other words ,i want to know the phase relationship between the local clock and the CDR ,and i had setted the PAM_RX_CFG as the user guide .I had tested and verified much,but,ican't have a expectant consequence.

Are there any other mechanism  for the phase of the CDR? I have no ideas!

 

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borisq
Xilinx Employee
Xilinx Employee
8,686 Views
Registered: ‎08-07-2007

hi, 

 

PMA_RX_CFG[10:0] should be tied to all zeros during eye scan.

sweep PMA_CDR_SCAN[6:0] from 0x00 to 0x7F to vary the CDR phase to find out the link margin.

 

Thanks,

Boris

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zero_china
Visitor
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Registered: ‎09-15-2014

@venkata 

What do you mean by the default setting of the PMA_RX_CFG?  I can't find a default setting of the PMA_RX_CFG in the user guide.

 

 

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venkata
Moderator
Moderator
8,676 Views
Registered: ‎02-16-2010

I meant the value generated by GT wizard. You would have changed it for eye scan operation (PMA_RX_CFG[10:0] should be tied to all zeros during eye scan.)
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