cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
Contributor
Contributor
5,968 Views
Registered: ‎05-28-2015

question about GTP byte alignment

HI,

In artix 7 GTP, i use a comma alignement of BC.

In mode 8b/10b ENCODING.

 

I don't understand one thing.

 

Alignment can be on the first or the second byte.

If it's in the second byte so data are not correct.

 

Is GTP control this problem automatically, or It's my job to code a vhdl control of this problem?

 

Best regards

 

0 Kudos
7 Replies
Highlighted
Scholar
Scholar
5,793 Views
Registered: ‎06-23-2013

Re: question about GTP byte alignment

How wide is your interface to the GTP?  20 bits?  If so, the GTP will not be able to tell between 16'hBCBC encoded as 20 bits and the opposite order for the bytes: 16'hBCBC.  You will have to take care of this.

 

Daniel

 

0 Kudos
Highlighted
Moderator
Moderator
5,767 Views
Registered: ‎02-16-2010

Re: question about GTP byte alignment

Are you setting the alignment position to even byte boundaries and not supplying the comma on even bytes?
------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------
0 Kudos
Highlighted
Contributor
Contributor
5,699 Views
Registered: ‎05-28-2015

Re: question about GTP byte alignment

Hi,

My interface is 20 Bits, so, before recept data,  i need to check if data are in order?

But actually i don't check the order and my system work. Perhaps i'm lucky but i program my device a lot of time.

 

venkata, i don't understand your question.

Actually, i decode valid comma only (see attachement)

 

In the lane, the value comma (BC) is present until a information is transmit.

BCBC    BCBC    BCBC    BCBC   BCBC  ------  information  ------- BCBC  BCBC

 

In the header of the information transmit there a coma information, in this case BC transmit 3 times and one octet to dIstinguish the command :

EX : BCBC BCFD

 

When no information is send, there are no problem.

But when i receive the first header of a information i can receive :

BCBC BCFD or BCBC FDBC. In the second case all data are inversed.

 

So, is I need to check the order before transmit data to my code?

 

Best regard.

 

 

 

Sans titre.png
0 Kudos
Highlighted
Moderator
Moderator
5,693 Views
Registered: ‎02-16-2010

Re: question about GTP byte alignment

I see you have selected "Any byte boundary" for "Align to" option. With this option, the alignment can happen at any byte position.

If you select "even byte boundary" then you will get the alignment to even bytes always.
------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------
Highlighted
Moderator
Moderator
5,692 Views
Registered: ‎02-16-2010

Re: question about GTP byte alignment

Check the comma alignment section in ug482 for more details about this aspects
------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------
0 Kudos
Highlighted
Contributor
Contributor
5,596 Views
Registered: ‎05-28-2015

Re: question about GTP byte alignment

Hi,

I don't have "even byte boundary". I have any, two or three byte boundary so i suppose that you would say "two byte boundary".

I think that it's the solution of my question but i cannot verified them because actually i don't have problem of alignment.

I not understand why.

The gtp is configured in "any byte boundary" i verified them.

 

Thanks

0 Kudos
Highlighted
Moderator
Moderator
5,497 Views
Registered: ‎02-16-2010

Re: question about GTP byte alignment

May be you need to re-adjust the byte order after the alignment is completed by GT.
------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------