I have a Virtex 5 design that uses a GTP. I have a simple simulation that
justs transmits some data and looks at the received data. The simulation
works fine and I see the correct received data. The trouble is when I run
the design in hardware and look at the data using chipscope it doesnt
match. I am using 8b10b coding and the comma character is detected
correctly but the following data is not correct. The data doesnt seem to be
rubbish as if I send two bytes that are the same (4A 4A) I get two bytes
that are the same (38 38) just the wrong value. Has anybody seen anything
like this?

Thanks

Jon 	   
					
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Posted through http://www.FPGARelated.com

On Oct 29, 11:08=A0am, "maxascent"
<maxascent@n_o_s_p_a_m.n_o_s_p_a_m.yahoo.co.uk> wrote:
> I have a Virtex 5 design that uses a GTP. I have a simple simulation that
> justs transmits some data and looks at the received data. The simulation
> works fine and I see the correct received data. The trouble is when I run
> the design in hardware and look at the data using chipscope it doesnt
> match. I am using 8b10b coding and the comma character is detected
> correctly but the following data is not correct. The data doesnt seem to =
be
> rubbish as if I send two bytes that are the same (4A 4A) I get two bytes
> that are the same (38 38) just the wrong value. Has anybody seen anything
> like this?
>
> Thanks
>
> Jon =A0 =A0 =A0 =A0
>
> --------------------------------------- =A0 =A0 =A0 =A0
> Posted throughhttp://www.FPGARelated.com

How did you attach the ChipScope ILA?  Is it instantiated in your
project or did
you use the inserter?  I have in the past tried to debug bit-ordering
issues that
ended up being ChipScope re-ordering the bits for me.  See if you can
map
the values you get to the expected values by re-arranging the bits.
For example
hex 38 and hex 4A each have exactly three 1 bits and five 0 bits.

Regards,
Gabor

I have the ILA instantiated in the design. As I said the data does seem to
have some sort of pattern so I guess it could be a chipscope issue. Its a
bit strange that the comma value is correct but the data isnt. I will have
a go using the inserter and see if that makes any difference.

Cheers
Jon	   
					
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