ALTGX byte ordering problem

--- Quote Start ---

Hello,

I am using two stratix II signal integrity development kits, and try to communicate between them using the ALTGX megacore. I am using it in 16-bit width.

I am experiencing a problem with the order of the bytes - I send two words, i.e. "AABB", "CCDD" but the receiver side receives "DDAA", CCBB" or something similar.

What could be the problem?

--- Quote End ---

A wild shot in the dark but maybe you don't have a word reversal problem but a word alignment problem or a bit order problem. Try sending methodical test cases like "96" followed by "D1". If you have a byte order reversal you will get "69" then "1D". If you have a bit order reversal you will get "69" then "8B".

I might be off in my explanation but you get the idea... You have to isolate the problem before you can solve it. It might be as simple as a bit order issue.

David

I'll give another example which implies it's not bit ordering:

the transmitter sends "0000", "0220","7C0B","0000" but the receiver receives "2000","0B02","007C"....