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Altera_Forum
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15 years ago

ALTGX byte ordering problem

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 wi...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

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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?

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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