Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

about the 8B/10B encoder altgx

hello, according with the manual, in double width mode, the 8B/10B encoder starts the LSByte with a negative disparity (RD-)and the MSByte with a positive disparity (RD+) after reset. In my si...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

I don't see a problem.

It's just how 8B/10B works: RD doesn't always toggle from byte to byte.

Consider a single encoder:

a) Most cases are encoded such that RD toggles after each byte.

b) However, there are some cases which are encoded in such a way that the RD stays the same.

For the double encoder scheme, which are used for every other byte, this becomes:

a) Most cases, each encoder's RD stays quiet.

b) In some cases, both encoders toggle their RD.