Hey Dude,Originally posted in cdnusers.org by jmueller
1) CRC checking can be done by creating 2 signals: A the original vector with CRC field. B the same vector with one bit flipped (this is a constraint like "countones(A xor B) = 1"). The vector itself is unconstrained, but the CRC field needs to be correctly calculated. Your CRC decoder should provide the corrected vector on the output. Similary you can detect 2 flipped bits. IFV did pretty good jobs with CRC blocks in the past.
2) pure connectivity checking is described in a paper from Freescale at CDNLive 2006 Silicon Valley. Please browse the proceedings there.