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Altera_Forum
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18 years ago

PCI Express translation

Hello, I have a problem to understand how you calculate the DLLPs CRC in the Altera PCI Express Megacore function. I ran the testbench generated and I took the first 4 bytes of some DLLPs and I...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

Yes you have to unscramble the data before checking the DLLP CRC. Scrambling is a Physical Layer function. CRC is a Data Link Layer function. Likewise when transmitting you have to generate the CRC first and then scramble the data.

Data from the PHY is still scrambled because that is the way the PIPE interface specification specifies it to be done.