Which chips automatically do CRC on UDP?

Question

I looked into the datasheets of all the chips (6100,5100s,5300…) The only one that seems to refer to any kind of CRC is the 5300. Is the 5300 the only one doing the CRC in UDP mode?

Eugeny · Answer

CRC of what and at which protocol level? What is the real problem or question?

Eugeny · Answer

Regarding W5300 from datasheet it is not clear what CRC has to do with and what is the origination of the CRC (network or CRC is being calculated on the received data) because datasheet says to discard the CRC and it may be for some other diagnostic purposes. In addition, CRC is 4 bytes instead of required 2 bytes. I have seen statements that IPv4 calculation algorithm has some caveats, therefore we must have confirmation from the WIZnet developers if it was really employed (properly). You can, of course, take packet sent by the chip and calculate CRC yourself to see if it is correct (and not just a -0 as a placeholder), but again it is not a guarantee. If RFC says the CRC is optional then unfortunately… the most secure and reliable way to implement your own CRC.

Benjamin Couture · Answer

I got an answer from wiznet. The w6100 and w5100s do the CRC automatically in IPv4. I don’t know about the others. The chip does the discarding automatically without the cpu involved. You won’t be able to read the CRC ( not sure why you would want to) or the corrupt dataframe (which I don’t care). On the PC side, some allows to read the CRC and other stuff, but being on the lower layer network,those are not always accessible, which is kind of the whole point of lower layers (cpu offloading). So in sum, it’s been confirmed that w6100 and w5100s does CRC on IP.