UDP data packet on W5500

Question

All, I am looking at the code for the UDP receive function, UDPRecv. It is taking the first 6 bytes as being the destination IP address? I thought the header was like this: 2 bytes, source port 2 bytes, destination port 2 bytes, data length 2 bytes, check sum Then the data. Is the W5500 changing the UDP header, or am I missing something here? Thanks, Jim

ventosus · Answer

Yes, the W5500 (and also W5200 and W5100) return a custom UDP packet info structure. I think the W5500 manual misses this information, but the W5200 manual has it, look it up there. UDP data is specially structured in the RX memory, like this: PACKET-INFO 4 bytes: destination IP address 2 bytes: destination port number 2 bytes: byte size (N) of data packet DATA-PACKET N bytes: real data

hjjeon0608 · Answer

Hi, W5x00 series all have the same UDP header frame. 780×233 46 KB Best regards.

JimMartz · Answer

Thanks for the reply. I got the W5200 manual and that answered a few questions I had. The whole section 5 of the W5200 data sheet is missing from the W5500 manual, I hope this gets included in the W5500 datasheet for people like me that have not used a previous wiz chip. Thanks, Jim

luckyluka · Answer

Hi! I am a bit confused about this UDP checksum. Does W5500 generate it? If not, who does? Below is a screenshot of a of package sent by w5500. Checksum is definitely present. Where is it generated? Can it be configured? image1056×574 24.2 KB Thank you.