WIZnet 5200 (Ethernet, UDP) + STM32

The Wiz5200 has 24 general-purpose registers and 24 socket control registers.
I don’t see the point of reprinting the datasheet.
I’ll just recommend taking mine, with registers already bookmarked (and why didn’t the developers do it?..)

In this part, everything turned out to be simple and understandable.
The addresses of all registers consist of two bytes. First, the eldest is sent, then the younger.
Immediately after the address – there are two bytes of data length (specify how many bytes we want to write or receive).
Attention, in the very first bit, in the highest byte of the length (on the diagram from the signature OP) you need to choose the direction of the data – OP in 1 – write, 0 – read.
The recording also occurs (remember about the OP bit))