I am using the W5500 with STM32F303 with external transformer due to POE.
I need some confirmations regarding the layout:
-are the 10K pulldown resistors useful on all RSVD lines? i have seen implementation with all RSVD pulled down with 10k but the official schematic https://wizwiki.net/wiki/lib/exe/fetch.php?media=wiznet_schematic:ethernet_chip:w5500_sch_v110_use_trans_.pdf
leave them N.C. In my current implementation i leaved all RSVD N.C. except pin23 whic i tied to GND.
-what is the purpose of the 33R resistors on all SPI lines? my system is 3.3V and i wonder if i could get rid of them.
-are pull-up/down resistors needed to configure PMODE lines? i used solder jumpers and tied them directly to GND/3V3.
-what is the right way to connect Tx and Rx center taps? i have seen various implementations, in my case the difficulty is that there is a POE.
The schematic below is my current wiring, its on 4 layer PCB, all differential pairs are matched length and controlled impedance. There is an AGND but it may be replaced by a 0R or solder jumper since i have read it causes problems of excessive ESD sensitivity.
i initially had VA1A and VA2A (POE) connected to center tap, its been removed when i changed the terminations on this side of transformaer, i wonder if and how i should conect them back.
Any advise will be warmly welcome