Module not starting correctlly

I made a pcb with W5100S.
The software starts with DHCP discovery. the DHCP fail many trails, but then after a very long time, it seems to get an IP, and everything works well from this point on (fast and reliable TCP connection).
When I use the same software with W5100S module (WIZ810io) all is working well and DHCP discovery is normal ( < 10 seconds).
What could be the problem?

Please provide

  • circuit diagram of your design.
  • Wireshark log from the PC pn the network between W5100s and DHCP server (or from DHCP server if it is able to run Wireshark).
  • any differences in LED operation between your design and WIZnet module.

Here is a link to the schematics.

I am not very familiar with wireshark, I am looking at it right now, will upload log later.
Let me know if something is wrong/missing from this design.
Also, I wonder if there are some grounding issues that can create such problems.

I nailed it…
termination resistors on PHY connection were 49.9 K instead of 49.9 Ohm…
Makes a lot of difference.
Now all works OK.

1 Like

You are not the first one with this mistake, and not the last one :slight_smile:

BTW, will it be OK if I replace the W5100S with the pin compatible W6100 on board? (hardware - I know the library need to change)