Module not starting correctlly

Question

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?

Eugeny · Answer

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.

johanan · Answer

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.

johanan · Answer

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) Thanks