ENC28j60 prblem with Relay toggle

[Sharagim]

Hi,
I am making a board for toggling relay remotely with enc28j60.
The relay is connected to Contactor for handling more current, The relay is connected to mcu(Atxmega64a3) with optoocouple and transistor.
I had a problem which after some toggle I see enc28j60 wont reply anymore, I put a _delay_ms(x) after each toggle which seems help on this device , but when I put two device the second one has this problem when the first one toggle ports.
I think some spike or ... making this problem but don't know how to prevent it.
Thanks in advance

 

[crutschow]

Do you have diodes across the relay coils for transient suppression?

 

[Sharagim]

Sure there is a diode.
you can see the schematic in attache.

 

[alec_t]

The problem could be due to ground bounce. Make sure the current path for heavy current loads such as the relay and contactor does not include the path from the micro Vss terminal to ground, so that the IxR drop in the ground trace of the micro is negligible. Use a star ground configuration.