Ethernet module

Hello everyone,

I have designed a costume board with atmega2560 microcontroller connected with wiznet850 ethernet module. thr module is powered on but there is no signal coming from it. what i have done in my pcb design is the following:
2 layer pcb and the fill the top layer as ground plane, and back side as 5V plane. do you think this way of design might cause the interference of SPI signal with 5v planes?

what are the connections between ATmega and the W5500?