I need help on connecting multiple PHY controllers to a single MAC over an MII interface. In IEEE 802.3u it was mentioned that MII interface can support 32 different phy addresses. But most of the PHY controllers have an separate RXTRI or ISOLATE pin for tristating the output (RX) pins. I guess this will be a big problem in software because microprocessor must select which phy to enable and this is not controlled over MII interface. Also the configuration register 0.10 bit can isolate the phy in the same manner and this becomes meaningless if a separate pin is used.
If MII is tri stated over software control (register 0.10) there may be an collusion (short cct) at startup since both phys are sharing the same MII bus.
I am wondering if any one of you has implemented this kind of application. I need your help on this subject.
Engin Ciftci