Multiple PHYs to a single MAC

Multiple PHYs to a single MAC

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Subject Author Date
Multiple PHYs to a single MAC Engin Ciftci 04-11-2007
Posted by Engin Ciftci on April 11, 2007, 10:30 am
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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


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other useful resources:
The Federal Communications Commission (FCC)
Telecommunications Industry Association
Electronic and Software Security Products and Services
International Telecommunication Union

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