GMII<->MII

GMII<->MII

Post by w » Fri, 04 Jul 2003 02:25:31



Hi,

Is it possible to connect GMII MAC layer to 10/100 MII PHY?
Does it require any HW changes or the PHY should just be connected to
a subset of the GMII signals in the MAC layer?

Regards,
wd.

 
 
 

GMII<->MII

Post by Marri » Fri, 04 Jul 2003 05:30:43


This depends on whether your gigabit MAC is capable of 10/100
operation. If it is you need to configure your MAC for 10/100
operation and connect a subset of the GMII signals. That is leave
the upper nibbles of rxd and txd unconnected. You need to be
careful with tx_clk. tx_clk is an input to the MAC in 10/100 mode
while gtx_clk is an output of the MAC in gigabit mode.

If you download the 802.3 spec from get IEEE you can read about
this in clause 35.3


Quote:> Hi,

> Is it possible to connect GMII MAC layer to 10/100 MII PHY?
> Does it require any HW changes or the PHY should just be connected to
> a subset of the GMII signals in the MAC layer?

> Regards,
> wd.