Datasheet

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DP83849I
3.5 Flexible MII Port Assignment
The DP83849I supports a flexible assignment scheme for
each of the channels to the MII/RMII interface. Either of
the MII ports may be assigned to the internal channels A/B.
These values are controlled by the RMII and Bypass Reg
-
ister (RBR), address 17h. Transmit assignments and
Receive assignments can be made separately to allow
even more flexibility (i.e. both channels could transmit from
MII A while still allowing separate receive paths for the
channels).
In addition, the opposite receive channel may be used as
the transmit source for each channel. As shown in
Figure 4, Channel A receive data may be used as the
Channel B transmit data source while Channel B receive
data may be used as the Channel A transmit data source.
For proper clock synchronization, this function requires the
device be in RMII mode or Single Clock MII mode of opera
-
tion. A configuration strap is provided on pin 56,
RXD2_B/EXTENDER_EN to enable this mode.
MII
Channel A
Port
A
TX
RX
TX
RX
MII
Channel B
Port
B
TX
RX
TX
RX
10BASE-T
or
100BASE-TX
10BASE-T
or
100BASE-TX
Figure 4. MII Port Mapping