Fast Ethernet Controller (FEC)
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
18-10
Freescale Semiconductor
If the DA is a group (multicast) address and flow control is disabled, the microcontroller performs a group
hash table lookup using the 64-entry hash table programmed in GAUR and GALR. If a hash match occurs,
the receiver accepts the frame.
If flow control is enabled, the microcontroller does an exact address match check between the DA and the
designated PAUSE DA (01:80:C2:00:00:01). If the receive block determines that the received frame is a
valid PAUSE frame, the frame is rejected. The receiver detects a PAUSE frame with the DA field set to
the designated PAUSE DA or the unicast physical address.
If the DA is the individual (unicast) address, the microcontroller performs an individual exact match
comparison between the DA and 48-bit physical address that the user programs in the PALR and PAUR
registers. If an exact match occurs, the frame is accepted; otherwise, the microcontroller does an individual
hash table lookup using the 64-entry hash table programmed in registers, IAUR and IALR. In the case of
an individual hash match, the frame is accepted. Again, the receiver accepts or reject the frame based on
PAUSE frame detection, shown in
If neither a hash match (group or individual) nor an exact match (group or individual) occur, then if
promiscuous mode is enabled (RCR[PROM] = 1), the frame is accepted and the MISS bit in the receive
buffer descriptor is set. Otherwise, the frame is rejected.
Similarly, if the DA is a broadcast address, broadcast reject (RCR[BC_REJ]) is asserted, and promiscuous
mode is enabled, the frame is accepted and the MISS bit in the receive buffer descriptor is set. Otherwise,
the frame is rejected.
In general, when a frame is rejected, it is flushed from the FIFO.
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60
