NXP Semiconductors LPC24XX UM10237 - Manual (Page 269)

UM10237_4 © NXP B.V. 2009. All rights reserved.
User manual Rev. 04 — 26 August 2009 269 of 792
NXP Semiconductors
UM10237
Chapter 11: LPC24XX Ethernet
Ethernet MAC will stop writing further data in the frame to memory; the FailFilter bit in the
status word of the frame will be set to indicate that the software device driver can discard
the frame immediately.
Unicast, broadcast and multicast
Generic filtering based on the type of frame (unicast, multicast or broadcast) can be
programmed using the AcceptUnicastEn, AcceptMulticastEn, or AcceptBroadcastEn bits
of the RxFilterCtrl register. Setting the AcceptUnicast, AcceptMulticast, and
AcceptBroadcast bits causes all frames of types unicast, multicast and broadcast,
respectively, to be accepted, ignoring the Ethernet destination address in the frame. To
program promiscuous mode, i.e. to accept all frames, set all 3 bits to 1.
Perfect address match
When a frame with a unicast destination address is received, a perfect filter compares the
destination address with the 6 byte station address programmed in the station address
registers SA0, SA1, SA2. If the AcceptPerfectEn bit in the RxFilterCtrl register is set to 1,
and the address matches, the frame is accepted.
Imperfect hash filtering
Fig 33. Receive filter block diagram
IMPERFECT
HASH
FILTER
AcceptUnicastEn
AcceptMulticastEn
AcceptMulticastHashEn
AcceptUnicastHashEn
HashFilter
PERFECT
ADDRESS
FILTER
packet
CRC
OK?
HF
Re
a
d
y
HF
M
a
tc
h
PA
R
e
a
d
y
PA
M
a
tc
h
RxAbort
FReady
FMatch
RxFilterEnWoL
RxFilterWoL
StationAddress
AcceptPerfectEn