
Philips Semiconductors
PNX15xx Series
Volume 1 of 1
Chapter 23: LAN100 — Ethernet Media Access Controller
PNX15XX_SER_3
Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet
Rev. 3 — 17 March 2006
23-63
Figure 13 depicts a functional view of the receive lter.
On the top of the diagram, the Ethernet receive packet enters the lters. Each lter is
controlled by signals from the software view. Each lter produces a “Ready” output
and a “Match” output. If Ready is 0, then the Match value is “don’t care”; a lter will
assert its Ready output when it is nished. If the lter nds a packet that matches, it
will assert its Match output along with its Ready output. The results of the lters are
combined by logic functions into a single RxAbort output. If the RxAbort output is
asserted, the packet need not be received.
The blocks in the left-hand side of the diagram are used for WoL and are discussed in
In order to reduce memory trafc, the Receive Datapath of the LAN100 has a FIFO
buffer that stores 68 bytes of receive data, so the LAN100 will only start writing the
received packet to memory after a 68-byte delay. If the RxAbort signal is asserted
during the initial 68 bytes of the packet, the packet can be discarded. The packet will
be removed from the buffer and not stored to memory at all, thereby also not using
any receive descriptors. If the RxAbort signal is asserted
after the initial 68 bytes in a
packet, part of the packet is already written to memory, and the LAN100 will stop
writing further data in the packet to memory; the FailFilter bit in the status word of the
packet will be set to indicate the software device driver can discard the packet
immediately.
Figure 13: Receive lter block diagram
Packet
AcceptUnicastEn
AcceptMulticastEn
AcceptBroadcastEn
AcceptMulticastHashEn
AcceptUnicastHashEn
HashFilter
Imperfect
StationAddress
AcceptPerfectEn
Perfect
PatternMatchEn
PatternMatchJoin
PatternMatchMask0/1/2/3
PatternMatchCRC0/1/2/3
PatternMatchSkip0/1/2/3
Pattern
HFReady
HFMatch
AND
OR
AND
AND/
OR
P
AReady
P
AMatch
FMatch
CRC
OK?
RxFilterWoL
RxFilterEnWoL
AND
FReady
AND
FMatch
AndOr
FReady
AND
~FMatch
RxAbort
Hash
Filter
Hash
Filter
Match
Filter