IP100A LF
Preliminary Data Sheet
11.3
Wake Event Data Structures
The first Wake Event Data Structure is the Pseudo Packet. A Pseudo Packet is a set of patterns loaded
into the IP100A LF TxFIFO which specify bytes to be examined within received frames. A CRC is
calculated over these bytes and compared with a CRC value supplied in the Pseudo Packet. If a match is
found, the IP100A LF issues a Wake Event. The matching technique may result in false wake events
being reported to the host system. Each Pseudo Packet consists of one or more byte-offset/byte-count
pairs (or Pseudo Patterns), a terminator symbol, and a 4-byte CRC value. The byte offsets within the
Pseudo Patterns indicate the number of received frame bytes to be skipped in order to reach the next
group of bytes to be included in the CRC calculation. The byte-counts within the Pseudo Patterns
indicate the number of bytes in the next group to be included in the CRC calculation. The terminator
indicates the end of the Pseudo Patterns for the Pseudo Packet. Immediately following the terminator is
a 4-byte CRC. If there is another Pseudo Packet, it will immediately follow the CRC value.
The second Wake Event Data Structure is the Magic Packet. Magic Packets are uniquely formatted
frames, which upon reception invoke a Wake Event by the IP100A LF. Once the IP100A LF has been
placed in Magic Packet mode and put to sleep, it scans all incoming frames addressed to it for a data
sequence consisting of a synchronization stream followed immediately by 16 consecutive repetitions of
the station’s own 48-bit Ethernet MAC station address. The sequence can be located anywhere within
the received frame.
The pseudo packet and Magic Packet data structures are shown in Figure 12
IP100A
pseudo
packet
PseudoPattern 1
Terminator
PseudoPattern n
PseudoCRC
0x00
0x01
0x00+n+1
0x00+n
0x00+n-1
Received Packet
0x00
0x06
Ethernet Header
MagicSyncStream
MagicSequence
Ethernet CRC
Magic
PacketTM
FIGURE 12 : Wake Event Data Structures, Pseudo Packet and Magic Packet
40/97
March. 30, 2007
Copyright © 2004, IC Plus Corp.
IP100A LF-DS-R17
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