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Sundance Technology ST201 PRELIMINARY draft 2
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 ST201 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
ST201 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 Pat-
terns), 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 ST201. Once the ST201 has been placed in
Magic Packet mode and put to sleep, it scans all incoming frames addressed to it for a data sequence con-
sisting 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 10.
0x00
0x00+n
0x00+n+1
PsuedoPattern 1
Terminator
PsuedoCRC
psuedo
FIGURE 10: Wake Event Data Structures, Pseudo Packet and Magic Packet
packet
ST201 TXFIFO
Ethernet Header
Received Packet
MagicSyncStream
MagicSequence
0x00
0x06
Ethernet CRC
Magic
Packet™
0x00+n-1PsuedoPattern n
0x01PsuedoPattern 2