Sundance Spas manual Wake Event Data Structures, ST201 Txfifo

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.

psuedo

ST201 TXFIFO

PsuedoPattern 1

PsuedoPattern 2

PsuedoPattern n

0x00

0x01

0x00+n-1

Received Packet

Ethernet Header

packet Terminator

PsuedoCRC

0x00+n

0x00+n+1

Magic

Packet™

MagicSyncStream

MagicSequence

0x00

0x06

Ethernet CRC

FIGURE 10: Wake Event Data Structures, Pseudo Packet and Magic Packet

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