IP100ALF datasheet(25/97 Pages) ETC2

25 / 97 page

IP100A LF

Preliminary Data Sheet

The frame patterns in the transmit FIFO specify which bytes in received frames are to be examined.

Each byte in the transmit FIFO specifies a four bit relative offset (from the start of the received frame) in

the most significant nibble and a four bit length indicator in the least significant nibble. Relative offsets

describe the number of bytes of the received frame to skip from the last relevant byte, beginning with

byte 0x00. Relative offsets with a value of 0xF indicate the actual relative offset is larger than 15, and is

specified by the next 8 bit value in the transmit FIFO. Length indicators with a value of 0xF indicate the

actual length indicator is larger than 15, and is specified by the next 8 bit value in the transmit FIFO. If

both the relative offset, and the length indicator are 0xF, the first byte following the relative offset/length

indicator pair is the actual relative offset, and the second following byte is the actual length indicator. A

byte value of 0x00 indicates the end of the pattern for that wake frame. Immediately following the

end-of-pattern is a 4-byte CRC. The calculation used to for the CRC is the same polynomial as the

Ethernet MAC FCS.

An example pseudo-packet (based on the ARP packet example from Appendix A of the “OnNow

Network Device Class Power Management Specification”) which would be loaded into the transmit FIFO

of the IP100A LF is shown in Figure 8.

TxFIFO

pseudo

packet

0xc2

0xf3

0x00

0x10

0xf4

0x71

0xd7

0x08

0x19

FIGURE 8: Example Pseudo Packet

Using the pseudo packet in Figure 8, the IP100A LF will assert a wake event if a packet of the form

shown in Figure 9 is received whereby a 32-bit CRC over the indicated bytes of the received packet

yields the value 0xf31908d7.

March. 30, 2007

25/97

IP100A LF-DS-R17

IP100ALF Datasheet(PDF) 25 Page - List of Unclassifed Manufacturers