ENC28J60-CSLASHML datasheet(54/96 Pages) MICROCHIP

54 / 96 page

ENC28J60

DS39662B-page 52

Preliminary

8.3

Magic Packet™ Filter

The Magic Packet filter checks the destination address

and data fields of all incoming packets. If the destination

address matches the MAADR registers and the data

field holds a valid Magic Packet pattern someplace

within it, then the packet will meet the Magic Packet filter

criteria. The Magic Packet pattern consists of a sync

pattern of six 0xFF bytes, followed by 16 repeats of the

destination address. See Figure 8-4 for a sample Magic

Packet.

FIGURE 8-4:

SAMPLE MAGIC PACKET™ FORMAT

8.4

Hash Table Filter

The hash table receive filter performs a CRC over the

six destination address bytes in the packet. The CRC is

then used as a Pointer into the bits of the EHT regis-

ters. If the Pointer points to a bit which is set, the packet

meets the hash table filter criteria. For example, if the

CRC is calculated to be 0x5, bit 5 in the hash table will

be checked. If it is set, the hash table filter criteria will

be met. If every bit is clear in the hash table, the filter

criteria will never be met. Similarly, if every bit is set in

the hash table, the filter criteria will always be met.

8.5

Multicast Filter

The multicast receive filter checks the destination

address of all incoming packets. If the Least Significant

bit of the first byte of the destination address is set, the

packet will meet the multicast filter criteria.

8.6

Broadcast Filter

The broadcast receive filter checks the destination

address of all incoming packets. If the destination

address is FF-FF-FF-FF-FF-FF, the packet will meet

the broadcast filter criteria.

FCS

Type/Length

22 33 44 55 66

00 FE

09 0A 0B 0C 0D 0E

Received

Data

Field

77 88 99 AA BB CC

EF 54 32 10

FF FF FF FF FF 00

FF FF FF FF FF FF

22 33 44 55 66

19 1A 1B 1C 1D 1E

Data

Sync Pattern

Sixteen Repeats of

the Station Address

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