ENC28J60
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.
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
FIGURE 8-4:
SAMPLE MAGIC PACKET™ FORMAT
Received
Data
Field
Comments
11 22 33 44 55 66
77 88 99 AA BB CC
00 FE
DA
SA
Type/Length
09 0A 0B 0C 0D 0E
FF FF FF FF FF 00
FF FF FF FF FF FF
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
11 22 33 44 55 66
19 1A 1B 1C 1D 1E
EF 54 32 10
Sync Pattern
Data
Sixteen Repeats of
the Station Address
FCS
8.4
Hash Table Filter
8.5
Multicast 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.
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.
DS39662B-page 52
Preliminary
© 2006 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
