UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
720 of 1269
NXP Semiconductors
UM10503
Chapter 26: LPC43xx Ethernet
PMT supports four programmable filters that allow support of different receive frame
patterns. If the incoming frame passes the address filtering of Filter Command, and if
Filter CRC-16 matches the incoming examined pattern, then the wake-up frame is
received.
Filter_offset (minimum value 12, which refers to the 13th byte of the frame) determines the
offset from which the frame is to be examined. Filter Byte Mask determines which bytes of
the frame must be examined. The thirty-first bit of Byte Mask must be set to zero.
The remote wake-up CRC block determines the CRC value that is compared with Filter
CRC-16. The wake-up frame is checked only for length error, FCS error, dribble bit error,
MII error, collision, and to ensure that it is not a runt frame. Even if the wake-up frame is
more than 512 bytes long, if the frame has a valid CRC value, it is considered valid.
Wake-up frame detection is updated in the PMT Control and Status register for every
remote Wake-up frame received. A PMT interrupt to the Application triggers a Read to the
PMT Control and Status register to determine reception of a wake-up frame.
26.7.1.3 Magic packet detection
The Magic Packet frame is based on a method that uses Advanced Micro Device’s Magic
Packet technology to power up the sleeping device on the network. The MAC receives a
specific packet of information, called a Magic Packet, addressed to the node on the
network.
Only Magic Packets that are addressed to the device or a broadcast address will be
checked to determine whether they meet the wake-up requirements. Magic Packets that
pass the address filtering (unicast or broadcast) will be checked to determine whether
they meet the remote Wake-on-LAN data format of 6 bytes of all ones followed by a MAC
Address appearing 16 times.
The application enables Magic Packet wake-up by writing a 1 to Bit 1 of the PMT Control
and Status register. The PMT block constantly monitors each frame addressed to the
node for a specific Magic Packet pattern. Each frame received is checked for a 0xFFFF
FFFF FFFF pattern following the destination and source address field. The PMT block
then checks the frame for 16 repetitions of the MAC address without any breaks or
interruptions. In case of a break in the 16 repetitions of the address, the 0xFFFF FFFF
FFFF pattern is scanned for again in the incoming frame. The 16 repetitions can be
anywhere in the frame, but must be preceded by the synchronization stream (0xFFFF
FFFF FFFF). The device will also accept a multicast frame, as long as the 16 duplications
of the MAC address are detected.
If the MAC address of a node is 0x0011 2233 4455, then the MAC scans for the data
sequence:
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
...CRC
Magic Packet detection is updated in the PMT Control and Status register for Magic
Packet received. A PMT interrupt to the Application triggers a read to the PMT CSR to
determine whether a Magic Packet frame has been received.