KSZ8841-PMQL(2006) Ver la hoja de datos (PDF) - Micrel

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KSZ8841-PMQL
(Rev.:2006)

Single-Port Ethernet MAC Controller with PCI Interface

Micrel 

Micrel, Inc.

KSZ8841-PMQL

A wake-up signal is caused by:

1. Detection of a change in the network link state

2. Receipt of a network wake-up frame

3. Receipt of a Magic Packet

Link Change

Link status wake events are useful to indicate a change in the network’s availability, especially when this change may

impact the level at which the system should re-enter the sleeping state. For example, a change from link off to link on

may trigger the system to re-enter sleep at a higher level (D2 versus D3) so that wake frames can be detected.

Conversely, a transition from link on to link off may trigger the system to re-enter sleep at a deeper level (D3 versus D2)

since the network is not currently available.

Note: References to D0, D1, D2, and D3 are power management states defined in a similar fashion to the way they are defined for

PCI. For more information, refer to the PCI specification at www.pcisig.com/specifications/conventional/pcipm1.2.pdf.

Wake-up Packet

Wake-up packets are certain types of packets with specific CRC values that a system recognizes as a ‘wake up’ frame.

The KSZ8841-PMQL supports up to four users defined wake-up frames as below:

1. Wake-up frame 0 is defined in registers 0x0220-0x022A and is enabled by bit 0 in wakeup frame control register.

2. Wake-up frame 1 is defined in registers 0x0230-0x023A and is enabled by bit 1 in wakeup frame control register.

3. Wake-up frame 2 is defined in registers 0x0240-0x024A and is enabled by bit 2 in wakeup frame control register.

4. Wake-up frame 3 is defined in registers 0x0250-0x025A and is enabled by bit 3 in wakeup frame control register

Magic Packet

Magic Packet technology is used to remotely wake up a sleeping or powered off PC on a LAN. This is accomplished by

sending a specific packet of information, called a Magic Packet frame, to a node on the network. When a PC capable of

receiving the specific frame goes to sleep, it enables the Magic Packet RX mode in the LAN controller, and when the

LAN controller receives a Magic Packet frame, it will alert the system to wake up.

Magic Packet is a standard feature integrated into the KSZ8841-PMQL. The chip implements multiple advanced power-

down modes including Magic Packet to conserve power and operate more efficiently.

Once the KSZ8841-PMQL has been put into Magic Packet Enable mode (WFCR[7]=1), it scans all incoming frames

addressed to the node for a specific data sequence, which indicates to the chip this is a Magic Packet (MP) frame.

A Magic Packet frame must also meet the basic requirements for the LAN technology chosen, such as Source Address

(SA), Destination Address (DA), which may be the receiving station’s IEEE address or a multicast or broadcast address

and CRC.

The specific sequence consists of 16 duplications of the IEEE address of this node, with no breaks or interruptions. This

sequence can be located anywhere within the packet, but must be preceded by a synchronization stream. The

synchronization stream allows the scanning state machine to be much simpler. The synchronization stream is defined

as 6 bytes of FFh. The device will also accept a broadcast frame, as long as the 16 duplications of the IEEE address

match the address of the machine to be awakened.

EXAMPLE

If the IEEE address for a particular node on a network is 11h 22h, 33h, 44h, 55h, 66h, the LAN controller would be

scanning for the data sequence (assuming an Ethernet frame):

DESTINATION SOURCE MISC: 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 - MISC -CRC.

There are no further restrictions on a Magic Packet frame. For instance, the sequence could be in a TCP/IP packet or

an IPX packet. The frame may be bridged or routed across the network without affecting its ability to wake-up a node at

the frame’s destination

If the LAN controller scans a frame and does not find the specific sequence shown above, it discards the frame and

takes no further action. If the controller (KSZ8841-PMQL) detects the data sequence, however, it then alerts the PC’s

power management circuitry (asserted the PMEN pin) to wake up the system.

June 2006

15

M9999-061206-1.2

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