DP83815 datasheet(89/108 Pages) NSC

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6.0 Power Management and Wake-On-LAN

6.1 Introduction

The DP83815 supports Wake-On-LAN (WOL) and the PCI

Power Management Specification version 1.1. These

features allow the device to enter a power saving mode,

and to signal the system to return to a normal operating

state when a wake event occurs. This section describes

the power management operation on the DP83815.

6.2 Definitions (for this document only)

•

Power Management - a PCI specification that defines

power-saving states of PCI devices and systems. A

spec-compliant device implements two PCI Configu-

ration registers to control and report status for its

Power Management function.

•

Wake event - An event that causes a PCI device in

Power Management mode to signal the system.

•

PME Enable (PMEEN) - bit 8 of the Power Manage-

ment Control/Status Register (PMCSR - offset 44h in

the PCI configuration space). Setting this bit to 1 al-

lows the device to assert the PMEN pin when it de-

tects a wake event.

•

Sleep mode - A device is in sleep mode if it is pro-

grammed to a Power Management state other than

the fully operational state and is not allowed to signal

a wake event to the system. In this mode, the PME

Enable bit is 0.

•

Wake-On-LAN mode - A device is in Wake-On-LAN

(WOL) mode if it is programmed to a Power Manage-

ment state other than the fully operational state and is

allowed to signal a wake event to the system. In this

mode, the PME Enable bit is 1.

•

PMEN (pin59) - this pin is similar in function to a sys-

tem interrupt (INTAN pin). When asserted, it signals

the system that a wake event has occurred.

•

PME Status - bit 15 of PMCSR. When 1, indicates the

device detected a wake event. If PME Enable is also

set to 1, the device will assert PMEN whenever PME

Status is 1. Software writes a 1 to this bit to clear it.

•

Magic Packet

: “A specific packet of information sent

to remotely wake up a sleeping or powered off PC on

a network, it is handled in the LAN controller. The

Magic Packet

 must contain a specific data se-

quence which can be located anywhere within the

packet but must be preceded by a synchronization

stream. The packet must also meet the basic require-

ments for the LAN technology chosen (e.g. ethernet

frame). The specific data sequence consists of 16 du-

plications of the MAC address of the machine to be

awakened. The synchronization stream is defined as

6 bytes of FFh.”

•

ACPI-compatible operating system - An operating

system that takes advantage of the PCI Power Man-

agement interface. These include Windows 98 (when

installed with ACPI), Windows 2000, and Windows

ME (when installed with ACPI).

6.3 Packet Filtering

When the PME Enable bit is set to 1, incoming packets are

filtered based on settings in the Receive Filter Control

the Wake Command/Status Register (WCSR - offset 40h in

operational registers). In other words, a packet must pass

both filters to be accepted. This is a desirable feature in

WOL mode since it prevents non-wake packets from filling

the receive FIFO. However, it is not desirable in normal

operating mode since it will not allow non-wake packets

from being received. Therefore, the driver should ensure

that the PME Enable bit is set to 0 for normal operation.

6.4 Power Management

The Power Management Specification presents a low-level

hardware interface to PCI devices for the purpose of

saving power. The DP83815 supports power states D0,

D1, D2, D3hot, and D3cold as defined in the PCI Power

Management

Specification.

These

states

provide

increasing power reduction in the order they are listed.

Table 6-1 lists the different Power Management modes and

the methods of power reduction in DP83815 devices.

Table 6-1 Power Management Modes

Power State

PME Enable

(PMEEN)

Wake

Conditions

Power Management

Mode

PCICLK

Physical Layer

Cell

(SW sets to 0)

Unconfigured

Normal

Don’t Care

WOL

Don’t Care

WOL

May be Off

D3hot

Off

Don’t Care

Sleep

May be Off

Off

D3hot

Don’t Care

Unconfigured

Sleep

May be Off

Off

D3hot

Configured

WOL

May be Off

D3cold

Off

Don’t Care

Sleep

Off

D3cold

Don’t Care

Unconfigured

Sleep

Off

D3cold

Configured

WOL

Off

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