Electrical computers and digital processing systems: support – Computer power control – Power conservation
Reexamination Certificate
2000-12-27
2004-10-05
Browne, Lynne H. (Department: 2116)
Electrical computers and digital processing systems: support
Computer power control
Power conservation
C713S300000, C713S323000, C710S036000, C710S038000
Reexamination Certificate
active
06802018
ABSTRACT:
Field
The present invention relates generally to a method and apparatus to allow a computer system to receive information while the CPU is in a sleeping state, and more particularly to a first peripheral device with multiple modes of operation to receive, buffer, and process data, including directly accessing a second peripheral device, while the computer's CPU is in a sleeping or suspended state.
BACKGROUND OF THE INVENTION
As mobile computing devices seek to extend time-of-operation between charges, power management has become increasingly important. One way in which power management is accomplished is by completely, or partially, shutting down computer components, such as the central processing unit (CPU), hard disk drive, display, and other input/output (I/O) devices: when the computer is not performing operations.
During some of these power management modes, also known as sleeping states, the computer's CPU may cease communications with and control of its peripheral resources, including I/O components, and those resources may not be accessed by any other computer component. Such power management techniques are not unique to any one computer system architecture.
One hardware system specification, the Advanced Configuration and Power Interface (ACPI) Specification, by Intel, Microsoft, and Toshiba, Revision 1.0b, Feb. 2, 1999, provides a technique for enhancing power management in a personal computer (PC) system architecture. The ACPI specification describes the transfer of power management functions from the Basic Input/Output System (BIOS) to the operating system, thereby enabling demand-based peripheral and power management. Through the application of this specification, PC computers manage power usage of peripheral devices such as CD-ROMs, network cards, hard disk drives, audio codecs, and printers, as well as consumer electronics connected to a PC, such as video cassette recorders, television sets, telephones, and stereos.
As shown in the table below, the ACPI specification defines several low-power sleeping states, S1-S5, that reduce the power consumed by the CPU by limiting the operations it may perform. S0 is herein used as an indicator of ‘no sleeping state’. These various operating states are herein referred to as power management states. ‘Context’, refers to variable data held by the CPU and other computer devices. It is usually volatile and can be lost when entering or leaving certain sleeping states.
Sleeping Description
States
S0 Normal operation, active state.
S1 The S1 sleeping state is a low wake-up latency sleeping state. In this state, no system context is lost (CPU or chip set) and hardware maintains all system context.
S2 The S2 sleeping state is a low wake-up latency sleeping state. This state is similar to the S1 sleeping state except the CPU and system cache context is lost (the OS is responsible for maintaining the caches and CPU context). Control starts from the processor's reset vector after the wake-up event.
S3 The S3 sleeping state is a low wake-up latency sleeping state where all system context is lost except system memory. CPU, cache, and chip set context are lost in this state. Hardware maintains memory context and restores some CPU and L
2
configuration context. Control starts from the processor's reset vector after the wake-up event.
S4 The S4 sleeping state is the lowest power, longest wake-up latency sleeping state supported by ACPI. In order to reduce power to a minimum, it is assumed that the hardware platform has powered off all devices. A copy of the platform context is written to the hard disk.
S5 The S5 state is similar to the S4 state except the OS does not save any context nor enable any devices to wake the system. The system is in the “soft” off state and requires a complete boot when awakened.
Typically, in the PC computing architecture, data may only be transferred between two peripheral devices by having the host operating system manage such transfer. That is, the CPU, through one of its auxiliary components, must control the data flow to and from peripheral devices.
FIG. 1
is a conventional, system-level diagram of relevant components of the PC computing architecture. In this architecture, the I/O Controller Hub (ICH)
122
manages communications to and from peripheral devices
116
,
118
,
134
by controlling data flow to the Memory Controller Hub (MCH)
106
. The bus between the ICH
122
and MCH
106
is known as the Hub Link bus
112
. The MCH
106
may store data received from the ICH
122
in memory (RAM)
110
and the CPU
102
may access such data via the MCH
106
.
The ICH
122
communicates with various peripheral devices and I/O components via standard buses or interfaces. Typically, the ICH
122
acts as the “master”, controlling the communication, and the peripheral device as the “slave”, responding to the ICH's
122
commands. One peripheral device is a hard disk drive (HDD)
118
, which may be connected to the ICH
122
via an Integrated Drive Electronics (IDE) or Extended IDE (EIDE) interface
120
. The ICH
122
may also communicate with a codec (AC '97)
116
through the AC '97 Link
132
. Other peripheral devices may also be interfaced with the ICH
122
through such interfaces as a Peripheral Component Interconnect (PCI), Universal Serial Bus (USB), RS-232 serial port, or parallel port.
Regardless of the interface or peripheral device, the ICH
122
routes data, indicated by the dashed bidirectional lines, between said interface or device and the MCH
106
as indicated in FIG.
1
. The host computer's operating system (OS) acts as the Hub Link bus master when the CPU
102
is not in a sleeping state. When the CPU
102
is in sleeping states S3-S5, the Hub Link bus
112
is not usually operable. That is, while the CPU
102
is in these sleeping states, its resources are often unavailable and communications with the computer and its peripheral devices is not generally possible without awakening the CPU
102
. Currently, the ICH
122
is designed with a single Hub Link interface and can handle only one default bus master. In order to comply with existing standards, it is desirable to avoid changing the ICH
122
architecture.
One increasingly common peripheral component in mobile computers is a mobile communications device compatible with the Bluetooth Specification. The Bluetooth Specification, v. 1.0B, Dec. 1, 1999, is a communications standard for wireless communications between mobile PCs, mobile phones, and other portable devices. This standard makes possible the interconnection of a wide range of computing and telecommunications devices via ad hoc, short-range radio links. Presently, most computers utilize external I/O devices to serve as Bluetooth-compliant transceivers. These devices are often connected to a computer via a Universal Serial Bus (USB) port or some other standard I/O interface. They also rely on the computers'CPU
102
to process the messages received and store them in memory
110
. Therefore, these Bluetooth-compliant transceivers would not be able to operate during those times when the computers'CPU
102
is in a sleeping state. However, keeping the CPU
102
powered just to enable the connectivity of Bluetooth compliant devices is wasteful of the limited power available to mobile computers.
The Audio Codec '97 (AC '97) is a computer component which provides analog and digital audio processing functions. The AC '97 Specification was announced Jun. 12, 1996 by co-developers Analog Devices, Inc., Creative Labs, Inc., Intel Corp., National Semiconductor Corp. and Yamaha Corp. An AC '97 component is generally mounted on a host computer's motherboard. On the PC computing architecture, shown in
FIG. 1
, the AC '97
116
is a peripheral device coupled to the ICH
122
. “Coupled” as used herein, includes electrically coupling two or more components.
The AC '97
116
provides support functions for generating audio sounds. In some applications, the AC '97
116
may be used by other peripheral devices
Bormann David
Cline Leslie E.
Hart Frank
Rughoonundon Rudi
Blakely , Sokoloff, Taylor & Zafman LLP
Browne Lynne H.
Trujillo James K.
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