BRIEF DESCRIPTION OF THE DRAWINGS
The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element.
FIG. 1 depicts a block diagram of an information handling system and portable audio device operable to selectively communicate an analog audio signal across a serial link;
FIG. 2 depicts a block diagram of a system for communicating analog information across a USB link;
FIG. 3 depicts a flow diagram of a process for transitioning a USB link to communicate an analog audio signal from a portable audio device to an information handling system; and
FIG. 4 depicts a flow diagram of a process for transition from communication of the analog audio signal to communication of digital audio information for rendering at the information handling system.
DETAILED DESCRIPTION
Communication of an analog audio signal from a portable audio device to an information handling system over a serial link allows use of audible speakers at the information handling system without requiring power to many of the information handling system components for rendering a digital audio file. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.
Referring now to FIG. 1, a block diagram depicts an information handling system and portable audio device operable to selectively communicate an analog audio signal across a serial link. Information handling system 10 includes a variety of processing components to process information, such as a CPU 12, RAM 14, a hard disk drive 16 and a chipset 18. For example, CPU 12 retrieves audio files having a compressed digital format, such as MP3 files, from hard disk drive 16 and renders the audio digital files in cooperation with an audio card 20 of chipset 18 to provide an analog audio signal to audio subsystem 22 for presenting the audio information as audible sounds. Similarly, CPU 12 renders visual information in cooperation with a video card 24 to present visual information at a display 26. In addition to locally stored audio information, a link controller 28 supports communication with remote storage devices through a serial link 30 to retrieve audio files for rendering by CPU 12. For example, a portable audio device 32, such as an MP3 player, has a CPU 34 to render audio files stored in a mass storage 36 as selected through a local menu 38. Portable audio device 32 includes a link interface 40 so that information handling system 10 can retrieve digital audio files from mass storage 36 for rendering at the information handling system.
Portable audio device 32 generally provides an analog audio signal to a headset for presentation to a user and generally does not include speakers for audible play. However, by interfacing portable audio device 32 with information handling system 10 through serial link 30, CPU 12 retrieves digital audio files from mass storage 36 for rendering at information handling system 10 to play audible sound from speakers 42. Using information handling system 10 in this manner to play digital files from mass storage 36 uses most of the processing components and, thus, tends to draw a significant amount of power, which is detrimental to battery life in portable systems. In order to reduce power consumption of information handling system 10, a system module 44 and player module 46 cooperate to transition audio information sent over serial link 30 from a digital format to an analog format. Player module 46 has CPU 34 render the digital audio file to an analog format, such as is used to communicate audio analog to a headset, and switches link interface 40 to send the analog audio signal instead of a digital signal. System module 44 switches communication from link 30 to proceed directly to audio subsystem 22 and provides for continuation of power to audio subsystem 22 at power down of information handling system 10. Communication of the analog audio signal directly to audio subsystem 22 allows audible play of the audio file without using information handling system 10 components to render the file, thus substantially reducing power consumption. At power up of information handling system 10, system module 44 and player module 46 cooperate to resume transfer of the digital audio file through link 30 for rendering at information handling system 10. A synchronizer 48 associated with system module 44 tracks the playback state of the audio file during transitions to maintain a seamless audio playback during transitions. System module 44 and player module 46 are hardware, firmware and/or software components that may be distributed between information handling system 10 and portable audio device 32.
Referring now to FIG. 2, a block diagram depicts a system for communicating analog information across a USB link. A USB CODEC 50 codes and decodes audio information to generate an analog output 52 for use by a headset 54. USB CODEC 50 also communicates digital audio information through USB lines 56 of USB link 30 for communication to USB controller 28. With information handling system 10 in an operating state, digital audio information communicated to USB controller 28 is forwarded to the CPU and related components for rendering. With information handling system 10 in a powered down state, such as suspended or standby states, an analog switch 58 interfaces analog output 52 with USB lines 56 so that decoded analog audio information is communicated to information handling system 10. A switch 60 at information handling system 10 interfaces the analog audio signal directly to audio subsystem 22 for presentation by speakers 42. By having the audio information decoded at portable audio device 32, only limited power is drawn by components on information handling system 10 to play audible audio at speakers 42. Menu selection and control of digital audio file selection are managed through the menu of portable audio device 32. Transition of information handling system 10 between operating and powered down states is communicated through manipulation of power settings on power line 62, such as by toggling power or issuing a power on reset. Transition of USB lines 56 between communication of analog or digital audio information is managed by selection of the positions for switches 58 and 60.
Referring now to FIG. 3, a flow diagram depicts a process for transitioning a USB link to communicate an analog audio signal from a portable audio device to an information handling system. At step 64, power down of the information handling system is detected, such as by a suspend, standby or off request. At step 66, the playback state of digital audio files currently provided from the portable audio device to the information handling system is stored, such as the content name and playback location. At step 68, the USB lines are switched to communicate directly to the audio subsystem, such as an audio amplifier, instead of to the USB controller. At step 70, power is continued to the audio subsystem while other components are powered down, such as through BIOS implementation of a suspend or standby state. At step 72, upon completion of the power down sequence, the USB power line is toggled to initiate a power on reset from the information handling system to the portable audio device. At step 74, the portable audio device responds to the power on reset by attempting to look for a USB initialization sequence. Failure by the portable audio device to detect the USB initialization sequence results in setting up the portable audio device to send analog audio signals through the USB lines. At step 76, rendering of the digital audio file from its playback state is initiated at the portable audio device and, at step 78, the rendered audio analog signal is sent through the USB link to the audio subsystem for presentation at the information handling system.
Referring now to FIG. 4, a flow diagram depicts a process for transition from communication of the analog audio signal to communication of digital audio information for rendering at the information handling system. The process begins at step 80 with detection of a power on from a power down state to an operating state by the information handling system. At step 82, a power toggle is sent from the information handling system to the portable audio device through the USB link to indicate a change in power state of the information handling system. At step 84, the portable audio device stores the playback state of the audio file currently sent over the USB link as an analog audio signal. At step 86, a power on reset is sent to the portable audio device to initialize the USB link at step 88 so that the audio file can be sent as a digital file over the USB link. At step 90, the stored playback state is sent from the portable audio device to the information handling system, which, at step 92 retrieves the digital audio file at the playback state over the USB link. At step 94, the digital audio file is rendered at the information handling system from the playback state for presentation by the audio subsystem.
Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.
Patent Application
20080082838
