PATENT DOCUMENT

Publication Number: US-8171322-B2
Application Number: US-13512208-A
Country: US
Kind Code: B2

Title: Portable electronic devices with power management capabilities

Abstract:
An electronic device may operate in standby and active modes. A headset may be coupled to the electronic device. The electronic device may have audio codec circuitry. The audio codec circuitry may use general purpose input-output circuitry in handling button and headset activity during active mode. Processing circuitry may be used to reconfigure the audio codec in real time. When the electronic device is in the standby mode and activity is detected, the codec may be configured to provide an interrupt signal to a power management unit that wakes the device. When the electronic device is in active mode and no user inputs are received within a given period of time, the central processor in the electronic device may place the device in standby mode.

Claims:
1. A portable electronic device, comprising:
 processing circuitry; 
 a power management unit; and 
 an audio codec circuit coupled to the processing circuitry and the power management unit, wherein the audio codec circuit includes general-purpose input-output circuitry that receives input from a button and that directs the power management unit to transition from a standby mode of operation to an active mode of operation when button activity from the button is detected, wherein the processing circuitry is configured to place the device in the standby mode of operation to conserve power in response to a first interrupt from the audio codec circuit. 
 
     
     
       2. The portable electronic device defined in  claim 1  wherein the processing circuitry is configured to place the portable electronic device in the standby mode of operation when it is determined that standby mode criteria have been satisfied. 
     
     
       3. The portable electronic device defined in  claim 1  wherein the processing circuitry is configured to place the portable electronic device in the standby mode of operation when directed to enter the standby mode by a user request. 
     
     
       4. The portable electronic device defined in  claim 1  wherein the processing circuitry is configured to place the portable electronic device in the standby mode of operation when the portable electronic device has been inactive for a given inactivity period. 
     
     
       5. The portable electronic device defined in  claim 1  further comprising a path between the audio codec circuit and the power management unit, wherein the audio codec circuit asserts a second interrupt on the path to direct the power management unit to transition from the standby mode of operation to the active mode of operation when the audio codec detects the button activity. 
     
     
       6. The portable electronic device defined in  claim 5  wherein the path comprises a first of two paths, wherein a second of the two paths is coupled between the audio codec and the processing circuitry, wherein the audio codec asserts the first interrupt on the second path. 
     
     
       7. The portable electronic device defined in  claim 6  further comprising a bus between the processing circuitry and the audio codec circuit that conveys register settings for the audio codec circuit to configure the audio codec:
 to assert the second interrupt on the first path when the button activity is detected by the audio codec circuit while the audio codec circuit is in active mode; and 
 to assert the first interrupt on the second path when the button activity is detected by the audio codec circuit while the audio codec circuit is in standby mode. 
 
     
     
       8. The portable electronic device defined in  claim 7  further comprising a connector that is used in connecting the audio codec circuit to an external headset having a headset button, wherein the button activity is detected by the audio codec circuit when a user operates the headset button. 
     
     
       9. The portable electronic device defined in  claim 7  further comprising a button that is coupled to the audio codec circuit. 
     
     
       10. The portable electronic device defined in  claim 7  wherein the audio codec circuit comprises a general purpose input-output circuit that is connected to a button, wherein the general purpose input-output circuit is used in detecting the button activity. 
     
     
       11. The portable electronic device defined in  claim 7  wherein the audio codec circuit comprises a general purpose input-output interface circuit that generates the first and second interrupts for the first and second paths. 
     
     
       12. The portable electronic device defined in  claim 11  further comprising a button that is coupled to the general purpose input-output interface circuit, wherein the general purpose input-output circuit handles button activity from the button for the device. 
     
     
       13. The portable electronic device defined in  claim 1  further comprising a bus between the processing circuitry and the audio codec circuit that conveys register settings for the audio codec. 
     
     
       14. A portable electronic device, comprising:
 processing circuitry; 
 a power management unit; 
 an audio codec circuit coupled to the processing circuitry and the power management unit, wherein the audio codec circuit includes general-purpose input-output circuitry that receives input from a button and that directs the power management unit to transition from a standby mode of operation to an active mode of operation when button activity from the button is detected; 
 a bus between the processing circuitry and the audio codec circuit that conveys register settings for the audio codec, wherein the audio codec circuit comprises a general purpose input-output circuit that has associated registers and wherein the register settings conveyed over the bus are loaded into the registers to configure the general purpose input-output circuit. 
 
     
     
       15. A method for operating a portable electronic device having processing circuitry, a power management unit, and an audio codec with registers that control the operation of the audio codec, comprising:
 with the processing circuitry, loading settings into the registers that configure the audio codec to provide a first interrupt to the power management unit when button activity is detected by the audio codec while the portable electronic device is in a standby mode of operation; and 
 with the processing circuitry, loading settings into the registers that configure the audio codec to provide a second interrupt to the processing circuitry when an event is detected by the audio codec while the portable electronic device is operating in an active mode of operation. 
 
     
     
       16. The method defined in  claim 15  wherein the event comprises an event that is indicative that the device is to enter the standby mode of operation. 
     
     
       17. The method defined in  claim 16  wherein the event comprises button activity, the method comprising:
 with general purpose input-output circuit in the audio codec, directing the power management unit to transition to a standby mode in response to the button activity. 
 
     
     
       18. The method defined in  claim 15  wherein the button activity comprises headset button activity, the method further comprising:
 in response to the detected headset activity, asserting the first interrupt with the audio codec. 
 
     
     
       19. The method defined in  claim 18  further comprising:
 powering down unused circuitry in the audio codec during the standby mode. 
 
     
     
       20. The method defined in  claim 15  wherein the loaded settings in the registers configure the audio codec to provide the first interrupt to the power management unit when microphone activity is detected by the audio codec while the portable electronic device is in the standby mode, the method further comprising:
 in response to the detected microphone activity, asserting the first interrupt with the audio codec. 
 
     
     
       21. The method defined in  claim 15  further comprising:
 when no user inputs are received by the portable electronic device within a given period of time, directing the power management unit to transition to a standby mode. 
 
     
     
       22. A method for minimizing power consumption in a portable electronic device that has audio codec circuitry, a headset jack, a power management unit, and processing circuitry, wherein the audio codec circuitry has a headset activity detection circuit that detects activity on the headset jack, has first and second outputs that are respectively coupled to the power management unit and the processing circuitry, and has a register that contains register data and wherein the audio codec circuitry asserts an interrupt signal on a given one of its outputs when it detects activity on the headset jack, the method comprising:
 when placing the portable electronic device in a standby mode, providing register data to the register that configures the audio codec circuitry so that the interrupt signal is asserted on the first output and is received by the power management unit; and 
 when placing the portable electronic device in an active mode, providing register data to the register that configures the audio codec circuitry so that the interrupt signal is asserted on the second output and is received by the processing circuitry. 
 
     
     
       23. The method defined in  claim 22  further comprising:
 when the portable electronic device enters the standby mode, powering down the processing circuitry; and 
 when the portable electronic device enters the active mode, powering up the processing circuitry. 
 
     
     
       24. The method defined in  claim 23  further comprising:
 with the headset activity detection circuit, detecting activity on the headset jack, wherein detecting activity on the headset jack comprises detecting the coupling of a headset to the headset jack. 
 
     
     
       25. The method defined in  claim 23  further comprising:
 with the headset activity detection circuit, detecting activity on the headset jack, wherein detecting activity on the headset jack comprises detecting the decoupling of a headset from the headset jack. 
 
     
     
       26. The method defined in  claim 23  wherein the headset jack receives a headset with a headset button, the method further comprising:
 with the headset activity detection circuit, detecting activity on the headset jack, wherein detecting activity on the headset jack comprises detecting the decoupling of the headset from the headset jack, detecting the coupling of the headset to the headset jack, and, when the headset is coupled to the portable electronic device, detecting when the headset button is pressed. 
 
     
     
       27. The method defined in  claim 23  wherein the audio codec circuitry has an input coupled to a button, wherein the audio codec circuitry asserts the interrupt signal on the given one of its outputs when it detects activity on the input that is coupled to the button, and wherein the headset jack receives a headset with a headset button, the method further comprising:
 with the headset activity detection circuit, detecting activity on the headset jack, wherein detecting activity on the headset jack comprises:
 detecting the decoupling of a headset from the headset jack; 
 detecting the coupling of the headset to the headset jack; and 
 when the headset is coupled to the portable electronic device, detecting when the headset button is pressed; and 
 
 with the audio codec circuitry, detecting when the button is pressed, wherein the audio codec circuitry asserts the interrupt signal on the given one of its outputs when it detects activity on the input coupled to the button. 
 
     
     
       28. The method defined in  claim 27  further comprising:
 when the power management unit receives the interrupt signal, configuring the portable electronic device to operate in the active mode, wherein configuring the portable electronic device to operate in the active mode comprising powering up the processing circuitry. 
 
     
     
       29. The method defined in  claim 23  wherein the audio codec circuitry has an input coupled to a button, the method further comprising:
 with the audio codec circuitry, detecting when the button is pressed; and 
 in response to detecting activity on the input coupled to the button, asserting the interrupt signal on the given one of the audio codec circuitry outputs.

Description:
BACKGROUND 
     This invention relates generally to portable electronic devices, and more particularly, to portable electronic devices with power management capabilities. 
     Handheld electronic devices and other portable electronic devices are becoming increasingly popular. Examples of handheld devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. Popular portable electronic devices that are somewhat larger than traditional handheld electronic devices include laptop computers and tablet computers. 
     Due in part to their mobile nature, portable electronic devices are often provided with wireless communications capabilities. For example, handheld electronic devices may use long-range wireless communications to communicate with wireless base stations and may use short-range communications to communicate with accessories and local networks. 
     Portable electronic devices are also sometimes provided with music playback capabilities. The circuitry used for functions such as wireless communications and media playback can consume a relatively large amount of power. Nevertheless, manufacturers have made attempts to miniaturize the batteries used in handheld electronic devices, which reduces battery capacity. Unless care is taken to consume power wisely, these devices may exhibit unacceptably short operating times. 
     It would therefore be desirable to be able to provide portable electronic devices with improved power management capabilities. 
     SUMMARY 
     A portable electronic device such as a handheld electronic device is provided with power management capabilities. The power management capabilities of the device may be used to help conserve power. For example, the power management functions of the device may be used to power-down unused circuitry in certain modes of operation. 
     The portable electronic device may operate in two or more power management modes to optimize performance and battery life. For example, the electronic device may operate in an active mode (i.e., a full-power mode) when a user is interacting with the electronic device (e.g., during normal operations) and may operate in a standby mode when a user is not interacting with the electronic device. When the electronic device is operating in the standby mode, circuitry and suitable components such as a central processing unit or CPU in the electronic device may be powered down or operated in a low-power mode to minimize the power consumption of the electronic device. The electronic device may have power management circuitry that generates power control signals that direct circuitry and components in the electronic device to enter their standby mode or, when awakening from standby, to enter their active mode. For example, when entering standby mode, power management circuitry may send signals to components in the electronic device that cause those components to turn off or to operate in a reduced power mode. 
     The portable electronic device may have audio codec circuitry that provides audio input-output functionality. The audio codec may facilitate media player and cellular telephone operations in the electronic device. For example, the codec circuitry may have an analog-to-digital converter for converting a user&#39;s voice received through a microphone to digital signals for cellular telephone calls, recorded memos, or video sound tracks. The codec circuitry may also have a digital-to-analog converter for converting digital audio signals into analog signals for playback over a speaker (e.g., as part of a telephone call or a media playback operation). 
     The portable electronic device may have an audio jack. The audio jack may provide connectivity for an external audio accessory such as a headset. A headset may have stereo speakers, a microphone, and a button for controlling the device. Headsets such as these are sometimes referred to as cellular telephone headsets. The codec circuitry may receive signals from a button in an external accessory such as a headset and from one or more buttons on the electronic device (e.g., the codec circuitry may detect button activity from one or more buttons). The codec circuitry may have headset activity detection circuitry that can detect when a headset is connected to or disconnected from the electronic device and when a button is pressed on a headset that is connected to the electronic device. 
     When the codec circuitry detects user activity such as headset activity or button activity, the codec circuitry may generate an interrupt signal. The codec circuitry may have registers that contain settings data that determines how the codec circuitry operates. The codec circuitry may be configured to assert the interrupt signal on one of two paths by providing the registers with appropriate settings data. For example, when the electronic device is operating in its standby mode, the codec circuitry may be configured with appropriate settings data to assert interrupt signals on a path that is coupled to a power management unit or power management circuitry. When the power management circuitry receives this interrupt, the power management circuitry may power up the electronic device. When the electronic device is operating in its active mode, the codec circuitry may be configured with appropriate data to assert interrupt signals on a path that is coupled to processing circuitry such as a central processor. When the processing circuitry receives the interrupt, the processing circuitry may perform an appropriate action (e.g., an action prompted by the detected activity). 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device having power management capabilities in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative portable electronic device in accordance with an embodiment of the present invention. 
         FIG. 3  is a diagram of a conventional tip-ring-ring-sleeve connector. 
         FIG. 4A  is a circuit diagram of an illustrative headset device that may be coupled to an electronic device with power management capabilities in accordance with an embodiment of the present invention. 
         FIG. 4B  is a circuit diagram of an illustrative headset device that has a microphone and a button wired together in parallel and that may be coupled to an electronic device with power management capabilities in accordance with an embodiment of the present invention. 
         FIG. 4C  is a circuit diagram of an illustrative headset device that has a microphone and a button wired together in series and that may be coupled to an electronic device with power management capabilities in accordance with an embodiment of the present invention. 
         FIG. 5  is a circuit diagram of an illustrative electronic device and an illustrative headset in accordance with an embodiment of the present invention. 
         FIG. 6A  is a state diagram of illustrative operating modes of an illustrative electronic device with power management capabilities in accordance with an embodiment of the present invention. 
         FIG. 6B  is a flow chart of illustrative steps involved in using an electronic device with power management capabilities in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to portable electronic devices, and more particularly, to power management in portable electronic devices. 
     The portable electronic devices may be portable electronic devices such as laptop computers or small portable computers of the type that are sometimes referred to as ultraportables. Portable electronic devices may also be somewhat smaller devices. Examples of smaller portable electronic devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. With one suitable arrangement, the portable electronic devices may be handheld electronic devices. 
     The portable electronic devices may be, for example, cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controllers, global positioning system (GPS) devices, and handheld gaming devices. The portable electronic devices may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid portable electronic devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes game and email functions, and a portable device that receives email, supports mobile telephone calls, has music player functionality and supports web browsing. These are merely illustrative examples. 
     An illustrative portable electronic device in accordance with an embodiment of the present invention is shown in  FIG. 1 . Device  10  of  FIG. 1  may be, for example, a handheld electronic device. 
     Device  10  may have housing  12 . Antennas for handling wireless communications may be housed within housing  12  (as an example). 
     Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including, plastic, glass, ceramics, metal, or other suitable materials, or a combination of these materials. Housing  12  may have a bezel  14 . The bezel  14  may be formed from a conductive material and may surround a display or other device with a planar surface on device  10 . 
     Display  16  may be a liquid crystal display (LCD), an organic light emitting diode (OLED) display, or any other suitable display. The outermost surface of display  16  may be formed from one or more plastic or glass layers. If desired, touch screen functionality may be integrated into display  16  or may be provided using a separate touch pad device. An advantage of integrating a touch screen into display  16  to make display  16  touch sensitive is that this type of arrangement can save space and reduce visual clutter. 
     Display screen  16  (e.g., a touch screen) is merely one example of an input-output device that may be used with electronic device  10 . If desired, electronic device  10  may have other input-output devices. For example, electronic device  10  may have user input control devices such as button  19 , and input-output components such as port  20  and one or more input-output jacks (e.g., for audio and/or video). Button  19  may be, for example, a menu button. Button  27  may be, for example, a ringer A/B switch that is used to place device  10  in vibrate mode when silent operation is desired. Port  20  may contain a 30-pin data connector (as an example). Openings  22  and  24  may, if desired, form microphone and speaker ports. Speaker port  24  may be used when operating device  10  in speakerphone mode. Opening  25  may also form a speaker port. For example, speaker port  25  may serve as a telephone receiver that is placed adjacent to a user&#39;s ear during operation. In the example of  FIG. 1 , display screen  16  is shown as being mounted on the front face of handheld electronic device  10 , but display screen  16  may, if desired, be mounted on the rear face of handheld electronic device  10 , on a side of device  10 , on a flip-up portion of device  10  that is attached to a main body portion of device  10  by a hinge (for example), or using any other suitable mounting arrangement. 
     Device  10  may have an audio input-output jack such as jack  23 , which may be referred to as a headset jack. As shown in  FIG. 1 , jack  23  may formed in a recess in the top edge of device  10  (e.g., the outline of jack  23  is illustrated by dotted lines to indicate how jack  23  may extend into the interior of device  10 ). In general, jack  23  may be formed in any suitable location on device  10 . Jack  23  may contain a 4-pin connector such as a female connector that is sometimes referred to as a tip-ring-ring-sleeve (TRRS) connector (as an example). Jack  23  may receive a male connector that is sometimes referred to as a TRRS plug. With one suitable arrangement, jack  23  may be used to provide connectivity between device  10  and a cellular telephone headset that has a microphone, a speaker, and a button (e.g., a headset with input and output audio capabilities and a button that controls a function in device  10  such as hanging up a telephone call). With another suitable arrangement, the functionality of jack  23  may be provided with two or more connectors. For example, a first jack may provide speaker functionality and a second jack may provide microphone and user input functionality. 
     A user of electronic device  10  may supply input commands using user input interface devices such as button  19  and touch screen  16  and using external devices (e.g., through headset jack  23 ). Suitable user input interface devices for electronic device  10  include buttons (e.g., alphanumeric keys, power on-off, power-on, power-off, and other specialized buttons, etc.), a touch pad, pointing stick, or other cursor control device, a microphone for supplying voice commands, an external device such as a headset with user input functionality, or any other suitable interface for controlling device  10 . Although shown schematically as being formed on the top face of electronic device  10  in the example of  FIG. 1 , buttons such as buttons  19  and  27  and other user input interface devices may generally be formed on any suitable portion of electronic device  10 . For example, a button such as button  19  or other user interface control may be formed on the side of electronic device  10 . Buttons and other user interface controls can also be located on the top face, rear face, or other portion of device  10 . If desired, device  10  can be controlled remotely (e.g., using an infrared remote control, a radio-frequency remote control such as a Bluetooth remote control, etc.). 
     Electronic device  10  may have ports such as port  20 . Port  20 , which may sometimes be referred to as a dock connector, 30-pin data port connector, input-output port, or bus connector, may be used as an input-output port (e.g., when connecting device  10  to a data port or a mating dock connected to a computer or other electronic device). Device  10  may also have audio and video jacks that allow device  10  to interface with external components. Typical ports include power pins to recharge a battery within device  10  or to operate device  10  from a direct current (DC) power supply, data pins to exchange data with external components such as a personal computer or peripheral, headset jacks, audio-visual jacks (e.g., TRRS jacks such as jack  23 ) to drive headphones, a monitor, or other external audio-video equipment, a subscriber identity module (SIM) card port to authorize cellular telephone service, a memory card slot, etc. The functions of some or all of these devices and the internal circuitry of electronic device  10  can be controlled using input interface devices such as touch screen display  16 . 
     Components such as display  16  and other user input interface devices may cover most of the available surface area on the front face of device  10  (as shown in the example of  FIG. 1 ) or may occupy only a small portion of the front face of device  10 . Examples of locations in which antenna structures may be located in device  10  include region  18  and region  21 . These are merely illustrative examples. Any suitable portion of device  10  may be used to house antenna structures for device  10  if desired. 
     If desired, electronic device  10  may be a portable electronic device such as a laptop or other portable computer. For example, electronic device  10  may be an ultraportable computer, a tablet computer, or other suitable portable computing device. Electronic device  10  may also be a handheld device. Power management considerations are particularly important in small devices such as handheld devices, because space is at a premium in small devices which limits the amount of space available for batteries. 
     A schematic diagram of an embodiment of an illustrative portable electronic device such as a handheld electronic device is shown in  FIG. 2 . Portable device  10  may be a mobile telephone, a mobile telephone with media player capabilities, a handheld computer, a remote control, a game player, a global positioning system (GPS) device, a laptop computer, a tablet computer, an ultraportable computer, a combination of such devices, or any other suitable portable electronic device. 
     As shown in  FIG. 2 , device  10  may include storage  34 . Storage  34  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
     Processing circuitry  36  may be used to control the operation of device  10 . Processing circuitry  36  may be based on a processor such as a microprocessor (also sometimes referred to as a central processor unit or application processor) and other suitable integrated circuits such as power management units, cellular telephone processor chips, audio codecs, etc. With one suitable arrangement, processing circuitry  36  and storage  34  are used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. Processing circuitry  36  and storage  34  may be used in implementing suitable communications protocols. Communications protocols that may be implemented using processing circuitry  36  and storage  34  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, protocols for handling 2G and 3G cellular telephone services, etc. 
     To minimize power consumption, processing circuitry  36  or other suitable control circuitry on device  10  may be used in implementing power management functions. For example, processing circuitry  36  may be used to adjust the power consumption of device  10  by controlling when device  10  enters a low power mode such as a standby mode. In a low power or standby mode, certain components in device  10  may be powered down, may be powered using reduced power supply voltages, or may be operated in a reduced performance mode in which the frequency of clocks that are used to control the operation of the components is reduced. These adjustments to the operation and power consumption of device  10  may be made automatically in real time. With one suitable arrangement, processing circuitry  36  may include one or more power management units (chips) that act as power management control circuits and that handle power management functions. If desired, one or more power management units may remain active when device  10  is operating in its standby mode and may wake up a central processing unit (CPU) when device  10  enters its active mode (from its standby mode). 
     Input-output devices  38  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Display screen  16 , buttons  19  and  27 , headset jack  23 , and dock connector port  20  are examples of input-output devices  38 . 
     Input-output devices  38  can include user input-output devices  40  such as buttons, headsets, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device  10  by supplying commands through user input devices  40 . Display and audio devices  42  may include liquid-crystal display (LCD) screens or other screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  42  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  42  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     Wireless communications devices  44  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Device  10  can communicate with external devices such as accessories  46 , computing equipment  48 , and wireless network  49  as shown by paths  50  and  51 . Path  51  may be a wireless path. Paths  50  may include wired and wireless paths. For example, paths  50  may include a jack such as jack  23  that provides connectivity between device  10  and a cellular telephone headset. 
     Accessories  46  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content), a peripheral such as a wireless printer or camera, etc. With one suitable arrangement, accessories  46  may include a wired headset with a speaker, a microphone, and with user input functionality. For example, accessories  46  may include a cellular telephone headset that has stereo speakers (i.e., a left speaker and a right speaker), a microphone, and that has a button for user input functionality. The button may be used to start or end a cellular telephone call, to mute the microphone and/or speaker, to initiate a voice recognition program in device  10 , to control media playback operations (e.g., the button may be used as a play/pause button), or for any other suitable function. 
     Accessories  46  such as a cellular telephone headset may also be used to wake up device  10  from a low-power mode such as a sleep or standby mode. For example, accessories  46  such as a cellular telephone headset may be used to wake up device  10  when a button is pressed on the headset or when the headset is removed or coupled to device  10  (e.g., coupled to a jack such as jack  23 ). This type of arrangement may be used, for example, when device  10  is being carried in a backpack and the headset and its button are the only portions of device  10  that are readily accessible to the user. 
     Computing equipment  48  may be any suitable computer. With one suitable arrangement, computing equipment  48  is a computer that has an associated wireless access point (router) or an internal or external wireless card that establishes a wireless connection with device  10 . The computer may be a server (e.g., an internet server), a local area network computer with or without internet access, a user&#39;s own personal computer, a peer device (e.g., another portable electronic device  10 ), or any other suitable computing equipment. 
     Wireless network  49  may include any suitable network equipment, such as cellular telephone base stations, cellular towers, wireless data networks, computers associated with wireless networks, etc. 
     A conventional tip-ring-ring-sleeve connector of the type that may be used to connect a headset to a handheld device is shown in  FIG. 3 . Connector  100  has tip portion  102 , first ring portion  104 , second ring portion  106 , and sleeve portion  108 . Each of conductor portions  102 ,  104 ,  106 , and  108  corresponds to a conductor inside connector  100  (e.g., a conductor inside cable  101 ). Conductor portions  102 ,  104 ,  106 , and  108  are physically and electrically isolated from each other by isolation bands  110 . With one suitable arrangement, a conventional tip-ring-ring-sleeve connector such as connector  100  of  FIG. 3  can be used to couple an accessory (such as accessory  46  of  FIG. 2 ) to an electronic device (such as device  10  of  FIG. 2 ) using three separate signal paths and a ground path (sometimes referred to as a return path) that is shared by the three electrical signal paths. 
     A circuit diagram of an illustrative headset device that may be coupled to device  10  using a connector such as the conventional TRRS connector of  FIG. 3  or other suitable connector is shown in  FIG. 4A . A headset device such as device  46  may be coupled to device  10  over path  50 . Path  50  may be formed from four individual paths (conductors) such as paths  52 ,  54 ,  56 , and  58 . With one suitable arrangement, a headset device such as device  46  may allow a user to operate device  10  in what is commonly referred to as a hands-free mode. For example, device  10  may be a handheld device with cellular telephone capabilities and device  46  may be a wired cellular headset that allows a user to operate device  10  as a cellular telephone without requiring the user to touch device  10 . 
     Device  46  may receive audio signals such as the audio signals for a telephone call from device  10  (e.g., over paths  52  and  54 ) and may play those audio signals over a speaker such as speaker  55 . Speaker  55  may be, for example, a passive speaker such as the type of speaker commonly used in headphones or an active speaker which includes amplifier circuitry to boost the audio signals (e.g., to increase the volume of the audio signals). Device  46  may receive monaural or stereo audio signals from device  10 . 
     Device  46  may have a microphone such as microphone  57  that picks up the voice of a user and converts the user&#39;s voice into audio signals (e.g., analog electrical signals). Microphone  57  may be coupled to device  10  over path  56  and ground path  52 , so that device  46  provides audio signals corresponding to the user&#39;s voice to device  10 . 
     Device  46  may have a button such as button  59 . Button  59  may be coupled to device  10  over path  58  and ground path  52 , as an example. In general, button  59  may be used to control any suitable function of device  10 . For example, when device  10  is operating as a cellular telephone, button  59  may be used by a user to control telephone-related functions of device  10  such as a push-to-talk feature, a mute feature, an end call feature (e.g., a hang-up feature), an answer call feature (e.g., to answer an incoming telephone call), a redial feature, etc. When device  10  is operating as a media player, button  59  may be used to control functions related to media playback operations such as play, pause, stop, fast forward, etc. These are merely illustrative examples. 
     With one suitable arrangement, button  59  may be used to initiate a voice recognition program in device  10  such as a voice recognition program in which device  10  recognizes commands that are vocalized by a user and responds accordingly. For example, device  10  may respond (e.g., perform an appropriate action) when a user issues voice commands such as “call home”, “call 555-1234”, “redial”, “call voicemail”, etc. 
     Device  46  (e.g., a cellular telephone headset) may be used to control power management functions in device  10 . For example, device  46  may be used to wake up device  10  from a low-power or standby mode. With one suitable arrangement, circuitry in device  10  may sense activity associated with the use of device  46  such as when device  46  is coupled to or decoupled from device  10 , when button  59  is pressed or otherwise activated, or when sound is detected through microphone  57 . If desired, circuitry in device  10  may use a microphone such as microphone  57  to sense activity associated with the use of device  10  such as loud noises, silence, and other suitable tones and noises (e.g., circuitry in device  10  may detect microphone activity). When device  10  is in a standby (sleep) mode and senses activity from device  46  or a button on device  10 , wake command control signals may be generated that cause sleeping circuitry to enter a full-power or active mode (e.g., the device may wake up from standby). If desired, button  59  may be a standby button which, when pressed, causes device  10  enter its standby mode. 
     As shown in  FIGS. 4B and 4C , device  46  may have two speakers that together provide stereophonic (i.e., stereo) sound to a user. For example, device  46  may have a left speaker such as left speaker  200  and a right speaker such as right speaker  202  that together provide stereo to the user. 
       FIGS. 4B and 4C  also show how button  59  and microphone  57  may share a common connection to device  10  (e.g., button  59  and microphone  57  may both be coupled to device  10  through path  58  and return path  52 ). In the  FIG. 4B  example, microphone  57  and button  59  are wired in parallel between paths  52  and  58 . In this type of configuration, button  59  may temporarily short path  58  to path  52  when pressed, thereby producing a sudden increase in the current (i.e., a microphone bias current) flowing through path  52 . This current increase can be detected by circuitry in device  10  (e.g., by a headset activity detection circuit). In the  FIG. 4C  embodiment, microphone  57  and button  59  are wired in series between paths  52  and  58 . In this type of configuration, button  59  may temporarily isolate path  52  from path  58  when pressed, thereby producing a drop in the current flowing through path  52  that can be detected by circuitry in device  10 . 
     With conventional power management schemes, it is often necessary to operate large blocks of circuitry, even in standby mode. Although button and headset activity can be detected when operating in this way, large amounts of power are consumed. In accordance with an embodiment of the present invention, low power circuits such as audio codec circuits can be used to monitor button and headset activity in sleep mode. This can reduce power consumption and extend battery life. 
     A circuit diagram showing circuitry that may be used in implementing power management functions in device  10  is shown in  FIG. 5 . As shown in  FIG. 5 , device  10  may have audio codec  64 , one or more power management units such as power management unit  74 , and other circuitry  78  (e.g., a central processor unit, etc.). Headset device  46  may be used in controlling the operation of device  10  and, as an example, may be used in controlling power management unit  74  when device  10  is operating in a standby mode. As illustrated by  FIG. 5 , device  46  may be coupled to device  10  over a path such as path  50 . Path  50  may be a single cable with multiple conductors, as described in connection with  FIGS. 4A ,  4 B, and  4 C. Device  46  may be coupled to device  10  through a connector such as jack  23  (e.g., a headset jack). 
     Codec circuitry  64  may have headset activity detection circuitry  60 . Headset activity detection circuitry  60  may be used to detect activity from headset device  46  over jack  23 . For example, headset activity detection circuitry  60  may detect when device  46  is coupled to or decoupled from device  10  and may detect when a button such as button  59  is pressed. If desired, headset activity detection circuitry  60  may include a current detection circuit that detects sudden changes in a microphone bias current (e.g., a current that is continually passed through a microphone such as microphone  57  to operate the microphone when the microphone is coupled to device  10 ). As an example, headset activity detection circuitry  60  may detect changes in the microphone bias current that occur when button  59  is pressed and that occur when device  46  is coupled to or decoupled from device  10 . When circuitry  60  detects activity associated with headset  46 , circuitry  60  may convey relevant information to an interrupt control circuit such as circuit  62 . For example, circuitry  60  may send signals to circuit  62  indicating that circuit  62  should assert an interrupt signal on path  80  or path  76 . 
     Audio codec  64  may include reconfigurable input-output circuitry for handling general purpose input and output tasks. This circuitry is sometimes referred to as general purpose input-output circuitry. General purpose input-output circuitry such as GPIO circuitry  70  may be used to receive signals from one or more physical buttons on device  10  such as button(s)  88  (e.g., buttons such as ringer A/B switch  27 , menu button  19 , etc.). When circuitry  70  detects that one of the physical buttons on device  10  coupled to circuitry  70  has been pressed (i.e., moved, depressed, or released, depending on the how the button operates), circuitry  70  may convey relevant information to an interrupt control circuit such as circuit  62  in codec  64 . For example, circuitry  70  may send signals to circuit  62  indicating that circuit  62  should assert on interrupt signal on path  80  or path  76 . 
     Codec circuitry  64  and, in particular, circuitry  79  may provide device  10  with audio input and output capabilities as well as general purpose input and output capabilities. For example, codec circuitry  64  may be used to provide audio output signals to external devices and may be used to receive audio input signals from external devices. Digital-to-analog conversion circuitry in circuitry  79  may be used to create analog output signals for driving speakers. Analog-to-digital conversion circuitry in circuitry  79  may be used to digitize analog audio signals from a microphone. Circuitry  64  may also be used to send or receive control signals (e.g., signals from a physical button on device  10  such as button(s)  88  and from a button on headset  46  such as button  59 ). With one suitable arrangement, general purpose input and output (GPIO) functions such as receiving signals from buttons  19 ,  59 , and  88  may be implemented using GPIO control circuitry  70 . 
     GPIO registers  72  may be used to configure GPIO circuitry  70 . For example, when device  10  is in a standby mode, GPIO registers  72  may be programmed with register settings that configure circuitry  70  to assert interrupt signals on path  76 . Path  76  is connected to power management unit  74  so that the interrupt signals on path  76  are received by power management unit  74 . When device  10  is in an active (e.g., a normal operational) mode, GPIO registers  72  may be programmed with register settings that configure circuitry  70  to assert interrupt signals on path  80 . Path  80  is connected to circuitry  78 , so this interrupt may be received by a central processing unit in device  10 . Interrupt signals may asserted in response to any suitable conditions that are indicative of a need to transition between sleep and active modes (e.g., headset activity, button activity, application activity, etc.). 
     When activity is detected through circuit  60  (i.e., headset activity) or through GPIO circuit  70  (such as button(s)  88  activity), interrupt control circuitry  62  may receive information from circuit  60  or circuit  70  and may generate interrupt signals that are sent out of codec circuitry  64  through general purpose input-output circuitry  70 . GPIO circuitry  70  may assert these interrupt signals on path  80  and path  76  depending on settings in registers  72  (e.g., settings that are associated with which mode device  10  is operating in). Circuitry  78  (e.g., a central processing unit and associated memory) may be used in loading appropriate settings data into registers  72 . 
     Power management units may be used in managing the operation and power consumption of components in device  10 . Power management units may, for example, receive power from a battery and may supply appropriately regulated direct current (DC) power supply voltages to integrated circuits and other components in device  10 . State machine circuitry in the power management units may be used in controlling the behavior of the power management units in different device operating modes. As an example, circuitry in the power management units may be used to ensure that the power management units provide one set of DC output voltages when operating in an active mode and provide another set of DC output voltages when operating in a standby mode. 
     In a typical scenario, device  10  may include a “radio” power management unit that is always powered. The radio power management unit may be used to detect activity in wireless communications devices  44  ( FIG. 2 ). For example, the radio power management unit may be used to listen for incoming wireless telephone calls. When an incoming call is detected, the radio power management unit may wake up appropriate circuitry in device  10  to ensure that the call can be handled properly. 
     Device  10  may also include a power management unit that manages the operation and power consumption of device  10  in response to other events. This power management unit, which is shown schematically as power management unit  74  of  FIG. 5 , may be used to supply DC power supply voltages to circuitry  78  (e.g., components such as volatile random-access memory, non-volatile memory such as boot flash memory, a central processing unit, display  16  and an associated touch screen, etc.) and audio codec circuitry  64 . The power management unit may supply each integrated circuit and other component in device  10  with one or more power supply voltages. For example, lines such as lines  66  may be used by power management unit  74  to supply audio codec  64  with voltages such as a digital core voltage (e.g., 1.8 volts) a pin-driver voltage (e.g., 1.8 volts), and a headphone power voltage (e.g., that may be supplied at 3.0 volts during active mode and that may not be supplied during standby mode). If desired, one or more of lines  66  may be a common ground path (e.g., a 0 volt path sometimes referred to as a ground rail) that serves as a return path for currents sent to codec  64 . Audio codec  64  may also be provided with a raw battery supply voltage that ranges, for example, from 3.0 to 4.2 volts. 
     General purpose input-output circuit  70  may be used in processing button activity from buttons  88  during normal operation. During normal operation, information on button presses may be passed to processing circuitry in circuitry  78  over paths such as path  86 . This processing circuitry may use the button press data in operating device  10  (e.g., to display appropriate menu screens for the user in response to button presses, to change device settings in response to button presses, etc.). When standby criteria are satisfied, circuitry  78  can place device  10  in standby mode. In general, any suitable conditions may be used to place device  10  in standby mode. As an example, processing circuitry  78  may monitor activity levels in device  10  such as the presence or absence of button activity, the presence or absence of software application activity, etc. If a user-defined or default period of inactivity is reached, processing circuitry  78  may place device  10  in standby (e.g., processing circuitry  78  may direct system components such as a power management unit  74  and codec  64  to enter standby). As another example, a user may affirmatively place device  10  in standby using a button press, a software application option, or any other suitable standby request such as a standby request supplied using input devices  40 . If desired, combinations of these arrangements may be used. For example, device  10  may be configured to enter standby following a default or user-defined period of inactivity provided that a user is not running certain applications. Standby mode may also be initiated upon completion of a task (e.g., when an outgoing email message has been sent or when device  10  completes the playback of a media file). These are merely illustrative examples. Processing circuitry  78  may be configured to place device  10  in standby mode when any suitable standby mode criteria have been satisfied. 
     When operating in standby mode, circuitry  78  may be powered down to reduce power consumption. While operating in this reduced power mode, relatively low-power circuitry associated with audio codec  64  (e.g., interrupt control circuit  62 , headset activity detection circuit  60 , and general-purpose input-output interface circuitry  70 ) may be used to monitor button activity and headset activity. If activity is detected, codec  64  may report the occurrence of this activity to power management unit  74  to initiate the process of waking up device  10  from standby mode. Activity may be reported to power management unit using an interrupt on path  76 . 
     To ensure proper operation of audio codec  64  in both active and standby modes, codec  64  may be reconfigured when device  10  switches between its active and standby modes (e.g., by loading registers such as registers  72  with appropriate settings). When placed in its active mode configuration, audio codec  64  will assert the interrupt on path  80  in response to detected activity. When placed in its standby mode configuration, audio codec  64  will assert the interrupt on path  76  in response to detected activity. Settings data for registers in codec  64  (e.g., for registers  72 ) may be stored in memory. During reconfiguration operations, a central processing unit or other circuitry  78  may load the settings data from memory into registers in codec  64  over a path such as path  86 . Path  86  may be, for example, a bidirectional control bus such as an I 2 C bus. 
     Power management unit  74  may have state machine circuitry that controls the operation of power management unit  74  in active mode and standby mode. Power management unit  74  may produce one set of outputs when operating in active mode and may produce another set of outputs when operating in standby mode. 
     During normal operation of device  10 , power management unit  74  may be in its active state and GPIO circuitry  70  may be configured to provide interrupt signals to circuitry  78  (i.e., a central processor in device  10 ) over path  80 . When device  10  is in its active mode and circuitry  78  receives an interrupt signal such as an interrupt from circuitry  62 , circuitry  78  may interrogate components in device  10  to determine the source and cause of the interrupt and, after the source and cause are determined, circuitry  78  may perform an associated action. For example, when button  59  is pressed, interrupt control  62  may produce an interrupt that is sent (by GPIO  70 ) to circuitry  78  over path  80 . Circuitry  78  may respond to the interrupt by sending a query to circuitry  64  over path  86  to determine what event triggered the interrupt. In this example, circuitry  64  will inform circuitry  78  that button  59  was pressed and circuitry  78  will take an appropriate action. If desired, power management unit  74  may assert interrupt signals on path  84  (e.g., which may include an interrupt line) when power management unit  74  needs to signal an event to processing circuitry  78 . 
     When device  10  is in its standby mode, GPIO circuitry  70  may be configured to provide interrupt signals to circuitry  74  (i.e., a power management unit) over path  76 . When device  10  is in its standby mode and circuitry  74  receives the interrupt from circuitry  62 , circuitry  74  may wake up device  10  (e.g., circuitry  74  may place device  10  in its active mode). When device  10  wakes up from its standby mode, circuitry  78  may interrogate power management unit  74  to determine the source and cause of the wake up event (i.e., the reason why device  10  woke up from its standby mode). Circuitry  78  may interrogate power management unit  74  using a bi-directional communications path such as path  84 , as an example. In response to this interrogation, power management unit may send signals over path  84  to circuitry  78  that inform circuitry  78  of the source of the wake up event (i.e., circuitry  64 ). Circuitry  78  may then query the source of the wake up event (i.e., circuitry  64 ) to determine the cause of the wake up event (e.g., whether a button was pressed, whether a headset was removed or attached, etc.). Once circuitry  64  informs circuitry  78  of the nature of the wake-up activity, circuitry  78  may take appropriate action. If desired, circuitry  74  may send signals over path  84  to circuitry  78  indicating the source of the wake up event along with signals indicating the cause of the wake up event (e.g., so that circuitry  78  need not interrogate circuitry  64  directly). 
     Circuitry  79  may include circuitry such as digital-to-analog converters, analog-to-digital converters, audio amplifiers, speaker drivers (e.g., headphone amplifiers), digital signal processors, microphone amplifiers, microphone biasing circuitry, and other audio circuitry. With one suitable arrangement, circuitry  79  may include circuitry that interfaces with a microphone (e.g., a microphone in device  10  or in headset  46 ). 
     Circuitry  78  may, in general, include any circuitry in device  10  such as processing circuitry  36 , circuitry associated with storage  34 , circuitry associated with input-output devices  38 , etc. 
     To minimize power consumption, processing circuitry  78  may send signals to components in device  10  such as codec circuitry  64  and power management unit (PMU)  74  to direct the components reduce their power consumption (e.g., by turning off unnecessary components) and may enter its standby mode. For example, processing circuitry  78  may send signals to components in device  10  to reduce their power consumption. If desired, the last signals sent by processing circuitry  78  as it enters its standby mode may be signals to power management unit  74  instructing unit  74  to turn off processing circuitry  78 . Standby mode may be entered at any suitable time (e.g., after a period of inactivity, when a user selects an on-screen sleep option on display  16 , when a user presses a sleep button on device  10 , etc. When device  10  enters its standby mode, circuitry  78  and/or unit  74  may produce signals that are used to reduce the power consumption of device  10  (e.g., by turning off unnecessary components). The signals produced by circuitry  78  and power management unit  74  may include control signals, power supply signals (such as power supply signals provided to codec  64  over paths  66 ), clock signals, etc. These signals may be provided over any suitable path such as paths  82 ,  84 , and  86 . When circuitry  64  receives appropriate signals from circuitry  78  or power management unit  74 , circuitry  64  may shut down circuitry  79  and circuitry  78  may shut down large portions of its circuitry or may power down completely, thereby minimizing the power consumption of device  10  and maximizing the device&#39;s battery life. With one suitable arrangement, when device  10  is operating in a standby mode, processing circuitry, storage circuitry, displays, and other suitable components of device  10  are either turned off or are operated in a low power mode. 
     When device  10  enters its standby mode, registers  72  in GPIO circuitry  70  may be programmed so that future interrupt signals (sometimes referred to as flags) are asserted on path  76 , rather than path  80 . Registers  72  may be reprogrammed using data provided by circuitry  78  (as an example). When device  10  enters its active mode, registers  72  may be programmed so that future interrupt signals are asserted on path  80 , rather than path  76 . 
     When a user interacts with device  10  or when another action is taken that makes it appropriate for device  10  to power up, device  10  may resume normal operations (e.g., device  10  may power up from standby and may enter its active mode). For example, if device  10  is a cellular telephone, device  10  may power up from standby when device  10  receives a text message, a voice mail alert, or an incoming telephone call. Device  10  may also power up as a result of internal activity such as an alarm or a calendar event. Device  10  may wake up when a headset such as headset  46  is coupled to or is decoupled from device  10  (i.e., when headset  46  is connected to or disconnected from a jack such as jack  23 ). 
     Because interrupt control circuit  62 , headset activity detection circuit  60 , and GPIO circuit  70  preferably remain active during standby mode, a user may wake up device  10  by interacting with any suitable user input-output devices such as user input devices  40 , headset  46  (e.g., button  59 ), buttons  19 ,  27 , and  88 , etc. For example, a user may wake up device  10  by attaching or detaching a headset such as headset  46  to device  10  through jack  23 . In situations in which device  10  is a handheld device with cellular telephone capabilities, buttons  88  may include a switch such as switch  27  that is sometimes referred to as a ringer A-B switch and that selects whether device  10  has a silent telephone ring (e.g., is in a silent or vibrate mode) or has an audible telephone ring. If desired, activity on the ringer A-B switch  27  (or headset  46 ) may cause device  10  to temporarily enter its active mode to adjust internal settings (e.g., such as configuring device  10  so that future incoming calls activate a vibrator rather than an audible telephone ring). Device  10  may thereafter reenter its standby mode. Power management circuitry  74  may send signals over paths such as paths  82  and  84  to direct circuitry  64  and  78  to resume normal operations (e.g., power up) when desired. With one suitable arrangement, power management unit  74  may send signals over paths such as path  84  that wake up only processing circuitry  78 . In this arrangement, software running on processing circuitry  78  may then be used to determine which portions or components in device  10  are needed and may then selectively power only those components by sending signals over paths such as paths  84  and  86 . 
     In order to minimize the power consumption of device  10  while retaining the ability to detect activity on headset  46  and buttons on device  10  such as button  88  in standby mode, the central processing unit and other such circuitry  78  may be powered down and codec circuitry  64  may power down portions of circuitry such as circuitry  79  while circuits  60 ,  62 , and  70  (which includes registers  72 ) remain powered. With one suitable arrangement, circuitry  60  may sense the presence (absence) of headset  46  by measuring the resistance between paths  52  and  56 . This resistance may be essentially infinite when headset  46  is not coupled to device  10  and may have a finite value when headset  46  is coupled to device  10 . These are merely illustrative examples. In general, circuitry  60  may sense activity in headset  46  (or button  88 ) using any suitable technique. Circuitry  60  may be able to sense headset and button activity while circuit  64  is consuming only, for example, approximately 8 milliwatts of power. Once this activity is detected, the central processing unit and other circuitry  78  on device  10  may be powered up. The power-up process may be initiated by placing power management unit  74  in its active state, even while the central processing unit is in standby mode. Conventional arrangements in which a central processing unit remains powered to detect headset activity may result in power consumption levels of over 100 mW. 
     As illustrated in  FIG. 6A , a device such as device  10  that has power management capabilities may operate in multiple modes to conserve power. 
     In mode  215 , device  10  is in an active mode. When device  10  is in its active mode, power management unit  74  may be in its active state and central processing circuitry such as an application processor or circuitry  78  may be powered. Codec circuitry  64  and other components in device  10  may be power or unpowered as needed. 
     As illustrated by standby initiated line  226 , when it is desired to reduce the power consumption of device  10 , device  10  may enter standby mode  210 . Device  10  may enter standby mode  210  when a user actively commands device  10  to enter its standby mode, when device  10  has not received any user input for some period of time, when battery levels drop below a certain threshold, or for any other suitable reason. 
     As device  10  enters its standby mode, device  10  may perform the operations of box  217 . For example, as device  10  enters its standby mode, device  10  may reconfigure itself for proper operation in standby mode and then enter standby mode  210 . Device  10  may reconfigure itself by shutting down components in device  10 , by providing updated register data to registers  72 , and by placing power management unit  74  in its standby state, as an example. After performing the operations of box  217 , device  10  is in standby mode  210 . 
     In standby mode  210 , device  10  is operating in a low-power mode. Codec circuitry  64  and other circuits in device  10  may be listening for activity such as user activity associated with a headset. For example, codec circuitry  64  may be monitoring path  50  for headset activity. 
     When activity such as headset activity is detected, device  10  may enter its active mode, as illustrated by line  220 . As device  10  is entering its active mode, device  10  may perform the operations of box  213 . For example, as device  10  enters its active mode, device  10  may provide power to wake up components in device  10  such as a central processor (e.g., circuitry  78 ) and device  10  may reconfigure itself to operate in its active mode (e.g., by placing power management unit  74  in its active state and providing updated register data to registers  72 ). After performing the operations of box  213 , device  10  is in its active mode  215 . 
       FIG. 6B  is a diagram of illustrative operating modes and steps involved in using a device such as device  10  that has power management capabilities of the type described in connection with  FIG. 5 . 
     In standby mode  210 , device  10  and codec circuitry  64  may be operating in a low power mode (e.g., one or more of lines  66  such as a headset power line may be receiving a reduced DC power signal from power management unit  74  and some or all unneeded circuitry  79  such as unused input-output buffers, analog-to-digital and digital-to-analog converters may be powered down). While operating in this low power mode, coded circuitry  64  may monitor headset  46  and buttons  88  for activity. For example, headset activity detection circuit  60  may be used to monitor currents flowing over path  50 . These currents may change with activity from headset  46  (e.g., when button  59  is pressed or when headset  46  is coupled to or decoupled from device  10 ). General purpose input-output circuitry  70  may be used to monitor signals from buttons such as buttons  88 . 
     In standby mode  210 , electronic device  10  may be in standby mode. In particular, power management unit  74  may be in its standby state and may be providing (or may have already provided) signals that power down portions of device  10  such as display  16 , processing circuitry  36 , storage  34 , and other power-intensive components in circuitry  78  and device  10 . Power management unit  74  may monitor the status of interrupt line  76 . Codec circuitry  64  may assert an interrupt on path  76  when activity from a headset or button is detected. If desired, power management unit  74  may also listen for interrupt signals from other components in device  10 . Such interrupts may, for example, be generated by wireless circuitry  44  in response to an incoming phone call (as an example) or may be generated by other components in device  10  that have remained active in the device&#39;s standby mode. 
     As indicated by line  220 , when headset or button activity is detected (e.g., by circuitry  60  or  70 ), device  10  may take appropriate action at step  212 . During the operations of step  212 , codec circuitry  64  may assert an interrupt on path  76  to direct power management unit  74  to enter its active state. In response to the interrupt from circuitry  64 , power management unit  74  may wake up device  10  (e.g., by supplying appropriate power supply signals to the central processing unit and other components of device  10 ). When device  10  wakes up from its standby mode, processing circuitry such as circuitry  78  may interrogate power management unit  74  to determine which component in device  10  caused the device to wake up (e.g., which component in device  10  such as codec circuitry  64 , transceiver circuitry  44 , etc. caused device  10  to wakeup). In response to the processing circuitry&#39;s interrogation, power management unit  74  may interrogate the component that initiated the wake up event (i.e., the codec circuitry) to determine the cause of the wake up event (e.g., the specific event that occurred such as a button press or the removal of device  46  from the audio jack) and may report the cause of the wakeup to the processing circuitry. If desired, the processing circuitry may interrogate the component that initiated the wake up event directly (rather than through the power management unit). Once the processing circuitry has determined the specific event that cause device  10  to wake up, the processing circuitry can take an appropriate action. 
     Device  10  may enter its active mode following the detection of headset or button activity, as indicated by line  224 . When device  10  enters its active mode (step  214 ), processing circuitry (e.g., circuitry  36  and/or circuitry  78 ) may use path  86  to load registers  72  with settings data that configure codec circuitry  64  so that future events are reported directly to the processing circuitry. For example, the processing circuitry may send updated register settings to registers  72  so that future interrupt signals from interrupt control  62  are sent over path  80  to the processing circuitry (rather than over path  76  to power management unit  74 ). 
     In step  215 , electronic device  10  may be in its active mode. In the active mode, components in device  10  such as processing circuitry  78 , audio codec circuitry  64 , and other components in device  10  may be powered or unpowered as needed. 
     As indicated by line  226 , when it is not necessary to fully power device  10 , device  10  may enter its standby mode (steps  216  and  218 ). Device  10  may be automatically placed in standby mode when no user inputs have been received within a given period of time, when a user actively directs device  10  to enter standby mode by pressing an appropriate button or otherwise providing device with a command to enter standby, when the amount of remaining battery power in device  10  drops below a given value, or for any other suitable reason. Before device  10  enters its standby mode, processing circuitry (i.e., circuitry  36  and/or  78 ) may configure codec circuitry  64  to report future activity to power management unit  74 . For example, processing circuitry may send updated register settings to registers  72  over path  86  so that general purpose input-output circuitry  70  is configured to convey interrupt signals from interrupt control circuit  62  to power management unit  74  over path  76 . In step  216 , processing circuitry (i.e., circuitry  36  and/or  78 ) may power down portions of device  10 . 
     As indicated by line  228 , following the operations of step  216 , power management unit  74  may enter its standby state  210  and may power down processing circuitry such as circuitry  36  and/or circuitry  78  (e.g., in step  218 ). 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20080606
Publication Date: 20120501
Grant Date: 20120501
Priority Date: 20080606
Inventors: FIENNES HUGO
YEH MICHAEL VICTOR
LI XINGQUN
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/3215", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/3215", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 41401386