Abstract:
The present invention includes apparatuses and methods comprising a means for detecting the presence of speakers and microphones coupled to a portable multi-function device (such as Apple&#39;s iPhone™). In response, a portable multi-function device can adapt its output depending on the nature of the coupled headset device. In particular, a portable multi-function device containing the present invention can, upon detecting only one speaker in a coupled headset accessory device, combine the multiple channels of a stereo audio signal into a single mono audio signal. Likewise, a portable multi-function device containing the present invention can alert users to the absence of a coupled microphone.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This claims the benefit of U.S. Provisional Application No. 61/010,030, filed Jan. 3, 2008, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to distinguishing between stereo and mono audio devices (such as headset speakers). More particularly, this invention relates to controlling the output of portable multi-function devices based upon detected conditions. 
     The widespread popularity of mobile telephones and other portable multi-function devices (e.g., portable MP3 players, portable video players, media-capable mobile telephones) is largely due to their portability. These devices enable users to enjoy media and conduct telephone calls while on the go. 
     As portable multi-function devices have proliferated, so too have headsets. Headsets contain one or more speakers that can emit sound generated by a portable multi-function device. Headsets capable of emitting one channel of audio are sometimes referred to herein as “mono headsets.” Headsets that can emit more than one channel of audio are sometimes referred to herein as “stereo headsets.” 
     Some headsets also include one or more microphones and facilitate a conversation between two people. Headset microphones and their corresponding circuitry can convert sound, which may be produced by a user, to electrical signals which are sent to a portable multi-function device. 
     Stereo and mono headsets offer different advantages. For example, a stereo headset that includes two speakers is most desirable for listening to recorded media. This is because almost all commercial audio recordings divide audio among two or more stereo channels—a technique that provides a rich and pleasant listing experience. By contrast, telephone conversations only require one channel of audio, and, therefore, only require one speaker. In part, this is because telephones are primarily used for communication, rather than auditory enjoyment. Additionally, telephone users commonly engage in activities that require an awareness of one&#39;s surroundings (e.g., driving, bicycling while using a headset). For at least these reasons, some mobile telephone users prefer mono headsets. 
     However, a problem arises when, for example, a mono headset is used with a portable multi-function device outputting audio in stereo. Stereo audio includes two channels of sound, but mono headsets can emit only one channel of sound. A user listening to a stereo recording on a mono headset would have a severely diminished listening experience because some of the recording would not be heard. 
     Another problem arises when, due to defect, damage, or any other cause, one or more speakers in a headset do not operate properly. For example, a damaged or defective stereo headset may have only one operational speaker. Similarly, a damaged or defective stereo headset may have one speaker that operates properly, and another speaker that produces distorted or intermittent sound. A user listening to a stereo recording on a defective or damaged headset would have a severely diminished listening experience because distorted or intermittent sound would be produced. 
     Another problem arises when a headset that does not contain a microphone is used for applications requiring a microphone (e.g., telephone calls). For example, a headset lacking a microphone coupled to a mobile telephone or a portable multi-function device having mobile telephony capability cannot properly carry a telephone call because it cannot receive a user&#39;s voice. (Portable multi-function devices having mobile telephony capability, such as Apple Inc.&#39;s iPhone™, which can be used to perform various functions, including those related to communications and entertainment, may also be referred to herein as hybrid devices. iPhone™ is a trademark owned by Apple Inc.) Because portable multi-function devices cannot automatically detect the presence or absence of a headset microphone, users are not alerted when a microphone is not present. 
     Yet another problem arises when, due to defect, damage, or any other cause, a headset microphone does not operate properly. For example, a damaged or defective headset microphone may fail to convey audio signals, or may convey distorted or intermittent audio signals. The user in such cases may be unaware of the malfunction. 
     Another problem arises in detecting and responding to a headset being connected or disconnected from a portable multi-function device. For example, some portable multi-function devices, like Apple Inc&#39;s iPod™, pause the playback of media signals when headsets are removed. (iPod™ is a trademark owned by Apple Inc.) Such portable multi-function devices utilize a mechanical switch to detect insertion or removal of a headset tip. The mechanical switch is toggled physically by the insertion or removal of the headset tip, regardless of whether a functional headset is coupled to the portable multi-function device&#39;s connector. For example, among other things, nonfunctioning headsets or even a loose wire with a headset tip would toggle the switch. 
     SUMMARY OF THE INVENTION 
     The present invention, in various embodiments, addresses the above problems and others by providing systems, means, methods, and computer readable media that can be used to detect and respond to the presence and/or functional capabilities of a headset coupled to a portable multi-function device. The functional capabilities may be associated with physical components, circuitry, speakers, and microphones. Responses may include combining multiple stereo channels into a mono channel, or generating alerts. 
     In various configurations, the invention employs one or more headset channel detection sensors in a portable multi-function device. A headset channel detection sensor may include a circuit of connected electrical components (e.g., resistors, capacitors, transistors) which responds to changes in current caused by the introduction of a functional speaker or microphone to a portable multi-function device. 
     In one configuration, the detection circuit is triggered upon the insertion of a headset plug, or when an audio signal is initiated. Portable multi-function devices such as the iPhone™ presently generate such triggers. (Apple Inc. owns the iPhone™ trademark.) Upon being triggered, the headset channel detection circuit operates for a brief period of time, sensing the presence of speakers and microphones. In another configuration, the headset channel detection sensor operates continuously and does not use a trigger. 
     In some embodiments, a headset channel detection sensor is connected to each audio channel output on a portable multi-function device. When an operational stereo headset is present, the headset channel detection sensor for each stereo channel signals the portable multi-function device. In response, said device generates stereo audio data for each channel. Alternatively, when a headset with only one operational speaker (e.g., a mono headset or damaged stereo headset) is connected, only one headset channel detection sensor signal is sent to the portable multi-function device. In response, the portable multi-function device combines multiple stereo channels into a new mono channel, which is sent to the operational output audio channel. 
     In some embodiments, a headset channel detection sensor is connected to the headset microphone channel of a portable multi-function device. When an operational headset microphone is introduced, the headset channel detection sensor for that channel signals the portable multi-function device. Conversely, when an operational headset microphone is either absent or damaged, the headset channel detection sensor for that channel does not signal the portable multi-function device. If said device is then used for tasks that may require a headset microphone (e.g., telephone calls, or recording, monitoring and/or processing of sound), a warning is sent to the user. This warning may include audio, visual, or kinetic (e.g., vibrational) feedback. 
     In certain embodiments, one or more headset channel detection sensors aid in detection of headset insertion and removal. When the tip of a headset jack (sometimes referred to herein as a “headset tip”) is inserted into a portable multi-function device, headset channel detection sensors only signal if the headset jack is coupled to a functional headset. Thus, a portable multi-function device will not respond to the insertion or removal of a non-functioning or otherwise invalid accessory device. 
    
    
     
       SUMMARY OF THE FIGURES 
       The above and other features of the present invention, including its various advantages, will be more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
         FIG. 1  is an illustrative portable multi-function device in accordance with one embodiment of the present invention; 
         FIG. 2  is another illustrative portable multi-function device in accordance with another embodiment of the present invention; 
         FIG. 3  is an illustrative block diagram of an portable multi-function device in accordance with one embodiment of the present invention; 
         FIG. 4  is an illustrative headset tip, showing the tip profile for a stereo connection with microphone; 
         FIG. 5  is an illustrative headset tip, showing the tip profile for a mono connection with a microphone; 
         FIG. 6  is an illustrative schematic diagram of the connection between a headset jack and a stereo headset; 
         FIG. 7  is an illustrative schematic diagram of the connection between a headset jack and a mono headset; 
         FIG. 8  is an illustrative schematic diagram of the internal electrical connections between a portable multi-function device and a stereo headset tip; 
         FIG. 9  is an illustrative schematic diagram of the internal electrical connections between a portable multi-function device and a mono headset tip; 
         FIG. 10  is an illustrative schematic diagram of one embodiment of the invention operating within a portable multi-function device; 
         FIG. 11  is an illustrative schematic diagram of one embodiment of the invention; 
         FIG. 12  is an electrical timing diagram of one embodiment of the invention; 
         FIG. 13  is an illustrative flowchart of a process in accordance with an embodiment of the present invention; and 
         FIG. 14  is an illustrative flowchart of a process in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although portable multi-function devices currently enable users to communicate and be entertained, portable multi-function devices currently do not intelligently determine the input or output capabilities of coupled headsets. For example, as discussed earlier, portable multi-function devices currently do not distinguish between stereo or mono headsets. Similarly, portable multi-function devices currently do not detect whether coupled microphones or headset speakers are inoperative due to damage or defect. 
     The present invention, among other things, adds intelligence to the physical connection between portable multi-function devices and headsets. For example, the present invention can permit a portable multi-function device to automatically distinguish between mono and stereo headsets, based upon the headsets&#39; enabled functionality. A portable multi-function device in accordance with the present invention may, for example, combine multiple stereo audio channels into a single mono audio channel when a headset with only one operable speaker is coupled to the portable multi-function device. The present invention can also enable a portable multi-function device to detect and alert users to a missing, defective, or damaged headset microphone. 
       FIG. 1  shows system  100 . System  100  may include portable multi-function device  102  and accessory device  104 . Portable multi-function device  102  may function as, among other things, a mobile telephone, satellite telephone, voice-over internet protocol (“VOIP”) user device, personal digital assistant, pager, handheld computer, portable media player (e.g., MP3 player), remote controller, portable communications device, remote ordering interface, audio tour player, handheld internet device, or any other portable multi-function device capable of generating and/or processing audio data. Portable multi-function device  102  may be battery-powered and highly portable so as to allow a user to listen to music, play games or video, record audio, video, and/or photographs, communicate with others, and/or control other devices. Portable multi-function device  102  may also be used in conjunction with other devices or structures such as, for example, a vehicle, video game system, home appliance, article of clothing, helmet, eye glasses, wearable apparel, stereo system or other entertainment system, other portable device, etc. 
     In some embodiments, portable multi-function device  102  may be coupled to and/or synchronized with, for example, one or more remote computing systems, servers and/or other electronic device(s). Portable multi-function device  102  may also receive media files (using wireless and/or wired communications paths from one or more other devices). Media files can include, for example, video, audio, image, multi-media and/or any other types of digital data. The files may be formatted in any manner. 
     Portable multi-function device  102  may include housing  106 , display  108 , and connector  110 . In some embodiments, housing  106  may include, for example, polymer-based materials, metals, etc. Housing  106  defines the form factor of portable multi-function device  102 . In some embodiments, housing  106  encloses and/or supports components of portable multi-function device  102  such as, for example, display  108 , connector  110 , one or more circuit boards and circuitry, internal antennas, speakers, microphones, storage devices, processors, and/or other components. Further details regarding exemplary internal components are discussed below in connection with  FIG. 3 . 
     Portable multi-function device  102  may also include display  108 . Display  108  may include any suitable display screen or projection system for displaying information and/or graphical user interfaces to the user. For example, display  108  may be an LCD screen. As another example, display  108  may include a projection system (e.g., a video projector) for providing a display of content on any surface remote from portable multi-function device  102 . 
     Portable multi-function device  102  may be coupled to accessory device  104  via connector  110 . Connector  110  may include any suitable port for transmitting, among other things, audio data. For example, connector  110  can be a female 3.5 mm stereo port (sometimes referred to as a TRS connector port). As another example, connector  110  may be a universal serial bus (“USB”) port, a 30-pin connector port, any other type of port or any combination thereof. In some embodiments, more than one connector may be included in portable multi-function device  102 . 
     Accessory device  104  may be, for example, a headset, headsets or any other device capable of producing sound based on audio data it receives. In some embodiments, such as when accessory device  104  is physically coupled to portable multi-function device  102 , accessory device  104  may include cable  112 . In other embodiments (not pictured), cable  112  can be a wireless communications path. 
     Cable  112  can facilitate the transfer of audio data from portable multi-function device  102  to accessory device  104 . In one embodiment, accessory device  104  includes left speaker  114  and right speaker  116 , which preferably correspond respectively to the left and right audio channels of stereo sound. Speakers  114  and  116  may include, among other things, an audio speaker, internal circuitry, and an acoustic assembly. Accessory device  104  may also include microphone  118 , which can facilitate the generation of audio data from sound (e.g., the user&#39;s voice). Speaker  114 , speaker  116 , and microphone  118  are sometimes referred to herein as transducers. One skilled in the art would appreciate that microphone  118  may be omitted from accessory device  104 . 
       FIG. 2  shows system  200 , which may include portable multi-function device  202  coupled to mono headset accessory device  208 . Portable multi-function device  202  and its components may be similar to or the same as portable multi-function device  102 . Unlike stereo headset  104 , mono headset  204  contains only one speaker (shown in  FIG. 2  as speaker  206 ). Although microphone  208  is shown in  FIG. 2  as being incorporated into headset  204 , one skilled in the art would appreciate that a microphone may be omitted in various embodiments of accessory device  204 . 
       FIG. 3  is an illustrative block diagram of components that can be included in portable multi-function device  300 . Portable multi-function device  300  is an electronic device in accordance with embodiments of the present invention, and may be the same as or similar to portable multi-function devices  102  and/or  202 . 
     Portable multi-function device  300  may include bus  302 , processor  304 , clock  306 , storage  308 , memory  314 , vibration source driver  316 , headset connector  318 , transducer  320 , communications circuitry  322 , display circuitry  324 , and power supply  326 . One skilled in the art would appreciate that one or more of the components shown in  FIG. 3  may be functionally combined, omitted and/or included in a device coupled to portable device  300 . One skilled in the art would appreciate that each component included in  FIG. 3  may represent a plurality of components. 
     Bus  302  may provide a data transfer path for transferring data to, from, or between any or all components of portable multi-function device  300 . Bus  302  may be, for example, a conduit composed of one or more electrically conductive pathways (e.g., wires), one or more optical pathways, or any other medium capable of transferring data among the components of portable multi-function device  300 . One skilled in the art would appreciate that bus  302  may transfer data in serial and/or parallel fashion. One skilled in the art would also appreciate that bus  302  may operate locally within portable multi-function device  300 , or may extend to components external to portable multi-function device  300 . 
     System  300  may also include processor  304 . Processor  304  may control and/or coordinate the operation of many functions and other components included in portable multi-function device  300 . Processor  304  may, for example, coordinate inputs received from I/O circuitry  314  and, in response, cause corresponding display(s) to be generated by display circuitry  324 . Display circuitry  324  may, for example, facilitate the generation of images and text on the display of a portable multi-function device (e.g., display  108  of  FIG. 1 ). 
     Clock  306  may be included within processor  304 , and may be an oscillator, dedicated clock circuit and/or IC, a software-based clock or timer application. Clock  306  may be synchronized with a remote timing source such as a network clock, remote server clock, timing standard source. 
     Storage device  308  may store media files (e.g., music and video files), software (e.g., for implanting functions on portable multi-function device  300 ), preference information (e.g., media playback preferences), lifestyle information (e.g., food preferences), exercise information (e.g., information obtained by exercise monitoring equipment), transaction information (e.g., information such as credit card information), wireless connection information (e.g., information that may enable portable multi-function device  300  to establish wireless communications with another device), subscription information (e.g., information related to podcasts, television shows or other media a user subscribes to and/or pays money to access), and any other suitable data. Storage device  308  may include one more storage mediums, including for example, a hard-drive, permanent memory such as ROM, semi-permanent memory such as RAM, or cache. 
     Memory  310  may include one or more different types of memory which may be used for performing device functions. For example, memory  310  may include cache, ROM, and/or RAM. 
     Coder/decoder (CODEC)  312  may be included to convert digital audio data into analog signals directed toward transducer  320  via headset connector  318  to produce sound, including voice, music, and other audio. CODEC  312  may also convert audio signal inputs from transducer  320  into digital audio data. Transducer  320  may, for example, facilitate the conversion of electrical energy to acoustic energy (e.g., sound) and/or the conversion of acoustic energy to electrical energy. Headset connector  318  may include any suitable port for transmitting or receiving, among other things, audio data. 
     I/O circuitry  314  may convert signals and/or data generated by user input into data for use by portable multi-function device  300 . For example, I/O circuitry  308  may convert signals generated by a user&#39;s contact with a multi-touch display screen into data. (A multi-touch display screen, referred to herein, is a display screen capable of sensing, among other things, multiple regions of physical contact between a user and the screen&#39;s surface). I/O circuitry  314  may also convert data generated by portable multi-function device  300  into signals and/or data for use by various output devices. For example, I/O circuitry  308  may convert data generated by portable multi-function device  300  into signals that control vibration source driver  316 . 
     Vibration source driver  316  may, for example, facilitate sending motion, vibration, and/or movement information related to an operation of the portable multi-function device. For example, vibration source driver  316  may enable a portable multi-function device to vibrate when a call is received by activating vibration-capable elements housed within a portable multi-function device. 
     Communications circuitry  322  may include circuitry for wireless communication (e.g., short-range and/or long range communication). For example, the wireless communication circuitry may be wi-fi enabling circuitry that permits wireless communication according to one of the 802.11 standards. Other wireless network protocol standards may also be used, either in alternative to the identified protocols or in addition to the identified protocols. Other network standards may include Bluetooth, the Global System for Mobile Communications (GSM), and code division multiple access (CDMA) based wireless protocols. Communications circuitry  322  may also include circuitry that enables device  300  to be electrically coupled to another device (e.g., a computer or an accessory device) and communicate with that other device. Power supply  326  may be an electrical storage device (e.g., a battery) or any other device capable of providing a compact portable multi-function device with the energy needed to operate. 
       FIG. 4  shows stereo headset tip  400 . Stereo headset tip  400  is the portion of, for example, accessory device  104  that couples to a headset connector (such as connector  110  of  FIG. 1 ) of a portable multi-function device. In the embodiment shown, stereo headset tip  400  includes conductive regions  402 ,  404 ,  406  and  408 , separated by non-conductive regions  410 ,  412 , and  414 . Conductive regions  402 ,  404 ,  406  and  408  are capable of conveying data (which may be, e.g., digital or analog audio data) from a portable multi-function device to transducers and vice-versa. Non-conductive regions  410 ,  412 , and  414  do not convey data as electrical signals. In the exemplary embodiment shown in  FIG. 4 , conductive region  408  is shown as the terminus of stereo headset tip  400 , which would be the first region to enter a headset connector of a portable multi-function device. In other embodiments, although conductive regions assigned to different audio channels may not contact one another, the sequence, layout, or relative locations of headset tip regions may vary. Further from the terminus is headset wire housing  416  and headset wire shroud  418 . Headset wire shroud  418  can protect the encased wires from elements such as water or dirt. 
       FIG. 4  also shows a cross-sectional cut-away view of headset wire shroud  418 , revealing left channel headset wire  420 , right channel headset wire  422 , microphone channel headset wire  424 , and ground headset wire  426 . As discussed further below in connection with, e.g.,  FIG. 6 , wires  420 ,  422 ,  424  and  426  can couple speaker and microphone components of a headset to a portable multi-function device. One skilled in the art would appreciate that the microphone channel depicted in  FIG. 4  may be omitted in other embodiments. 
     Wire  420 , as shown in  FIG. 4 , passes through headset wire housing  416  and is electrically coupled to conductive region  408  (the terminus of headset tip  400 ). Wire  422 , as shown in  FIG. 4 , passes through headset wire housing  416  and is electrically coupled to conductive region  406 . Microphone channel wire  424  passes through headset wire housing  416  and is electrically coupled to conductive region  402 . Similarly, ground wire  426  passes through headset wire housing  416  and is electrically coupled to conductive region  404 .  FIG. 4  depicts just one of many possible assignments of audio channels to conductive regions on a stereo headset tip. Similarly,  FIG. 4  depicts just one of many possible embodiments of a stereo headset tip that may connect to a headset jack on a portable multi-function device. One skilled in the art would appreciate that, although the most common implementation is illustrated in  FIG. 4 , the present invention can be used with any type of physical connectors that facilitate the transfer of audio data. 
     When inserted into a device&#39;s connector component (like connector  110  of  FIG. 1 ), conductive regions  402 ,  404 ,  406  and  408  may be physically and electrically coupled to corresponding internal conductive regions of the connector. These internal conductive regions help facilitate the transfer of, e.g., audio data to a headset&#39;s left and right speakers as well as audio data from a headset&#39;s microphone. Further, the connector&#39;s internal conductive regions provide electrical ground, which can help power a headset&#39;s speakers and microphone. This is discussed in greater detail below in connection with, e.g.,  FIGS. 8 and 9 . In the exemplary embodiment shown in  FIG. 4 , non-conductive regions  410 ,  412 , and  414  provide electrical separation between the conductive regions of the tip. These non-conductive regions allow a headset&#39;s speakers and microphone to carry distinct channels of audio data. 
       FIG. 5  shows mono headset tip  500 . Mono headset tip  500  is the portion of, for example, accessory device  204  that couples a headset or other accessory device to a headset connector (such as connector  210  of  FIG. 2 ) of a portable multi-function device. In the embodiment shown, mono headset tip  500  includes conductive regions  502 ,  504 , and  508 , separated by non-conductive regions  510 , and  514 . Conductive regions  502 ,  504 , and  508  are capable of conveying audio data (which may be digital or analog) from a portable multi-function device to transducers and visa-versa. Non-conductive regions  510  and  514  may not convey audio data as electrical signals. In the exemplary embodiment shown in  FIG. 5 , conductive region  508  is shown as the terminus of stereo headset tip  500 , which would be the first region to enter a connector of a portable multi-function device. In other embodiments, although conductive regions assigned to different audio channels may not contact one another, the sequence, layout, or relative locations of headset tip regions may vary. Further from the terminus is headset wire housing  516  and headset wire shroud  518 . Headset wire shroud corresponds to, for example, headset wire  212  of  FIG. 2  and protects encased wires from elements such as water or dirt. 
       FIG. 5  also shows a cross-sectional cut-away view of headset wire shroud  518 , revealing mono channel headset wire  520 , microphone channel wire  524 , and ground wire  526 . As discussed further below in connection with, e.g.,  FIG. 7 , wires  520 ,  524  and  526  couple speaker and microphone elements in a headset to a portable multi-function device. One skilled in the art would appreciate that the microphone channel depicted in  FIG. 5  may be omitted in other embodiments. 
     Wire  520 , as shown in  FIG. 5 , passes through headset wire housing  516  and is electrically coupled to conductive region  508  (the terminus of headset tip  500 ). Microphone channel wire  524  passes through headset wire housing  516  and is electrically coupled to conductive region  502 . Similarly, ground wire  526  passes through headset wire housing  516  and is electrically coupled to conductive region  504 .  FIG. 5  depicts just one of many possible assignments of audio channels to conductive regions on a mono headset tip.  FIG. 5  depicts just one of many possible embodiments of a mono headset tip that may connect to a headset jack on a portable multi-function device. One skilled in the art would appreciate that, although the most common implementation is illustrated in  FIG. 5 , the present invention can be used with any type of physical connectors that facilitate the transfer of, e.g., audio data. 
     When inserted into a device&#39;s connector component (like connector  210  of  FIG. 2 ), conductive regions  502 ,  506  and  508  may be physically and electrically coupled to corresponding internal conductive regions of the connector. These internal conductive regions help facilitate the transfer of, e.g., audio data to a headset&#39;s mono speaker as well as audio data from a headset&#39;s microphone. Further, the connector&#39;s internal conductive regions provide electrical ground, which can help power a headset&#39;s speakers and microphone. This is discussed in greater detail below in connection with, e.g.,  FIGS. 8 and 9 . In the exemplary embodiment shown in  FIG. 5 , non-conductive regions  510  and  514  provide electrical separation between the conductive regions of the tip. These non-conductive regions allow a headset&#39;s speakers and microphone to carry distinct channels of audio data. 
       FIG. 6  is a simplified schematic diagram of exemplary electrical connections between the connector of a portable multi-function device (e.g., connector  110  of portable multi-function device  102 ) and a stereo headset&#39;s speakers and microphone (e.g., accessory device  104 &#39;s speakers  114  and  116  and microphone  118 ). One skilled in the art would appreciate that headset microphone circuitry  606  shown in  FIG. 6  may be omitted in other embodiments without departing from the spirit of the present invention. 
     Left channel headset wire  618  may facilitate the transfer of, e.g., audio data stored and/or generated by a portable multi-function device. Left channel headset wire  618  can facilitate the transfer of data to left headset speaker  602 , which may be any type of transducer that can convert audio data to sound. Left headset speaker  602  may require a voltage differential to operate. In such embodiments, the required voltage may be the difference in electrical potential between left channel headset wire  618  and ground wire  622 , which connects to left headset speaker  602 . 
     Similarly, right channel headset wire  620  may carry audio data stored and/or generated by a portable multi-function device. Right channel headset wire  620  can facilitate the transfer of data to right headset speaker  604 , which may be any type of transducer that converts audio data to sound. Right headset speaker  604  may require a voltage differential to operate. In such embodiments, the required voltage may be the difference in electrical potential between left channel headset wire  620  and ground wire  622 , which connects to right headset speaker  604 . 
     Microphone channel audio wire may carry data generated by headset microphone circuitry  606 . Microphone circuitry  606  may require a voltage differential to operate. In such embodiments, the required voltage may be provided by a coupled portable multi-function device. 
     Headset microphone switch  608  may enable users to control the functionality of the portable multi-function device and/or accessory device(s). Headset microphone switch  608  can be, for example, electrically coupled to headset microphone circuitry  606 , as shown in  FIG. 6 , and physically located in a manner convenient to the user. When toggled, headset microphone switch  608  can activate or deactivate headset microphone circuitry  606  and generate headset microphone PTT (“push to talk”) signal on wire  628 . Upon receiving the headset microphone PTT signal, the portable multi-function device may, for example, begin, end, or mute a telephone call, music, and/or perform any other function. 
       FIG. 7  is a simplified schematic diagram of exemplary electrical connections between the connector of the portable multi-function device (e.g., connector  210  of portable multi-function device  202 ) and a mono headset&#39;s speaker and microphone (e.g., speaker  204  and microphone  218  of accessory device  204 ). System  700  and its components may be similar to or the same as system  600 , with the exception that, unlike system  600 , system  700  contains only one speaker (shown in  FIG. 7  as speaker  702 ). One skilled in the art would appreciate that headset microphone circuitry  706  shown in  FIG. 7  may be omitted in other embodiments without departing from the spirit of the present invention. 
       FIG. 8  is a simplified schematic diagram of system  800 , which includes exemplary electrical connections between a portable multi-function device and a stereo headset tip ( 822 ).  FIG. 8  includes audio CODEC  802 , which may generate left channel audio data on wire  804  and right channel audio data on wire  806 . Audio CODEC  802  may also receive microphone channel audio data on wire  808  if a headset microphone is present in a headset accessory device. In the exemplary embodiment shown, wire  804  may carry one channel of audio data to conductive region  824  of stereo headset tip  822 . Similarly, wire  806  may carry one channel of audio data to conductive region  826  of stereo headset tip  822 . Conductive region  830  of stereo headset tip  822  provides audio data  808  to audio CODEC  802 . Finally, wire  818  may carry a ground signal directly to conductive region  828  of stereo headset tip  822 . In other embodiments, the arrangement, sequence or relative locations of audio data paths and headset tip regions may vary. 
     In certain embodiments, left and right channel audio (carried respectively on wires  804  and  806  in preferred embodiments of the portable multi-function device) can be filtered by one or more filtering mechanisms before reaching stereo headset tip  822 . Such filtering may block unwanted audio frequencies or other signals generated by audio CODEC  802 . Filters may be placed, for example, between audio CODEC  802  and stereo headset pin  822 . A left channel filter may include capacitor element  810  and resistor element  814 . Similarly, a right channel filter may include capacitor element  812  and resistor element  816 . One skilled in the art will appreciate that capacitor elements  810  and  812  can block DC signals. One skilled in the art will also appreciate that capacitor elements  810  and  812  may each be properly biased by a resistor, such as resistor elements  814  and  816 , as depicted in  FIG. 8 . As such, signal filters may block unwanted audio frequencies or other signals from audio CODEC  802  while preserving wanted audio data. 
     Some embodiments of portable multi-function devices feature a headset tip detect signal which may indicate the physical presence of a headset tip in the connector of a portable multi-function device. A headset tip detect signal may be generated, for example, when a stereo headset tip is present in the connector of a portable multi-function device. In the exemplary embodiment shown in  FIG. 8 , a headset tip detect signal is generated on wire  820  when stereo headset tip  822  is present in the headset jack of a portable multi-function device. In the absence of headset tip  822 , wire  820  may carry the signal carried by headset tip detect control wire  832 . However, when headset tip  822  is present in the portable multi-function device, conductive region  824  interrupts the headset tip detect control signal carried upon wire  832 , thus generating a headset tip detect signal on wire  820 . Some embodiments of portable multi-function devices may respond to a headset tip detect signal by, for example, starting or stopping audio playback. 
       FIG. 9  is a simplified schematic diagram of system  900 , which includes exemplary electrical connections between a portable multi-function device and a mono headset tip ( 922 ). System  900  may be similar to or the same as system  800 , with the exception that unlike system  800 , system  900  contains a mono headset tip  922 , which may drive a speaker in an accessory mono headset device. Wire  904  of system  900  may carry one channel of audio data to conductive region  924  of mono headset tip  922 . However, because only one channel of audio data may be sent to mono headset tip  922 , only one channel of sound may be generated by the speaker of a headset accessory device coupled to the portable media player. Thus, for example, if two channels of audio data were generated by the portable multi-function device, one channel of audio data would not be audible to a user. 
       FIG. 10  is a simplified schematic diagram of system  1000 , which includes exemplary electrical connections between a mono headset tip and a portable multi-function device incorporating elements of the present invention. System  1000  may be similar to or the same as system  800  and/or  900 , with the exception that system  1000  may contain one or more detector blocks (shown in  FIG. 10  as  1040  and  1042 ), which contain circuitry capable of responding to the electrical resistance created by a coupled headset device. Left channel detector block  1040  and right channel detector block  1042  (sometimes referred to herein as “detector blocks”) may receive audio data  1004  and  1006 , generated by CODEC  1002 . Detector blocks  1040  and  1042  may also receive headset tip detect signal on wire  1020  (discussed above), and headset detect voltage on wire  1044  (a stable voltage source). 
     A headset tip detect signal is generated on wire  1020  in response to the presence of headset tip  1022  in the connector of a portable multi-function device (discussed earlier with respect to  FIGS. 8 and 9 ). Detector blocks  1040  and  1042  may respond to this headset tip detect signal by monitoring the resistive loads on wires  1004  and  1006 . Headset detector block  1042  may generate a headset detect signal on wire  1048  in response to a functional speaker being coupled to the left audio channel of headset tip  1022 . Similarly, if a functional speaker is coupled to the right audio channel of headset tip  1022 , headset detector block  1040  may generate a headset detect signal on wire  1046 . The internal operation of one possible embodiment of a headset detector is detailed in  FIG. 11 . 
       FIG. 11  is a schematic diagram of system  1100 , which includes exemplary electrical circuitry incorporating elements of the present invention. System  1100  can, among other things, detect headset transducers connected to portable multi-function devices.  FIG. 11  includes wire  1102 , which may carry an audio signal between a CODEC and a transducer in a connected headset (discussed earlier with respect to, e.g.,  FIGS. 8 ,  9 , and  10 ). The electrical equivalent of a transducer is represented in  FIG. 11  by resistor  1108 , transistor  1110 , and wire  1112 . As shown in  FIG. 11 , an alternating control signal on wire  1112  can simulate the connection and disconnection of a headset. One skilled in the art will appreciate that a headset transducer could be shown in place of resistor  1108 , and that toggling transistor  1110  in  FIG. 11  could simulate the removal and insertion of a headset transducer. 
       FIG. 11  also contains junction  1104 , which joins wire  1102 , resistor  1106 , resistor  1108 , and the emitter of transistor  1114 . In some embodiments of the present invention, resistor  1106  can be of greater electrical resistance than resistor  1108 . The introduction of a headset transducer to system  1100  can cause the total electrical resistance at junction  1114  to decrease. 
     Transistor  1114  and transistor  1120 , as shown in  FIG. 11 , represent and can function as a constant source of electrical current at the emitter of transistor  1114 . This is accomplished by connecting both transistors to voltage source  1130 . Thus, when a headset is introduced to system  1100 , voltage drops at junction  1104  because electrical current remains constant and resistance drops. 
     Because the emitter voltage of transistor  1114  can decrease when a headset is inserted, the voltage at its base can also decrease. In turn, the base of transistor  1118 , which is connected to the base of transistor  1114  via junction  1116 , can also decrease. Voltage can then increase at the collector of transistor  1118 . This voltage increase can be seen on wire  1128  as a “detect” signal, indicating the presence of a transducer in a connected headset. Similarly, removal of a connected headset can cause a corresponding drop in voltage on output wire  1128 . 
       FIG. 12  is an electrical timing diagram showing the states of INPUT VOLTAGE, OUTPUT VOLTAGE, and TRANSDUCER INSERTION VOLTAGE in accordance with the embodiments of the present invention discussed in connection with  FIG. 11 . In  FIG. 12 , INPUT VOLTAGE corresponds to the voltage carried on wire  1132  of  FIG. 11 , OUTPUT VOLTAGE corresponds to the voltage on wire  1128  of  FIG. 11 , and TRANSDUCER INSERTION VOLTAGE corresponds to the insertion or removal of a headset transducer, as represented by transistor  1110  in  FIG. 11  switching between open and closed states. 
     Starting at time t 0 , INPUT VOLTAGE is set to the low value of v 0 . This may be because, among other things, the portable multi-function device is not in use. Because the circuit is not powered, OUTPUT VOLTAGE is also at the low power level of v 0 . At time t 1 , INPUT VOLTAGE is increased to v 2 . This may be because, among other things, the portable multi-function device is activated. As depicted in  FIG. 12 , INPUT VOLTAGE provides constant power to the circuit until time t 4 . 
     At time t 2 , a headset transducer is connected to the media player. As a result, TRANSDUCER INSERTION VOLTAGE can increase to v 1 . With respect to  FIG. 11 , this voltage represents a toggle of transistor  1110 , thus introducing resistor  1108  to the circuit. Because there is a constant current source fed by the emitter of transistor  1114 , the voltage at junction  1104  can drop, as can the voltage at junction  1116 . As a result, OUTPUT VOLTAGE can rise to v 3 , as discussed earlier with respect to  FIG. 11 . 
     At time t 3 , a headset transducer is removed from the media player. As a result, TRANSDUCER INSERTION VOLTAGE can decrease to v 0 . With respect to  FIG. 11 , this voltage drop toggles transistor  1110 , thus removing resistor  1108  from the circuit. In response, because the emitter of transistor of  1114  may no longer feed a constant current source, OUTPUT VOLTAGE drops back to v 0 , as discussed earlier with respect to  FIG. 11 . 
       FIG. 13  shows process  1300 , which is an exemplary flow diagram depicting how a portable multi-function device may combine stereo audio signals into a single mono audio signal in response to detecting a mono headset accessory device being coupled to the portable multi-function device. Process  1300  starts at step  1302 , and proceeds to step  1304 , where the portable multi-function device is active may be waiting to receive a headset tip detect signal. For example, the portable multi-function device could be an Apple iPhone™ without a headset or anything else coupled to the iPhone&#39;s headset connector. After step  1304 , process  1300  proceeds to step  1306 , where a determination is made as to whether a headset tip is coupled to the connector of the portable multi-function device. If no headset tip is coupled to the connector of the portable multi-function device, process  1300  returns to step  1304 . However, if a headset tip is coupled to the connector of the portable multi-function device, the process advances to step  1310 , where a determination is made as to whether the coupled headset accessory device is stereo or mono. 
     Next, process  1300  advances to the conditional step  1312 . In response to the presence of a stereo headset accessory device, process  1300  advances from step  1312  to state  1314 , where stereo audio data is generated by the portable multi-function device. Process  1300  then advances to step  1316  when the stereo headset accessory device is removed from the connector of the portable multi-function device. After step  1316 , process  1300  ends at step  1330 . 
     In response to a mono headset accessory device, process  1300  advances from step  1312  to step  1320 , where a determination is made as to whether mono or stereo audio data is being generated by the portable multi-function device. In response to the generation of mono audio data, process  1300  advances to step  1322 , where the mono audio data is sent to the mono headset speaker. If the audio data is stereo, the process advances from step  1320  to step  1326 , where the portable multi-function device combines stereo audio channels into a new combined mono data signal containing audio data from the multiple stereo channels. The combination of channels may be achieved by hardware or software running on the device. The new combined mono audio data is directed toward whichever audio channel is coupled to a headset speaker in the headset accessory device coupled to the portable media player. The process advances to step  1324  when the headset accessory device is removed from the connector of the portable media player, or when the portable media player is no longer active (for example, due to a user turning the device off, or due to an automatic shut-down). After step  1316 , process  1300  ends at step  1330 . 
       FIG. 14  shows process  1400 , which is an exemplary flow diagram depicting how a portable multi-function device may alert a user to the absence of a headset microphone, in cases where such a microphone may be needed. Process  1400  starts at step  1402 , and proceeds to state  1404 , where the portable multi-function device is active and waiting to receive a headset tip detect signal. For example, the device could be an Apple iPhone™ without any headset accessory device coupled to the headset jack. After step  1404 , process  1400  proceeds to step  1406 , where a determination is made as to whether a headset tip is coupled to the connector of the portable multi-function device. If not, process  1400  returns to step  1404 . However, if a headset tip is coupled to the connector of the portable multi-function device, the process advances to step  1408 , where a determination is made as to whether the coupled headset accessory device includes a functioning microphone. Next, process  1400  advances to the conditional step  1410 . 
     In the presence of a microphone, process  1400  advances from step  1410  to step  1412 , where the process waits for a headset to be decoupled. Next, process  1400  advances to the conditional step  1414 . In response to a coupled headset, process  1400  returns to step  1412 . However, in response to the decoupling of a headset, process  1400  advances to step  1418 . 
     In the absence of a microphone, process  1400  advances from step  1410  to step  1420 , where the process waits for a user input event. A user input event could include, for example, any data, signal or signals resulting in whole in part from a user&#39;s interactions with a portable multi-function device. For example, a user input event as referred to herein could include a telephone call, a command to play an audio or video file, a command to record, monitor, or process sound, or even the decoupling of a headset or other accessory device. 
     When a user input event takes place, process  1400  first determines at step  1424  whether the headset accessory device has been decoupled. In response to the decoupling of a headset accessory device, the process advances to end step  1418 . Otherwise, the process advances to step  1426 , at which a determination is made as to whether the device is being used in a manner that may require a microphone—For example, the initiation of a telephone call, or a command to record, monitor, or process sound. In response to the portable multi-function device being used in a manner that will not require a microphone, process  1400  returns to step  1420 . However, in response to the portable multi-function device being used in a manner that may require a microphone, process  1400  advances to step  1428 , where the portable multi-function device generates an alert. The purpose of this alert is to inform users that the device may require a microphone and that no microphone is present. The alert may be visual, audible, kinetic (i.e., vibrations) or any combination thereof. Following the alert at step  1428 , process  1400  returns to step  1420 . 
     It is understood that the various features, elements, or processes of the foregoing figures and description are interchangeable or combinable to realize or practice the invention described herein. Those skilled in the art will appreciate that the invention can be practiced by other than the described embodiments, which are presented for purposes of illustration rather than of limitation, and the invention is limited only by the claims which follow.