AUDIO I/CV HEADSET HEADSET PLUG AND PLUG DETECTION CIRCUITRY

[0001] This relates to portable electronic devices, and more particularly to headset plugs and plug detection circuit:ry ,

[0002] Portable electronic devices may include jacks or sockers for receiving connector plugs .e,g , stereo plug, for headphones or headsets. Audio signals may be passed from the jack to the headset through electrical connections formed between the plug and the jack when the plug is inserted into the jack. Known jacks inc l ude single prong monaural and stereo plugs and douoble prong stereo plugs. A drawback of such plugs is that they jack the ability to handle additional signals which may be provided by either the headset or the :jack. In additicn, the double prong plug retires a double prong jack, which may occupy valuable real estate in the media device,

of handling at least one additional signal in addition to one or more audio signals. What is also needed is plug detection circuitry to detect which type of plug

is received in the jack and to detect user activated functions that rr.ay be performed with a headset connected to the plug.

Sumrr.ary of the Invention

[0004] A single prong, multiple signal conducting plug is provided, This plug may be electrically coupled to a stereo headset including a microphone. The plug rr.ay include four signal conducting regions arranged in a predetermined order along the length of the prong. As such, this plug m,ay be referred to as a four region plug. The signal conducting regions include a left audio signal region, a right audio signal region, a ground region, and a m.icrcphone region, where the ground region is located between the microphone region and either the left or right audio signal regions.

[0005] Detection circuitry m,ay be operative to determine whether a m.icrcphone type of plug (e.g., a four region plug including a m.icrophone region and two audio regions, or a three region plug including a microphone region and only one audio region) or a non- m.icrophone type of plug (e.g., stereo plug) is inserted into the jack of the electronic device (e.g., mobile phone) . The detection circuitry may provide a signal that indicates whether the received plug is a microphone or non-micrcphone type. For example, when the plug is received, the signal m.ay indicate that a m.icrophone type of plug is received. Detection circuitry m.ay provide another signal that indicates whether a plug is received by the jack. Both signals m.ay be provided to ether circuitry, such as a

processor, within the electronic device for further processing ,

[0006] Detection circuitry may also detect user activated functions performed m response to user activation of one or more switches included with the headset. For example, the headset may include a single switch for performing a function with respect to a m.icrophone (e.g., end-call function) . Vfcen the user presses the switch, the detection circuitry may detect the occurrence of a switch activation event and provide a signal indicative of that activation that switch to other circuitry (e.g., a processor) located in the device, In other embodiments, the headset m.ay include multiple switches (e.g., two switches) . The detection circuitry m.ay detect which one of the switches is activated and provide a signal indicative of which switch is activated.

Brief Description of the Drawings [0007] The above and other features of the present invention, its nature and various advantages will become m.cre apparent upon consideration of the following detailed description, taken m conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which :

[0008] FIG. 1 shews a simplified block diagram of portable m.edia player m accordance with an embodiment of the present invention; [0009] FIG. 2 shows an illustrative personal m.edia device capable of receiving two different types of plugs in accordance with an embodiment of the present invention;

[0010] FIG. 3 is a simplified schematic diagrarri of headset system including stereo headphones, a microphone, and a four region plug in accordance with an err-ocάirr.er.t of the present invention; [0011] FIG. 4 shows a more detailed yet simplified view of a four region plug in accordance with an embodiment of the present invention;

[0012] FIG, 5 shews a schematic diagram of detection circuitry m accordance with an embodiment of the present invention;

[0013] FIG. 6 is an exemplary timing diagram showing the state of the signals provided by detection circuitry in accordance with an embodiment of the present invention; [0014] FIG. 7 shows another exemplary timing diagram illustrating operation of detection circuitry using power management in accordance with an embodiment of the present invention; [0015] FIG. 8 illustrates an exemplary timing diagram when a plug that does not have a microphone region is inserted into ;ack 510 in accordance with an embodiment of the present invention;

[0016] FIG. 9 shows a schematic diagram, of detection circuitry including secondary switch detection circuitry according to an embodiment of the present invention;

[0017] FIG. 11 shows a schematic diagram of detection circuitry including alternative secondary switch detection circuitry according to an embodiment of the present invention;

[0018] FIG. 12 shows an exemplary timing diagram, illustrating assertion of signals based on detected

current: levels using detection circuitry operating in accordance with an embodiment of the present invention;

[0019] FIGS. 13 and 14 show two illustrative examples of dual switch configurations that may be implemented with respect to a microphone m accordance with a embodiments of the present invention;

[0020] FIG. 15 is a flowchart illustrating steps that may be implemented by detection circuitry in accordance with an embodiment of the present invention; [0021] FIG. 16 is flowchart showing m more detail hew one of the steps of FIG. 15 may be implemented in accordance with an embodiment of the present invention; and

[0022] FIG. 17 is a flowchart of steps that may be taken when one or more switch activation events are detected m accordance with an embodiment of the present invention,

Detailed Description of the Invention [0023] FIG. 1 shows a simplified block diagram, of illustrative portable electronic device 100 m accordance with the principles of the present invention. Device 100 m.ay include processor 102, storage device 104, user interface 108, display 110, CODEC 112, bus 118, memory 120, communications circuitry 122, and jack 130. Processor 102 can control the operation of m.any functions and other circuitry included in m.edia player IOC. Processor 102 may drive display 110 and m.ay receive user inputs from user interface 108.

[0024] Storage device 1C4 m.ay store media (e.g., music and video files), software (e.g., for implementing functions on device 100, preference

information (e.g., redia 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 media device to establish a wireless connection sαch as a telephone connection) , subscription information (e.g., mforrration that keeps tracks of podcasts or television shews or other media a user subscribes to), telephone information (e.g., telephone numbers), and any other suitable data. Storage device 104 may mcl-de one more storage mediums, including for example, a hard-drive, permanent memory such as RCX, semi-permanent memory such as RAM, or cache .

[0025] Memory 120 may include one or more different types of memory which may be used fcr performing device functions. For example, memory 120 may include cache, Flash, RCM, and/or RAM. Memory may be specifically dedicated to storing firmware. For example, memory may be provided fcr store firmware for device applications (e.g., operating system, user interface functions, and processor functions). [0026] 3us 118 may provide a data transfer path for transferring data to, from, or between storage device 104, codec 112, communications circuitry 123, baseband circuitry 124, memory 120, and processor 102. [0027] Coder/decoder (CCDEC) 112 may be included to convert digital audio signals into an analog signal, which may be provided to ;ack 130. For example, CODEC 112 may provide audio signals (e.g., left and right audio signals to ;ack 130 to be converted into

sound by a headset (net shown) . In one embodiment, CODEC 112 may provide the left and right audio signals as single ended outputs. CODEC 112 m.ay receive one or mere signals from jack 130, For example, jack 130 m.ay receive audio signals from, a microphone included with a headset connected to the jack. In one embodiment, CODEC 112 m.ay receive the microphone audio signals as a differential m.onaural input. [0028] Jack 130 may be constructed to receive single prong plugs of a predetermined length and diameter.

For example, jack 130 m.ay receive four region plugs and three region plugs, The plugs may be connected to headsets that m.ay provide microphone and m.ono or stereo functionality. If desired, the headsets m.ay include integrated switches, that when activated, cause a function to be executed. Examples of headsets that include switches can be found, for example, in commonly assigned Eric Daniels et al, U.S. Patent Application Xo. , filed (Attorney Docket No. 104677-0012 (P4640)), entitled "Bend Switch for Wired Headset, ' and Evans Hankey et al . U.S. Patent

Application No. , filed (Attorney

Docket No. 104677-0067 (P5021)), entitled ^' Wired Headset with Integrated Switch, " both disclosures of which are hereby incorporated by reference herein in their entireties.

[0029] In addition, :ack 130 m.ay include detection circuitry 132. Various embodiments of detection circuitry are discussed in m.ore detail below. Jack 130 may be electrically coupled to processor 102 to transmit signals between jack 130 and processor 102, For example, detection circuitry 132 m.ay provide a HEADSET DETECT signal and MIC signal to processor 102.

The MIC signal m.ay indicated the presence of headset having a microphone connected to jack 130 and may indicate when a microphone switch is activated. Processor 102 may interpret the signals received from detection circuitry 132 to determine, for example, which plug type is connected to jack 130 and whether a microphone switch is activated. In other embodiments, detection circuitry 132 may provide three or m.ore signals to processor 102. For example, when a headset includes two or mere switch functions, a signal conducting pathway may be need for each switch function, where one of the pathways may also be used to indicate to processor 102 whether a four region plug is inserted into jack 130. [0030] Communications circuitry 122 may be included m a carrier circuitry portion (delimited by dashed lines 125) of device 100. Carrier circuitry portion 125 may be dedicated primarily to processing telephone functions and other wireless ccmm.unications (e.g., v;i-Fi or 3iuetooth) , For example, baseband circuitry 124 m,ay handle telephone functions. It is understood that the carrier circuitry portion operate independent of other device components operating in device 100. That is, carrier circuitry m.ay be an independently operating subsystem within device 100 that m.ay communicate with other components within device 100.

[0031] User interface 108 m.ay allow a user to interact with the device 100. For example, the user input device 108 can take a variety of forms, such as a button, keypad, dial, a click wheel, or a touch screen. Communications circuitry 122 m.ay include circuitry for wireless communication (e.g., short-range and/or long

range comm.ur.ication) . For example, the wireless communication circuitry rray be wi-fi enabling circuitry that permits wireless communication according to one of the 802,11 standards or a private network, Other wireless network protocols standards could also be used, either in alternative to the identified protocols or in addition to the identified protocol, Another network standard may be Bluetooth, [0032] Communications circuitry 122 m.ay also include circuitry that enables device 100 to be electrically coupled to another device (e.g., a computer or an accessory device) and communicate with that other device. As indicated above, communications circuitry 122 m.ay also include baseband circuitry for performing relatively long-range communications (e.g., telephone communications) . If desired, ccmmunications circuitry 122 may include circuitry for supporting both relatively long-range and short-range ccmmiunications . For example, ccmm.unications circuitry 122 may support telephone, Wi-Fi, and 3luetooth ccmm.unications. [0033] In one embodiment, device 100 may be a portable computing device dedicated to processing m.edia such as audio and video. For example, device 100 may be a m.edia player (e.g., XP3 player), a game player, a remote controller, a portable communication device, a rem.ote ordering interface, an audio tour player, a mobile telephone, or other suitable personal device. In another em.bcdim.ent, m.edia player 100 m.ay be a portable device dedicated to providing m.edia processing and telephone functionality m single integrated unit. Xedia player ICC m.ay be battery-operated and highly portable so as to allow a user to listen to music, play gam.es or video, record video or take pictures, place

and take telephone calls, communicate with others, control ether devices, and any combination thereof. In addition, device 1OC m.ay be sized such that it fits relatively easily into a pocket or hand of the user. 3y being handheld, device ICO is relatively small and easily handled and utilized by its user and thus may be taken practically anywhere the user travels. [0034] FIG. 2 shews an illustrative portable electronic device 210 capable of receiving two different types of plugs. As shown, plug 230 of headset system 220 and plug 250 of headphone system 240 m.ay be inserted into jack 212. Headset system, 220 can include stereo headset with a microphone 224 which is connected to four region plug 230 via wired link 224. Stereo headset with a microphone 224 m.ay include left and right speakers and a microphone.

[0035] Plug 230 m.ay include four signal conducting regions arranged m a predetermined order along the length of a single prong. As shown, plug 230 includes, starting from the tip of plug 230, a left audio signal region 231, a right audio signal region 232, a ground region 233, and a microphone region 234. The left and right audio signal regions may be interchanged, however, m this embodiment, ground region is located between the microphone region and the right audio signal region. The regions may be separated by insulating rings 235 that electrically isolate the regions from each other. The electrical connection of headset system 220 is discussed below in more detail in connection with FIG. 3 and a more detailed of four region plug is discussed below m connection with FIG, 4.

[0036] Headphone system. 240 can include stereo headset 242 which is connected to plug 250 via wired link 244. Stereo headset 242 may include left and right speakers. Plug 250 includes, starting from the tipf? a left audio signal region 251, a right audio signal region 252, and a ground region 253. The location of left and right audio regions 251 and 252 may be switched. The regions may be isolated from each by insulating rings 255 [0037] FIG. 3 is an illustrative simplified schematic diagram; of headset system 300 including stereo headphones, a microphone, and a four region plug. FIG. 3 shows how the regions of plug 310 electrically connect to the left and right acoustic elem.er.ts 330 and 332 (e.g. , speakers) , and m.icrcphone 340. As shewn, the left audio signal region, the right audio signal region, and m.icrophone region can be connected to the positive terminals of left acoustic element 330, right acoustic elem.ent 332, and m.icrophone 340, respectively. The ground region can be connected to the negative terminals of left acoustic elem.ent 330, right acoustic elem.ent 332, and microphone 340, respectively. [0038] Headset system 300 r.ay include a switch 350, for example, to enable a user to activate a function with respect to the microphone. Switch 350 m.ay be connected to the microphone and ground regions of plug 310. Switch 350 may be a norm.ally O?E\ ^T switch, meaning that in its norm.al state, m.icrcphone 340 is permitted to transmit signals to the microphone portion of plug 310. '/Then switch 350 is CLCSξD, m.icrophone 340 is shorted.

[0039] FIG. 4 shows a m.ore derailed yet illustrative simplified view of a four region plug 400. Plug 400 includes four regions, delineated by the numbers 1-4, separated by insulating rings 405. Plug 400 may be a 3.5mm plug, where the outer diameter of regions 2-4 is 3.5mm. depending on which headset or headphone system plug 400 is connected to, the regions may be used for different signal conducting purposes. The table accompanying FIG. 4 shows the signal conducting purpose of each region for several different systems. For example, for a monaural headset, region 1 may be used for a speaker, regions 2 and 3 m.ay be used as ground, and region 4 m.ay be used for a microphone. Note that for the headset, regions 3 and 4 m.ay be combined to form, a single region (not separated by an insulating ring), thereby providing a three-region plug. Further note that for the monaural headset, regions 2 and 3 may be combined to form a single region, providing a three- region plug with a ground region between a microphone region and an audio signal region. Alternatively, in the monaural headset, region 2 m.ay exist but may not connect to, for example, a speaker in the headset and region three m,ay be dedicated to ground. [0040] FIG. 5 shews an illustrative schematic diagram of detection circuitry 500. Detection circuitry 500 may be operative to determine whether a microphone type of plug (e.g., a four region plug including a microphone region and two audio regions, or a three region plug including microphone region and only one audio region) or a non-microphone type of plug

(e.g., stereo plug) is inserted into the jack of the electronic device (e.g., mobile phone) , The detection circuitry may provide a XIC signal that indicates

whether the received plug is a microphone or r.on- m.icrophcr.e type. For example, when the plug is received, a LOW XIC signal may indicate that a microphone type of plug is received. Detection circuitry 500 m.ay also provide a HEADSET DETECT signal that indicates whether a plug is received by the jack. The XIC and HEADSET DETECT signals m.ay be provided to other circuitry, such as a processor, with the electronic device for further processing by that other circuitry.

[0041] Circuitry 500 includes jack 510 for receiving a plug (e.g., a four region plug) . Jack 510 includes XIC connector 512, GND connector 513, right connector 514, left connector 515, and headset detect connector 516. Connectors 512-515 are staggered such that each connector contacts a different region of a plug inserted into jack 510. For example, assuming plug 230 of FIG. 2 is inserted into jack 510, microphone region 234 contacts XIC connector 512, ground region 233 contacts GND connector 513, right region 232 contacts right connector 514, and left region 231 contacts left connector 515. [0042] Connecters 512-515 m,ay be arranged in a particular crder to ensure desired ;ack connector to plug regions contacts are m.ade and to ensure that detection circuitry SCO is able to correctly determine which type of headset (e.g., headset with or without microphone) is connected to ;ack 510. The arrangement of connectors 512-515 can match that of a four region plug according to the invention. That is, GND connector 513 may be located between XIC connector 512 and right connector 514. In another embodiment, GND

connector 513 rr.aybe located between XIC connector 512 and left connector 515.

[0043] XIC connector 512 rr.ay be electrically coupled to CODEC circuitry 520 via bias resistor 527 and transistor 532 (e.g., a FET) via resistor 530. GND connector 512 may be connected to a ground source. Right and left connectors 514 and 515 may be electrically connected to CODEC circuitry 520. In addition, right and left connectors 514 and 515 may be electrically connected to ground via resistors 522 and 524, respectively. Headset connector 516 may be electrically connected to a power source, called Vdd, via resistors 528 and 529. Vdd rr.ay also be connected to a teπir.ai of transistor 532 via resistor 534. [0044] Left connector 515 and headset detect connector 516 rray be selectively connected together by a normally closed switch 518. Switch 518 inay be CLOSED when no plug is inserted into ;ack 510. When CLOSED, Vcc is pulled to ground through resistor 522. Thus, when switch 518 is CLOSED, the HEADSET DETECT signal, which m.ay be provided to a processor (e.g., processor 102 of FIG. 1), is LOW. A LCW HEADSET DETECT signal ray indicate that no plug is inserted m ;ack 51C. A HIGH HEADSET DETECT signal rray indicate that a plug is inserted in jack 510, The HEADSET

DETECT signal rray go HIGH when a plug is inserted into jack 510, the plug causes switch 518 to OPEN. When switch 518 is OPEN, headset detect connector 516 can be pulled up to Vdd. [0045] Detection circuitry 500 m.ay provide a XIC signal, for example, to a processor (e.g., processor 102 of FIG. 1) . The state of the XIC signal m.ay indicate whether a headset with a microphone is

connected tc jack 510. In addition, if a microphone headset is connected to jack 510, changes in the state of the XIC signal may indicate the occurrence of a switch activation (e.g., a user presses a switch to end a telephone call) .

[0046] MIC signal may be HIGH when transistor 532 is CFF and LOW when transistor 532 is ON. Transistor 532 may be an XMOS transistor. CODEC 520 m.ay bias the gate of transistor 532 so that it is turned ON when a plug is absent from jack 510 and when a plug including a microphone region is inserted into jack 510. [0047] The operation of detection circuitry 500 is new discussed in combination with FIG. 6, which is an exemplary timing diagram shewing the state of the HEADSET DETECT and XIC signals in accordance with an embodiment of the present invention. Starting at tim.e t0, when jack 510 is empty, the both the HEADSET DETECT and XIC signals are LOW. HEADSET DETECT may be LOW because switch 518 is CLOSED, effectively tying connector 516 to ground. XIC signal may be low because CODEC circuitry 520 is biasing transistor 532 to be turned ON, pulling XIC signal to ground. [0048] At time tl, when a plug with a microphone region is inserted into jack 510, HEADSET DETECT signal goes HIGH and XIC signal m.ay pulse HIGH due to shorting of wire contacts during plug insertion, but goes LOW. The processor m.ay be configured to ignore any XIC signal until at least a predetermined period of time after HEADSET DETECT goes HIGH to avoid erroneous detection. HEADSET DETECT signal m.ay go HIGH because switch 51S OPENS in response to :ack 510 receiving a plug. XIC signal m.ay continue to stay LOW because

transistor 532 is still biased to be turned ON (by CODEC circuitry 52C) .

[0049] Between tirr.es t2 and t3 , a switch activation event occurs. During this event, MIC signal goes HIGH because transistor 532 is turned OFF. Transistor 532 ray be turned OFF when MIC connector 512 is shorted to ground through resistor 524. For example, MIC connector 512 rr.ay be shorted when a switch such as switch 35C of FIG. 3 is CLOSED. vrhen shorted, the voltage, including a bias voltage provided by

CODEC 520, on connecter 512 drops below a threshold voltage on transistor 532, thereby causing transistor 532 to turn OFF. 'λ'hen transistor 532 is turned OFF, the MIC signal is pulled to Vdd via resistor 534. After tirr.e t3, the switch activation event ends, at which point transistor 532 turns back ON, pulling the MIC signal down to ground. [0050] FIG. 7 shews another exerr.plary timing diagram illustrating operation of headset detection circuitry 5CC using power management in accordance with the principles of the present invention. Using power management, CCDξC circuitry 520 m.ay provide a bias voltage only when a plug is inserted into jack 510. Starting at time t0 (an empty jack 510) , HEADSET DETECT signal is LO'λ', which m.ay prevent CODEC circuitry 520 from supplying a bias voltage, thus providing power savings. MIC signal is HIGH because no bias voltage is provided to turn transistor 532 CN. At time tl, when a plug with a microphone region is inserted into ;ack 51C, HEADSET DETECT goes HIGH, which m.ay cause CODEC circuitry 520 to provide a bias voltage that turns transistor 532 ON, pulling MIC signal LOV, ¹ . Between times t2 and t3, a switch activation event

occurs, during which XIC signal is HIGH. At tine t4, the plug is removed, causing HξADSξT DξTξCT signal to go LCW. This causes CCDEC circuitry 520 to cease supplying a bias voltage and XIC signal goes HIGH. [0051] With respect to FIGS. 6 and 7, a processor m,ay determine whether the type of plug inserted into ;ack 51C is a plug having a m.icrophcne region by checking the state of the XIC signal a predetermined time after the HEADSET DETECT signal gees HIGH. In both FIGS. 6 and 7, the XIC signal is LOW a predetermined time (e.g., 10ms) after HEADSET DξTξCT goes HIGH, thus indicating that a microphone is present . [0052] FIG. 8 illustrates an exemplary timing diagram, when a plug that dees not have a microphone region is inserted into jack 51C. Starting at step tθ, when no plug is inserted into jack 510, both HξADSξT DETECT and XIC are LOV,'. At time tl, when a plug with a XIC region is inserted into jack 510, both HξADSξT DξTξCT and XIC go HIGH. XIC may go HIGH because the XIC connector 512 is tied to ground, effectively pulling the gate of transistor 532 to ground, turning it OFF. XIC connector 512 may be coupled to ground connector 513 by a ground region of the plug. For example, assuming that plug 250 of FIG. 2 is inserted into jack 510, ground region 255 may electrically couple XIC connector 512 to ground connector 513. [0053] FIG. 9 shews a schematic diagram, of detection circuitry 900 including secondary switch detection circuitry 950. Detection circuitry 900 m.ay be the same as detection circuitry 5CC, therefore a detailed discussion of all the components and operation of circuitry 900 is not needed, Secondary switch

detection circuitry 950 may be included for detecting switch activation events of headsets including multiple switches. For exar.ple, a headset may include two switches, where activation of each switch rr.ay perform a different function, and where simultaneous activation of both switches may perform, yet another function. FIGS. 13 and 14 show two illustrative examples of dual switch configurations that m.ay be implemented with respect to a microphone. FIGS. 13 and 14 show a normally closed switch connected in series with the MIC region of a plug (not shown) and a normally open switch connected m parallel with the MIC region of the plug. The tables accompanying FIG. 13 and 14 show which switch is activated, if any, depending on the open and close positions of switches Sl and S2. The table also indicates whether an XIC OPEN event (e.g., an event in which the MIC is electrically disconnected from the ;ack) or MIC SHORT event (e.g., an event in which the MIC is short circuited to ground. A normal action may occur when switches Sl and S2 are in their normal positions .

[0054] Referring back to FIG. 9, secondary switch detection circuitry 950 may m.cnitor a voltage level to determine the occurrence of switch activation events, Detection circuitry 950 may include voltage detection circuitry 952 electrically coupled to node 948. Voltage detection circuitry 952 provide a HIGH or LOW signal, labeled MIC ACTION DETECT, depending on the voltage seen at node 948. In one embodiment, the voltage detection circuitry may include a comparator that compares to the voltage at node 948 to a reference voltage. The voltage at node 948 may vary am.ong several different voltage levels, For example,

node 943 may see a no plug present voltage, a first switch activation voltage, a second switch activation voltage, a combined first and second switch activation voltage, and a normal operating voltage. Depending on the voltage seen at node 948, detection circuitry 900 provides the appropriate signals for MIC and KIC ACTION DETECT.

[0055] FIG. 1C shews an exemplary timing diagram illustrating assertion of signals based on detected voltage levels using detection circuitry 900 operating in connection with a dual switch, such as those shewn in FIGS. 13 and 14. FIG. 10 shews the state of the MIC and MIC ACTIOX DETECT signals and the voltage detected at node 948, labeled VDξTξCT. The detected voltage may range from an OPEX MIC voltage to a normal voltage to a MIC short circuit voltage. A normal voltage may be detected when a plug with a microphone is inserted into ;ack 910 and the microphone is operating m a normal mode (e.g., no switches are being activated) , as indicated at time tθ. The normal voltage may be the voltage produced when the CODEC circuitry biases the microphone and the transistor 932. Between times tl and t2, a MIC short circuit event occurs. During the MIC short circuit event, MIC signal goes HIGH and VDETECT goes to the MIC short circuit voltage (or ground) . Also, during the MIC short circuit event, the bias voltage is driven to ground, resulting in a negligible voltage at node 948. Between times t2 and t3, detection circuitry 900 returns to normal operation. Between times t3 and t4, a MIC OFEK event occurs. During the MIC OPEN event, VDξTξCT may go to CPξN CIRCUIT voltage, which results m MIC ACTION DETECT going HIGH. The voltage at node 948 may be

higher during a MIC OPEN event than norτr.ai operation because the microphone is no longer biased by the CODEC circuitry ,

[0056] FIG. 11 shows a schematic diagram of defection circuitry 1000 including alternative secondary switch detection circuitry 1050. Detection circuitry 1000 may be the same as detection circuitry 500, therefore a detailed discussion of all the components and operation of circuitry 1000 is not needed. Secondary switch detection circuitry 1050 may include current detection circuitry 1054 for detecting a current level flowing through resistor 1052. Depending on the detected current level, circuitry 1050 m.ay provide the appropriate signal (e.g., HIGH or LOW signal) to MIC ACTION DETECT,

[0057] In one embodiment, three different current levels m.ay exist. A first current level may correspond to a microphone short condition (e.g. current flow m.ay be high) . A second current level m.ay correspond to a normal microphone bias condition (e.g., current flow m.ay be such that the microphone is biased) . And a third current level may correspond to a microphone open condition (e.g., current flcv; m,ay be low and the microphone is no longer biased) . Current detection circuitry 1050 m.ay assert MIC ACTION DETECT when the third current level is detected. The MIC signal may be asserted when a microphone short condition exist. [0058] FIG. 12 shows an exemplary timing diagram illustrating assertion of signals based on detected current levels using detection circuitry 1100 operating in connection with a dual switch, such as those shewn in FIGS. 13 and 14. FIG. 12 shews the state of the MIC and MIC ACTION DETECT signals and the current voltage

detected at node 948, labeled DETECTION CURRENT. DETECTION CURRENT rr.ay range from a short circuit current to a normal bias current to an open circuit current. The normal bias current rr.ay be detected when a microphone electrically connected detection circuitry HCO is operating in a norural m.ode, as indicated between tirres tO and tl. 3etv,-een tirr.es tl and t2 , a MIC short event occurs, which rray result in MIC signal going HIGH and DETECTION CURRENT going increasing to short circuit current. Between times t3 and t4, a MIC OPEN event occurs, which rray result in MIC ACTION DETECT going HIGH and DETECTION CURRENT decreasing to a open circuit current, [0059] It is understood that although FIGS. 9-14 are discussed m terms of handling switch activation event executed by two different switches, circuitry rray be provided to detect simultaneous activation of two switches and additional switches. [0060] FIG. 15 is an illustrative flowchart of various steps that may be implemented by detection circuitry. Starting at step 1510, one of at least two types of plugs is received, for example, in a jack of the detection circuitry, For example, the plug may be a four region plug including a microphone region (with a ground region located between the m.ic region and an audio signal region) , a three region plug including a microphone region (with a ground region located between the m.ic region and an audio signal region) , or a three region plug with no microphone region. At step 1520, a HEADSET DETECT signal may be provided (e.g., asserted) to indicate that a plug has been received. After the HEADSET DETECT signal is asserted, the bias power may be provided to bias, for example, the MIC DETECT

transistor (e.g., transistor 532), if it is not already being biased.

[0061] At step 1530, a determination is made as to which one of the at least two types of plugs is received. This determination may be m.ade a predetermined period of time after the HEADSET DETECT signal has been asserted to provide sufficient settling time' before making the determination. The determination may be m.ade m one of several different ways, one of which is illustrated m the steps shown m FIG. 16. Referring to FIG. 16, at step 161C, bias power is provided. For example, bias power m.ay be provided by CCDEC circuitry. At step 162C, a determination is made as to whether the plug has a microphone region m the anticipated microphone region. If yes, the process proceeds to step 1630, which provides the bias power to the microphone region, At step 1632 the bias power is provided to XIC detect circuitry. If no, the process proceeds to step 1640, which provides the bias power to ground. At step 1642,

XIC detect circuitry is electrically coupled to ground. [0062] Referring back to FIG. 15, after the determination is r.ade at step 1530, the appropriate XIC signal is provided at step 1540. For example, if a microphone region is detected, the XIC signal .may be

LO'/, ⁷ , ana HIGH if not detected. If a microphone region is not detected, then the XIC DETECT transistor (e.g., transistor 532) may be turned OFF to save power. XIC DETECT transistor rray be turned by ceasing the supply of the bias power.

[0063] FIG. 17 is an illustrative flowchart of various steps that may be taken when one or mere switch activation events are detected in accordance with the

principles of the present invention. Starting at step 1710, a plug having a microphone region and is electrically connected to at least one microphone switch is received. For example, the plug may be electronically connected to a single or dual switch headset. At step 1720, the plug may be monitored for a switch activation event. If the headset has two switches, switch activation event caused by both switches may be monitored. Fcr exam.ple, one switch may cause an OPEN MIC switch activation event and the other switch may cause a KIC short circuit activation event when activated (e.g. pressed by the user) . At step 1730, a signal is provided in response to a monitored switch activation event. Fcr example, if a single switch headset is connected to the detection circuitry and is activated, the MIC signal may be asserted (for at least the duration of the switch activation event) . [0064] It is understood that the steps shown in FIGS. 15-17 are merely illustrative and that steps m.ay be modified, added, or omitted.

[0065] Thus it is seen that plug with microphone regions and system.s and methods detecting such plugs and switch activation events are provided. 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.