Abstract:
This invention relates to a method, a computer program product, an apparatus and a system enabling a communication between a first electronic device and a compatible second electronic device via the identification (ID) pin of a serial interface of the first electronic device.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a method, an apparatus, a computer program product and a system for an electronic device comprising a serial interface. 
       BACKGROUND OF THE INVENTION 
       [0002]    A serial interface such as the Universal Serial Bus (USB) is a technology which provides a fast, cabled data connection between a complex device (e.g. a PC) which is called the Host and a connected peripheral (e.g. a mouse, keyboard etc.) which is called the Device. 
         [0003]    A serial interface according to the USB standard comprises two data lines (D+ and D−) a ground line (GND) and a voltage supply line (V Bus ). 
         [0004]    According to the USB standard, the D+ and D− lines are configured to be used for data transfer. 
         [0005]    The VBus line enables a connected device, which might not have an own power supply or where the device internal power supply is limited (e.g. a battery pack) to receive electrical power from the other connected device. 
         [0006]    In accordance with the USB standard the devices roles (host role and device role) are fixed, i.e. by the type of connector of each device (A-plug and B-plugs) the role of the devices is defined and e.g. connection of one host to another host device is not possible. 
         [0007]    The USB On-The-Go standard (USB_OTG) extends the basic USB standard in such a way that the interface contains and additional identification (ID) line which enables the devices to switch and/or negotiate the host/device role of the connected devices. 
         [0008]    According to the USB OTG standard the A-plug (connected to USB OTG host) the ID pin is connected to ground and the B-plug (connected to USB OTG device) the ID pin is left floating. 
         [0009]    For a more detailed description of the USB OTG standard it is hereby referred to the USB OTG standard “On-The-Go Supplement to the USB 2.0 Specification; Apr. 4, 2006”. 
         [0010]    Small devices like mobile phones, audio players, personal digital assistants and so on can only provide limited space for connectors and interfaces for connection to other devices and accessories. 
         [0011]    For instance, traditionally audio devices that used 2.5 mm or 3.5 mm universal headsets (UHS) required a bulky and expensive 2.5 mm or 3.5 mm universal headset jack (UHJ). Devices that also provided USB functionality required two connectors. 
       SUMMARY OF THE INVENTION 
       [0012]    According to the invention a method, a computer program, a computer program product, an apparatus and a system for enabling enhanced communication from a first electronic device to another electronic device via a serial interface is presented. 
         [0013]    A method is proposed, comprising enabling a communication between a first electronic device and a compatible second electronic device via the identification pin of a serial interface of said first electronic device. 
         [0014]    The serial interface might be an interface as known as an USB interface or any other interface comprising at least one data line for data communication and at least one ID line for device role (host/device) identification purposes, e.g. as provided by the USB OTG standard. 
         [0015]    The first electronic device comprises a serial interface, wherein said serial interface may represent a Micro USB interface or a Mini USB interface or any other USB interface comprising at least five pins or any other serial interface, wherein the ID pin of said serial interface is used to allow a communication with a compatible second electronic device in case this second electronic device is connected to the first electronic device via said serial interface. Compatible according to the invention means, that the second device is configured to communicate via the ID pin of the serial interface of said first electronic device. 
         [0016]    Said communication may comprise a transmission from said second electronic device to said first electronic device via said ID pin and/or it may comprise a transmission from said first electronic device to said second electronic device via said ID pin. Said transmission may be any kind of transmission, e.g. like digital data transmission, or transmission of an analog signal, or a combination of both. For instance, said transmission may be used for signaling, or for transmitting an analog signal, e.g. an audio signal, or for transmitting digital data. 
         [0017]    For instance, the first electronic device may contain a signal unit connected to the ID pin of the serial interface connector and configured to perform the communication via the ID pin. 
         [0018]    E.g., according to the USB OTGstandard, the ID pin of a USB Micro B-plug is floating and the ID pin of a Micro A-plug is connected to ground. Thus, if said first USB interface represents a USB Micro interface, then it may be a Micro Type B-plug or a USB Micro receptacle suited to be configured to a Micro Type B-plug. For instance, the first device may comprise a first Micro Type B USB receptacle connected to the first USB interface, or said first USB interface may represent a first Micro Type B USB receptacle, or, the USB interface may be connected to cable terminated with a Micro Type B-plug. Furthermore, said USB interface may be a Mini USB interface. 
         [0019]    Thus, the present invention allows to use the ID-pin of the first serial interface for data communication to a compatible second electronic device, which enables enhanced data communication between both devices, because besides the at least one data line of the serial interface connection a third line via the ID pin may be used for communication. For instance, any suited link system may be used for this communication, wherein the first electronic device may comprise a signal unit which is adapted to perform signaling according to the link system. For instance, said communication via the ID pin may be performed by a dual impedance Enhancement Control Interface (ECI), or by an accessory control interface (ACI). 
         [0020]    For instance, the at least one data line of the serial interface may be used according to the respective serial interface standard, and without interfering this serial interface standard, a further communication may be performed via the ID pin of said first interface. 
         [0021]    Thus, the present invention may allow to use the full serial interface functionality via said at least one data line and may allow simultaneously a further communication via the ID pin without interfering the serial interface standard. 
         [0022]    For instance, said first electronic device may represent an accessory device which is configured to be connected to a terminal like mobile phone, PC or a handheld, wherein this accessory may be a headset, or any other kind of accessory. 
         [0023]    According to an embodiment of the present invention, said serial interface may represent a USB interface. 
         [0024]    Thus, both the first device and the second device may represent devices having USB standard/protocol compatibility, i.e. USB compliance. A compatible USB device according to the invention represents a USB device which is configured to communicate via the ID pin of an USB interface, and a non-compatible USB device according to the invention represents a USB device which is not configured to communicate via the ID pin of an USB interface. Furthermore, the first device and/or the second device may comprise an USB interface without providing USB compliance. 
         [0025]    For instance, the at least one data line may present the D+ and D− lines of the USB interface, and these D+ and D− lines may be used according to the USB standard, and without interfering this USB standard, a further communication may be performed via the ID pin of said first interface. 
         [0026]    According to an embodiment of the present invention, said method further comprises at least one out of transmitting at least one information parameter for identifying the first electronic device via said communication; and receiving at least one information parameter for identifying the second electronic device via said communication. 
         [0027]    Thus, based on said at least one information parameter the first electronic device may identify a connected second electronic device and/or the connected second electronic device may identify the first electronic. device without interfering the USB standard. 
         [0028]    According to an embodiment of the present invention, said communication via the ID pin of said serial interface is based on an Enhancement Control Interface (ECI) link. 
         [0029]    Said ECI link may be performed by a signal unit connected to the ID pin of the USB interface. 
         [0030]    According to an embodiment of the present invention, said method further comprises negotiating, based on said at least one information parameter, a configuration for a wireless interface of said first electronic device, said configuration enabling a wireless connection between said first and said second electronic device. 
         [0031]    For instance, said first electronic device may represent an accessory which comprises a wireless interface, which may be connected via a RF unit to an antenna. For instance, said wireless interface may be a Bluetooth interface, or a WLAN interface or any other wireless interface suited to establish a wireless connection to said second electronic device. Said second electronic device may represent a terminal. 
         [0032]    Said first electronic device may be connected to a terminal by means of said serial interface, thereby establishing a serial interface connection between the first electronic device and the terminal. The first electronic device may enable a communication via the ID pin with the connected terminal, and e.g. at least one information parameter may be transmitted from the first electronic device to the connected terminal via the ID pin in order to identify the connected first electronic device. Based on this identification, the terminal may determine a configuration for the wireless communication between the first electronic device and the terminal, and/or, the terminal may transmit a wireless configuration via the ID pin communication to the first electronic device for negotiating a configuration for the wireless interface, and the wireless connection between the first electronic device and the terminal may be established. The wireless connection may be started by the first electronic device, or by the connected terminal. 
         [0033]    Summarized, the communication via the ID pin may be used to negotiate a wireless configuration between the first electronic device and a connected terminal in order to establish a short-range radio connection. This way, the present invention allows any easy and simple configuration of wireless interfaces of a first electronic device to a terminal via the serial interface, wherein this configuration does not effect the serial interface standard since the data pins of the serial interface may not be used for negotiating the wireless configuration. After establishing the wireless communication, everything else like audio, or control operations may be performed via the wireless communication link. For instance, said first electronic device may be any kind of a wired Bluetooth accessory or headset, wherein the wireless connection is established automatically when connected to the terminal. 
         [0034]    According to an embodiment of the present invention, the method further comprises receiving power from said second electronic device via said serial interface. 
         [0035]    According to an embodiment of the present invention, said first electronic device comprises a rechargeable power supply, the method further comprises charging said rechargeable power supply with said received power. 
         [0036]    According to an embodiment of the present invention, said communication via the ID pin of the serial interface comprises at least one out of: transmitting an analog signal via the ID pin, and receiving an analog signal via the ID pin. 
         [0037]    For instance, said analog signal may represent an audio signal, or a video signal, or any other analog signal. 
         [0038]    For instance, said first electronic device may represent a terminal, wherein said terminal is configured to be connected to an USB audio device, e.g. a headset or anything else. 
         [0039]    According to an embodiment of the present invention, said method further comprises detecting whether a device connected to the serial interface of said first electronic device represents a compatible device, wherein a compatible device under the invention represents a device being configured to communicate via the ID pin of a serial interface. 
         [0040]    For instance, said first electronic device may comprise a detection unit for performing said detecting. Said detection may be performed by means of the ID pin of said serial interface, e.g. by detecting a voltage level at the ID pin, wherein a detected voltage within a predetermined range may indicate a compatible device. 
         [0041]    According to an embodiment of the present invention, said serial interface comprises at least one data line, and in a first state said first electronic device is configured to enable serial interface functionality via at least one out of the at least one data line of said serial interface, and wherein in a second state said first electronic device is configured to enable communication via the ID pin of the serial interface; and wherein the method comprises: switching said first electronic device into the first state in case the connected device is identified as a non-compatible device; and switching said first electronic device into the second state in case the connected electronic device is identified as a compatible device. 
         [0042]    Thus, if a common serial interface device which is not suited to communicate with the first electronic device via the ID pin is detected, then the first electronic device switches into the first state and is configured to provide the full serial interface functionality via the at least one data line, and wherein in said second state the communication via the ID pin is enabled. 
         [0043]    According to an embodiment of the present invention, said serial interface is a USB interface, and in said first state said first device is configured to enable USB functionality via at least one out of the D+ pin and D−pin. 
         [0044]    Thus, according to the first state said device may provide full USB compliance, i.e. USB standard/protocol compatibility. 
         [0045]    According to an embodiment of the present invention, said first electronic device comprises an audio unit, said audio unit being configured to communicate to a compatible USB audio device, and wherein in said second state said first electronic device enables said audio unit to communicate at least one audio signal between the first electronic device and the compatible USB audio device via at least the ID pin of said USB interface. 
         [0046]    According to an embodiment of the present invention, said compatible USB device is configured to be switched into one out of at least two states, and wherein said method further comprises: detecting a state out of said at least two states of said second electronic device, and switching the first electronic device into a state corresponding to the detected state of the compatible USB device. 
         [0047]    According to an embodiment of the present invention, said detecting is based on detecting a voltage level at the ID pin of the serial interface. 
         [0048]    E.g., this serial interface may be a USB interface. 
         [0049]    For instance, each state of said at least two states may correspond to a voltage range, and based on the detected voltage level at the ID pin the corresponding state can be determined. 
         [0050]    According to an embodiment of the present invention, said compatible USB audio device is configured to be switched into one out of at least two states, wherein a first state of said at least two states represents a normal audio mode, and wherein a second state of said at least two states represents a hook mode suited for performing control operations; and wherein said method further comprises: detecting a state out of said at least two states of said second electronic device; switching the first electronic device into the second state in case the first state is detected; and switching the first electronic device into a third state in case the second state is detected, wherein in said third state said first electronic device is configured to receive control signals from the audio device. 
         [0051]    According to an embodiment of the present invention, said compatible USB audio device represents one out of a headset and a headset-USB adapter, wherein in said second state of the first electronic device the audio unit connects a microphone input line of said audio unit to the ID pin of said USB interface and connects at least one speaker line of said audio unit to at least one of the D+ and D− pin of said USB interface. For instance, two speakers may be connected to both the D+ and D− pins of said USB interface. 
         [0052]    According to an embodiment of the present invention, said first electronic device comprises a USB transceiver which is configured to enable said USB functionality according to the first state, said method further comprising one out of: turning off said USB transceiver in case that the first electronic device is not in the first state; and switching said USB transceiver into three-state logic state in case that the first electronic device is not in the first state. 
         [0053]    Thus, any loading interference between the D+/D− lines and the audio lines may be eliminated. 
         [0054]    Furthermore, an electronic device is proposed, comprising: a serial interface; and a signal unit configured to enable a communication between said first electronic device and a compatible second electronic device via the ID pin of said serial interface. 
         [0055]    The explanations concerning the method mentioned above and the embodiments thereof also holds for this electronic device and its embodiments. E.g., said serial interface may represent a USB interface. 
         [0056]    Furthermore, a further electronic device is proposed, comprising: a serial interface comprising at least one data line and an identification pin (ID pin); and a wire configured to be connected to one out of a speaker and a microphone, wherein said wire is configured to be connected to the ID pin of said serial interface. 
         [0057]    According to an embodiment of the present invention, said further device is one out of a headset and a headset serial interface-adapter, wherein said headset serial interface-adapter is configured to connect a headset with a serial interface of an electronic device. 
         [0058]    According to an embodiment of the present invention, said further device is configured to be switched into one out of at least two states, wherein a first state of said at least two states represents a normal audio mode wherein said wire is connected to the ID pin of said serial interface, and wherein a second state of said at least two states represents a hook mode suited for performing control operation, wherein in said second state said device is configured to switch a predetermined voltage level to the ID pin of said serial interface. 
         [0059]    According to an embodiment of the present invention, said serial interface is a USB interface. 
         [0060]    Furthermore, a system is proposed, comprising a first electronic device as mentioned above, and comprising a further electronic device as mentioned above, wherein said first electronic device and said further electronic device are connected via their serial interfaces, and wherein both the first and the further electronic devices are configured to communicate via the ID-pin of their serial interfaces to each other. 
         [0061]    Further, an electronic device is proposed, comprising: serial interface means; and signal means for enabling communication between said first electronic device and a compatible second electronic device via the ID pin of said serial interface means. 
         [0062]    Finally, a computer program product in which a program code is stored in a computer readable medium is proposed, said program code realizing the method mentioned above. Said program code may further realize the embodiments of the method mentioned above. 
         [0063]    These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0064]    In the figures show: 
           [0065]      FIG. 1 : a block diagram of a first exemplary embodiment of an electronic device according to the present invention; 
           [0066]      FIG. 2 : a block diagram of a second exemplary embodiment of an electronic device according to the present invention; 
           [0067]      FIG. 3 : a flowchart of a first exemplary embodiment of a method according to the present invention; 
           [0068]      FIG. 4 : a flowchart of a second exemplary embodiment of a method according to the present invention; 
           [0069]      FIG. 5   a : a block diagram of a third exemplary embodiment of an electronic device according to the present invention; 
           [0070]      FIG. 5   b : a block diagram of a fourth exemplary embodiment of an electronic device according to the present invention; 
           [0071]      FIG. 6   a : a block diagram of a fifth exemplary embodiment of an electronic device according to the present invention; 
           [0072]      FIG. 6   b : a block diagram of a sixth exemplary embodiment of an electronic device according to the present invention; 
           [0073]      FIG. 7   a : a flowchart of a third exemplary embodiment of a method according to the present invention; 
           [0074]      FIG. 7   b : a flowchart of a fourth exemplary embodiment of a method according to the present invention; 
           [0075]      FIG. 8 . an exemplary state diagram for an exemplary embodiment of an electronic device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0076]      FIG. 1  depicts a block diagram of a first exemplary embodiment of a first electronic device  100  according to the present invention. The first device  100  comprises a serial interface  110 , wherein said serial interface  110  comprises at least one data line  112 ,  113  and one identification pin  114 . Furthermore, said serial interface may comprise a power supply line  111 , and a ground line  115 . The serial interface  110  of the first electronic  100  depicted in  FIG. 1  is only an exemplary serial interface  100 , e.g. said serial interface  100  may only comprise one data line or more than two data lines, and it is not restricted to an USB interface. 
         [0077]    Thus, any kind of serial interfaces  110  comprising at least one data line and at least one ID line may be used for the serial interface  110  depicted  FIG. 1 . The same holds for the following exemplary embodiments. 
         [0078]    The ID pin  114  of said serial interface is used to allow a communication with a compatible second electronic device (not shown in  FIG. 1 ) in case this second electronic device is connected to the first electronic device  100  via said serial interface  110 . Compatible according to the invention means, that the second device is configured to communicate via the ID pin  114  of the serial interface  110  of said first electronic device  100 . 
         [0079]    Said communication may comprise a transmission from said second electronic device to said first electronic device  100  via said ID pin  114  and/or it may comprise a transmission from said first electronic device  100  to said second electronic device via said ID pin  114 . Said transmission may be any kind of transmission, e.g. like digital data transmission, or transmission of an analog signal, or a combination of both. For instance, said transmission may be used for signaling, or for transmitting an analog signal, e.g. an audio signal, or for transmitting digital data. 
         [0080]    For instance, the first electronic device  100  may contain a signal unit  120  connected to the ID pin of the serial interface  110  and configured to perform the communication via the ID pin  114 . 
         [0081]    Thus, the present invention allows to use the ID-pin of the first serial interface  110  for data communication to a compatible second electronic device, which enables enhanced data communication between both devices, because besides the at least one data line  112 ,  113  of the serial interface connection a third line via the ID pin  114  may be used for communication. For instance, any suited link system may be used for this communication, wherein the signal unit  120  is adapted to perform signaling according to the link system. 
         [0082]    Furthermore, the present invention might allow signaling via the ID pin without interfering the serial interface standard, since according to a data transfer according to a serial interface standard may be performed via the at least one data line  112 ,  113 . Thus, an additional signaling can be implemented easily. 
         [0083]    For instance, said serial interface  110  may represent a first USB interface  110 , wherein said USB interface  110  may represent a Micro USB interface or a Mini USB interface or any other USB interface comprising at least five pins. Said first USB interface  110  comprises a VBus pin  111 , a D+ pin  112 , a D− pin  113 , an ID pin  114  and a GND pin  115 . Said electronic device  100  further comprises a signal unit  120  which is connected to the ID pin  114  in order to enable a communication between said electronic device and a second electronic device being connected to said first USB interface  110 . Said second electronic device may represent an electronic device being similar to that depicted in  FIG. 1 , i.e. the second electronic device may comprise a signal unit connected to the ID pin of an USB interface of said second electronic device, wherein said signal unit is configured to communicate via the ID pin to the signal unit  120  of said first electronic device. 
         [0084]    Thus, both the first electronic device  100  and the second electronic device may represent devices having USB standard/protocol compatibility, i.e. USB compliance. A compatible USB device according to the invention represents a USB device which is configured to communicate via the ID pin of an USB interface, and a non-compatible USB device according to the invention represents a USB device which is not configured to communicate via the ID pin of an USB interface. Furthermore, the first device and/or the second device may comprise an USB interface without providing USB compliance. 
         [0085]    According to the USB standard, the ID pin of a USB Micro B-plug is floating and the ID pin of a Micro A-plug is connected to ground. Thus, if said first USB interface  110  represents a USB Micro interface, then it may be a Micro Type B-plug or a USB Micro receptacle suited to be configured to a Micro Type B-plug. For instance, the first device  100  may comprise a first Micro Type B USB receptacle connected to the first USB interface  110 , or said first USB interface  100  may represent a first Micro Type B USB receptacle, or, the first USB interface  110  may be connected to cable terminated with a Micro Type B-plug. Furthermore, said first USB interface  110  may be a Mini USB interface. 
         [0086]    Thus, the present invention allows to use the ID-pin of the first USB interface for data communication to a compatible second electronic device, which enables enhanced data communication between both devices, because besides the D+ and D− lines of the USB connection a third line via the ID pin may be used for communication. For instance, any suited link system may be used for this communication, wherein the signal unit  120  is adapted to perform signaling according to the link system. For instance, said communication via the ID pin may be performed by a dual impedance Enhancement Control Interface (ECI), or by an accessory control interface. 
         [0087]    The purpose of the so called ACI is to enable identification of different accessory (types) by parameters stored as digital data within a memory of an ACI ASIC, which can be placed within the accessory or preferably the accessory connector. The ACI functionality is e.g. described in the published patent application WO03/077504. 
         [0088]    In contrast to this the ECI is rather about determining features and functionalities of a connected accessory rather then detecting the accessory itself. ECI functionality is described for example in the published patent application WO06/045617. 
         [0089]    Furthermore, the present invention may allow signaling via the ID pin without interfering the USB OTG standard, since according to the USB OTG standard data transfer is performed via the D+ and D− lines. Thus, an additional signaling can be implemented easily. 
         [0090]    For instance, the D+ and D− pins  112 ,  113  may be used according to the USB OTG standard, and without interfering the USB OTG standard, a further communication may be performed via the ID pin  114  of said first interface  114 . 
         [0091]      FIG. 3  shows a first exemplary embodiment of a method according to the present invention, wherein after serial interface a second electronic device is connected to the first electronic device  100  via the serial interface  110  (step  310 ), i.e. by connecting said second electronic device to said serial interface  110 , a communication via the ID pin  114  between the first electronic device  100  and the second electronic device is established (step  320 ). For instance, said serial interface  110  may represent a USB interface  110 , and said serial interface connection may represent a USB connection, e.g. a USB OTG connection. 
         [0092]    The explanations and advantages concerning this first exemplary embodiment of a first electronic device  100  according to the present invention also hold for the succeeding exemplary embodiments. 
         [0093]      FIG. 2  depicts a block diagram of a second exemplary embodiment of a first electronic device  200  according to the present invention. The first device  200  comprises a first serial interface  110  according to the first exemplary embodiment depicted in  FIG. 1 . 
         [0094]    For instance, in case the first serial interface  110  represents a USB interface, this first electronic device  200  may represent an USB accessory  200  that can be connected to an Mini or USB connector of a terminal, e.g. by means of a Mini or Micro USB connector, wherein said accessory  200  may receive power from a connected terminal via the power supply line VBus  111  of the USB interface  110 . For instance, said accessory may comprise a rechargeable power supply  230 , wherein said rechargeable power supply  230  is charged with said received power. 
         [0095]    Furthermore, said accessory  200  comprises a signal unit  220 , wherein this signal unit  200  enables communication via the ID pin  114  to a connected terminal, e.g. for identification of said accessory  200 . For instance, said signal unit  220  may be an ECI or an ACI unit. 
         [0096]    Further, said accessory  200  may comprise a wireless interface  240 , which may be connected via a RF unit  250  to an antenna  260 . For instance, said wireless interface may be a Bluetooth interface, or a WLAN interface or any other wireless interface suited to establish a wireless connection to said terminal. 
         [0097]    The configuration of said wireless interface  240  in order to communicate with said terminal will be explained by means of the second exemplary embodiment of a method according to the present invention depicted in  FIG. 4 : Said first electronic device  200  may be connected to a terminal by means of said serial interface  110 , thereby establishing a serial interface connection with the first electronic device (step  410 ),e.g. USB interface connection in case the serial interface  110  represents a USB interface. The first electronic device  200  enables a communication via the ID pin  114  with the connected terminal (step  420 ), and at least one information parameter is transmitted from the first electronic device  200  to the connected terminal via the ID pin in order to identify the connected first electronic device  200  (step  430 ). Based on this identification, the terminal may determine a configuration for the wireless communication between the first electronic device  200  and the terminal, and/or, the terminal may transmit a wireless configuration via the ID pin communication to the first electronic device for negotiating the configuration for the wireless interface  240  (step  440 ), and the wireless connection between the first electronic device  200  and the terminal can be established (step  450 ). The wireless connection may be started by the electronic device  200 , or by the connected terminal. 
         [0098]    Summarized, the communication via the ID pin may be used to negotiate a wireless configuration between the first electronic device  200  and a connected terminal in order to establish a short-range radio connection. This, the present invention allows any easy and simple configuration of wireless interfaces of an electronic device  200  to a terminal via the serial interface  110 , which may represent a USB interface, wherein this configuration may not affect the serial interface standard since the at least one data pin  112 ,  113 , e.g. the D+ and D− lines of an USB interface, are not used for negotiating the wireless configuration. After establishing the wireless communication, everything else like audio, or control operations may be performed via the wireless communication link. For instance, said first electronic device may be any kind of a wired Bluetooth accessory or headset, wherein the wireless connection is established automatically when connected to the terminal. 
         [0099]      FIG. 5   a  depicts a block diagram of a third exemplary embodiment of an electronic device  580 , in the sequel denoted as second electronic device  580 , according to the present invention, and  FIG. 5   b  depicts a block diagram of fourth exemplary embodiment of an electronic device  500 , in the sequel denoted as first electronic device  500 , according to the present invention. 
         [0100]    For instance, the first electronic device  500  may represent a terminal, e.g. a PC or a mobile phone or a handheld or anything else, wherein said terminal  500  comprises a serial interface  510 , e.g. a Micro or Mini USB interface  510 , and wherein said USB interface  510  may represent a Mini or Micro Type B USB receptacle/plug. In the sequel, this serial interface  510  will be exemplarily assumed to represent a USB interface, but the following embodiments are not restricted to USB interfaces exclusively. 
         [0101]    Furthermore, said terminal  500  comprises an signal unit  520 , wherein said signal unit  520  may be configured to connect the terminal to a headset. For instance, said signal unit may represent an audio unit  520  or a video unit  520  or any other unit suited for enabling analog signal transmission and/or receiving. The D+ pin  512 , the D− pin  513  and the ID pin  514  of said USB interface may be used for transmitting/receiving analogue signals, for instance audio signals or video signals. E.g. in case of an audio transmission, said signal unit  520  represents an audio unit  520 , and in case of stereo audio transmission the audio unit  520  may transmit the right channel to a right speaker of a headset via the D+ pin  512  and may transmit the left channel to a left speaker of a headset via the D− pin  513 , or vice versa, and the audio unit may receive a microphone signal of said headset via the ID pin  514 . The association of the D+ pin  512 , the D− pin  513  and the ID pin  514  to right/left speaker channel and microphone line is not limited and not restricted to the given example depicted in  FIGS. 5  an  6 . In case of a mono transmission, e.g. if a mono headset is connected to the terminal  500 , then the audio unit  520  may be connect to one or both of D+ pin  512  and D− pin  513 . Thus, at least one of the at least one data line  512 ,  513  can be used for transmitting an analog signal. 
         [0102]    Furthermore, the second electronic device  580  may represent a headset configured to communicate to said first electronic device  500 , or an adaptor  580  configured to connect a headset to the serial interface  510  of said first electronic device  500 , wherein the second device  580  comprises a cable  585  and a serial interface  590 . For instance, this serial interface  590  may represent a USB interface, wherein the assignment of the D+ pin  592 , the D− pin  593 , and the ID pin  594  of the USB interface of said second electronic device  580  may correspond to the assignment of the corresponding pins of the USB interface of the first electronic device  500 . The second electronic device may comprise a Micro or Mini USB cable  585  terminated with an USB interface  590  in order to connect to the terminal  500 . For instance, said USB interface  590  may represent a Mini or Micro USB Type B plug/receptacle. 
         [0103]    Thus, according to the present invention, a headset  580  or a headset USB adapter  580  comprising a cable  585  and a USB interface  590  may be connected to a terminal  500  via a single USB connection, so that only one connector is necessary, and a second connector, such as a 2.5 mm jack, is not needed. Hence, the invention may solve the size, cost and industrial design problem of devices that employ analogue audio headset and USB features, for instance USB OTG features or other non-OTG USB features. The invention eliminates the need for a headset jack (HJ), e.g. a 2.5 mm or 3.5 mm connection, thus reducing cost and improving the industrial design by eliminating the surface blemish of a HJ. 
         [0104]    Further, for instance, it may be designed that when a headset  580 , or a headset USB micro/mini adapter  580 , is connected by its cable  585  and its USB connector  590  to the terminal  500  it physically blocks the connection of any other USB cable (not shown in  FIGS. 5   a  and  5   b ), and when a USB cable of another USB device is connected, it blocks the connection of the headset  580  or the headset USB micro/mini adapter  580 . 
         [0105]    Thus, according the present invention, providing a stereo sound to a headset while simultaneously receiving a microphone signal is possible by means of a single USB micro/mini connection. 
         [0106]    The explanations and advantages concerning this third and fourth exemplary embodiment of an electronic device according to the present invention also hold for the succeeding exemplary embodiments depicted in  FIGS. 6   a  and  6   b , respectively. 
         [0107]      FIG. 6   a  depicts a block diagram of a fifth exemplary embodiment of an electronic device  680 , in the sequel denoted as second electronic device  680 , according to the present invention, wherein said second electronic device  680  may basically correspond to the second electronic device  580  depicted in  FIG. 5   a  and may for instance represent a headset  680  or a headset adapter  680  comprising a serial interface  590 , for instance a headset  680  or a headset USB adapter  680 . This headset  680  or headset USB adapter  680  may further comprise a hook unit  682 , which may be connected to a hook button (not shown) via signal line  683 . The function of this hook button will be explained in the sequel. Furthermore, also a headset or a headset USB adapter as exemplarily depicted in  FIG. 5   a  without a hook function may be connected to the electronic device  600  depicted in  FIG. 6   b.    
         [0108]      FIG. 6   b  depicts a block diagram of a sixth exemplary embodiment of an electronic device  600 , in the sequel denoted as first electronic device  600 , according to the present invention, wherein said first electronic device  600  may basically correspond to the first electronic device  500  depicted in  FIG. 5   b  and may represent any kind of terminal, e.g. a mobile phone or a handheld or a PC or anything else. Said terminal  600  may comprise a USB interface  610 , a USB transceiver  640  being adapted to be connected to the D+ pin  612 , the D− pin  613  and the VBus pin  611  of said USB interface  610 . The terminal further comprises a controller  625 , which is configured to control said USB OTG transceiver  640 , an audio codec  630  and a detection block  620 . Said audio codec may basically correspond to the audio unit  520  depicted in  FIG. 5   b  in is configured to communicate via a headset  680  or a headset USB micro/mini adaptor  680  via the ID pin  614  and the D+ pin  612  and the D− pin  613 . 
         [0109]    The USB transceiver  640  may support USB device detection and data transmission, and the audio codec  630  and the audio unit  520  may process analog and digital audio signals and route audio in and out. The detection block may detect the voltage level in ID pin  614  and communicates this voltage level to the controller. The optional USB filter may compensates the D+/D− waveforms and protects the audio pins, and the optional EMC filter  650  may protect the microphone line for RF immunity. 
         [0110]    Details of the function of this terminal  600  will now be explained with respect to the flowchart of a third exemplary embodiment of a method according to the present invention depicted in  FIG. 7   a , and with respect to the flowchart of a fourth exemplary embodiment of a method according to the present invention shown in  FIG. 7   b , and with respect to an exemplary state diagram for an exemplary embodiment of an electronic device according to the present invention depicted in  FIG. 8 . 
         [0111]    In case that no USB cable is connected to the USB interface  610  and after switching on the power of the terminal  600 , the terminal  600  may be in an USB idle mode  810  waiting for the connection of device the USB interface  610  (step  710 ). 
         [0112]    If a USB cable is connected to the USB interface  610 , the connected USB device may be detected by the USB transceiver  640  (step  710 ) and the controller  640  is informed. Then, it may be determined whether said connected USB device is a compatible device or not (step  720 ), wherein a compatible device according to the present invention may represent a device being configured to communicate to the terminal  600  via the ID pin  614  of the USB interface  610 , like a headset  680  or headset USB adaptor  680  depicted in  FIG. 6   a . Said detection may be performed by the detection block  620 , wherein a connected device may be determined to be compatible if the detected voltage at the ID pin  614  is between a first voltage threshold VT 1  and a second voltage threshold VT 2 , wherein VT 1 &lt;VT 2  may hold, or for instance by detecting whether the voltage at the ID pin  614  is below the highest value out of VT 1  and VT 2 . Thus, a compatible device may indicate itself by setting the voltage of the USB ID pin to a value into a range between VT 1  and VT 2 , or to a value being below VT 2 . 
         [0113]    For instance, the voltage of the microphone line of a headset  680  or a headset USB adaptor  680  is fixed in a narrow range during operation due to the voltage drop across the microphone when it is biased by a power supply, so that this microphone voltage on the microphone line can be detected by the detection block  620  in case the microphone line of the headset  680  or headset USB adapter  680  is wired to the ID pin  694  of the USB plug  690  and connected to the ID pin  614  of the terminal  600 , wherein VT 1  and VT 2  is chosen that the microphone voltage is between VT 1  and VT 2 . Thus, the headset  680  or the headset USB adapter  680  automatically communicates an information signal via the ID pin  694  well-suited for identification at the terminal  600 . 
         [0114]    If the detection block  620  detects that a compatible USB device is connected to the USB interface  610 , e.g. a headset  680  or headset USB adapter  680  as depicted in  FIG. 6   a , then the terminal  600  may be switched into a second state (step  730 ), wherein in this second state the controller  625  enables the audio codec  630  and enables the audio lines to D+ and D− pins  612 ,  613  of the USB interface  610 . Before enabling the audio codec  630 , the USB transceiver may be switched into three-state logic state or may be switched off by the controller in order to prevent any loading interference between the USB D+/D− lines and the audio lines. This second state of said terminal  600  corresponds to the audio mode  820  depicted in  FIG. 8 , and in this second state the terminal  600  communicates with the headset  680  or headset USB adapter  680  via the ID pin  614  by means of receiving a microphone signal. 
         [0115]    If the detection block  620  detects that a non-compatible USB device is connected to the USB interface  610 , i.e. a common USB device not being suited to communicate via the ID pin, then said terminal  600  is switched into a first state (step  740 ), wherein in this first state the controller enables USB data transmission of said USB transceiver  640 . This detection may be performed by detecting a voltage at the ID pin  614  being higher than VT 2 . Before enabling USB data transmission, the audio codec is switched off or switched in to three-state logic state in order to prevent any loading interference. This first state of said terminal  600  corresponds to the USB mode  840  depicted in  FIG. 8 . 
         [0116]    For instance, the switching into the first and the second state may be performed by a mechanical switch, a hardware controlled switch, or a software controlled switch. 
         [0117]    If the connected USB micro/mini device is disconnected (step  750 ), then the terminal switches into the idle mode  815  and returns to step  710 . 
         [0118]    Furthermore, the headset  680  or the headset USB adapter  680  may be configured to be switched into one out of two states, wherein a first state corresponds to a normal audio mode suited to connect the speakers and the microphone to the terminal as mentioned above in the first state of said terminal, and wherein a second state corresponds to a hook mode suited for performing control operation, e.g. stopping playing music in a music player or changing the radio channel or answer or and a call in a mobile phone. The headset  680  or the headset USB OTG adapter  680  may comprise a hook unit  682  for signaling the second state, e.g. in response that a user presses a hook button or in response to another hardware or software control via the line  683 . For instance, said hook unit  682  switches the voltage on the microphone line to a voltage value being below VT 1  in case that the headset USB adapter  680  or the headset  680  is switched into the second state, e.g. by connecting the microphone line to GND. 
         [0119]    This way, the hook mode can be detected by the detection unit  620  in case that the voltage at the ID pin  615  falls below VT 1 , and in this case the terminal  600  goes into a third state which corresponds to an audio hook mode  830  depicted in  FIG. 8 , wherein the controller  625  may perform related operations. 
         [0120]    As depicted exemplarily in  FIG. 7   b , wherein the flowchart of  FIG. 7   b  may be inserted into the flowchart depicted in  FIG. 7   a  at the points of intersection  715  and  755 , respectively, at step  720  the detection unit  620  may first determine whether the connected device is a compatible device based on the voltage level at the ID pin  614 , wherein in case the detected voltage level at the ID pin  614  is higher than VT 2  the method switches to step  740  (not shown in  FIG. 7   b ) depicted in  FIG. 7   a  and the terminal is switched in to the first state, and otherwise it is checked whether the compatible device is in the first state (step  721 ), i.e. if the voltage level at the ID pin  614  is between VT 1  and VT 2 . If this is the case, then the terminal  600  is switched into the second state (step  722 ) as mentioned above, and thus the audio mode  820  according to  FIG. 8  is enabled. If the detected voltage level is below VT 1 , then the compatible device is not in the first state, e.g. it is switched into the hook mode, and the terminal  600  is switched into said third state (step  723 ). 
         [0121]    At steps  724  and  725 , it is checked whether the headset  680  or the headset USB adapter  680  is switched from the second into the first state or vice versa, and if this is the case, the method jumps to steps  723  and  722 , respectively, in order to change the state of the terminal. If it is detected that the headset  680  or the headset USB adapter  680  is disconnected (steps  726 ,  727 ), then the method jumps to step  710  depicted in  FIG. 7   a  corresponding to the USB idle mode  810  depicted in  FIG. 8 . 
         [0122]    The state machine depicted in  FIG. 8  may be implemented in the controller  620 . 
         [0123]    The steps  720  and  721  depicted in  FIG. 7   b  may be performed in a single stage, wherein the detection unit  620  detects the voltage VD of the ID pin  614  and switches to step  723  in case that the VD&lt;VT 1 , and switches to step  722  in case that VT 1 &lt;=VD&lt;VT 2 , and switches to step  740  (depicted in  FIG. 7   a ) in case the VD&gt;=VT 2 . 
         [0124]    Thus, the present invention allows a connection of an audio/video device to a terminal via a serial interface, e.g. a USB interface, for analog signal transmission, wherein after disconnecting the audio/video device the serial interface can be used according to the serial interface standard. 
         [0125]    The invention has been described above by means of exemplary embodiments. It should be noted that there are alternative ways and variations which are obvious to a skilled person in the art and can be implemented without deviating from the scope and spirit of the appended claims. 
         [0126]    Even as this document takes the USB interface as an example for describing a variety of embodiments of the invention it should be noted that the invention can be implemented with any serial interface which uses data and ID lines in a similar way as provided in the USB (USB OTG, Mini and Micro USB, with and without On-The-Go capability) standard.