Abstract:
Electronic device comprising audio/video functionalities including: —a central processing unit ( 100 ) comprising means of storage of audio/video files; —a Bluetooth communication controller ( 200 ) allowing the wireless communication of audio/video files towards a satellite ( 20 ), said communication controller comprising a buffer ( 210 ) ensuring the provisional storage of audio/video data received by the central processing unit; characterized in that it comprises —means for transmitting a packets burst of audio/video data towards said communication controller; —means for ensuring an intermittent deactivation of said central processing unit between two bursts of audio packets in order to reduce the electricity consumption of said central processing unit.

Description:
TECHNICAL FIELD 
     The present invention relates to the field of electronic circuits and more specifically to a process of audio data exchange between a central processing unit and a wireless communication Bluetooth controller. 
     BACKGROUND ART 
     Wireless communication tend to be generalized in the apparatuses forming part of our everyday life, and these are in particular the apparatuses and devices designed for the public. 
     In this respect, the wireless communication protocol known as BLUETOOTH is particularly illustrative and its use has been grown quickly. 
     An essential quality of an audio reader, such as an mp3 reader for example, lies in the operation life of its battery. The high number of necessary functionalities required in the most recent devices, in which, one multiplies at will the applications such as the mobile telephony, the electronic agendas and organizers and the color screens, obviously results in reducing the lifespan of the battery, which reduction is a major problem. 
     It is thus desirable to envisage solutions permitting to reduce the electricity consumption of a sophisticated audio reader using a wireless bluetooth connection, as much as possible. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to propose an exchange process between a central processing unit and a bluetooth controller ensuring the possibility of a constant reading of audio files (streaming) while allowing a succession of idle and operation periods of the central processing unit in order to reduce electricity consumption. 
     Another object of this invention consists in proposing a process allowing the to communication of a continuous audio stream (streaming) towards a wireless audio headset according to Bluetooth technology, since a bluetooth communication controller, intermittently communicating with a central processing unit, alternating between idle phases and operation phases. 
     A third object of the present invention consists in producing a mobile phone or a Personal Document Assistant equipped with audio functionalities and exchanging with an audio headset according to a wireless technology, and allowing a longer battery lifespan. 
     These objects are achieved by the invention, by means of an electronic device comprising audio/video functionalities including:
         a central processing unit having means of storage of audio/video files;   a Bluetooth communication controller allowing the wireless communication of the audio/video files towards a satellite, said communication controller comprising a buffer ensuring the provisional storage of audio/video data received by the central processing unit;       

     characterized in that it comprises
         means for generating a HCI type command transmitted to said Bluetooth communication controller, which HCI type command defines a threshold value representative of a amount of audio/video data to be received in a burst mode by the communication controller;   means for transmitting packet bursts of audio/video data towards said communication controller;   means for ensuring an intermittent standby or idle state of said central processing unit between two audio packet bursts in order to reduce the electricity consumption of said central processing unit.       

     In an embodiment, the central processing unit comprises means for transmitting a A2DP_enable request to the controller, defining a threshold value (T 1 ) for the buffer, before transmitting a packets burst of audio/video files. 
     Preferably, the communication controller answers to said request defining the threshold value (T 1 ) by a command specifying the number N of packets being able to be received and stored in said buffer. 
     In an embodiment, the central processing unit proceeds to the successive transmission of N packets before its setting in idle state during a predetermined period. 
     The invention is particularly adapted to the production of a mobile phone comprising audio/video functionalities. 
     The invention also allows the achievement of a process of data exchange between a central processing unit comprising means of storage of audio/video files and a Bluetooth communication controller allowing the wireless communication of audio/video files towards a satellite, such as a wireless headset for example, said communication controller comprising a buffer ( 210 ) ensuring the provisional storage of audio/video data received by the central processing unit. 
     The process comprises the following steps:
         transmission by the central processing unit of a command corresponding to a burst reading mode, comprising a threshold value (T 1 );   reception by the central processing unit of a confirmation coming from the communication controller in order to specify the number of packets which can be received during each burst;   transmission of a packets burst of audio/video data by the central processing unit towards said communication controller,   setting in idle mode the central processing unit during a determined duration corresponding to the number N of packets which can be stored in the buffer;   reactivation of the central processing unit beyond said idle duration and retransmission of a new packets burst of audio/video data.       

     In a particular embodiment, the controller transmits a UART_WAKE request when the level of filling said buffer passes below said threshold value (T 1 ). 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Other characteristics, objects and advantages of the invention will appear by the reading of the description and the drawings hereafter, given only as non limitative examples. On the annexed drawings: 
         FIG. 1  illustrates the general architecture of a device used to implement the process of  FIG. 2 . 
         FIG. 2  illustrates the details of the flow control between the central processing unit and the bluetooth controller, as well as the management of the buffers. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  describes the general architecture of an electronic device comprising audio functionalities, such as an MPEG audio reader (mp3), being able to advantageously use the process according to the invention. 
     The invention is particularly adapted to the production of a last generation mobile phone comprising wide audio functionalities allowing the transmission of audio stream on coder-decoders (Codec) or on a wireless headset corresponding to to the Bluetooth standard. 
     According to  FIG. 1 , one observes a device  10  which comprises a central processing unit or host  100 , for example a baseband module in the case of a telephone, comprising functionalities of files storage, such as mp3 files, and a user interface allowing the selection of files and the activation of functions by the user. A person skilled in the art will understand immediately that the architecture is also applicable to any Personal Document Assistant (PDA) or portable data processing device. 
     Typically, the central processing unit is structured around an appropriate processor  110 , communicating via an address and data bus  101  with one or a plurality of input/output units  120 , like with Read Access Memory  130  and storage memory  140 , such as ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory or FLASH etc. . . . ). Generally, the storage memory is used for storage of the users files, in particular the audio files of mp3 format, but it is also used for the storage of microprograms instructions in particular for implementing the advanced functionalities of the device  10 . In the case of a mobile phone, the central processing unit  100  further comprises the reception and transmission circuits likely to allow a wireless communication in accordance with a given standard. 
     In addition, the portable device  10  comprises a bluetooth controller  200  intended to manage a wireless communication according to the Bluetooth protocol and in particular for an audio data transmission with a distant satellite  20 , such that of a wireless headset for example. The audio data received in continuous stream (streaming) is encapsulated, as it is known, in a A2DP (Advanced Audio Distribution Profile). 
     The Bluetooth controller  20  comprises its own processor (not represented) and its accessory circuits allowing the transfer of audio data in continuous mode (streaming) with the satellite unit  30  or the wireless headset, as well as with a buffer  210  (FIFO). 
     The communication between the central processing unit (host)  100  and the bluetooth communication controller is performed by means of a UART (Universal Asynchronous Receiver Transmitter) standard interface. 
     The problem results from the fact that, when all the circuits of the central processing unit  100  are active, the latter consume a high level of current thus reducing the battery life. 
     In order to reduce the current consumption, one envisages to modify the Bluetooth communication controller  200  so as to incorporate in the latter the management software layer of A2DP profile which is, usually and according to normative recommendations, integrated into the level of the central processing unit  100 . 
     Thus, the controller  200  becomes autonomous and can only manage communication of an audio data stream (streaming) towards the satellite  20 . 
     Generally, the A2DP profile is well-known to a man skilled in the art and will not be further detailed. 
     The delocalization in the Bluetooth controller  200  is based on the API definition allowing the initialization and the configuration of the A2DP profile normally carried out in the central processing unit (host). 
     One describes now, in relation to  FIG. 2 , a communication process between the central processing unit  100  and the bluetooth communication controller  200  allowing an intermittent deactivation of the central processing unit while ensuring, in particular, a constant communication (streaming) of audio data towards the satellite  20 . One particularly describes the flow control mechanism between the central processing unit  100  and the controller  200 . 
     In a step 1, the central processing unit is configured in a “A2DP burst” mode and defines a variable of threshold T 1 . 
     Then, in a step 2, the central processing unit transmits a specific command HCI (Host Control Interface), comprising the value of the variable of threshold T 1 , and informing the controller  200  of the activation of the “A2DP_burst” mode. In a practical manner, this command is carried out by means of a specific code is standardized in the Bluetooth specification (0x3F). 
     Then, in a step 3, the communication controller  200  stores in its built-in memory the threshold value T 1  and is configured in a “A2DP_burst” mode in order to receive, in an intermittent way, packets or chunks of data stream. 
     In a step 4, the controller transmits a confirmation message to the central processing unit  100 , also confirming the number N of packets which can be received and stored within the buffer. Then, the controller initializes the buffer  210 . 
     In a step 5, the central processing unit transmits, in a sequential manner, the N packets (chunks) of audio data which then are successively stored within the centre of the buffer  210  of the controller  200 . 
     Then, in a step 6, the central processing unit is set in a idle mode, thus limiting the electronic consumption during one predetermined period corresponding to the time of memory dump of the buffer (FIFO)  210 . 
     On its side, the controller  200  in a step 7 detects the reception of packets received from the central processing unit, typically until the complete filling of the buffer. 
     Then, in a step 8, the controller  200  proceeds to the encapsulation of packets according to the Bluetooth protocol and to its emission with destination to satellite  20  or to the wireless headset. In addition, the controller monitors the level of filling of buffer  210 . 
     In a step 9, the controller  200  detects the decrease of the filling of the buffer  210 , and specifically the fact that the level passes under the threshold value T 1  which, as mentioned above, is predetermined and fixed by the central processing unit  100 . It proceeds to the transmission of a so-called UART_WAKE request intended for controlling the wake-up of the re-activation of the central processing unit. 
     This command, indicated as UART_WAKE, can be embodied in multiple forms according to the particular implementation for the mobile phone . . . . 
     In an example, one can be be based on the Bluetooth standard which gives the possibility of transmitting “owners” messages (i.e specifically chosen by the manufacturer) to the central processing unit in order to command its activation. One will be able to advantageously use a reserved code such as 0xFF. 
     Alternatively, according to the implementation, one will be able to hold a particular physical circuit or a particular logical channel in order to convey the specific UART_WAKE command intended to the activation of the central processing unit. 
     In a step 10, the central processing unit  100  proceeds to the exit of idle state and to the reactivation of its internal circuits. Consequently, it can confirm the appropriate reception of the UART_WAKE request. 
     Then, in a step 11, the central processing unit  100  can proceed to the reiteration of the preceding stages in order to carry out the transmission of a new data burst destined for the Bluetooth controller  200 , before a new setting in an idle state, etc. . . . 
     As it is seen, this mechanism makes it possible to carry out an uninterrupted reading of an audio stream, for example of mp3 type, while significantly reducing the electricity consumption of the central processing unit. 
     The embodiment which has just been described is perfectly adapted to the streaming reading of audio files, but also video files.