Abstract:
A device for connecting a user station to a CAN bus, the user station in the active state being able to exchange messages with other user stations via the CAN bus using the device, according to the standard ISO 11898; the user station in the at-rest state being able to be activated using the device, in response to the reception of a wake-up information; the wake-up information configured as a CAN message according to the standard ISO 11898; in the device, a suitable first arrangement selectively evaluating the wake-up information received, so that the wake-up process is initiated only in response to the presence of wake-up information that is specified or specifiable for the respective user station which is characterized in that a storage arrangement is provided in the device in order, in case the wake-up process is initiated, which store the wake-up information evaluated for this entirely or partially.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is based on a method and a device for waking users of a CAN bus system. 
         [0002]    BACKGROUND INFORMATION 
         [0003]    For example, thee ISO standard family 11898-1 through -5 describes the Controller Area Network (CAN) as well as an extension of the CAN designated as “time-triggered CAN” (TTCAN). The media access control method used in the CAN is based on a bit-wise arbitration. The user stations are simultaneously able to begin transmitting a message over the bus. The messages sent have an identification which is transmitted after a single “start of frame” bit. In the bit-wise arbitration, while sending the bits belonging to the identification, are simultaneously able to ascertain the logical state (0 or 1) of the bus. If the value of a bit sent by a first user station does not correspond to the ascertained logical state of the bus, another user station has obviously sent a message having a higher priority, and the first user station therefore ends its send access to the bus. The bit-wise arbitration thus achieves a non-destructive transmission of that message via the bus that wins the arbitration process. 
         [0004]    With the increasing electronization of modern vehicles, and the advent of additional systems for the improvement of driving safety, for example, or driver convenience, the requirements with respect to the consumption of electric power are growing constantly. At the same time, the necessity exists of limiting the power usage, in order to take into account ecological and legal requirements. Even against the background of the increased introduction of electrically driven vehicles, it is indicated that power usage by control and regulating systems and safety and convenience systems should be kept within limits, since the electric power used has a direct effect on the vehicle&#39;s distance range. 
         [0005]    For that reason, it is provided in new vehicles that one should put individual bus users or groups of bus users completely or partially at rest if the function exerted by them or the respective subfunctionality is not required. Along with that comes the requirement to wake up again or to activate bus users that are at rest, wholly or partially, when the function or the subfunctionality that is at rest is required again. 
         [0006]    In this connection, German Patent Application DE 103 58 584 A1 discusses a device and a method for selectively waking up users of a bus system, in which a detecting arrangement, particularly a counter, is provided which detects at least one predefined signal property of the signals transmitted on the bus system and initiates the further wake-up procedure once a specifiable number has been reached. 
         [0007]    Patent Application DE 102 25 578 A1 discusses a method and a device for the selective activation of bus users, which is distinguished by providing a separate voltage regulator for the protocol controller present in the bus user. Because of that, when bus communication takes place, the protocol controller may first be awakened without the associated application controller, the former then being available for comparing the messages present on the bus to one or more previously stored reference messages. If there is agreement, the application controller and with that, the entire bus user is awakened. 
         [0008]    In the devices from the related art, after the waking process has taken place, the information as to by which signal or which message the waking process was triggered, is no longer present. This may be of disadvantage, particularly if different messages are supposed to lead to different properties of the awakened bus users. For example, if different waking messages for waking different subfunctionalities are to be drawn upon, the related art then does not supply satisfying results in every respect, since after the waking process has taken place, no information is available on the content of the message that has led to the waking up. If it were present, this information could be used to adjust the waking process depending on the reason for the waking, that is, depending on the requested functionality. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is therefore based on an object of providing a possibility, after a wake-up process has taken place, of continuing to provide the content of the successful wake-up information. This object is attained by the device and the associated method according to the independent claims. 
         [0010]    In the following, the present invention and its advantages will be described with reference to drawings and exemplary embodiments. Advantageous developments are described by the dependent claims. The subject matter of the present invention is not limited to the represented and described exemplary embodiments. 
         [0011]    In one advantageous application case, the door control device in a motor vehicle could contribute a subfunction to various vehicle functionalities, such as to the functionality of central locking of the operation of the door lock, for certain safety functionalities an automatic locking of the window, or, for convenience functionalities, a certain rearview mirror adjustment, such as automatically folding it away. Different ones of these functionalities are activated depending on the current status of the vehicle. The central locking could be turned off, for example, above a certain limit speed, or a safety functionality could first be activated above a speed threshold. A convenience functionality, such as the folding away of the rearview mirror could be made executable only at a standstill. Accordingly, depending on the vehicle state, different subfunctions or contributions of the door control device are required, and under suitable circumstances, the door control device may be put completely into an at-rest state. When waking up the door control device, it is meaningful to be able to activate subfunctions separately. For this purpose, it is advantageous if the information is present at the door control device as to by which wake-up message or for which functionality the waking process was carried out. 
         [0012]    A further example is parking systems whose functionalities have to be provided in different ways, as a function of the vehicle state. For example, the sensors and the evaluation unit are usually completely activated when shifting into reverse takes place. In normal driving operation, on the other hand, the sensors are possibly not needed at all or only partly, depending on the speed, perhaps for measuring a parking space or for monitoring the blind spot, and the evaluation control unit has to carry out deviating or restricted functionalities. Here too, it may therefore be useful to be able to activate subfunctions of the parking system separately, starting from the at-rest state. Again, for this purpose, it is advantageous if the information is present at the parking control device as to by which wake-up message or for which functionality the waking process was carried out. 
         [0013]    Additional advantageous possibilities of use of the device, according to the present invention, in the vehicle are also conceivable. 
         [0014]    Starting from a method and a device for waking up users of a CAN bus system from the related art, in which a suitable first arrangement is provided for selectively evaluating the wake-up information received, and in which the wake-up process is initiated only if the wake-up information that is specified or specifiable for the respective user station is present, it is advantageous in the case of the device, according to the present invention, that a storage arrangement is provided so that, in the case in which the wake-up process is initiated, the wake-up information evaluated for this may be stored. 
         [0015]    It is also of advantage that, in the device, a suitable further arrangement is provided so that, as a function of the stored wake-up information, different subfunctionalities of the user station and/or different application controllers and/or different operating modes of the at least one application controller are activated. 
         [0016]    These additional arrangement(s) may be configured so that at least one application controller of the user station has provided to it reading access to the stored wake-up information. Thereby one may achieve rapid availability of the wake-up information to the application controller. In another specific embodiment, the additional arrangement(s) may also be configured so that the stored wake-up information is supplied to the communication controller. Thereby the wake-up information reaches that application controller delayed in time, as a normal bus message, which reduces the expenditure for establishing the method in the application controller. 
         [0017]    In the case mentioned last, the further arrangement includes at least one coder for converting the stored wake-up information to a serial input signal for the communication controller. A changeover switch for changing over the input signal for the communication controller between the signal present on the bus and the serial signal generated by the coder is of advantage, in order to avoid collisions between incoming bus signals and the wake-up information provided by the coder at the input to the communication controller. 
         [0018]    The first arrangement that is provided selectively to evaluate the wake-up information received, advantageously include a decoder which enters the serial message in a receiving storage area, the receiving storage area, a filter storage unit and a comparator unit. In this way, a rapid and reliable comparison is made possible of the message received with the entries of the filter storage unit. 
         [0019]    The present invention will now be described in greater detail on the basis of the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  schematically shows a bus system having bus users, who have the device according to the present invention. 
           [0021]      FIG. 2  shows a simplified block diagram of a device according to the present invention. 
           [0022]      FIG. 3  shows a second exemplary embodiment of the wake-up message memory, which is an essential element of the present invention. 
           [0023]      FIG. 4  shows a second exemplary embodiment of the wake-up message memory, which is an essential element of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  shows a bus system  100  having four bus users  110 ,  120 ,  130 ,  140 . Each bus user has a device  111 ,  121 ,  131 ,  141 , by which he is connected to the bus line. The device is connected to a communication controller, designated by  112 ,  122 ,  132 ,  142 . In addition, the various bus users have application controllers that are designated by  113 ,  123 ,  124 ,  134 , and  145 . The application controllers are configured, in this example, to carry out one or more functions, and belong to one or more subnetworks. In this connection, each subnetwork is used to provide a certain functionality in the vehicle assembly. 
         [0025]    Application controller  113  and  123 , in the example shown here, together supply functionality A, application controllers  124  and  134  together supply functionality B and application controller  145  supplies alternatively function C or D. In another specific embodiment, an application controller could naturally also contribute to a plurality of functionalities. 
         [0026]    The advantage of the present invention may be illustrated using bus user  120  as an example. If it is assumed that, under certain circumstances, functionalities A and B would not be needed, the bus user may be switched off in these driving situations or put in an at-rest state, since he is not needed. Now, if a situation occurs in which functionality A is required, one of the active users, for instance, user  110 , sends out a wake-up message. Bus user  120  is in an at-rest state. His bus-connecting unit  121 , which represents the device according to the present invention, observes in the at-rest state the message traffic on the bus. It analyzes the wake-up message received and determines that a wake-up message relevant to bus user  120  is involved. Accordingly, it activates communication controller  122  and one or more application controllers. Moreover, it provides the content of the wake-up message received in a memory area provided for this. Because the wake-up information is available in the bus user, selectively only application controller  123 , which is required for carrying out functionality A, is able to be awakened, while application controller  124  remains in the at-rest state. 
         [0027]    A further possibility of using the device according to the present invention may be shown on the example of bus user  140 : as was shown before, application controller  145  is able to carry out alternatively functionality C or D. Starting from a situation in which neither of the two functionalities is required, bus user  140  is in an at-rest state. Now, if a situation arises in which functionality C is required, a bus user sends out a corresponding wake-up message, which is evaluated by device  141  in bus user  140  according to the present invention, and is stored in a suitable memory area, according to the present invention. Application controller  145  is started and is now able to evaluate or read in the wake-up information stored, and take up associated functionality C. If functionality D is requested, a deviating wake-up message is sent out and stored according to the present invention. Application controller  145  evaluates stored wake-up information or it is supplied to it by device  141 , according to the present invention, and as result it takes over deviating functionality D. 
         [0028]      FIG. 2  represents a simplified block diagram of an exemplary embodiment of device  121  of the present invention. It includes as core part a control unit  210 , which includes wake-up unit  220 . Control unit  210  is connected to three interface units  230 ,  240  and  250 , these, in the present example, each representing interfaces to an application controller, to a communication controller and to a voltage regulator. The associated terminals are designated, for example, by SPI, TxD, RxD and INH. One or more of these interface units may also be provided several times in other specific embodiments if, for example, a plurality of application controllers are in connection with control unit  210  or wake-up unit  220 . Furthermore, control unit  210  is connected to reception unit  260 , as well as to sending unit  270 . These, in turn, are connected to the bus lines of bus system  100 . Finally, the control unit still has one local wake-up terminal designated as LWU. 
         [0029]    In normal operating mode, device  121  receives bus signals via reception unit  260  and passes these on via interface unit  240  and line RxD serially to the communication controller. In the sending case, the device receives on line RxD serial signals from the communication controller and transmits these via sending unit  270  to the bus lines. In the at-rest state of the bus user, for example, only reception unit  260  and control unit  210  are active with wake-up unit  220 . Waking up the bus user is possible by various waking signals: the bus user may be activated, for instance, by the local waking terminal. Waking up by a bus message is of interest for the present invention. If a message is received in the at-rest state, it is passed on via reception unit  260  to wake-up unit  220 , is decoded there and stored, in its entirety or partially, and is compared to one or more specified wake-up messages. In the case of agreement, the bus user is awakened through interface unit  250  and the INH terminal, which is in connection with a suitable arrangement, such as a voltage regulator. 
         [0030]    Because the wake-up information has been stored and is available to the bus user, the wake-up process may be made a function of the content of the wake-up information. Thus, different application controllers may be activated as a function of the wake-up information, for example, or different functions may be carried out by the application controller. This may possibly be implemented in that, via interface unit  250 , two voltage regulators are actuated which wake up two application controllers by supplying them with voltage. Alternatively, two interface units may also be provided for this. Each of the application controllers, during the wake-up process or after its end, scans the content of the memory area which includes the wake-up information. 
         [0031]    If different application controllers are to be activated as a function of the wake-up information, in the case of agreement, the active state is maintained, while in the case of non-agreement the respective application controller takes on an at-rest state again, by outputting, for instance, a command for reducing the supply voltage via a suitable interface to the appropriate voltage regulator. If different functions are to be activated as a function of the wake-up information on the application controller(s), as a contribution to certain vehicle functionalities, the active state of all application controllers is maintained, but different programs are executed by the one or the plurality of application controllers as a function of the content of the storage area that includes the wake-up information. 
         [0032]      FIG. 3  shows an exemplary embodiment for the schematic configuration of wake-up unit  220 , which includes an arrangement for the storage, according to the present invention, of the wake-up information. The wake-up message received serially by reception unit  260  is decoded in a decoding unit  340  provided for this, and is filed in reception storage area  330 . One might also want to file only parts of the wake-up message, to the extent that these parts include the components required for the evaluation and restoration of the wake-up information. Filter storage area  310  includes filtering data which include, for example, the possible specifiable wake-up messages or the relevant components. In comparator unit  320  arranged for this, the message received in reception storage area  330  is compared to the filtering data from filter storage area  310 . When the result is positive, that is, when the message received is one of the specified wake-up messages, the wake-up process takes place on the one hand, for example, the activation of the voltage regulator via interface  250 . On the other hand, the wake-up message recognized as valid, that is present entirely or partially in reception storage area  330 , is transmitted into wake-up information storage area  350  that is provided for this purpose. In the embodiment variant shown, the application controller has direct access to wake-up information memory area  350  via interface  230 . Thus, the wake-up information is able to be read out and evaluated by the application controller. In this way, the application controller gets information on the wake-up information that has led to a wake-up, and is able to perform corresponding reactions, for instance, activate established subfunctions and/or wake up other application controllers and/or take up again an at-rest state itself. 
         [0033]    By contrast, the reading out of reception storage area  330  by the application controller, in order to obtain information on wake-up information that has led to a waking-up has the disadvantage that reception storage area  330  is able to be overwritten by subsequently received messages that represent no wake-up messages relevant to the bus user. By the transfer of the wake-up information to wake-up information storage area  350  after successful checking by comparator unit  320 , in contrast to this, the advantageous effect is achieved that the message, which has led to the wake-up of the bus user, is still available to the application controller, even after the arrival of further messages. 
         [0034]      FIG. 4  represents a further exemplary embodiment for the schematic configuration of wake-up unit  220 . In this case, no direct access takes place of the application controller to wake-up information storage area  350  via interface  230 , but the wake-up information stored there is serialized again by a coding unit  360  arranged for this, and is transmitted serially via changeover switch  370  and interface unit  240  to the communication controller, or rather its RxD input. The communication controller, or rather its RxD input passes on the information included, processed as usual, to the application controller. Thus, in this case, the application controller receives the wake-up information stored in wake-up information storage area  350 , after the wake-up process has taken place, in a delayed manner, as a usual message via the communication controller, whereby the additional expenditure for arranging the direct access of the application controller to wake-up information storage area  350 , which is necessary in the exemplary embodiment of  FIG. 3 , is able to be omitted. In return for that, in the example in  FIG. 3 , the wake-up information is, as a rule, more quickly available to the application controller than is the case in the exemplary embodiment of  FIG. 4 . With this as background, the two possibilities should be weighed against each other.