Abstract:
A device and a method are described for bidirectional single-wire data transmission of information between a control unit and at least one peripheral unit, having the following steps: generating a first current flow from the control unit to the peripheral unit during first time slots via a single-wire line to transmit voltage-coded or current-coded information from the control unit to the peripheral unit; and/or generating a second current flow from the peripheral unit to the control unit during second time slots via the single-wire line to upload voltage-coded or current-coded information from the peripheral unit to the control unit; the first and second time slots being implemented so they do not mutually overlap; and/or generating, in the first and/or second time slots, additional information to be transmitted and/or uploaded, which is transmitted as digital or analog signals by modulating the current or the voltage of the single-wire line and is analyzed in the control unit or the peripheral unit.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method and a device for bidirectional single-wire data transmission of data information between a control unit and at least one peripheral unit, the function of the single-wire line being able to be diagnosed.  
       BACKGROUND INFORMATION  
       [0002]     Although it is applicable to any arbitrary systems which include a control unit and at least one peripheral unit connected thereto using a line, the present invention and the set of problems on which it is based will be explained in relation to an ignition system or an injection system for gasoline engines in the field of motor vehicles, for example.  
         [0003]     In current motor vehicle technology, systems are used in which peripheral units are connected via lines to a control unit. In this case, the corresponding peripheral units are usually spatially separated from the control unit, because of which special requirements are to be placed on the lines and the interfaces.  
         [0004]     Some interfaces and/or bus systems for motor vehicle applications are already known, such as the CAN bus system. These bus systems are not suitable for real-time systems, however, i.e., for immediate triggering of the switching operation in the microsecond range, but rather solely for non-time-critical data exchange in the millisecond range of spatially distributed systems.  
         [0005]     Further systems have the disadvantage that they may only upload information during activation of the peripheral unit by the control unit.  
       SUMMARY OF THE INVENTION  
       [0006]     The method according to the present invention and the corresponding device have the advantage in relation to the known approaches that a fail-safe interface having only one line between the control unit and the particular peripheral unit to be activated, such as an ignition coil or a fuel injector of a motor vehicle engine, is provided, the interface having real-time capability for the existing chronological conditions, as they exist in ignition systems or injection systems in motor vehicles, for example.  
         [0007]     Furthermore, using the system according to the present invention, feedback information may be uploaded from the peripheral unit to the control unit, even if there is no activation of the peripheral unit by the control unit.  
         [0008]     In addition, the status of the single-wire line may be monitored for proper functioning.  
         [0009]     The idea on which the present invention is based is that a first current flow from the control unit to the peripheral unit is generated during first time slots via a single-wire line to transmit voltage-coded or current-coded information from the control unit to the peripheral unit, and a second current flow from the peripheral unit to the control unit is generated during second time slots via the same single-wire line to upload voltage-coded or current-coded feedback information from the peripheral unit to the control unit, the first and second time slots being implemented so they do not mutually overlap.  
         [0010]     Therefore, a bidirectional single-wire interface is provided, in which information is exchangeable bidirectionally between a peripheral unit and a control unit via the same single-wire line using current flows generated separately in each case. For this purpose, the peripheral unit has its own power supply. Therefore, feedback information may be transmitted from the peripheral unit to the control unit even at the instants at which there is no activation of the peripheral unit by the control unit.  
         [0011]     Within the first time slots and/or second time slots, the peripheral unit and/or the control unit may additionally generate a status signal by performing a current manipulation in the event of voltage-coded information or performing a voltage manipulation in the event of current-coded information, respectively.  
         [0012]     Preferably, in the automobile field, the peripheral unit is connected to a 12 volt or a 42 volt battery voltage. This may be the same battery voltage as for the supply of the control unit or a separate supply voltage.  
         [0013]     According to a preferred refinement, the peripheral unit is powered during the first time slots by the first current flow from the control unit to the peripheral unit. In this way, in case of activation by the control unit, for example, the low-power component of the electronics of the peripheral unit, specifically the driver device and the information-processing electronics, including the communication logic and/or the activation signals of the power electronics, may be powered.  
         [0014]     According to a further preferred refinement, the information to be transmitted and/or uploaded is implemented as binary signals or analog signals.  
         [0015]     According to a further preferred refinement, the information to be uploaded from the peripheral unit to the control unit is implemented as a diagnostic signal for diagnosis of the peripheral unit. Therefore, the control unit may perform an analysis of the status of the peripheral unit using the uploaded information.  
         [0016]     According to a further preferred refinement, combustion chamber signals are implemented as information which is usable for engine regulation by the control unit.  
         [0017]     According to a further preferred refinement, the information uploaded from the peripheral unit to the control unit is analyzed and implemented as a new control signal for controlling the peripheral unit. Therefore, the control unit may control the assigned peripheral unit in a way tailored to the current status of the system.  
         [0018]     According to a further preferred refinement, the control unit is implemented as an engine control unit.  
         [0019]     According to a further preferred refinement, the peripheral unit is implemented as an ignition coil or fuel injector of a motor vehicle engine or the like.  
         [0020]     The control unit contains first means and the peripheral unit contains second means for information transmission. According to a further preferred refinement, the first and/or second means have resistors and switches, such as transistor switches and/or current or voltage sources, for generating the voltage-coded or current-coded information, the corresponding voltage or the corresponding current, respectively, being altered on the basis of a specific event and the corresponding information to be transmitted thus being generated.  
         [0021]     According to a further preferred refinement, the status of the single-wire line between control units and peripheral units is checked for plausibility. In particular, a short-circuit to ground, a short-circuit to the supply voltage, and a line interruption may be detected.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  shows a schematic illustration of a device according to the present invention including a control unit  2  and a peripheral unit  3 , connected thereto via a single-wire line  4 .  
         [0023]      FIG. 2  shows a more detailed illustration of a device according to the present invention according to an exemplary embodiment of the present invention, the current flow during the first time slots being illustrated.  
         [0024]      FIG. 3  shows a more detailed illustration of a device according to the present invention according to an exemplary embodiment of the present invention, the current flow during the second time slots being illustrated.  
         [0025]      FIG. 4  shows a more detailed illustration of a device according to the present invention according to an exemplary embodiment of the present invention, the status signal in the first time slots being illustrated.  
         [0026]      FIG. 5  shows a more detailed illustration of a device according to the present invention according to an exemplary embodiment of the present invention, the status signal in the second time slots being illustrated.  
         [0027]      FIG. 6  shows a more detailed illustration of a device according to the present invention according to an exemplary embodiment of the present invention, the status message in the second time slots being illustrated.  
         [0028]      FIG. 7   a  shows the shape of a voltage curve over time of the activation during the first time slots in a switch-on operation of the first switch (S 1 ) according to an exemplary embodiment of the present invention as shown in  FIG. 2 .  
         [0029]      FIG. 7   b  shows the shape of a current curve over time on the single-wire line during the first time slots having a status signal from the peripheral unit according to an exemplary embodiment of the present invention.  
         [0030]      FIG. 7   c  shows the shape of a signal curve over time of the primary current of an ignition coil during the first time slots, which, if a specific event occurs, triggers a status change at the peripheral unit according to an exemplary embodiment of the present invention.  
         [0031]      FIG. 7   d  shows the shape of a curve over time of the primary voltage of an ignition coil in the second time slots in the peripheral unit according to an exemplary embodiment of the present invention.  
         [0032]      FIG. 7   e  shows the shape of a curve over time of a first signal, which describes the duration of the bracketing and is transmitted from the peripheral unit to the control unit, according to a further exemplary embodiment of the present invention as shown in  FIG. 3 .  
         [0033]      FIG. 7   f  shows the shape of a curve over time of a second signal, which describes the spark duration of the ignition spark and is transmitted from the peripheral unit to the control unit, according to a further exemplary embodiment of the present invention as shown in  FIG. 3 .  
         [0034]      FIG. 8  shows diagnosis of the single-wire line. 
     
    
     DETAILED DESCRIPTION  
       [0035]     Identical reference numerals identify identical or functionally identical components in the figures.  
         [0036]      FIG. 1  shows a schematic illustration of a device  1  for bidirectional transmission of data information via a single-wire line  4  between a control unit  2  and a peripheral unit  3  having an ignition coil  35 , a fuel injector of a motor vehicle engine, a sensor or an actuator, or the like, for example.  
         [0037]     In the following, the device is to be explained with reference to  FIG. 1  as an example in regard to an ignition system  5  of a motor vehicle engine. Ignition system  5  includes, for example, a spark plug  6 , a high-voltage connection  37 , an ignition coil  35 , an ignition trigger, such as a logic  31 , an ignition output stage  32 , a voltage supply  33 , and a driver circuit  30  in a peripheral unit  3  and an engine control unit  2  having an ignition driver  20 . Control unit  2  additionally contains an electronic controller  21  and a power supply  22 .  
         [0038]     Controller  21  is connected to a driver device  20  of control unit  2 . Driver device  20  is connected via a single-wire line  4  to a driver device  30  of peripheral unit  3 . As shown in  FIG. 1 , driver device  30  of peripheral unit  3  is connected to an information processing device  31 , which may in turn be connected to power electronics  32  of peripheral unit  3 . Furthermore, driver device  30  and power electronics  32  of peripheral device  3  are preferably connected to an external battery voltage, the power circuit preferably being closed via an electronic ground  34 .  
         [0039]     Information for switching an ignition coil  35  in peripheral unit  3  is transmitted from electronic controller  21  and/or control unit  2  in first time slots. The activation is ended when sufficient energy is stored in the coil and the desired moment of ignition has been reached. In this case, the first current flow from control unit  2  to peripheral unit  3  is ended. Subsequently, during second time slots, a second current flow from peripheral unit  3  to control unit  2  via the same single-wire line  4  may be generated, which indicates a specific event in peripheral unit  3 .  
         [0040]     It is to be noted that the first and second time slots may not overlap, since only one current flow in one direction via single-wire line  4  may occur in a specific time slot.  
         [0041]     Information for a diagnosis of peripheral unit  3  and/or ignition coil  35 , information for regulation of ignition coil  35 , or similar information may be uploaded to control unit  2 .  
         [0042]     In the following, with reference to  FIG. 2 , the method according to the present invention will be explained in greater detail through an exemplary embodiment of the present invention for bidirectional single-wire data transmission, the resistor systems and switches generally merely being shown symbolically for a system of current sources and/or current sinks, which allow alteration and measurement of the interface current.  
         [0043]     Control unit  2  has a driver device  20 , which is preferably activated via an electronic controller  21 . Driver device  20  is essentially composed of two areas according to one exemplary embodiment. The first area is used for generating a first current flow from driver device  20  via single-wire line  4  to peripheral unit  3 . For this purpose, the driver device has a resistor R 1 , which is connected to a power supply  22 . Resistor R 1  is connected via a switch S 1  and via single-wire line  4  to driver device  30  of peripheral unit  3 . The second area of driver device  20  also includes a resistor R 2 , which is applied to ground and, via a second switch S 2 , is also connected via single-wire line  4  to driver device  30  of peripheral unit  3 .  
         [0044]     Resistors R 1  and R 2  are each connected via a detector unit  201  and by interface logic  202  to the electronic controller. Switches S 1  and S 2  are preferably also connected by interface logic  202  to the electronic controller.  
         [0045]     Driver device  30  also includes two areas according to the exemplary embodiment of the present invention. The first area preferably includes a resistor R 3 , which is connected to a power supply  33  and, in addition, to a switch S 3 , which is connected to single-wire line  4 .  
         [0046]     The second area includes a resistor R 4 , which is applied to ground and, in addition, is connected to a switch S 4 , which is in turn connected to single-wire line  4 .  
         [0047]     Resistors R 3  and R 4  are connected via a detector unit  301  and by interface logic  302  to information processing device  31 . Switches S 1  and S 2  are preferably also connected by interface logic  302  to information processing device  31 .  
         [0048]     In operation, for example, information transmission of control unit  2  to peripheral unit  3  is triggered in a first time slot. For this purpose, switches S 2  and S 3  must be open and S 4  must be closed. A first current flow is then generated from power supply  22  having 5 V, for example, via resistor R 1  and associated switch S 1  and transmitted via single-wire line  4  to peripheral unit  3 . In peripheral unit  3 , a detector unit  301  at resistor R 4  may detect an activation voltage.  
         [0049]      FIG. 3  shows an example of information transmission in a second time slot from peripheral unit  3  to control unit  2 . For this purpose, switches S 1  and S 4  must be open and S 2  must be closed. A second current flow is then generated from power supply  33  having 5 V, for example, via resistor R 3  and associated switch S 3  and transmitted via single-wire line  4  to electronic control unit  2 . In control unit  2 , a detector unit  201  at resistor R 2  may detect a feedback voltage.  
         [0050]      FIG. 4  shows a status signal in the first time slots. For this purpose, switches S 2  and S 3  must be open and S 1  and S 4  must be closed. During activation, for example, the current may be binary coded via an additional system in peripheral unit  3 , including resistor R 5  and a switch S 5  in driver device  30  of peripheral unit  3 , and the information may be uploaded to control unit  2  via same single-wire line  4 . If the additional system in peripheral unit  3  includes a controllable current sink, analog information may be uploaded.  
         [0051]     It may be determined, using a detector device  201  at resistor R 1  in driver device  20 , whether a specific event occurred in peripheral unit  3  in the first time slots, for example, by the opening of switch S 5  and the current reduction associated therewith.  
         [0052]     Driver device  20  subsequently preferably relays the received information to electronic controller  21  for further data evaluation and/or analysis.  
         [0053]      FIG. 5  shows a status signal in the second time slots. For this purpose, switches S 1  and S 4  must be open and S 2  and S 3  must be closed. During the information transmission from peripheral unit  3  to control unit  2 , for example, the current may be binary coded via an additional system in control unit  2 , including resistor R 6  and a switch S 6  in driver device  20  of control unit  2 , and the information may be uploaded to peripheral unit  3  via same single-wire line  4 . It may be determined, using a detector device  301  at resistor R 3  in driver device  30 , whether a specific event occurred in control unit  2  in the second time slots, for example, by the opening of switch S 6  and the current reduction associated therewith.  
         [0054]     If the additional system in control unit  2  includes a controllable current sink, analog information may be uploaded.  
         [0055]      FIG. 6  shows an example of an additional status signal in the second time slots. In this case, switches S 1 , S 4 , and S 5  are open and S 2  and S 3  are closed. For this purpose, the further resistor system, including resistors R 3  and R 7 , which are connected in parallel, is provided in driver device  30 . Resistors R 3  and R 7  are each connected via a switch S 3  or S 7 , respectively, to single-wire line  4 . Since this system, as shown in  FIG. 6 , is connected to its own voltage source  33 , an alteration of the second current flow from peripheral unit  3  to control unit  2  via same single-wire line  4  may be generated, whose value is a function of connectable resistor R 7 . It may be determined using a detector device  201  at resistor R 2  in driver device  20  whether a specific event occurred in peripheral unit  3 , for example, by the closing of switch S 7  and the current increase associated therewith.  
         [0056]     If the additional system in driver unit  30  in peripheral unit  3  includes a controllable current source, analog information may be transmitted.  
         [0057]     In the following, examples of the information and/or signals to be transmitted will be explained with reference to  FIGS. 7   a  through  7   f.    
         [0058]      FIG. 7   a  shows an example of the shape of the curve over time of a voltage activation of the peripheral unit in the first time slots when S 1  is switched on. By applying a voltage of this type, a first current flow from control unit  2  to peripheral unit  3  is generated ( FIG. 4 ).  
         [0059]     If a specific event occurs in peripheral unit  3 , e.g., the primary current in ignition coil  35  exceeds a specific value If 1 , as shown in  FIG. 7   c , switch S 5  is opened and the first current flow is reduced, as shown in  FIG. 4 . This is illustrated in  FIG. 7   b , which shows the shape of the curve over time of the first current flow as an example. This change in the first current flow may be detected by control unit  2  during the activation and analyzed, as was explained in detail above.  
         [0060]      FIG. 7   d  schematically shows the shape of the curve over time of the voltage at the primary terminal of ignition coil  35 , which is connected to power electronics  32 . In the second time slots, this voltage increases until it reaches a predefined voltage value, which is delimited by bracketing, for example. Upon reaching the maximum voltage value, one of switches S 3  or S 7  is closed, as explained in  FIG. 6 , for example, depending on which event has occurred in peripheral unit  3  and is accordingly to be communicated to control unit  2 .  
         [0061]     In  FIG. 7   e , the signaling that a first voltage threshold U 1  has been exceeded, using a first signal by closing first switch S 6 , for example, is illustrated. This information is transmitted from peripheral unit  3  to control unit  2  and analyzed according to the methods explained in detail above.  
         [0062]     In  FIG. 7   f , a further exemplary embodiment of an event, for example, the spark duration of a spark plug, is shown as an example of a signal. If the voltage in the second time slots has exceeded a threshold U 2 , which corresponds to the spark duration, this event is signaled, for example, by additionally closing switch S 7  and generating a corresponding current flow to control unit  2  via single-wire line  4 .  
         [0063]     Therefore, by analyzing the current strengths of the first and second current flows, specific events in the peripheral unit and/or in the system may be detected in real-time and transmitted bidirectionally in both time slots in a chronologically synchronized way.  
         [0064]      FIG. 8  and Table 1 show the diagnosis of single-wire line  4  in control unit  2 .  
         [0065]     The proper function of single-wire interface  4  may be diagnosed in the first time slots: if, for example, with closed switches S 1  and S 4  and open switches S 2  and S 3  as shown in  FIG. 2  or  FIG. 4 , no current is detected in the line at R 1 , there is probably an interruption of the line. If line  4  is short-circuited to ground, either the current is atypically high or the voltage at the interface is approximately at 0 V. A short-circuit to the battery voltage (Ubatt) of the vehicle electrical system either results in an inverse current, because, among other things, the supply voltage (Usupply) is less than the battery voltage of the vehicle electrical system, or the voltage at the interface is at Ubatt.  
         [0066]     In the second time slots: if, for example, with closed switches S 2  and S 3  and open switches S 1  and S 4  as shown in  FIG. 3  or  FIG. 5 , no current is detected in the line at R 2 , there is an interruption of the line or a short-circuit to ground. A short-circuit to the battery voltage of the vehicle electrical system either results in an atypically high current or the voltage at the interface is approximately at Ubatt.  
                                                                                       TABLE 1                       Switch   Switch   Current   Voltage           S1   S2   I   U   Status                                First time slots            On   Off   0   Usupply   Interruption       On   Off   I inverse   Ubatt   Short-circuit to Ubatt       On   Off   &gt;Imax   0   Short-circuit to ground            Second time slots            Off   On   0   0   Interruption or short-                       circuit to ground       Off   On   &gt;Imax   Ubatt   Short-circuit to Ubatt       Off   On   0   0   Interruption or short-                       circuit to ground                  
 
         [0067]     Although the present invention was described above on the basis of preferred exemplary embodiments, it is not restricted thereto, but rather may be modified in manifold ways.  
         [0068]     In particular, instead of a current-coded information transmission, a voltage-coded information transmission may also be performed. In this case, a constant current flow and a change in the corresponding applied voltage in case of an occurring event are to be ensured. The procedure, i.e., the uploading of the information and/or the analysis, is performed analogously to the exemplary embodiments explained in detail above. The corresponding components are merely implemented as current sources instead of as voltage sources. The resistor systems of driver device  30  of peripheral unit  3  are implemented in such a way that in the event of a voltage status signal, the total resistance is changed in such a way that in the event of a constant current, the particular applied voltage varies, i.e., voltage-coded information is uploaded.  
         [0069]     The information to be transmitted and/or uploaded may also be modulated and/or implemented, transmitted, and analyzed both as a binary signal and as an analog signal.