Display unit for an electrified manual transmission in a vehicle

Abstract

A display unit (10) for an electrified manual transmission in a vehicle, which display unit can be connected to a data line (2) via which messages can be exchanged between a transmission control unit (1) and the display unit (10), wherein- the display unit (10) has at least one microprocessor (11), a driver device (12) and a display means (13), wherein the microprocessor (11) evaluates the message containing gear information and feeds it to the driver device (12) for controlling the display means (13) for displaying the gear information, and- a monitoring means (14) is provided which checks the gear information fed to the display unit (10) in the message and / or the processing of the message carried out in the display unit (10) and, in the event of an error, brings about a safe state of the display means (13) before the gear information is displayed.

Description

The invention relates to a display device for an electrified transmission in a vehicle. The invention further relates to an electrified gearbox of a motor vehicle and to a method for operating a display device of an electrified gearbox in a vehicle.DE 19 64 524 A discloses a motor vehicle transmission in which the individual gears are engaged in an electronically controlled manner. The selector lever in this transmission is no longer mechanically connected to the transmission itself; it merely serves to select the desired gear stage. When it is actuated, it closes electrical contacts, the shift pulses of which are processed by a central evaluation circuit and are converted into corresponding commands to the control elements for the gear shift.Such manual transmissions are becoming increasingly widely used in modern motor vehicles. In order to inform the driver about the gear currently engaged, a display unit is provided, frequently in the instrument cluster of the instrument panel carrier. The individual gear stages of the transmission are designated here in a conventional manner with letters and numerals. The engaged gear stage, which is transmitted from a transmission control unit to the display unit, is displayed by the latter.The safety of such a display unit is subject to increased requirements, since haptic feedback on the basis of the position of the selector lever is no longer provided for the driver. In particular, no information may be displayed which does not signal a frictional connection in the case of an actual frictional connection of the transmission. There is no frictional engagement when the transmission is in the N or P stages but the transmission is actually in the D, R or particular gear position. A further fault to be prevented consists in signaling a "wrong" frictional connection. Thus, no R must be signalled in the display unit when the transmission is in stage D or in a gear designated for forward travel. The same applies to the reverse situation, in which a gear stage for the forward travel is indicated, although the gear stage R is engaged in the transmission. A further fault to be prevented is the presentation of a frictional connection, although the transmission actually does not have a frictional connection. This would be the case if the display unit signals, for example, D, but the transmission is actually in stage N.From this description it is already apparent that monitoring of the gear display represented by the display unit has to take place. In the display units in use so far, a plurality of light-emitting diodes are provided, which generate the desired display, e.g. D or N, by appropriate control. Monitoring of the correct representation is possible in a relatively simple manner by monitoring the current of each individual light-emitting diode. However, display units with a liquid crystal display (LCD) have recently been increasingly used, in which monitoring is no longer readily possible.DE 100 09 170 A1 discloses a device for regulating the driving speed of a motor vehicle as a function of an actual speed and a setpoint speed. In this case, the presentation of a desired speed vSet, a speed vAnzdisplayed by the vehicle and a speed vFgadjusted by the controller on a tacho should be optimized taking into account the tacho run-forward. It is proposed to apply the desired speed vSet as a reference variable to the vehicle speed controller and the speed vAnz with a lead as a controlled variable. The input variable vZgof the display control device is detected with a monitoring function and compared with the likewise detected output variable vAnz. If the difference between the two values vZgand vAnzis greater than a predefined value, an error message is carried out and the system is switched off.DE 10 2004 032 807 A1 describes a device for increasing the system safety of vehicle instrument displays and vehicle control devices. The device comprises a monitoring device which is separated from a display controller on the hardware and software side and is connected between a control device and the display controller. The monitoring device checks on the hardware side whether the display controller has implemented a function signal from the control unit. The software checks whether the software of the display controller is functioning properly and the display controller has actuated the corresponding display element.It is therefore an object of the present invention to provide a display unit and a display device for an electrified transmission in a vehicle, with which the false display of gear information can be prevented as reliably as possible. The display unit is intended to be usable in connection with a liquid crystal display. It is a further object of the present invention to specify a method for operating such a display device.These objects are achieved by a display unit having the features of patent claim 1, by a display device having the features of patent claim 17, by an electrified transmission of a motor vehicle having the features of patent claim 18 and by a method for operating a display device according to the features of patent claim 19. Advantageous embodiments are evident from the dependent patent claims.The display unit according to the invention for an electrified transmission in a vehicle can be connected to a data line via which messages can be exchanged between a transmission control unit and the display unit. The display unit has at least one microprocessor, a driver device and a display means, wherein the microprocessor evaluates the message containing gear information and supplies it to the driver device for driving the display means for the purpose of displaying the gear information. A monitoring means is provided which checks the gait information supplied to the display unit in the message and / or the processing of the message carried out in the display unit and, in the event of a fault before the display of the gait information, brings about a safe state of the display means.The display device according to the invention for an electrified transmission in a vehicle comprises an electronic transmission control unit, a display unit and a data line via which messages of the transmission control unit and of the display unit can be exchanged. The transmission control unit is configured to generate information about the gear of the transmission that is currently engaged. The display unit has at least one microprocessor, a driver device and a display means, wherein the microprocessor evaluates the message containing gear information and supplies it to the driver device for driving the display means for the purpose of displaying the gear information. A monitoring means is provided which checks the gear information supplied to the display unit in the message and / or the processing of the message carried out in the display unit and, in the event of a fault, brings about a safe state of the display means.An electrified transmission of a motor vehicle according to the invention has a display device designed according to the invention.In this context, a fault means that a shift state actually present in the transmission is represented in the display unit by a piece of gear information that is not corresponding. It is assumed here that the message generated by the transmission control unit, which message comprises at least the information about the gear currently engaged, corresponds to the actually engaged shift stage of the transmission.The data line is preferably a bus line (e.g. CAN (Controller Area Network) bus), wherein the transmission control unit and the display unit are bus subscribers of a bus system. In addition to these two bus subscribers mentioned, a large number of further bus subscribers can also be connected to the data line, which bus subscribers are not important for the present invention, however.By providing a monitoring means which checks the gear information supplied to the display unit in the message and additionally or alternatively the processing of the message carried out in the display unit, discrepancies between the actually engaged gear and the gear information to be displayed in the display unit can be detected before the display thereof. Thereby, it is possible to suppress such an erroneous display by bringing about a safe state of the display means.For this purpose, in one embodiment of the invention, the monitoring means is coupled to the data line and is designed to evaluate the message which is intended for the microprocessor and contains the gear information and to compare it with the evaluation result of the microprocessor as part of the check. The monitoring means, which is preferably designed in the form of a watchdog, thus represents a redundant processing unit to the microprocessor. The term "redundancy" is to be understood in this context, however, as meaning that there is not completely identical processing to the processing of the message by the microprocessor, but rather that the processing of the message information carried out by the microprocessor is verified on the basis of the same input data (message).For this purpose, the monitoring means is preferably coupled to the microprocessor and / or the driver device for the exchange of data. The exchange of data can be effected bidirectionally between the components respectively coupled to one another, so that current status information can be called on the one hand and an effect on respective components is enabled on the other hand.The security of the display device can be ensured in a particularly advantageous manner by the monitoring means being designed to read out the data supplied by the microprocessor of the driver device from a memory of the driver device and to compare it with the information contained in the message. The driver device, which is arranged between the display means and the microprocessor, essentially performs an interface function between the microprocessor, which decides which information is to be displayed on the display means, and the display means, wherein the driver device converts the information obtained from the microprocessor into corresponding signals for the display means in order to be able to visually display the information. The provision of the driver device thus enables a modular design of the display unit in which different types of microprocessors and display means can be combined with one another.The microprocessor uses the information contained in the message to determine which gear information is to be displayed in the display means and transmits the corresponding control data into the memory of the driver device. The driver device reads out the data contained in its memory and generates the control data for the display means on the basis of this information in order to make the gear information visible on the display means. According to the invention, the monitoring means can read out the information contained in the memory of the driver device, whereby the latter can determine which information is to be displayed. This information is compared with the information of the message supplied to the microprocessor evaluated by the monitoring means. On the basis of the comparison, the monitoring means can determine whether the actually engaged shift stage of the transmission corresponds to the display to be displayed on the display means. If this is not the case, the monitoring means can react to a fault and cause a safe state of the display means. This advantageous embodiment makes it possible to easily determine errors in the functioning of the microprocessor.Safe states of the display means are considered to be a masking out of the gear information or a switching dark of the display means. The display unit is therefore preferably designed to effect a masking out of the display of the display means by appropriate control of the driver device in the event of a fault. The control for masking out can be effected by the microprocessor. This is accomplished in that the corresponding information to be stored in the memory of the driver device corresponds to a masking out of the gear display.The decision as to whether the gear information item has to be blocked out can be made by the monitoring means and / or the microprocessor, both of which are designed accordingly.Furthermore, the display unit is designed to cause the display means to be switched dark by appropriate control of the driver device in the event of a fault. The switching of the display means to dark is preferably effected by the monitoring means by effecting a disconnection of the voltage supply to the driver device.While only the gear information is influenced by the functionality of the masking in the display means and further information, such as e.g. mileage, external temperature, time, etc., is still displayed in the usual form, the functionality of the display means is completely disabled when the gear display is switched off. Whether masking out or switching the display means to dark is carried out depends on the type of fault detected by the display unit. One difference is that the masking of the gear display could be caused, for example, by the error of a single message, it being possible for the masking to be carried out in an undoable manner if the further messages received from the display unit are correct. However, if the display means has been switched dark, then a reset is possible only by re-initializing the display unit.In addition to checking the message contents and checking the evaluation of this message information, the security of the display device can be further improved by providing a first voltage supply device, which is coupled to the microprocessor and to the driver device and has a voltage protection on respective connecting lines. The voltage protection can be provided in particular for protecting the microprocessor and the driver device and thus the display means in the form of respective zener diodes. If the first voltage supply device is also coupled to the monitoring means, it is likewise advantageous to provide this connecting line with a voltage protection. If such a voltage protection is not possible, it is expedient if the monitoring means according to a further embodiment is coupled to a second voltage supply device independent of the first voltage supply device.To increase safety, it is also expedient if the monitoring means is coupled to an oscillator which is assigned only to the latter. The remaining electronic components of the display unit are supplied by another oscillator.In a further embodiment, it can be provided to connect the display unit to the battery of the vehicle via a fuse.It is furthermore expedient if the components of the display unit are checked for their correct functioning. It is therefore provided that when the display unit is started, in particular after a wake-up signal has been applied to the data line, microprocessor and monitoring means are alternately checked and these components are initialized. Only when the check can be positively concluded can the display unit transition to its intended operation. In the other case, within the scope of the checking routine, a masking out of the gear information or a complete switching to dark of the display means of the display unit can be provided.The method according to the invention has the same advantages as have been explained above in connection with the display device according to the invention.The method according to the invention for operating a display device of an electrified transmission in a vehicle having an electronic transmission control unit, a display unit and a data line, via which messages can be exchanged between the transmission control unit and the display unit, comprises the following steps: a message generated by the transmission control unit and information about the gear of the transmission that has just been engaged is placed on the data line. The message present on the data line is received by the display unit and fed to a microprocessor for evaluation, the microprocessor feeding the message containing gait information after evaluation of the driver device for driving the display means for the purpose of displaying the gait information. The message present on the data line is fed to a monitoring means for evaluation, which checks the gait information supplied to the microprocessor in the message and / or the processing of the message carried out in the display unit and, in the event of a fault, brings about a safe state of the display means before the display of the gait information.The provision of the monitoring means in addition to the microprocessor actually provided for the evaluation of the message enables a display device in which false displays in the sense of deviating gear information regarding the shift stage currently engaged can be reliably prevented.In one embodiment of the method, the checking comprises reading the data supplied by the microprocessor of the driver device from a memory of the driver device and comparing this data with the information contained in the message. This method step makes it possible, regardless of where the fault has occurred or was caused in the display unit, for the information evaluated by the driver device to be subjected to an evaluation and in particular a comparison, so that a display of this gear information can be prevented if necessary. The conclusion about an error is made by the monitoring means, preferably in the form of a watchdog, and / or by the microprocessor.It is provided here that in the event of a fault detected outside the display unit, the gear information is displayed in the display means as a safe state. Such an error could have been caused, for example, when transmitting the message via the data line or else by the transmission control unit when generating the message.In the event of a fault detected within the display unit, according to another configuration, the gear information is blocked out as a safe state in the display means or the display means is switched dark. Such an error occurring within the display unit can be of both programming and hardware-technical nature.In this case, it is provided that the gating out of the gear information in the display means is effected by the microprocessor and / or the monitoring means by the microprocessor in that a corresponding control of the driver device takes place. The gear information is thus masked using programming means by acting on the information which corresponds to a "non-display" and which is to be written into the memory of the driver device.The switching of the display means to dark, on the other hand, is effected by the monitoring means in that the voltage supply to the driver device is cut off.In a further embodiment, it is provided that a change from the safe state to the normal operation of the display unit takes place when the fault detected outside the display unit is no longer present. This can be the case, for example, when the message present on the data line is received correctly again.Another embodiment of the method provides that a change from the safe state to the normal operation of the display unit takes place when the fault detected within the display unit is no longer present and the checking of the display unit could be successfully concluded.To further increase the operational reliability of the display unit, a cyclical checking of the components and an initialization, in particular of the display unit, are carried out during normal operation of the display device.In a further embodiment, the message present on the data line comprises at least one piece of gait information and one piece of complementary information, and the checking of the message present on the data line comprises a comparison of the gait information with the complementary information. This makes it possible to determine whether the information generated by the transmission control unit has been correctly transmitted.It is furthermore provided that a check for an alive information item takes place as part of the check of the message. An alive information item is a signal which is transmitted cyclically by the transmission control unit and on the basis of which it can be established by the display unit that the message is updated by the transmission control unit.It is furthermore provided that a check for a timeout takes place as part of the check of the message. In other words, the messages containing a piece of gait information are expected cyclically within specific time intervals. A non-compliance with this time condition indicates an error outside the display unit.The check as to a discrepancy between the actually engaged gear stage and the gear information to be displayed on the display means of the display unit is preferably carried out in the microprocessor and the monitoring means. This redundant check makes it possible in a simple manner to compare the results of the two components, it being possible to infer an error if a discrepancy is detected.It is furthermore advantageous if, during the checking of the message, trigger monitoring takes place in which the monitoring means monitors a trigger signal of the microprocessor and the microprocessor monitors a trigger signal of the monitoring means.The invention is explained in more detail below with reference to the figures. The following are shown: FIG. 1 shows a display device according to the invention in a schematic illustration, FIG. 2 is a state transition diagram of the display device according to the present invention; and FIG. 3 shows a flow chart of the display unit according to the invention, on the basis of which the functionality of the components of the display unit is checked within the scope of the start-up behavior.FIG. 1 shows a schematic illustration of the structure of a display device 100 according to the invention. A transmission control unit 1 and a display unit 10 are connected to a data line 2 designed as a bus line. The transmission control unit 1 and the display unit 10 form bus subscribers of a bus system which, in addition to these two, can have further bus subscribers which are not relevant to the invention. The data line 2 is, for example, a bus line according to the CAN (controller area network) principle.The transmission control unit 1 is coupled to a transmission of the motor vehicle (not shown) and, electronically controlled, sets the individual gear stages, automatically or selected by the driver. The transmission control unit 1 is additionally configured to generate information about the gear of the transmission that is currently engaged and to apply it to the data line 2 in the form of a message. The message containing gait information also has at least one piece of complementary information to the gait information, as a result of which message errors can be detected by the display unit 10.The display unit 10 comprises a microprocessor 11, a driver device 12 coupled to the latter via a line 24, and a display means 13 (line 25) coupled to the driver device 12. In the exemplary embodiment, the display means 13 is designed as an LC display (liquid crystal display). The display unit 10 represents, for example, the instrument comb in the motor vehicle. The microprocessor 11 is connected to the data line 2 via a line 31. The microprocessor 11 evaluates the message supplied to it via the line 31 and determines the gear information to be displayed on the display means 13. The microprocessor 11 transmits this information to the driver device 12 and stores it in a memory 23 of the driver device 12. The driving means 12 reads out the information contained in the memory 23 and converts it into corresponding pixel information so that the digit or letter corresponding to the gait can be displayed in the display means 13. The driver device 12 thus represents an interface between the microprocessor 11 and the display means 13 and carries out a conversion or conversion of the information determined by the microprocessor 11 into signals required for the display means 13.The microprocessor 11 and the driver 12 are supplied with a voltage suitable for them from a voltage supply 15. For this purpose, the voltage supply device 15 can comprise a linear regulator, a hysteresis circuit and further components. In order to avoid damage to the microprocessor 11 and the driver device 12, zener diodes 18, 19 are arranged on respective connecting lines 16, 17, which zener diodes ensure voltage protection. The voltage supply device 15 is in turn connected via a diode 30 to a fuse 22 arranged outside the display unit 10, which fuse prevents the display unit 10 from being damaged.To increase the security of the display device 100, a monitoring means 14 designed as a watchdog is also provided in the display unit 10. This is connected via a line 26 to the microprocessor 11, via a line 27 to the driver device 12 and via a line 28 to the data line 2. Furthermore, the monitoring means 14 has its own voltage supply device 20, e.g. a linear regulator, and its own oscillator circuit 21.The task of the monitoring means 14 is to receive and evaluate the message present on the data line 2 in accordance with the microprocessor 11. This allows the message information to be checked independently of one another in the microprocessor 11 and in the monitoring means 14. In particular, it is provided that monitoring means 14 reads out the data stored in memory 23 of driver device 12 by microprocessor 11 and compares it with the information contained in the message. This enables a conclusion to be drawn as to whether the information for the display means generated by the microprocessor 11 has possibly been transmitted incorrectly.The mode of operation of the display device according to the invention is better evident from the state transition diagram of FIG. 2. A "bus sleep" state 200 is assumed, in which the display device 100 is not in operation. Activation of the display unit is effected by a "bus wake-up" 206, which can be triggered by an external activation display unit 202 or an internal activation display unit 204. By detecting a wake-up signal, the components of the display unit 10 are checked in state 208, In particular, the microprocessor 11 is initialized, data are taken over from a memory of the microprocessor 11 (e.g. data about the type or variant of the transmission, the region of the display means to be described, etc.), and the data taken over are checked and the gear display is reset in the display means 13, which is followed in state 210 by initialization of the monitoring means 14 and testing of the monitoring means 14 if the check has been positive. If the initialization of the microprocessor 11 in the state 208 or the initialization or the test of the monitoring means 14 in the state 210 has resulted in an error, a transition is made to the state 214, in which a safe state of the display means 13 is brought about by masking out the gear information. The masking out is effected by appropriate control of the driver device 12 and manipulation of the data stored in the memory 23, from which the gear information for the display means 13 is effected.If no fault could be detected even during the initialization of the monitoring means 14, the display unit 10 then enters a normal operation (state 212). If an error is detected during normal operation, whether it be by the microprocessor 11 or the monitoring means 14, a transition is made to state 214. Such an error could be, for example, a message error, an error in monitoring means 14, an error in microprocessor 11 or an error in driver device 12. If the error was in an erroneous message, for example, and the messages following it are again in order, which can be checked, for example, on the basis of the complementary information with respect to the gear information, then a transition from state 214 to state 212 of normal operation is possible. If, on the other hand, there is a masking error which may in turn be caused by the above-mentioned components of the display unit 10, a transition is made to state 216, in which the display means 13 is switched to a dark state, in that the voltage supply to the driver device 12 is cut off by the monitoring means 14. To transition to the proper operation according to state 212, it is necessary to actuate the clamp 15 or clamp R to accomplish re-initialization of the display device 100 (state 218). The terminal 15 and the terminal R are operated by the ignition lock. After the actuation of the terminal 15 or the terminal R, a transition is made to the state 208 in which the initialization of the microprocessor 11 is started. Furthermore, a transition from state 212 (normal operation) to state 200 (bus sleep) is possible if a certain time of inactivity is present. The length of this time period can be defined arbitrarily.FIG. 3 shows the program sequence of the display unit 10, which is run through after starting up. This test is intended to check, in particular, whether the influencing of the display means functions as intended in the event of a fault, i.e. the masking out and / or the switching to dark. The starting point is the state 206 from FIG. 2, in which a wake-up signal is present on the data line 2. After a wake-up signal has been applied to the data line 2 (step 300), a self-test of the monitoring means 14 is carried out, which is designated in the figure as WD (for watchdog). If the self-test was positive (step 302), the monitoring means 14 transmits the self-test result to the microprocessor 11 (designated μC in the program flow chart) and requests a trigger stop from the microprocessor (step 306). If, on the other hand, the self-test of the monitoring means 14 was not positive, the test run ends and no test result is transmitted to the microprocessor 11 (step 304). When the self-test result of the monitoring means 14 is transmitted, the dark circuit test begins. This is represented by the arrow drawn in the program flow chart. In step 308, the monitoring means 14 checks whether the microprocessor 11 has recognized the request for a trigger stop and the debouncing time has expired. If this is not the case, the monitoring means switches off the voltage to the driver device 12 (referred to here as MLA) after a predetermined time has elapsed and the program sequence is continued before step 306. In the positive case, the monitoring means 14 switches off the voltage at the driver device in step 312. In step 314, the microprocessor 11 checks whether it has detected the shutdown of the supply voltage. If this is not the case, this check is repeated according to step 314. In the positive case, the microprocessor 11 acknowledges the shutdown to the monitoring means 14 (step 316). The monitoring means 14 checks in step 318 whether the acknowledgement has been received from the microprocessor 11. In the negative case, this check is repeated, and in the positive case, monitoring means 14 switches on the voltage of driver device 12 again, so that from now on, displays can be carried out in the display means--still without gear position (step 320). At this point, the dark-down test is completed and the start of the fade-out test (see arrow in the figure) begins.In step 322, the monitoring means 14 stops its trigger signal. In step 324, the microprocessor 11 checks whether it was able to identify a trigger stop of the monitoring means 14 and the debouncing time has expired. If this is not the case, step 324 is repeated, and if this is the case, the microprocessor 11 fades out the gear information in the display means 13 and reports the trigger stop, which corresponds to an error, back to the monitoring means 14 (step 326). The monitoring means 14 then checks in step 328 whether an error message has been received by the microprocessor 11. This check is repeated in the negative case. In the positive case, the monitoring means 14 waits in step 330 for gear information which does not correspond to a dark shift. Step 330 is repeated as long as such gear information could not be received. If the gear information has been received, the monitoring means 14 checks, after a predetermined time, in step 332 whether the information contained in the memory of the driver device corresponds to a dimming. If this is the case, the monitoring means 14 starts its trigger signal, whereupon the microprocessor 11 causes the gear information to be entered in the display means 13 (step 336). In the other case (step 334), masking is requested or a dark-down is initiated by the monitoring means 14. At this point, the test of the display unit 10 is completed.The monitoring of the gait information displayed in the display means is carried out in such a way that the display is hidden if the complementary information to the gait information in the message which is supplied to the display unit is not correct. Masking out is also effected if the position specification of the gear information is in itself conflicting. This would be the case, for example, if the gear information were simultaneously contained in the information P and D. Masking out also occurs when a timeout of the message occurs or an alive fault has been detected. The timeout is an algorithm for the temporal monitoring of signals, with the aim of identifying missing messages. A message update can be monitored on the basis of an alive information item. This allows "frozen" messages and the correct sequence of messages to be recognized. The check is carried out by the monitoring means 14 as well as by the microprocessor 11 When a fault is detected-either by the microprocessor 11 or the monitoring means 14-the gear information is blocked out in the display means 13. This is done by the microprocessor 11 providing corresponding information which is stored in the memory 23 of the driver device 12. This can be accomplished, for example, by writing the information FF into the memory 23. If an error occurs during masking-out, which can be detected by the monitoring means 14 by reading out the information contained in the memory 23 of the driver device 12, the display means 14 causes the display means 13 to be switched dark by the voltage supply of the driver device 12 being cut off-independently of the voltage supply of the remaining display unit.The invention describes a display device 100 for an electrified transmission, in which the individual gear stages are engaged in an electronically controlled manner. The information about the driving gear just engaged is displayed to the driver via a display unit 10, for example in the instrument cluster. For this purpose, the transmission control unit 1 is communicated with the display unit 10. To ensure a correct display, the gear information of the transmission control unit 1 is evaluated by the microprocessor 11 and made available to a driver device 12, which then displays it to the driver in a display means 13 designed as an LC display. To ensure the integrity of the safety function, a monitoring means 14 designed as an intelligent watchdog is used, which receives the message information via the data line 2 independently of the microprocessor 11 and carries out an evaluation of this information, in particular a comparison with data stored in the driver device 12.List of reference characters1 Transmission control unit 2 Data line 10 Display unit 11 Microprocessor 12 Driver device 13 Display means 14 Monitoring means 15 Voltage supply device 16 Connecting line 17 Connecting line 18 Voltage protection (Zener diode) 19 Voltage protection (Zener diode) 20 Voltage supply device 21 Oscillator 22 Fuse 23 Memory 24 Line 25 Line 26 Line 27 Line 28 Line 29 Reset input 30 Diode 31 Line 100 Display device 200 State 202 State 204 State 206 State 208 State 210 State 212 State 214 State 216 State 218 State 300 Method step 302 Method step 304 Method step 306 Method step 308 Method step 310 Method step 312 Method step 314 Method step 316 Method step 318 Method step 320 Method step 322 Method step 324 Method step 326 Method step 328 Method step 330 Method step 332 Method step 334 step 336 Step

Claims

Display unit (10) for an electrified transmission in a vehicle, which can be connected to a data line (2), via which messages can be exchanged between a transmission control unit (1) and the display unit (10), wherein - the display unit (10) has at least one microprocessor (11), a driver device (12) and a display means (13), wherein the microprocessor (11) evaluates the message containing gear information and feeds it to the driver device (12) for actuating the display means (13) for the purpose of displaying the gear information, and - a monitoring means (14) is provided, which checks the gear information supplied to the display unit (10) in the message and / or the processing of the message carried out in the display unit (10) and, in the event of a fault before the display of the gear information, brings about a safe state of the display means (13).Display unit (10) according to Claim 1, characterized in that the monitoring means (14) is coupled to the data line (2) and is designed to evaluate the message which is determined for the microprocessor (11) and contains the gear information and to compare it with an evaluation result of the microprocessor (11).Display unit (10) according to Claim 1 or 2, characterized in that the monitoring means (14) is coupled to the microprocessor (11) and / or to the driver device (12) for the exchange of data.Display unit (10) according to Claim 3, characterized in that the monitoring means (14) is designed to read out the data supplied by the microprocessor (11) to the driver device (12) from a memory (23) of the driver device (12) and to compare it with the information contained in the message.Display unit (10) according to one of the preceding claims, characterized in that the display unit (10) is designed to effect masking of the display of the display means (13) by appropriate control of the driver device (12) in the event of a fault.Display unit (10) according to Claim 5, characterized in that the control for masking out can be effected by the microprocessor (11).Display unit (10) according to Claim 5 or 6, characterized in that the monitoring means (14) and / or the microprocessor (11) are designed to make a decision for masking out.Display unit (10) according to one of Claims 1 to 4, characterized in that the display unit (10) is designed to effect, in the event of a fault, a switching of the display means (13) to dark by appropriate control of the driver device (12).Display unit (10) according to Claim 8, characterized in that the monitoring means (14) is designed to switch the display means (13) to dark by virtue of a voltage supply to the driver device (12) being disconnected.Display unit (10) according to one of the preceding claims, characterized in that a first voltage supply device (15), which is coupled to the microprocessor (11) and to the driver device (12), is provided and has a voltage protection device (18, 19) on respective connecting lines (16, 17).Display unit (10) according to one of the preceding claims, characterized in that the monitoring means (14) is coupled to a second voltage supply device (20) independent of the first voltage supply device (15).Display unit (10) according to one of the preceding claims, characterized in that the monitoring means (14) is coupled to an oscillator (21) assigned only to the latter.Display unit (10) according to one of the preceding claims, characterized in that the display unit (10) is connected to a battery of the vehicle via a fuse (22).Display unit (10) according to one of the preceding claims, characterized in that, when the display unit (10) is started, in particular after a wake-up signal has been applied to the data line (2), microprocessor (11) and monitoring means (14) are alternately checked and these components are initialized.Display unit (10) according to one of the preceding claims, characterized in that the data line (2) is a bus line.Display unit (10) according to one of the preceding claims, characterized in that the monitoring means (14) is designed as a watchdog.Display device (100) for an electrified transmission in a vehicle, having an electronic transmission control unit (1), a display unit (10) and a data line (2) via which messages can be exchanged between the transmission control unit (1) and the display unit (10), wherein - the transmission control unit (1) is configured to generate information about a gear of the transmission that has just been engaged, and - the display unit (10) is designed according to one of the preceding claims.Electrified gearbox of a motor vehicle, characterized in that it comprises a display device (100) according to Claim 17.Method for operating a display device (100) of an electrified transmission in a vehicle having an electronic transmission control unit (1), a display unit (10) and a data line (2) via which messages can be exchanged between the transmission control unit (1) and the display unit (10), in which - a message generated by the transmission control unit (1) with information about a gear of the transmission that has just been engaged is placed on the data line (2), - the message present on the data line (2) is received by the display unit (10) and fed to a microprocessor (11) for evaluation, wherein the microprocessor (11) feeds the message containing gear information after evaluation to a driver device (12) for actuating a display means (13) for the purpose of displaying the gear information, and - the message present on the data line (2) is fed to a monitoring means (14) for evaluation, the gear information supplied to the microprocessor (11) in the message and / or the processing of the message carried out in the display unit (10) are checked and, in the event of a fault before the display of the gear information, the display means (13) is in a safe state.Method according to Claim 19, characterized in that the checking comprises reading the data supplied by the microprocessor (11) of the driver device (12) from one of the memories (23) of the driver device (12) and comparing this data with the information contained in the message.Method according to one of Claims 19 or 20, characterized in that, in the event of a fault detected outside the display unit (10), the gear information is displayed in the display means (13) as a safe state.Method according to one of Claims 19 to 21, characterized in that, in the event of a fault detected within the display unit (10), the gear information is blocked out as a safe state in the display means (13) or the display means (13) is switched to dark.Method according to claim 21 or 22, characterised in that the gating of the gear information in the display means (13) is effected by the microprocessor (11) and / or the monitoring means (14) by the driver device (12) being controlled accordingly by the microprocessor (11).Method according to claim 22, characterised in that the display means (13) is switched to dark by the monitoring means (14) by disconnecting a voltage supply to the driver device (12).Method according to one of Claims 19 to 24, characterized in that a change from the safe state to a normal operation of the display unit (10) takes place if the fault detected outside the display unit (10) is no longer present.Method according to Claim 25, characterized in that a change from the safe state to the normal operation of the display unit (10) takes place if the fault detected within the display unit (10) is no longer present and the checking of the display unit (10) could be successfully concluded.Method according to Claim 25 or 26, characterized in that, before the display device changes to normal operation, microprocessor (11) and monitoring means (14) are alternately checked, and these components are initialized.Method according to one of Claims 25 to 27, characterized in that, during normal operation of the display device (100), a cyclical checking of the components and initialization is carried out.Method according to one of Claims 19 to 28, characterized in that the message present on the data line (2) comprises at least one piece of gait information and one piece of complementary information, and the checking of the message present on the data line (2) comprises a comparison of the gait information with the complementary information.Method according to one of Claims 19 to 29, characterized in that, as part of the checking of the message, a check for an alive information item takes place.Method according to one of Claims 19 to 30, characterized in that a check for a timeout takes place as part of the check of the message.Method according to one of Claims 29 to 31, characterized in that the checking is carried out in the microprocessor (11) and / or the monitoring means (14).Method according to one of Claims 19 to 32, characterized in that, during the checking of the message, trigger monitoring takes place in which the monitoring means (14) monitors a trigger signal of the microprocessor (11) and the microprocessor (11) monitors a trigger signal of the monitoring means (14).

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