Method for operating a lighting device for a motor vehicle
The method dynamically assigns multicast addresses to groups of lighting units based on an evaluation criterion, reducing data bus load and message inefficiencies in motor vehicle lighting systems.
Patent Information
- Application Number
- DE102019124960
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2019-09-17
- Publication Date
- 2026-05-13
- Estimated Expiration
- 2039-09-17
AI Technical Summary
Existing lighting systems for motor vehicles require additional grouping messages to control lighting units in groups, increasing data on the data bus and inefficiency in message transmission.
A method that dynamically assigns multicast addresses to groups of lighting units based on an evaluation criterion, reducing the number of grouping messages by ensuring only a few lighting units require new multicast addresses, thereby minimizing data bus load.
The method effectively reduces the number of grouping messages, allowing efficient control of lighting units with minimal data bus usage while maintaining control over light characteristics.
Smart Images
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Abstract
Description
[0001] The invention relates to a method for operating a lighting device for a motor vehicle and to a corresponding lighting device.
[0002] Automotive lighting devices are known from the prior art, comprising a plurality of lighting units that can be individually controlled via a data bus by control messages from a control unit to emit light with a predetermined characteristic. Such a lighting device is disclosed, for example, in publication WO 2017 / 084 881 A1. This lighting device comprises one or more processing modules, an internal data bus, and a plurality of LED units. The internal data bus is an SPI bus or a differential data bus, where a differential data bus encodes digital data via a voltage difference between two lines. Each processing module is assigned several LED units from the plurality of LED units, and the respective processing module is coupled to the assigned LED units via the internal data bus.The associated LED units each comprise one or more LEDs and an integrated circuit and are connected to a power supply for the LED(s). The respective processing module is configured to connect to an automotive data bus in order to receive initial digital control commands for operating the lighting device from the automotive data bus and to send secondary digital control commands to the internal data bus. The associated LED units are configured to supply their LEDs with current from the power supply based on the secondary digital control commands on the internal data bus, using the integrated circuits.
[0003] Document US 2009 / 0021955A1 discloses a lighting system for a transit vehicle that includes multiple LED-based lighting devices for providing interior lighting. A control network comprises multiple slave nodes for controlling the LED-based lighting devices and a master node for controlling the slave nodes.
[0004] German patent application DE 10 2015 003 001 A1 discloses a method for operating a lighting device with a lighting element arrangement. A current-controlled, pulse-width modulated supply current is received via one terminal contact and passed through to another terminal contact. The duration of each phase of the supply current is determined, and depending on the determined duration, one or more bits of a message are decoded. The message contains an address, which is determined by a control circuit and compared with an address stored in the lighting device. Only if the addresses match is a switching state selected for a switch arrangement of the lighting device. The message can also include a lighting pattern identifier, which specifies a color of light to be produced or a mixed lighting color.The selected switching state is set in the switch arrangement, so that the lighting element arrangement is operated by means of the supply current depending on the set switching state.
[0005] The German patent application DE 10 2013 210 261 A1 discloses a lighting device for a vehicle, comprising a plurality of light-emitting diodes divided into groups, a series resistor connecting the plurality of light-emitting diodes to a voltage source, and a control unit configured to control the light-emitting diodes or groups of light-emitting diodes by means of pulse width modulation and to output PWM control signals for the light-emitting diodes successively within one period and to vary the pulse widths of the PWM control signals for the light-emitting diodes.
[0006] US patent 2016 / 0284177A1 discloses a lighting system with a light strip comprising a plurality of light-emitting diodes (LEDs) along the length of the strip. The light strip includes three conductors connected to the LEDs in a connection arrangement that allows selected LEDs to be addressed to illuminate the diodes. The diodes are arranged in physical groups, with each diode in the physical group being addressed by a different address. The physical groups are repeated such that diodes with the same address, but located in different groups, are arranged in address groups. Address signals cause an address group to light up.
[0007] The publication US 2019 / 0132929A1 discloses a method for operating a plurality of drive units for driving electronic units, comprising an exchange of a data frame containing a bit sequence between a master control unit and at least one of the plurality of drive units at slave nodes. The method is preferably intended for operating LEDs in a lighting system of a motor vehicle.
[0008] It is therefore known from the above-mentioned publications that lighting units of lighting devices for motor vehicles can be controlled individually or in groups by means of a control unit via addresses, whereby both individual lighting units and several lighting units can be specifically addressed and light with variable characteristics can be emitted at each address.
[0009] To control a lighting device of the type described above, the individual lighting units can be addressed separately using unicast addresses. It is also possible to group lighting units and then address them together using multicast addresses. In this way, the light characteristics of all lighting units in a group can be changed using a single multicast message. Grouping messages are used to divide the lighting units into groups; these are transmitted over the data bus in the same way as the control messages. Consequently, while fewer control messages are required when controlling lighting units in groups, additional grouping messages are necessary, which increases the amount of data on the data bus.
[0010] The object of the invention is to create a method for operating a lighting device for a motor vehicle in which the lighting units of the lighting device are controlled in groups and at the same time the amount of data on the data bus is kept low.
[0011] This problem is solved by the method according to claim 1 or the lighting device according to claim 13. Further developments of the invention are defined in the dependent claims.
[0012] The method according to the invention serves to operate a lighting device for a motor vehicle, which comprises a plurality of lighting units, a data bus, and a control unit. In a particularly preferred embodiment, the lighting units are compact LED units and preferably RGB LED units comprising a red, green, and blue LED. The lighting units of the lighting device can emit light with variable characteristics and are coupled to the data bus, via which the control unit can address the lighting units using unicast and multicast addresses. Each individual lighting unit is assigned a unicast address. Furthermore, a set of multicast addresses is provided, each of which can be assigned to several lighting units in order to address the multiple lighting units simultaneously.
[0013] In the method according to the invention, the characteristics of the emitted light from the lighting units are repeatedly adjusted in successive cycles. In each cycle, which is preceded by another cycle (i.e., not in the initial cycle), the following steps a) to e) are carried out.
[0014] In step a), the lighting units are divided into groups by the control unit such that the lighting units which, in the respective cycle, are to emit light with the same characteristics according to control information in the control unit, are assigned to the same group, thus obtaining current groups for the respective cycle. The term "groups" is to be understood broadly. In one embodiment of the invention, the groups can also contain only one lighting unit. Preferably, however, a minimum number of several lighting units is specified for forming a group, e.g., two or three lighting units. In this case, a lighting unit that is the only one emitting light with a specific characteristic is not assigned to any group.
[0015] If the group classification in the current cycle changes compared to the group classification in the previous cycle, in step b) the control unit determines an evaluation measure for each combination of the current group and the old group determined in the previous cycle. This measure is higher the greater the number of matching luminous units between the current group and the old group of the respective combination. Furthermore, the evaluation measure is lower the greater the number of matching luminous units between the current group of the respective combination and the old groups not belonging to the respective combination, and the greater the number of matching luminous units between the old group of the respective combination and the current groups not belonging to the respective combination.
[0016] In step c), multicast addresses from the old groups are then assigned to the current groups. It is assumed that this assignment process is aborted once each current group has received a multicast address. Specifically, in step c), the control unit assigns the multicast addresses of the old groups to the current groups by assigning the multicast address of each old group to the current group that combination of current group and respective old group with the highest weighting factor, provided that the current group has not yet been assigned a multicast address in the current cycle. Conversely, if the current group already has a multicast address assigned to the combination with the highest weighting factor, the multicast address of the respective old group is assigned to another current group that does not yet have an assigned multicast address.In one variant of the invention, this assignment can be made without further consideration of the evaluation criteria. For example, a successive search can be performed for unassigned current groups, and the first current group found can then be assigned to the multicast address of the old group.
[0017] Furthermore, in step c), each of the current groups that have not yet received a multicast address (if any) after the multicast addresses of all previous groups have been assigned is assigned an unassigned multicast address from the predefined set of multicast addresses. The assignment of corresponding multicast addresses from the predefined set to current groups can be performed differently depending on the implementation. For example, an initial assignment of multicast addresses to groups can be used for this purpose.
[0018] In step d) of the method according to the invention, the control unit sends one or more grouping messages in the form of unicast and / or multicast messages to the lighting units via the data bus, with which the lighting units receive the multicast addresses of the current groups according to their assignment to the current groups.
[0019] In step e), the control unit sends a control message via the data bus for each current group in the form of a multicast message. This message includes the multicast address of the respective current group and a parameter value for setting the characteristic of the emitted light from the lighting units of the respective current group. The lighting units of the respective current group then emit light with this characteristic. In a preferred embodiment, the variable characteristic of the light from the lighting units is the light color, so that the parameter value above determines the light color. The term "parameter value" is to be interpreted broadly. In particular, a parameter value can also comprise several partial values.
[0020] The method according to the invention is based on the finding that by assigning multicast addresses to groups based on the evaluation criterion defined above, only a few lighting units require new multicast addresses, thereby keeping the number of grouping messages low and thus reducing the amount of data on the data bus.
[0021] In a preferred embodiment of the method according to the invention, if, according to the grouping of step a), one or more lighting units are not assigned to any current group, the control device sends a control message in the form of a unicast message for each of these lighting units via the data bus, which includes the unicast address of the respective lighting unit and a parameter value for setting the characteristic of the emitted light of the respective lighting unit, whereupon the respective lighting unit emits light with this characteristic.
[0022] In a particularly preferred embodiment, the evaluation measure for each combination of current group and old group is as follows: A⋅mij−∑k=0Mmik−∑k=0Nmkj where i = 0, 1,..., N is an index for numbering the old groups; where j = 1, ..., M is an index for numbering the current groups; where A > 2 and preferably A = 4; where m ij the number of matching luminous units between the current group with index j and the old group with index i, where the current group with index j and the old group with index i represent the respective combination of current group and old group.
[0023] Simulations have shown that the rating measure according to the above formula is particularly effective at reducing the number of grouped messages.
[0024] In a further preferred embodiment, if, during the assignment of a multicast address to a respective old group in step c), the current group has already been assigned a multicast address in the respective cycle to the combination with the highest weighting factor, the multicast address of the respective old group is assigned to the current group to the combination of the current group with the unassigned multicast address and the respective old group with the highest weighting factor. In other words, this assignment always searches for the combination with the highest possible weighting factor, which further reduces the number of grouping messages.
[0025] In a further preferred embodiment, the following steps i) to iii) are performed in the initial cycle, which is not preceded by any other cycle. In step i), the lighting units are divided into groups by the control device such that the lighting units which, in the initial cycle, are to emit light with the same characteristics according to a control signal in the control device, are assigned to the same group, thereby obtaining current groups for the initial cycle, wherein initially a multicast address from the predefined set of multicast addresses is assigned to each current group.
[0026] In step ii), the control unit sends one or more grouping messages in the form of unicast and / or multicast messages to the lighting units via the data bus, with which the lighting units receive the multicast addresses of the current groups according to their assignment to the current groups.
[0027] In step iii), the control unit sends a control message via the data bus for each current group in the form of a multicast message, which includes the multicast address of the respective current group and a parameter for setting the characteristic of the emitted light of the lighting units of the current group, whereupon the lighting units of the respective current group emit light with this characteristic.
[0028] In a preferred embodiment of the above, if, according to the grouping in step i), one or more lighting units are not assigned to any current group, the control device sends a control message in the form of a unicast message for each of these lighting units via the data bus, which includes the unicast address of the respective lighting unit and a parameter value for setting the characteristic of the emitted light of the respective lighting unit, whereupon the respective lighting unit emits light with this characteristic.
[0029] In a further preferred embodiment, the case is addressed in which, during the initial cycle in step i), at least a predetermined percentage (i.e., the predetermined percentage or more) of all lighting units are assigned to the same current group. In this case, first, with at least one grouping message in the form of a broadcast message addressing all lighting units of the lighting device, all lighting units temporarily receive the multicast address of this same current group. Subsequently, with at least one grouping message in the form of a unicast message, all lighting units that do not belong to this same current group receive the multicast address initially assigned to them according to their group membership. Preferably, the predetermined percentage above is set to 50% or more. This variant of the invention allows for a further reduction in the number of grouping messages.
[0030] In a further embodiment of the method according to the invention, it is checked whether, according to the grouping in step a), all lighting units of an old group become part of a current group. If this is the case, in step e), at least one grouping message in the form of a multicast message with the multicast address of the old group is sent by the control unit via the data bus, whereby the lighting units of the old group receive the multicast address of the current group by means of this at least one grouping message. With this variant, a group address can be communicated to several lighting units simultaneously via a multicast message, thereby further reducing the number of grouping messages.
[0031] In another preferred embodiment, a grouping message comprises a bitmask in which one bit is provided for each multicast address of at least a subset of the specified set of multicast addresses. Optionally, bits can be provided for all multicast addresses of the specified set. However, it is also possible for grouping messages to contain only bits for a subset of the specified set of multicast addresses. In each grouping message, the state of the respective bit specifies whether the lighting unit addressed by the grouping message receives the multicast address corresponding to that bit or not.
[0032] The method according to the invention can be used to control any motor vehicle lighting device. In particular, the lighting device can be an interior light for installation in the interior of the motor vehicle or an exterior light for mounting on the outside of the motor vehicle. In a particularly preferred embodiment, the lighting device is an ambient interior light.
[0033] In addition to the method described above, the invention relates to a lighting device for a motor vehicle, wherein the lighting device comprises a plurality of lighting units, a data bus, and a control unit. The lighting device is designed such that, during operation, it carries out the method according to the invention or one or more preferred variants thereof.
[0034] The invention further relates to a motor vehicle which includes one or more of the lighting devices according to the invention.
[0035] An embodiment of the invention is described in detail below with reference to the accompanying figures.
[0036] They show: Fig. 1 a schematic representation of an embodiment of a lighting device according to the invention; Fig. 2 a flowchart showing the procedure for operating the lighting device Fig. 1 reproduces; Fig. 3 a schematic representation which exemplifies the division of the lighting units into groups according to step S1 from Fig. 2 clarifies; Fig. 4 a schematic representation of the determination of a matching matrix for the groups from Fig. 3, wherein the matching matrix is used in the procedure of Fig. 2 is needed to determine the evaluation measures; and Fig. 5 a schematic representation which illustrates the determination of the evaluation measures using an example of a conformity matrix.
[0037] In the following, an embodiment of the invention is described with reference to the in Fig. The lighting device 100 shown in Figure 1 is described, which comprises a plurality of LED units arranged on a strip as lighting units. These LED units are arranged in Fig. 1 is designated with reference numeral 3. The individual LEDs of the LED units are designated with reference numerals 301, 302, and 303. LED 301 is a red LED, LED 302 is a green LED, and LED 303 is a blue LED. Each LED unit 3 contains an integrated circuit, which is designated with reference numeral 4. The LEDs and the integrated circuit are housed in a common package. The individual LED units 3 are controlled by a control unit 1, which generates a digital data stream in the form of a bitstream. This data stream is supplied to the individual LED units via an internal data bus 2 (i.e., a data bus provided internally within the lighting device).
[0038] The control unit 1 controls the LED units according to a selected operating program. The operating program can be selected, for example, based on commands entered by a user via a user interface (not shown) that is connected to the control unit 1 via an external data bus (e.g., a LIN bus) (not shown). If necessary, the control units of several lighting devices 100 can be connected to an external data bus, and in particular a LIN bus, which in turn is connected to a central vehicle control unit that sends control commands to the control units 1 via the external data bus.
[0039] In the embodiment described here, the internal data bus 2 is an SPI bus with one line CL for the clock signal and one line DL for the bitstream. In addition, two power lines L1 and L2 are provided, which are connected to a DC power supply 5. Based on the bitstream received via the data line DL, the current supplied to the individual LEDs 301 to 303 is PWM modulated in order to control the LEDs according to the bitstream on the data line DL.
[0040] In the embodiment described here, the LED units 3 are controlled by the control unit 1 in successive cycles, in each of which the control unit 1 transmits a so-called frame as a bitstream onto the data bus 2. Each frame transmits RGB color values to the respective LED units 3, based on which the PWM modulation of the LEDs in the respective LED units is set, so that the individual LED units emit light in the color corresponding to the transmitted color value. Each LED unit can be individually controlled with a different color value and thus illuminate in different colors.
[0041] Control messages SN are used to control the individual LED units 3 within a frame. These messages can be sent as either unicast or multicast messages via the control unit 1 onto the data line DL. The control messages contain a corresponding RGB color value FW, to which a single LED unit is set in the case of a unicast message, or multiple LED units in the case of a multicast message. Unicast addresses UA are used to address individual LED units using unicast messages, with each LED unit being assigned a fixed unicast address. The unicast addresses are listed in Fig. 2 generally designated with reference symbol UA. Pre-reserved multicast addresses are used to control multiple LED units via multicast messages; these are listed in Fig. 2 are generally designated with reference numeral MA.
[0042] The multicast addresses MA can be dynamically distributed to different groups of multiple LED units. The dynamic assignment of multicast addresses to corresponding groups of multiple LED units is accomplished using grouping messages GN, which, analogous to the control messages SN, are transmitted as unicast and / or multicast messages via control unit 1 onto the data line DL. The aim of the procedure described here is to group the LED units in each frame using as few grouping messages as possible, so that LED units which are to illuminate based on the same color value (i.e., with the same color) are assigned to the same group and controlled together via the same multicast message.In other words, the LED units should be controlled using as few messages as possible, so that the largest possible number of LED units can be operated according to the maximum utilization of the data bus.
[0043] Without loss of generality, an embodiment is described below in which there are a total of 16 multicast addresses MA for assignment to corresponding groups of LED units. Furthermore, the structure of a grouping message GN is such that it comprises a bitmask consisting of a control bit (range selection bit) and eight subsequent bits. The control bit indicates whether the grouping message refers to the first eight upper multicast addresses or the second eight lower multicast addresses. In other words, a control bit with a state of 0 indicates that the grouping message concerns the upper eight multicast addresses, whereas a control bit with a state of 1 indicates that the grouping message refers to the lower eight multicast addresses. The states of the bits following the control bit indicate which multicast addresses the LED unit addressed by the grouping message receives.A bit state of 1 corresponds to the assignment of a multicast address to the LED unit. A multicast address can also be revoked by changing the corresponding bit state from 1 to 0.
[0044] As mentioned above, the grouping messages GN, analogous to the control messages SN, can be sent as multicast messages with a corresponding multicast address to the currently existing groups. Likewise, the grouping messages can be sent as unicast messages with a unicast address for each individual LED unit being addressed. With the grouping message structure described above, it may be necessary to send two grouping messages to reassign multicast addresses. This is the case, for example, when a multicast address is removed from the upper eight multicast addresses of the addressed LED unit and a multicast address is assigned from the lower eight multicast addresses.
[0045] The following will be based on Fig. 2 a variant of the inventive method for operating the LED units 3 in the lighting device 100 Fig. 1 described. Steps S1 to S5 are carried out by the control unit 1. The starting point of the procedure are the unicast addresses UA, which are each permanently assigned to an LED unit, and the 16 dynamically assignable multicast addresses MA for assigning LED units to groups.
[0046] At the start of the process, consecutively numbered group identities are initially assigned to multicast addresses (MA). LED units that can be controlled with the same color value (FW) are then successively identified. The 16 largest groups of LED units, each with the same color value (FW), are assigned the same group identities and, consequently, the same multicast addresses. No multicast address is assigned to LED units that do not belong to the 16 largest groups. Subsequently, the control unit sends one grouping message (GN) to inform each LED unit of its group address, i.e., its corresponding multicast address. The minimum group size can be defined differently. In particular, it is possible for a group to consist of only one LED unit.However, a larger number of LED units, e.g., two or three LED units, is usually specified as the minimum size. In this case, not all LED units may be assigned to groups.
[0047] After the initial assignment of the group addresses, the control unit 1 sends the corresponding control messages SN with the color value FW as multicast messages to the groups, whereas unicast messages are transmitted as control messages with the corresponding color value to be set to the LED units not belonging to any group.
[0048] Based on Fig. Section 2 now describes the transmission of a frame for setting color values for the LED units 3 in a case where a frame has already been transmitted previously. In the control unit 1, in step S1, the individual LED units are first divided into groups, analogous to the initialization of the procedure, whereby LED units that are to be controlled with the same color value FW are assigned to the same group. An AVL tree, which is known per se, can optionally be used to search for LED units with the same color values. An AVL tree is a balanced, binary search tree which, in the embodiment described here, contains the LED units as nodes and searches for LED units with the same color values by comparing their binary color values.A search using an AVL tree speeds up step S1 compared to a search where the color value of an LED unit belonging to a group is compared with all color values of LED units that are not yet assigned to a group.
[0049] Step S1 is shown again as an example in Fig. Figure 3 illustrates a scenario where the lighting device contains a total of 13 LED units. The LED units are represented by circles, with circles having the same fill (i.e., white, dotted, diagonally hatched, or vertically hatched) being controlled with the same color value FW in the corresponding frame.
[0050] In the upper part of the Fig. Figure 3 indicates a previously performed grouping with subsequent control of the LED units for frame FRn-1. As can be seen, there are a total of four original groups assigned in frame FRn-1, labeled G0', G1', G2', and G3'. Group G0' contains four LED units, group G1' one LED unit, group G2' four LED units, and group G3' also four LED units. In the already processed frame FRn-1, corresponding multicast addresses are assigned to the individual groups G0', G1', G2', and G3' via sent grouping messages. In the frame FRn following frame FRn-1, the LED units are controlled with different color values, resulting in different group assignments. While there are again four groups G0, G1, G2, and G3, the individual groups contain different LED units than in frame FRn-1.
[0051] After the LED units have been divided into groups in frame FRn, group addresses in the form of multicast addresses must now be assigned to the newly formed groups using grouping messages. For this purpose, the addresses of the old groups in frame FRn-1 are assigned to the new, current groups in frame FRn using evaluation measures (BM). These evaluation measures are used in step S2 of the procedure. Fig. 2. A rating measure is determined for each combination of the old group in frame FRn-1 and the new group in frame FRn. The determination of the rating measures is illustrated below using an example of... Fig. 4 and Fig. 5 explained.
[0052] According to Fig. 4. To determine the evaluation measures, a matching matrix (MM) is first calculated. The group identities of the new group G0 to G3 represent columns of this matrix, and the group identities of the old groups G0' to G3' represent rows of this matrix. For each entry in the matrix, it is then determined how many matching LED units exist between the new group and the old group according to the entry's position in the matrix. This results in the following: Fig. The four displayed entries range between 0 and 3. For example, the entry in row G0' and column G1 has the value 3. How to determine this from Fig. If 3 is detected, the second to fourth LED units in frame FRn fall into group G1 in order from left to right, whereas these LED units in frame FRn-1 are in group G0', resulting in the value of three matching LED units.
[0053] After determining the agreement matrix MM, the evaluation measure BM is determined from it, as in Fig. Figure 5 indicates this. There, another agreement matrix is shown as an example, this time for three new groups G0, G1, and G3, and three existing groups G0', G1', and G2'. The rating measure BM for each entry in matrix MM is given by the following, in Fig. Formula shown in section 5 is given: A⋅mij−∑k=02mik−∑k=02mkj m ij This refers to the corresponding entry in the matching matrix MM in row i and column j.
[0054] As can be seen, the evaluation measure for a corresponding entry in matrix MM is determined by considering the value of the entry itself, as well as the sum of the values of the entries in the same column and row of the entry under consideration. The evaluation measure BM is higher the greater the number of matching LED units between the new and old groups of the corresponding entry. Furthermore, the evaluation measure becomes lower the higher the number of matching LED units in the same column or row of the entry under consideration. Additionally, the currently considered entry is weighted more heavily in the evaluation measure than the other entries by being multiplied by a factor of 4. Based on the evaluation measures BM for the entries of matrix MM, one finally obtains the following: Fig. 5. Rating matrix RM (English: Rating Matrix), which indicates the corresponding rating measure for each entry from the agreement matrix MM according to the formula above.
[0055] The RM evaluation matrix is then used in step S3 to determine the Fig. 2. The group addresses of the old groups are assigned to the new groups. In the embodiment described here, this is done by first determining the maximum of the evaluation measure for each row of the RM matrix. The corresponding position of the maximum in the RM matrix then indicates the assignment of the address of the old group to the new group. For example, in the first row of the RM matrix, Fig. 5. The entry in the first row and the first column is the entry with the maximum weighting factor in the first row. Consequently, the multicast address of the old group G0' is assigned to the new group G0. The same procedure is followed for the second and third rows. Should it occur that a multicast address is already assigned to the new group at the matrix position of the maximum weighting factor in a corresponding row, the entry used to assign the multicast address of the old group to the new group, in the embodiment described here, is the one that first relates to a combination for which the new group has not yet been assigned a multicast address, in order from left to right. Alternatively, it is also possible to always search for the entry with the next highest weighting factor that relates to a combination for which no multicast address has yet been assigned to the new group.
[0056] The allocation of multicast addresses using the evaluation measures BM described above takes into account the fact that the number of grouping messages decreases the greater the number of matching light units between the old and new groups with the same multicast address, and the smaller the number of matching light units for alternative combinations of old and new groups.
[0057] After the group addresses of the old group have been assigned to the new groups, step S4 of the Fig. 2. Grouping messages GN are now sent to data bus 2 by control unit 1. These grouping messages assign each LED unit 3 its new group address. No grouping messages are sent to LED units whose group address remains unchanged. First, it is checked whether the currently considered LED unit has been assigned to a group. If not, the LED unit is subsequently addressed individually with a control message SN in the form of a unicast message. A 16-bit leave mask is created for LED units that were assigned to a group in the previous frame. Each bit of this mask represents a group address. Similarly, a join mask is created for the LED units that are assigned to a group in the current frame. Both masks are present when both conditions are met.In the Leave mask, the bit corresponding to the group address of the previous frame is set to 1. This is because the LED unit needs to be informed of a change in the group address. In contrast, in the Join mask, the bit corresponding to the group address of the current frame is set to 1 to communicate the new group address. The mapping of the group addresses of the old groups to the new groups, determined in step S3, is used to create the Leave and Join masks.
[0058] As mentioned above, a grouping message consists of a control bit and eight additional bits. This control bit, along with the other eight bits, can be used to mask either the upper eight group addresses or the lower eight group addresses. The 16-bit leave and join masks must therefore be adapted to this division. Accordingly, the upper part is addressed first. If the leave and join masks are identical in this area, no grouping message needs to be sent, as this could mean either that the address remains the same or that the groups with the addresses in this area of the LED units are not assigned in either the previous or the current frame. If the masks differ, the corresponding area of the join mask and the appropriate preceding control bit are sent as the grouping message via the control unit.The control message is sent as a unicast message with the unicast address of the LED unit currently being viewed, onto the data bus.
[0059] After the grouping messages have been sent, the LED units can be addressed using their group addresses. Consequently, in step S5 of the... Fig. 2. The control messages SN are sent to the LED units. Each control message contains the color value FW to be set. For LED units that are controlled with the same color value and therefore belong to the same group, a multicast message with the assigned group address is sent as the control message. For all other LED units that do not belong to any group, corresponding unicast messages with the color value to be set are transmitted. In the next frame, steps S1 to S5 are then repeated.
[0060] Optionally, the procedure can be used to... Fig. 2. Further optimizations are also carried out. The first optimization concerns the initial assignment of group addresses at the beginning of the process. If it is determined that the number of lighting units assigned to the same group is greater than or equal to a predefined percentage of 50% of all lighting units, a broadcast message with a fixed broadcast address is sent, through which all lighting units temporarily receive the same group address. Subsequently, unicast messages are sent, whereby the minority of LED units that were incorrectly assigned to the temporary group receive their correct address according to the initial group assignment.
[0061] In a second optimization, the scenario of operating the lighting device is considered, in which the same LED units continuously change their light color in pulses. This optimization is performed after the group addresses have been assigned, i.e., after step S3 of the Fig. 2. If it is determined that all LED units of an old group will become part of a current group, grouping messages are sent to the LED units of the old group as multicast messages using the (still existing) multicast address of the old group, thus addressing all LED units of the old group simultaneously. This allows for a further reduction in the number of grouping messages.
[0062] The embodiments of the invention described above offer a number of advantages. In particular, a method is provided by which the lighting units of a lighting device in a motor vehicle can be controlled via a data bus based on a small number of messages. The data bus load is thus kept low, allowing a large number of lighting units to be controlled via the same data bus. Within the framework of the method according to the invention, not only are lighting units with the same color values controlled with only one multicast message, but it is also ensured that the number of messages for assigning these multicast addresses is kept low. Reference symbol list 100 lighting device 1 Control unit 2 Data bus 3 LED units 301, 302, 303 LEDs 4 integrated circuit 5 Power supply CL line for clock signal DL data line L1, L2 power lines SN Tax News FW color value GN Group News S1, S2, ..., S5 steps G0, G1, G2, G3 current groups G0', G1', G2', G3' old groups MM Matching Matrix BM rating scale RM rating matrix
Claims
Method for operating a lighting device (100) for a motor vehicle, comprising a plurality of lighting units (3), a data bus (2) and a control unit (1), wherein the lighting units (3) can each emit light with variable characteristics and are coupled to the data bus (2), via which the control unit (1) can address the lighting units (3) using unicast addresses (UA) and multicast addresses (MA), wherein each individual lighting unit (3) is assigned a unicast address (UA) and a set of multicast addresses (MA) is specified, each of which can be assigned to several lighting units (3) in order to address the several lighting units (3) simultaneously, wherein the characteristic of the emitted light of the lighting units (3) is repeatedly set in successive cycles (FRn-1, FRn) and in each cycle (FRn) preceded by a cycle (FRn-1),The following steps are performed: a) The lighting units (3) are divided into groups (G0, G1, G2, G3) by means of the control device (1) such that the lighting units (3) which are to emit light with the same characteristics in the respective cycle (FRn) are assigned to the same group (G0, G1, G2, G3), thereby obtaining current groups (G0, G1, G2, G3) for the respective cycle (FRn); b) If the group classification in the respective cycle (FRn) changes compared to the group classification in the previous cycle (FRn-1), a rating measure (BM) is determined by means of the control device (1) for each combination of current group (G0, G1, G2, G3) and old group (G0', G1', G2', G3') determined in the previous cycle (FRn-1), which is higher the greater the number of matching lighting units (3) between the current group (G0, G1, G2, G3) and the old group (G0', G1', G2', G3') of the respective combination is,and which is smaller the greater the number of matching light units (3) between the current group (G0, G1, G2, G3) of the respective combination and the old groups (G0', G1', G2', G3') not belonging to the respective combination; c) Multicast addresses (MA) of the old groups (G0', G1', G2', G3') are assigned to the current groups (G0, G1, G2, G3) by means of the control device (1) by assigning the multicast address (MA) of a respective old group (G0', G1', G2', G3') to the current group (G0, G1, G2, G3) of that combination of current group (G0, G1, G2, G3) and respective age group (G0', G1', G2', G3') with the highest rating (BM) is assigned if the current group (G0, G1, G2,G3) in the respective cycle (FRn) no multicast address (MA) has yet been assigned, otherwise the multicast address (MA) of the respective old group (G0', G1', G2', G3') is assigned to another current group (G0, G1, G2, G3) with a multicast address (MA) not yet assigned, and each of the current groups (G0, G1, G2, G3) which have not yet received a multicast address (MA) after the multicast addresses (MA) of all old groups (G0', G1', G2', G3') are assigned an unassigned multicast address (MA) from the specified set of multicast addresses (MA); d) by means of the control device (1) one or more grouping messages (GN) in the form of unicast and / or multicast messages are sent via the data bus (2) to the lighting units (3), with which the lighting units (3) are assigned according to their assignment to the current groups (G0, G1, G2, G3) the multicast addresses (MA) of the current groups (G0, G1, G2,G3) received;e) by means of the control device (1) a control message (SN) in the form of a multicast message is sent via the data bus (2) for each current group (G0, G1, G2, G3), which includes the multicast address (MA) of the respective current group (G0, G1, G2, G3) and a parameter value (FW) for setting the characteristic of the emitted light of the lighting units (3) of the respective current group (G0, G1, G2, G3), whereupon the lighting units (3) of the respective current group (G0, G1, G2, G3) emit light with this characteristic. Method according to claim 1, characterized in that the variable characteristic of the light of the luminaire units (3) includes the light color and the parameter value (FW) determines the light color. Method according to claim 1 or 2, characterized in that, in the event that, according to the grouping of step a), one or more lighting units (3) are not assigned to any current group (G0, G1, G2, G3), a control message (SN) in the form of a unicast message is sent via the data bus (2) for each of these lighting units (3) by means of the control device (1) in step e), which includes the unicast address (UA) of the respective lighting unit (3) and a parameter value (FW) for setting the characteristic of the emitted light of the respective lighting unit (3), whereupon the respective lighting unit (3) emits light with this characteristic. Method according to one of the preceding claims, characterized in that the evaluation measure (BM) for a respective combination of current group (G0, G1, G2, G3) and old group (G0', G1', G2', G3') is as follows: A ⋅ mij − ∑ k = 0 M mik − ∑ k = 0 N mkj where i = 0, 1,..., N is an index for numbering the old groups (G0', G1', G2', G3'); where j = 1, ..., M is an index for numbering the current groups (G0, G1, G2, G3); where A > 2 and preferably A = 4; where m ij the number of matching luminous units (3) between the current group (G0, G1, G2, G3) with index j and the old group (G0', G1', G2', G3') with index i, where the current group (G0, G1, G2, G3) with index j and the old group (G0', G1', G2', G3') with index i represent the respective combination of current group (G0, G1, G2, G3) and old group (G0', G1', G2', G3'). A method according to one of the preceding claims, characterized in that, in the case that, when assigning a multicast address (MA) to a respective old group (G0', G1', G2', G3') in step c) of the current group (G0, G1, G2, G3) of the combination with the highest weighting measure (FRn) has already been assigned a multicast address (MA) in the respective cycle, the multicast address (MA) of the respective old group (G0', G1', G2', G3') of the current group (G0, G1, G2, G3) is assigned to that combination of current group (G0, G1, G2, G3) with not yet assigned multicast address (MA) and respective old group (G0', G1', G2', G3') with the highest weighting measure (BM). Method according to one of the preceding claims, characterized in that in the initial cycle, which is not preceded by any cycle (FRn-1, FRn), the following steps are performed: i) the lighting units (3) are divided into groups (G0, G1, G2, G3) by means of the control device (1) such that the lighting units (3) which are to emit light with the same characteristics in the initial cycle are assigned to the same group (G0, G1, G2, G3), thereby obtaining current groups (G0, G1, G2, G3) for the initial cycle, wherein initially a multicast address from the specified set of multicast addresses (MA) is assigned to each current group;ii) By means of the control unit (1), one or more grouping messages (GN) in the form of unicast and / or multicast messages are sent via the data bus (2) to the lighting units (3), with which the lighting units (3) receive the multicast addresses (MA) of the current groups (G0, G1, G2, G3) according to their assignment to the current groups (G0, G1, G2, G3); iii) The control unit (1) sends a control message (SN) in the form of a multicast message for each current group (G0, G1, G2, G3) via the data bus (2), which includes the multicast address (MA) of the respective current group (G0, G1, G2, G3) and a parameter value (FW) for setting the characteristic of the emitted light of the lighting units (3) of the respective current group (G0, G1, G2, G3), whereupon the lighting units (3) of the respective current group (G0, G1, G2, G3) emit light with this characteristic.; Method according to claim 6, characterized in that, in the event that, according to the grouping of step i), one or more lighting units (3) are not assigned to any current group (G0, G1, G2, G3), a control message (SN) in the form of a unicast message is sent via the data bus (2) for each of these lighting units (3) by means of the control device (1), which includes the unicast address (UA) of the respective lighting unit (3) and a parameter value (FW) for setting the characteristic of the emitted light of the respective lighting unit (3), whereupon the respective lighting unit (3) emits light with this characteristic. A method according to claim 6 or 7, characterized in that, in the initial cycle in step i), at least a predetermined percentage of all lighting units (3) of the lighting device (100) are assigned to the same current group (G0, G1, G2, G3), first, with at least one grouping message (GN) in the form of a broadcast message addressing all lighting units (3) of the lighting device (100), all lighting units (3) temporarily receive the multicast address (MA) of this same current group (G0, G1, G2, G3), and then, with at least one grouping message (GN) in the form of a unicast message, all lighting units (3) that do not belong to this same current group (G0, G1, G2, G3) receive the multicast address (MA) initially assigned to them according to their group membership, wherein the predetermined percentage is preferably 50% or more. A method according to one of the preceding claims, characterized in that, if it is determined that according to the grouping of step a) all lighting units (3) of an old group (G0', G1', G2', G3') become part of a current group (G0, G1, G2, G3), in step e) at least one grouping message (GN) in the form of a multicast message with the multicast address of the old group (G0', G1', G2', G3') is sent by means of the control device (1) via the data bus (2), wherein by means of the at least one grouping message (GN) the lighting units (3) of the old group (G0', G1', G2', G3') receive the multicast address of the current group (G0, G1, G2, G3). Method according to one of the preceding claims, characterized in that a grouping message (GN) comprises a bitmask in which a bit is provided for each multicast address (MA) of at least a part of the specified set of multicast addresses (MA), wherein the state of the respective bit specifies whether the lighting unit (3) addressed by the grouping message receives the multicast address (MA) corresponding to the respective bit or not. Method according to one of the preceding claims, characterized in that the lighting units (3) are LED units and in particular RGB LED units. Method according to one of the preceding claims, characterized in that a lighting device (100) is an interior light in the motor vehicle or an exterior light on the outside of the motor vehicle. Lighting device for a motor vehicle, wherein the lighting device (100) comprises a plurality of lighting units (3), a data bus (2) and a control unit (1), wherein the lighting units (3) can each emit light with variable characteristics and are coupled to the data bus (2), via which the control unit (1) can address the lighting units (3) using unicast addresses (UA) and using multicast addresses (MA), wherein each individual lighting unit (3) is assigned a unicast address (UA) and a set of multicast addresses (MA) is specified, which can each be assigned to several lighting units (3) in order to address the several lighting units (3) simultaneously, wherein the lighting device is configured to repeatedly adjust the characteristics of the emitted light of the lighting units (3) in successive cycles (FRn-1, FRn) and in each cycle (FRn),preceded by a cycle (FRn-1) to execute steps a) to e) of claim 1. Lighting device according to claim 13, characterized in that the lighting device (100) is configured to carry out a method according to one of claims 2 to 12. Motor vehicle comprising one or more lighting devices according to claim 13 or 14.