COMMUNICATION SYSTEM FOR ACTUATION OF MULTIPLE SUBSCRIBERS IN A MOTOR VEHICLE, AND DATA BUS FOR SUCH A COMMUNICATION SYSTEM

Abstract

A communication system is used to actuate multiple subscribers, particularly LED modules within a motor vehicle, specifically for ambient lighting. The communication system has a controller and subscribers. The subscribers are connected in series in a ring structure via a data line and each has a control unit. For actuating the individual subscribers, a data bus having a communication protocol, which has a linear juxtaposition of data packets, is used, wherein for each subscriber, a subscriber-specific data packet is provided. A respective data packet is divided into a subscriber portion and an information portion. The information portion contains a respective piece of information about the status of a subsequent subscriber portion. The information portion is overwritable by a respective subscriber. Each subscriber evaluates the respective first data packet that has the status “not received” and changes the status to “received”. This provides a communication system that requires no addressing.

Claims

1. A communication system for a motor vehicle, the communication system comprising: a controller; a data line; and a plurality of subscribers, said subscribers being connected in series one after another by means of said data line to form a subscriber chain, each of said subscribers having a control unit, said subscribers being actuated by said data line and a communication protocol, the communication protocol having a linear array of data packets, wherein a subscriber-specific data packet is provided for each of said subscribers, a respective subscriber-specific data packet is divided into a subscriber portion and an information portion, the information portion containing a piece of information that a respective subscriber can write to about a status of the subscriber portion, the respective subscriber using a first subscriber-specific data packet with a status “Not received” as its applicable data packet and changes the status to “Received”.

2. The communication system according to claim 1, wherein said data line has a single wire for a data transmission by means of which said subscribers are connected to one another in series.

3. The communication system according to claim 1, wherein said subscribers are connected to one another in series in a ring structure and exclusively a last of said subscribers is connected to said controller by means of a return line section of said data line.

4. The communication system according to claim 1, further comprising a supply line, wherein individual ones of said subscribers are part of an integrated cable set in which said subscribers are connected directly to said data line and said supply line in a plug-free fashion.

5. The communication system according to claim 1, wherein at least a number of said subscribers overwrite the subscriber portion with subscriber-specific information.

6. The communication system according to claim 1, wherein the subscriber-specific data packet has a checksum that can be used to check an integrity of data contained in the subscriber-specific data packet.

7. The communication system according to claim 1, wherein said controller and said subscribers form a ring structure and said controller at an end of the subscriber chain checks whether the subscriber chain is correct.

8. The communication system according to claim 1, wherein a number of subscriber-specific data packets corresponds to a number of said subscribers plus any control data packet.

9. The communication system according to claim 1, wherein at an end of the communication protocol there is a control data packet contained for said controller that said controller uses to check whether the subscriber chain is correct.

10. The communication system according to claim 1, wherein said subscribers are LED modules.

11. The communication system according to claim 1, wherein said subscribers are sensors.

12. The communication system according to claim 1, wherein the subscriber portion has a maximum of 64 bits.

13. The communication system according to claim 1, wherein the information portion contains a maximum of 16 bits.

14. The communication system according to claim 5, wherein the subscriber-specific information includes measured values or self-diagnosis values.

15. The communication system according to claim 1, wherein the subscriber portion has a maximum of 24 bits.

16. The communication system according to claim 1, wherein the subscriber portion has a maximum of 32 bits.

17. The communication system according to claim 1, wherein the information portion contains a maximum of 4 bits.

18. An operating method, which comprises the steps of: providing a communication system, containing: a controller; a data line; and a plurality of subscribers, said subscribers being connected in series one after another by means of said data line to form a subscriber chain, each of the subscribers having a control unit, the subscribers being actuated by the data line and a communication protocol, the communication protocol having a linear array of data packets, wherein a subscriber-specific data packet is provided for each of the subscribers, a respective subscriber-specific data packet is divided into a subscriber portion and an information portion, the information portion containing a piece of information that a respective subscriber can write to about a status of the subscriber portion, the respective subscriber using a first subscriber-specific data packet with a status “Not received” as its applicable data packet and changes the status to “Received”; and using the communication system in a motor vehicle for the subscribers.

19. A data bus for a communication system for actuating subscribers of the communication system, the data bus comprising: a communication protocol having a linear array of data packets, a subscriber-specific data packet is provided for each of the subscribers, a respective data packet is divided into a subscriber portion and an information portion, the information portion containing a piece of information that a respective subscriber can write to about a status of the subscriber portion.

20. The data bus according to claim 19, wherein the status is selected from the group consisting of “Received” and “Not received”.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0032] FIG. 1 is a highly simplified schematic depiction of a communication system with a controller and a multiplicity of subscribers according to the invention;

[0033] FIG. 2 is a schematic detailed depiction of the controller with two subscribers;

[0034] FIG. 3 is a simplified depiction of the communication protocol and the successive execution of the communication protocol within the subscriber chain of the communication system; and

[0035] FIG. 4 is an illustration showing a bit sequence of a respective subscriber-specific data packet within the communication protocol.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a communication system 2 which has a controller K and a multiplicity of individual subscribers Ti, i being a sequential index where i =1 to n and n being the total number of subscribers Ti. The individual subscribers Ti are in this case part of an integrated cable set 8 that, in the exemplary embodiment, is connected to the controller K by a plug connection 10. In the exemplary embodiment of FIG. 1, a direct plug connection 10 to the controller K is indicated in this case. Alternatively, there is also the possibility of the controller K being arranged remotely from the integrated cable set 8 and being connected to this integrated cable set by a further cable connection. The controller K is arranged, by way of example, in a central control device, which is not depicted in more detail here. The communication system 2 is particularly arranged inside a motor vehicle. The subscribers Ti are particularly LED modules and the whole communication system 2 is used for ambient lighting inside a motor vehicle interior.

[0037] The individual subscribers Ti are lined up in linear succession and connected to one another by an in particular single-wire data line 12, so that a subscriber chain 14 is formed, which is also referred to as a “daisy chain”. The data line 12 begins and ends at the controller K, so that a ring structure is formed. It is broken down into a single-wire feed line section 12A from the controller K to the last subscriber Ti and a single-wire return line section 12B from the last subscriber Ti directly to the controller K.

[0038] Besides the data line 12, the integrated cable set 8 additionally also preferably has a two-wire supply line 16, as depicted by way of example in FIG. 2 (not contained in FIG. 1).

[0039] One wire 16a of the supply line 16 provides a voltage potential of 5 volts, for example. The second wire 16b is at ground potential, for example. FIG. 2 additionally depicts the data line 12 by which the individual subscribers Ti are connected to one another in series. A respective subscriber Ti has an integrated control unit 18 and multiple LEDs 20. In the exemplary embodiment, three LEDs 20 for the colors red, green and blue are depicted. Preferably, there is additionally also a white LED provided as a fourth LED. The control unit 18 and the individual LEDs 20 are usefully arranged on a common circuit board of the respective subscriber Ti referred to as an LED module.

[0040] The controller K communicates with and actuates the individual subscribers Ti using a data bus that uses a communication protocol P, as explained in more detail with reference to FIG. 3. FIG. 3 is also used to explain the serial communication between the controller K and the individual subscribers Ti within the ring structure. By way of example, this is illustrated on the basis of three subscribers Ti, namely the first subscriber T1, the second subscriber T2 and the third subscriber T3, and also the controller K. Since the communication protocol P is modified for each subscriber Ti, the different communication protocols Pi are likewise provided with a sequential index. The original communication protocol output by the controller has the sequential index 0.

[0041] The communication protocol Pi is made up of multiple subscriber-specific data packets Di, the index i being a sequential index for the respective subscriber Ti. In the exemplary embodiment, a communication protocol for 3 subscribers Ti is depicted by way of example. In addition, the communication protocol K in the exemplary embodiment also has a control data packet Dc at the end of the individual subscriber-specific data packets Di.

[0042] A respective subscriber-specific data packet Di is formed by a bit sequence, that is to say a linear succession of logic ones and zeros, the bit sequence being divided into at least two portions, namely an information portion I and a subscriber portion T. In the exemplary embodiment, there is also a bit sequence for a checksum C contained at the end of the respective subscriber-specific data packet Di.

[0043] A piece of information about the status of the subscriber T is contained inside the information portion I. Specifically, in the exemplary embodiment, a distinction is drawn here between the status “not received” and the status “received”. This is characterized in FIG. 3 by the label l(NE) for the status “not received” and by I(E) for the status “received”.

[0044] Accordingly, the subscriber portion T has control information for actuation for a respective subscriber Ti. This is denoted by T(S) in FIG. 3. If the subscriber portion T is overwritten with subscriber-specific information, however, this is denoted by T(TI) in FIG. 3. In addition, the data packets Di that are overwritten with subscriber-specific information TI have a grey background. The communication within the communication system 2 is as now described.

[0045] The controller K delivers the communication protocol P0 having the subscriber-specific data packets Di to the first subscriber Ti. All of the subscriber-specific data packets Di show the status “not received” (T(NE)) in the information portion I. This indicates that the respective data packet Di has not yet reached the associated subscriber Ti and been received thereby. In addition, the respective subscriber portion T contains respective actuation information S.

[0046] The first subscriber T1 therefore receives the original communication protocol P0, as depicted in the first row of FIG. 3.

[0047] The subscriber T1 uses the first data packet D1 and takes the applicable control information S contained therein. Subsequently, the first subscriber T1 overwrites the status information to “received” and at the same time preferably also overwrites the subscriber portion T with subscriber-specific information TI.

[0048] The communication protocol modified in such a way is forwarded as communication protocol P1 to the next subscriber T2. The latter—like every other subscriber 6 too—first evaluates the information portion I. In this case, the respective subscriber Ti ignores the respective data packet Di until it encounters the first data packet Di, for which the information portion I contains the status “not received”. The respective subscriber Ti then takes this as the data packet Di intended for it and uses the control information S contained therein. Subsequently, the respective subscriber Ti writes to the information portion of the data packet Di, changes the status to “received” and also writes to the subscriber portion T thereof. This takes place progressively until all data packets Di have been modified and written to. Each subscriber-specific data packet Di therefore has the status “received” in the information portion I at the end of the subscriber chain 14 and additionally contains subscriber-specific information TI in the subscriber portion T. This communication protocol P3 modified by the last subscriber Tn is then finally transmitted back to the controller K. The latter first uses the checksums C of the individual data packets Di to check the information contained in the respective subscriber portion T for integrity. Finally, the controller K also uses control data packet Dc to check whether the subscriber chain 14 is correctly operational.

[0049] FIG. 4 finally also depicts, by way of example, a bit sequence of a respective subscriber-specific data packet Di, particularly for the instance of application in which the subscriber Ti is a four-color LED module. For each of the four colors red, green, blue and white, a respective 8-bit data sequence R,G,B,W is reserved. This 4×8-bit data sequence forms the subscriber portion in this case. This is preceded by the information portion I, which is represented by a 4-bit data sequence in the exemplary embodiment. The subscriber portion T is finally followed by the checksum C, which is represented by a 4-bit data sequence.

[0050] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0051] 2 Communication system [0052] 8 Integrated cable set [0053] 10 Plug connection [0054] 12 Data line [0055] 12A Feed line section [0056] 12B Return line section [0057] 14 Subscriber chain [0058] 16 Supply line [0059] 16a,b Wire [0060] 18 Control unit [0061] 20LED [0062] K Controller [0063] Ti Subscriber [0064] Di Subscriber-specific data packet [0065] I Information portion [0066] T Subscriber portion [0067] S Control information [0068] TI Subscriber-specific information [0069] C Checksum [0070] Dc Control data packet [0071] P Communication protocol