JP3065652B2 - Data communication method in in-vehicle communication network - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a data communication method in a vehicle-mounted communication network, and more particularly to a data communication method suitable for use as a connection network for a vehicle-mounted AV (audio-visual) system. Related to the communication method.

[Conventional technology]

In recent years, in-vehicle audio systems have evolved from systems that merely listen to music to systems that include visual elements. A system having not only audio but also visual functions is known as an AV system.

In-vehicle AV systems are constructed with various elements. For example, the audio element includes a cassette tape deck, a radio tuner, a CD (compact disc) player, and the visual element includes a TV.
(Television) A tuner, a navigation device, and the like are included. An audio reproduction signal output from each of these elements is reproduced from a speaker mounted in the vehicle via an amplifier, and an image reproduction signal is similarly output as an image on a display mounted in the vehicle. Today, each of these elements is controlled by digital technology, which is controlled by a microcomputer-based controller.

In order to operate each of the above elements systematically,
It is necessary to control each element comprehensively. Therefore, in the on-vehicle AV system, the controllers of the above elements are connected by a bus network, and mutual control data is transmitted and received via a communication bus constituting the network.

In a conventional network, each controller is controlled by a polling method. The polling method is a method in which one of the controllers is given a priority position, the controller is set as the master, and the remaining controllers are set as the master-slave relationship, and the master is always used when the master collects data from the slave. This is a method for accessing the slave side from the server.

When the master transmits and accesses communication data to the slave by the conventional polling method, or when the slave returns data to the master, it is necessary to identify or specify each controller. Therefore, an address indicating the controller is assigned to each controller.

In the conventional address assignment method, a unique address is assigned to each controller. The control data includes instruction data (for example, a start instruction: O
N data).

[Problems to be solved by the invention]

The problems in the conventional communication method described above are that there are many communication data transmitted and received on a communication bus and that the data is complicated. That is, as described above, for example, the command system of the communication data transmitted from the master side is a fixed one which is determined in advance corresponding to each connection element corresponding to each connection element, and the number thereof is large. . Therefore, if you try to expand the AV system by adding new elements,
The command for the additional element must be increased accordingly.

In addition, communication data includes display data in addition to the commands issued from the master described above. If each communication data is grouped into one communication data, the communication data becomes complicated and long, and processing on the transmission side becomes longer. Becomes complicated.

Furthermore, when a new slave unit is connected,
If the format of the communication data is unknown, processing may not be possible.

An object of the present invention is to provide a data communication method in a vehicle-mounted communication network that can simplify communication data.

[Means for solving the problem]

In order to solve the above-mentioned problem, the present invention relates to a communication system in which one master device and one or more slave devices are connected to the same communication bus as shown in FIG. A data communication method in an in-vehicle communication network of a bus system for transmitting and receiving a communication data, wherein the communication data (DT)
There is characterized in that data communication is performed by adding the classified data classified in a hierarchy of magnitude (TP _L, TP _S) in accordance with the data contents to be transmitted.

[Action]

According to the present invention, the classification data added to the head position of the communication data (DT) is classified into the large classification data (TP
_L) and consisting of a small classification data (TP _S). This size classification is data (D) to be transmitted by the communication data (DT).
Are classified according to the content of Therefore, various command data are not mixed in one communication data (DT), and the data length of one communication data can be shortened and simplified. Therefore, communication data (DT) can be systematized, and processing on the transmission side and reception side of communication data (DT) can be simplified. Further, shortening one communication data makes it possible to shorten the occupation time of the bus, thereby improving the data transfer efficiency. In addition, since the large and small classification data is arranged at the head, the type of communication data can be easily determined on the receiving side, and debugging and failure analysis can be easily performed.

Also, the newly connected slave unit can be operated by the structured communication data.

〔Example〕

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

Power supply system of AV system The present invention is preferably applied to a vehicle-mounted AV system. As shown in FIG. 2, the AV system 103 receives power supply from the car battery 101 via the ACC switch 102. The ACC switch 102 is a switch that is linked to an engine key of the vehicle. By rotating the engine key to the position of the ACC switch 102, power is supplied to accessories in the vehicle. Therefore, in general, the power supply to the AV system 103 is repeatedly turned on / off each time the engine key is turned.

Example of Configuration of AV System FIG. 3 shows an example of the configuration of an AV system to which the present invention is applied. In the example of FIG. 3, a tape deck 6 for reproducing a recording signal from a cassette tape 1, a tuner 7 such as an FM for reproducing a radio wave received by an antenna 2, and a CD player for reproducing a recording signal from a CD 3 are used as an audio reproducing apparatus. 8
And a multi-CD player 9 including an auto-changer 5 for reproducing a recording signal from each CD of the multi-CD 4.
As the visual playback device, the TV received by antenna 2
A TV tuner (assumed to be built into the tuner 7) for reproducing radio waves or a CD-ROM 8
And a display 12 for outputting the recorded still image via the CD player 8. CD-RO
A typical example of using M is a navigation device. The external commander 10 includes a keyboard for inputting various operation commands from outside. The input device 13 can also be incorporated in the external commander 10.

Each of the above devices has a controller for controlling its own operation, and the controllers are connected to each other via a communication BUS 14 to form a bus-based control network. The structure of this network is shown in FIG. 4, and the details will be described later.

On the other hand, the reproduced signal of the audio reproducing apparatus is selectively input to the digital amplifier 16 via the selector 15 and is amplified by a predetermined amount and then emitted from the speaker 17. A digital signal circuit included in the digital amplifier 16 is also controlled by a built-in controller, and this controller is also connected to the communication BUS.

AV System Control Network FIG. 4 shows an example of an AV system control network. Here, for convenience of explanation, in FIG.
Each device connected to S14 is referred to as a “unit” as a general expression. As shown in FIG. 4, each unit is connected to the communication BUS 14 in parallel. One of the units is referred to as a “master” in order to control the entire network, and this is indicated by a master unit 200. Are all other remaining units "slave", these slave units 200 _-1 to 200
Shown by _-n .

Master controller 1 built in master unit 200
8 is connected to the communication BUS 14 via the communication interface IC25. In this example, the master controller 18 also controls the tape deck 6 and the tuner 7. Further, the control section of the tape deck 6 of the master controller 18 also controls the autochanger 5. Slave unit 200 _-1 to 2
Each of the slave controllers 19 to 24 built in 00- _n is similarly connected to the communication BUS 14 via the communication interface ICs 25 to 31.

FIG. 5 shows the master unit 200 and the slave unit 200.
A specific example of the connection state with _-n is shown. As shown in FIG.
Communication BU between master unit 200 and slave unit 200- _n
Connected by S14. The communication BUS 14 uses a twisted pair line composed of two lines. The communication data DT transmitted and received via the communication BUS 14 is transmitted to the communication interface IC 25 of the master unit 200 and the slave unit 200- _n.
And the communication interface IC31. The communication interface IC 25 is a communication driver / receiver 32
Similarly, the communication interface IC31 is separated into a communication driver / receiver 35 and a communication control IC36. In this regard, in the related art, it has been provided integrally in one IC. The communication control IC 33 is formed of CMOS transistors and has a communication driver /
The receiver 32 is formed of a bipolar transistor having a high current driving capability. The same applies to the communication driver / receiver 35 and the communication control IC 36.

Thus, regarding the communication interface IC 25, the communication control IC 33 and the communication driver / receiver 32
This makes it possible to cope with a change in the transmission medium of the communication BUS 14. For example, in the example of FIG.
Although a twisted pair wire is used as the communication BUS 14 for differential transmission, as shown in FIG. 6, when an optical communication cable 40 is used as the communication BUS 14, a communication driver / receiver
By using the electro-optical converter 38 instead of 32, it is possible to cope without changing other configurations. Further, the operation failure generated in the master unit 200 is largely due to disturbance noise mixed in from the communication BUS 14, and even if an excessive signal is mixed in for some reason, the communication driver / receiver 32 alone often fails. /
By replacing only the receiver 32, it is easy to return to the current state, which is advantageous for maintenance. In particular, for automotive
In the case of an AV system, there are many opportunities to mix noise generated from the engine system of an automobile, so that it is effective.

Also, from the viewpoint of IC manufacturing, it is easier to manufacture the IC and the cost is more advantageous if the CMOS transistor and the bipolar transistor having different manufacturing processes are separated from each other than the configuration of the Bi-CMOS IC. .

Incidentally, the above description has described a communication interface IC 25, and is separated into a communication driver / receiver and the communication control IC Similarly for communications interface IC26~31 the other slave units 200 _-1 to 200 DEG _-n.

Next, the transmission format of the communication data DT used in the present invention will be described.

FIG. 7 shows an example of a transfer format of the communication data DT. As shown in FIG. 7, the communication data DT, the master address data MA from the head indicates the address of the master unit 200, slave address SA indicating the addresses of the slave knit 200 _-1 to 200 DEG _-n, the message length of data D It comprises message length data N, classification data TP indicating the type of data D, and data D indicating transfer contents.

The configuration of the data D is the content of the communication data DT,
It differs depending on the classification data TP, and is roughly classified into three types of format configurations. As shown in FIG. 10, the first format is a format for confirming connection, the second format is a format for keys, display data, and the like, and the third format transmits a result of a checksum CS. Format. Furthermore, the format for confirming the connection is to transfer the communication data DT to the slave units _200-1 to 200-2.
The transfer from 00 _-n to the master unit 200 is different from the transfer from the other unit. In FIG. 10, the format of the key and the display data is the same from the physical status data PS to the logical mode data LM in the data configuration, and is not shown.

The classification data TP is a data area which is arranged at the head of the communication data DT and indicates the type of data D following the classification data TP. Classification data TP is composed of the most data TP _L and the small classification data TP _S. Large classification data TP _L, as shown in FIG. 8 represents the type of data D. For the bit allocation, when the entire classification data TP is 8 bits, the upper 4 bits are allocated. Small classification data TP _S, as shown in FIG. 9, mainly used to identify the format of the data D, the lower 4 bits are assigned.

Thus, the large classification data TP _L and the small classification data TP _S
Since the classification data TP is added, various command data are not mixed in one communication data DT, and the data length of one communication data can be shortened and simplified. . Therefore, communication data DT can be systematized, and processing on the transmission side and reception side of communication data DT can be simplified. Further, shortening one communication data makes it possible to shorten the occupation time of the bus, thereby improving the data transfer efficiency. Since the large and small classification data is placed at the head, the type of communication data can be easily determined on the receiving side, and debugging and failure analysis can be easily performed.

Physical address data PA is Figure 11, as shown in FIG. 12, the communication interface of the master unit 200 to slave unit 200 _-1 to 200 DEG _-n on the communication BUS 14 IC25～
This is an address in communication for specifying 31 and is an address indicating the master unit 200 and the slave units 200 _-1 to 200 _-n . Of the physical address data PA, the physical address data PA that specifies the master unit 200 is always fixed. As for the physical address data PA, basically, one physical address data PA is assigned to one unit. FIG. 14 shows an example in which physical address data PA is allocated in association with the unit configuration shown in FIG. In addition,
In FIG. 14, physical address data PA is also set in the master controllers 18 to 24. This is because, like the master unit 200, two functional elements of the tape deck 6 and the tuner 7 are provided in one controller master controller 18. Is connected. In a combination of one controller and one function, the physical address data PA and the logical address data LA have the same address as in the slave controllers 19 to 24.

The physical status data PS is status information relating to the master unit 200 and the slave units 200 _-1 to 200 _-n , and includes a functional address (that is, logical address data L to be described later) of the unit.
This is data indicating the number of A).

As shown in FIG. 13, the logical address data LA is data indicating the functions (that is, tuners and tape decks) of the master unit 200 and the slave units 200 _-1 to 200 _-n. Assigned for each function. The number of logical address data LA, when the connection confirmation request sequence, the number of the controller receives with functions defined by the physical address data PA, LA _1, LA ₂ ... not a constant number because The added so on. FIG. 14 shows logical address data LA corresponding to the unit configuration of FIG.
Here is an example in which is assigned.

The talker address data TL indicates the address of the transmission source (speaker) transmitting the communication data DT.

The listener address data LN indicates an address of a transmission destination (listener) for receiving the communication data DT.

The logical status data LS contains each logical address.
Indicates the state of the function corresponding to LA.

The logical mode data LM indicates an operation state (mode) of a function corresponding to each logical address.

The checksum data CS is data for error detection added in order to improve the reliability of the data D.

Communication operation In the AV system described above, the master unit 20
Communication data D between 0 and slave units 200 _-1 to 200 _-n
The operation when communicating T will be described below.

FIG. 15 shows a specific example. FIG. 15 shows an example of a connection confirmation sequence when the slave unit side accesses the own AV system between the slave device including the TV / FM tuner and the master unit.

In this network, unlike the conventional polling method, all slave units self-declare their own units to the master unit. The master unit does not actively access the slave unit.

Now, in FIG. 15, because the slave unit is connected confirmation request (self-reported), to transmit to the master unit via the communication BUS14 issue the communication data DT _1. At this time, the communication data DT ₁ sets its own physical address data PA to “1”.
23H "(H is hexadecimal hexadecimal), the physical address data PA of the partner master unit is" 100H ", and the classification data TP
As connection confirmation data “00H”, indicating that this data is connection confirmation data.
The logical address data LA ₁ = 05 and the logical address data LA ₂ =
This is indicated by 07 (see FIG. 13). The master unit 200 by the communication data DT ₁ is easily know that the device of the PA = 123H has sent the connection confirmation data TP = 00H, LA ₁ = 0
5. It is registered that the device having the function of LA ₂ = 07 is connected to the communication BUS 14, and this device will be handled as an AV system constituent member thereafter. The master unit communicates data
When the DT ₁ is sent to indicate that it has received the communication data DT _1, and returns the return data RDT ₁ to the slave unit. Next, in order to inform the newly connected sleeve unit of the constituent members of the AV system, the classification data TP is changed to the connection confirmation data “00H” as described above.
The communication data indicates that the connection confirmation data and transmits system connection information DT ₂ to the slave unit side as. The slave unit that has received the system connection information DT ₂ for acknowledgment, and returns the return data RDT ₂ to the master unit side. Then, after a predetermined time has elapsed, the slave unit transmits a connection confirmation request communication data DT ₁ of (self-reported) to the master unit side again. The transmission of the connection confirmation request communication data DT ₁ again after the elapse of the predetermined time is because, in the case of an in-vehicle AV system, ON / OFF of the power supply is performed.
This is because it depends on the ON / OFF of the ACC switch, so it is necessary to check the connection periodically.

Thus, the physical address data PA and the logical address data LA are always included, and the physical address data PA
Since the PA and the logical address data LA are mutually independent data, the communication data DT can be transmitted to an arbitrary destination by an arbitrary combination.

As described above, the communication data DT always includes the classification data.
There is a TP, and the transmission side and the reception side can easily determine what the communication data is based on the classification data TP, and the processing for each data is simplified.

In the above-described operation example, an example of communication for confirming connection between the slave unit and the master unit has been described. However, communication can be similarly performed between other communication data slave units.

In addition, the format of the communication data and the assignment of addresses to each unit are determined by the physical address PA as described above.
And the logical address LA, it is possible to connect a new unit if the logical address LA is clearly set even if the physical address PA is unknown. Communication between the unit and the already connected unit is possible.

Similarly, since the communication data is systematized by the classification data TP, a common communication data format can be used even when a new slave unit is connected, and the new unit and the already connected unit can be used. It is possible to interact with.

That is, it is assumed that a new slave unit 200- _m is connected to the communication BUS 14, as shown in FIG. In this case, even if the physical address data PA of the slave unit 200- _m is not assumed and the physical address data PA is 101, if the function is the “display function”, it is already registered in the slave unit 200. Since the same function exists with the logical address data LA = 01, the logical address data LA can be accessed, so that the slave unit 200- _m can be connected. In addition, the communication data organized by the classification data TP enables the operation of the slave unit 200- _m . This means that A
This will contribute to improving the scalability of the V system.

〔The invention's effect〕

As described above, according to the present invention, the classification data added to the head position of the communication data includes the large classification data and the small classification data that are classified into each other. The large and small classifications are classified according to the contents of data to be transmitted by the communication data. Therefore, various command data are not mixed in one communication data, and the data length of one communication data can be shortened and simplified.
Therefore, communication data can be systematized, and processing on the transmission side and the reception side of communication data can be simplified. Further, shortening one communication data makes it possible to shorten the occupation time of the bus, thereby improving the data transfer efficiency. Also,
Since the large and small classification data is placed at the head, the type of communication data can be easily identified on the receiving side, and debugging and failure analysis can be easily performed.

Also, the newly connected slave unit can be operated by the structured communication data.

[Brief description of the drawings]

FIG. 1 (a) is a diagram illustrating the principle of the invention described in claim 1, FIG. 1 (b) is a diagram illustrating the principle of the invention described in claim 2, FIG. 2 is a power supply system diagram of the AV system, FIG. Is an overall configuration diagram of the AV system, FIG. 4 is a block diagram of a control network of the AV system, FIG. 5 is a block diagram showing a specific example of a connection state between a master unit and a slave unit, and FIG. 6 is a master unit and a slave unit. FIG. 7 is an explanatory diagram showing a transfer format of communication data, FIG. 8 is an explanatory diagram showing the contents of classification data (major classification), and FIG. 9 is a classification data (classification data). FIG. 10 is an explanatory diagram showing a basic data format, FIG. 11 is an explanatory diagram showing an example of a physical address, FIG. 12 is an explanatory diagram showing an example of a physical address, FIG. The figure is an explanatory diagram showing an example of a logical address, FIG. 14 is a block diagram showing an example of assignment of physical addresses and logical addresses, FIG. 15 is an explanatory diagram showing an example of a communication operation, and FIG. 16 is a block diagram in a case where an additional slave unit is connected. ADR… Address data B… Communication BUS CS… Check sum data D… Data DT… Communication data LA, LA _{1 to} LA _n … Logical address data M… Master device PA, PA _{1 to} PA _n … ... physical address data PS ...... physical status data S ₁ to S _n ...... slave device TP ...... classification data 101 ...... car battery 102 ...... ACC switch 103 ...... AV system 200 ...... master unit 200 _{1-200 -n} ...... Slave unit 1 ...... Cassette tape 2 ...... Antenna 3 ...... CD 4 ...... Multi CD 5 ...... Autochanger 6 ...... Tape deck 7 ...... Tuner 8 ...... CD player 9 ...... Multi CD player 10 … External commander 11… Display 12… Display 13… Input device 14… Communication BUS 15… Selector 16, 16 A… Digital amplifier 17… Speaker 18… Master controller 19… Slave controller 20 Slave controller 21 Slave controller 22 Slave controller 23 Slave controller 24 Slave controller 25 Communication interface IC 26 Communication interface IC 27 Communication interface IC 28 Communication interface IC 29: Communication interface IC 30: Communication interface IC 31: Communication interface IC 32: Communication driver / receiver 33: Communication control IC 34: Controlled part 35: Communication driver / receiver 36: Communication control IC 37 Controlled part 38 Electrical / optical converter 39 Electrical / optical converter

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Shimoma 25-1, Nishimachi, Yamada, Kawagoe-shi, Saitama Prefecture Pioneer Corporation Kawagoe Factory (56) References JP-A-61-195453 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H04L 12/28

Claims (2)

(57) [Claims] 1. A data communication method in a bus-type vehicle-mounted communication network in which one master device and one or more slave devices are connected to a same communication bus and transmit and receive communication data via the bus. Data communication in the vehicle-mounted communication network, wherein data communication is performed by adding, to the communication data, classification data classified into a large or small hierarchical structure according to data content to be transmitted by the communication data. Method. 2. A data communication method in a bus-type vehicle-mounted communication network in which one master device and one or more slave devices are connected to the same communication bus and transmit and receive communication data via the bus. A data communication performed by adding classification data classified into a large and small hierarchical structure according to the data content to be transmitted by the communication data to a head position of the communication data, and performing data communication. Data communication method.