JP2966502B2 - Data communication method in in-vehicle communication network - Google Patents

Description

Description: TECHNICAL FIELD 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 in a connection network of 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. And
The control data is generated in a state where instruction data (for example, a start command: ON data) for the controller is added to the address data unique to each controller, and transmitted on the communication bus.

[Problems to be solved by the invention]

In the conventional connection network described above,
In the case of an AV system, the power supply is turned on / off each time the ACC switch (car accessory power supply switch) linked to the engine switch is turned on / off, so the connection status of the slave devices that make up the network must be changed each time. It is necessary to confirm. In this case, according to the polling method, every time the ACC switch is turned on, the master device must access each slave device for connection confirmation, and the burden on the master device is extremely large. . For example, when the address of the slave device is 12 bits, if the connection is confirmed using the serial ball of the master device, a maximum of 4096 accesses are required.

In addition, in the case of the polling method, in order for the master device to access the slave device, the master device needs to register the addresses of all the slave devices on the communication bus. No access can be made to the communication bus, and even if it is physically or electrically connected to the communication bus, it does not function. In order to function reliably, a procedure for assigning a unique address to the additional slave device and newly registering it is necessary.

If the method of accessing the master device from the slave device is adopted in order to solve such a problem of the polling method, the following problem arises. That is,
When the master device receives an access from a slave device, setting the reception time may cause variations in the rise of each slave device. For example, a slave unit that should have been connected at the time of the previous connection confirmation should be connected. May not be connected and may be disconnected.

Therefore, an object of the present invention is to provide a data communication method in a vehicle-mounted communication network that can reliably connect a slave device when a slave device accesses a master device side for a connection confirmation request.

[Means for solving the problem]

As shown in FIG. 1, the present invention provides 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, Each slave device transmits its own connection request information to the master device at the time of starting the network (ACC = ON, STEP1), and the master device transmits the connection request information for a predetermined time (t) from the time of starting the network (STEP1). After performing the waiting process for receiving the connection request information from the slave devices (STEP 2), if the reception of the connection request information from all the slave devices connected at the time of the previous network stop is not completed (STEP 4). , Further extend the reception waiting time (STEP6, STEP2, STEP3)
It is characterized by the following.

[Action]

According to the present invention, each slave device transmits its own connection request information to the master device when the network is started (for example, when the ACC switch is turned on (STEP1)) (self-report), and the master device is used when the network is started. From the slave device for a certain period of time (STEP
2). After a lapse of a predetermined time (t), the master device confirms whether or not all self-reports from the slave devices connected when the operation of the network was stopped last time (for example, when the ACC switch is OFF) have been completed (STEP 4). . This verification process
For example, the slave device at the time of the operation stop may be stored in a memory or the like, and the confirmation may be performed by comparing and comparing the addresses of the slave devices that have actually been declared. If the self-reports from all slave devices have not been completed, the system waits for a further fixed time (STEP6, STEP6).
3).

As described above, by extending the standby processing time, it is possible to prevent the slave device that should be connected from being disconnected due to the variation in the rising speed between the slave devices when the network is activated.

〔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 is also used as a controller for 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. Communication interface IC25 includes communication driver / receiver
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 a CMOS transistor, and the communication driver / 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 through an 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 includes the master address data MA including the address of the master unit 200 from the beginning, the slave address SA indicating the addresses of the slave units 200 _-1 to 200 _-n , and the message length of the data D. It consists of 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 uses the communication data DT as the slave units 200 _-1 to 200-1.
The transfer from 00- _n to the master unit 200 is different from the reverse transfer. 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. The classification data TP is composed of large classification data and small classification data. The major classification data is as shown in FIG.
Indicates the type of data D. Bit allocation is classified data TP
If the whole is 8 bits, the upper 4 bits are assigned. As shown in FIG. 9, the small classification data is mainly used to identify the format of the data, and the lower 4 bits are allocated.

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 function for one controller, 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 is equal to the number of functions of the controller determined by the physical address data PA.
LA _1, LA ₂ ... not a constant number because The added so on. FIG. 14 shows an example in which logical address data LA is allocated in association with the unit configuration in FIG.

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
The operation when communication data DT for connection confirmation is communicated between 0 and the slave units 200 _-1 to 200 _-n will be described below.

In this network, unlike the conventional polling method, all slave units 200 _-1 to 200 _-n self-declare their own units to the master unit 200. Master unit 200 is slave unit 200 _-1 to 200
Do not perform aggressive access operations on the _-n side.

That is, the connection confirmation sequence in the present invention is roughly divided into the communication sequence SEQ when the power is ON (ACC switch ON).
₁ and communication sequence S during power supply period (during normal operation)
Consisting of EQ ₂ Metropolitan.

(1) The basic algorithm of the communication sequence SEQ ₁ at power-on (at startup) is as follows (see FIGS. 15 (a) and 15 (b) for the detailed algorithm).

After each power supply is detected, each slave accesses the master and requests connection confirmation. The master sets the slave that has accessed it as the connected slave, and after a predetermined time elapses,
Provide information to each slave. (2) The communication sequence SEQ ₂ during the power supply period is
It includes a processing sequence SEQ ₃ when the slave units 200 _-1 to 200 _-n drop out and a processing sequence SEQ ₄ when the new slave unit 200 _-m joins, and their basic algorithms are as follows. (The detailed algorithm is
Figures (a) and (b).

(2-1) Processing sequence at the time of dropout SEQ ₃ “Each slave sends a connection confirmation request to the master at regular intervals. In contrast, the master always provides the latest connection information. For slaves that have not received a connection confirmation request, it is considered that they have been dropped off from the BUS, and necessary internal processing is performed, and to that effect (the latest connection information is provided.) (2-2) Processing sequence when joining SEQ ₄ "In the connection confirmation at power-on, if a slave whose connection has not been confirmed suddenly requests a connection confirmation, it is deemed to have joined and the necessary internal processing is performed. And the slave unit is provided with the (latest) connection information to that effect. ”In this case, the master unit 200 operates for a certain period of time t after the power is turned on (that is, when the network is started).
A standby process for self-reporting of connection request information from the slave units 200 _-1 to 200 _-n is performed (see FIG. 1, STEP 2 and FIG. 17 (b)). Then, during the last power OFF (i.e., the network time of stopping) all slave units 200 _-1 to 200 _-n, which is connected to, for example, from 200 _-1 to 200 _-3 connection request information DS ₁ to DS ₃ Check whether self-declaration has been completed (No.
Fig. 11, STEP3). When it is finished (Fig. 1, STEP3, YE
S) performs a normal operation in that state (FIG. 1, STEP 4).
However, 17 as shown in Figure (C), if the self-reported did not (FIG. 1 of the connection information DS ₃ from the slave unit 200 _-3 for a predetermined time t ₁ from when the current supply ON, STEP3, NO)
The master unit 200 further extends the predetermined time t ₂ only receiving process (FIG. 1, STEP3 → STEP2, FIG. 17 (b) refer). By extension of this reception waiting process, it can be repaired slave unit 200 _-3 from falling off.

The above communication sequence is stored as a control program in a controller constituting the master unit 200 and the slave units 200 _-1 to 200 _-n . It is assumed that the connection state of the slave units 200 _-1 to 200 _-n at the time of the previous power OFF is stored in a writable memory (RAM) provided in the master unit 200.

Next, a specific example is shown in FIG. FIG. 18 shows an example of a connection confirmation sequence when a slave unit including a TV / FM tuner and a master unit perform access confirmation access to their own AV system from the slave unit side.

Now, in FIG. 18, 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 master unit of the other party is set to" 100H ", and the logical address data indicates that its own slave unit has a configuration including a TV tuner and an FM / AM tuner. This is indicated by LA ₁ = 05 and logical address data LA ₂ = 07 (see Fig. 13.) The communication data DT ₁ allows the master unit M to have PA = 123H and LA ₁
It is registered that a unit having the functions of = 05 and LA ₂ = 07 has been connected to the communication BUS 14, and this unit will be handled as an AV system constituent member thereafter. The master unit is
When the communication data 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. Then, the slave unit which is newly connected, for notify the constituent members of the AV system, and transmits the system connection information DT ₂ to the slave unit side. Because the slave unit acknowledgment that has received this system connection information DT _2, return data RD
It returns the T 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.
After a lapse of a predetermined time, the communication data DT _{1 for the} connection confirmation request is returned again
This is because, in the case of an in-vehicle AV system, the ON / OFF of the power supply depends on the ON / OFF of the ACC switch, so that it is necessary to periodically check the connection.

In this way, the communication data DT always includes the physical address data PA and the logical address data LA, and since the physical address data PA and the logical address data LA are mutually independent data, The communication data DT can be transmitted to any destination.

In the above operation example, an example of communication between the slave unit and the master unit has been described, but communication can be similarly performed between other slave units.

In addition, the format of the communication data DT and the assignment of addresses to each unit
By separately performing the PA and the logical address LA, even if the physical address PA is unknown, if the logical address LA is clearly set, it is possible to connect a new unit, and the new unit can be connected. Communication between the main unit and the already connected unit is possible.

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. 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 master device performs a self-reporting standby process from the slave device for a certain period of time from the start of the network, and after a certain period of time, is connected when the previous operation of the network was stopped. Check whether all the self-reports from the slave devices have been completed, and if the self-reports from all the slave devices have not been completed, extend the standby processing time to allow each It is possible to prevent the slave device to be originally connected from being disconnected due to a variation in the rising speed between the slave devices.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a power supply system diagram of an AV system, FIG. 3 is an overall configuration diagram of the AV system, FIG. 4 is a block diagram of a control network of the AV system, and FIG. FIG. 6 is a block diagram showing a specific example of a connection state between a master unit and a slave unit. FIG. 6 is a block diagram showing another example of a connection state between 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 the classification data (major classification), FIG. 9 is an explanatory diagram showing the contents of the classification data (small classification), FIG. 10 is an explanatory diagram showing the basic data format, FIG. 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. 13 is an explanatory diagram showing an example of a logical address, and FIG. 14 shows an example of allocation of a physical address and a logical address. Block Diagram FIG. 15 is a flowchart showing a communication sequence when the power is turned on, FIG. 16 is a flowchart showing a communication sequence during a power supply period, FIG. 17 is a time chart of a reception standby operation in the present invention, and FIG. 18 is a communication operation. FIG. 19 is an explanatory diagram showing an example, and FIG. 19 is an explanatory diagram in a case where an additional slave unit is connected. ADR ...... address data B ...... communication BUS CS ...... checksum data D ...... data DS ₁ ~DS ₂ ...... connection request information DT ...... communication data LA, LA ₁ ~LA _n ...... logical address data M ...... master device PA, PA ₁ ~PA _n ...... physical address data PS ...... physical status data S ₁ to S _n ...... slave device TP ...... classification data t ...... standby time 101 ...... car battery 102 ...... ACC Switch 103 AV system 200 Master unit 200 _-1 to 200 _-n Slave unit 1 Cassette tape 2 Antenna 3 CD 4 Multi CD 5 Auto changer 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, 16A 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 Continuation of the front page (72) Inventor Hiroshi Shimama 25-1, Nishimachi, Yamada, Kawagoe-shi, Saitama Prefecture Pioneer Corporation Kawagoe Factory (56) References JP-A-61-176224 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) H04L 12/28

Claims (1)

(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 the same communication bus, wherein each of the slave devices is connected to the network. At the time of activation, the master device transmits its own connection request information to the master device. The master device waits for reception of connection request information from the slave device for a certain period of time from the time of activation of the network. A data communication method in an in-vehicle communication network, further comprising extending reception standby time when reception of connection request information from all slave devices connected at the time of stop has not been completed.