JPH04160935A - On-vehicle data communication system - Google Patents

Abstract

PURPOSE:To eliminate the necessity of setting time of receiving a request for connection of a slave unit in conformity with timing of issuing connection request information by setting a cycle for receiving the connection request information by the master unit at a value greater than at least double a cycle of issuing the connection request information. CONSTITUTION:In a communication sequence SEQ2 in a period of power supply, a master unit 200 detects the presence or absence of self reporting on connection confirmation request DREQ1 from slave units 200-1-200-n at every connection confirmation cycle TC. A period of time TC for confirming connection request information set at the master unit 200 is set at '5sec', a cycle time of issuing information of requesting for connecting slave units 200-1-200-n at '2sec', and a period of time for the confirmation at greater than double the cycle time of issuing the connection request information. So, since even if timing of issuing connection request information is irregular, it is confirmed within a predetermined confirmation period of time, it is unnecessary to set a period of time for confirmation in conformity with each slave unit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data communication system using an in-vehicle communication network, and particularly to a data communication system for an in-vehicle AV (audio-visual) system.

[Conventional technology]

In recent years, in-vehicle audio systems have been evolving from systems that simply 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.

An in-vehicle AV system is constructed from a wide variety of elements. For example, audio elements include a cassette tape deck, radio tuner, CD (compact disc) player, etc., and visual elements include:
It includes a TV (television) tuner, navigation device, etc.

The audio playback signals output from each of these elements are played back from the speakers installed in the car via an amplifier.
The image reproduction signal is similarly output as a video onto a display mounted inside the vehicle. Today, each of these elements is controlled by digital technology, and the control is performed by a controller using a microcomputer.

In order to operate each of the above elements systematically, it is necessary to control each element in an integrated manner. Therefore,
In an in-vehicle AV system, the controllers of each of the above-mentioned elements are connected through a bus-type network, and mutual control data is sent and received via a communication bus that constitutes the network.

In conventional networks, each controller is controlled by a polling method. The polling method gives priority status to one of the controllers and sets that controller as the master, and sets the remaining controllers as slaves in a master-slave relationship. When the master collects data from the slaves, the master side is always This is a method to access the slave side from.

When a master sends communication data to and accesses a slave using this conventional polling method, or when the slave side sends data back to the master, it is necessary to identify or specify each controller.

Therefore, each controller is assigned an address indicating the controller.

In the conventional address assignment method, each controller is assigned a unique address. The control data includes address data unique to each controller and instruction data for that controller (for example, a start command,
ON data) is added and sent and received on the communication bus.

On the other hand, especially in the case of a car-mounted AV system, the power supply is turned on every time the ACC switch (car accessory power supply switch) linked to the engine switch turns 0N10FF.
Since the 10FF state is reached, the connection state of the slave devices forming the network to the communication bus is checked each time. The connection status of this slave device to the communication bus is checked not only when the ACC switch is turned on, but also during normal operation to check if any slave device has fallen off due to a failure or if a new slave device has been added. It is also carried out in

[Problem to be solved by the invention]

However, there are generally a plurality of slave devices, and the timing of transmission of connection request information from each slave device is not uniform. In such a case, in order for the master device to accept connection request information in accordance with the transmission timing of connection request information from each slave device, a large number of timers are required, which increases the size of the device and increases costs. This is not a good idea. RAM is used to set the timer, but since in-vehicle AV systems in particular require miniaturization, it is necessary to utilize the RAM's storage capacity as effectively as possible.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an in-vehicle data communication system that can set the reception time of connection request information from a slave device without having to have many timers.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a method in which one master device and one or more slave devices are connected to the same communication bus, and the slave device transmits its own connection request information to the communication bus to the master device. In this in-vehicle data communication system, self-reporting is performed at predetermined intervals, and as shown in FIG. The present invention is characterized in that the connection request information is checked (STEPI) at a time interval (To) that is twice or more.

[Effect]

According to the present invention, the slave device self-reports connection request information to the master device via the communication bus at a predetermined period, and the time interval for receiving the connection request information from the master device (
Since T, ) is set to be at least twice the transmission period of the connection request information, the connection request information is always received within the reception time interval. As a result, as before,
There is no need for the master device to set a reception time that matches the transmission timing of connection request information from each slave device, and specifically, only one timer is required.

〔Example〕

Next, preferred embodiments of the present invention will be described based on the drawings.

Power supply system for AV system In a preferred embodiment, the present invention is applied to a vehicle-mounted AV system. As shown in FIG. 2, the AV system 103 receives power from the car battery 101 via the ACC switch 102. The ACC switch 102 is a switch that is linked to the engine key of the automobile, and by rotating the engine key to the position of the ACC switch 102, power is supplied to accessories in the automobile. Therefore, in general, the AV system 103
Power is supplied 0N10FF every time the engine key is turned.
will be repeated.

Configuration Example of AV System FIG. 3 shows a configuration example of an AV system to which the present invention is applied. In the example shown in FIG. 3, the audio playback device is a tape deck 6 that plays back recording signals from a cassette tape 1.
, a multi-CD player 9 including an FM tuner 7 for reproducing radio waves received by the antenna 2, a CD player 8 for reproducing recorded signals from a CD 3, and an autochanger 5 for reproducing recorded signals from each CD of a multi-CD 4. There is. The visual reproduction device includes a TV tuner (tuner 7) that reproduces TV radio waves received by antenna 2.
shall be built in. ), or in the case of a CD player 8 or a CD-ROM, a display 12 that outputs the recorded still image as an image via the CD player 8.
Contains such as. A typical example of using a CD-ROM is
It is a navigation device. The external commander 10 includes a keyboard for inputting various operation commands from the outside.

The input device 13 can also be incorporated into 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-type control network. The configuration of this network is shown in FIG. 4, and the details will be described later.

On the other hand, the playback signal from the audio playback device is selectively input to the digital amplifier 16 via the selector 15, amplified by a predetermined amount, and then radiated from the speaker 17. The digital signal system 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 14.

AV System Control Network FIG. 4 shows an example of an AV system control network. Here, for convenience of explanation, communication BU
The general expression for each device connected to S14 is “
unit. As shown in Figure 4,
Each unit is connected to the communication BUS 14 in parallel. One of the units is designated as a "master" in order to collectively control the network, and is designated as a master unit 200. All other remaining units are "slaves" and are referred to as slave unit 200. ~200--shown.

The master controller 18 built in the master unit 200 communicates with B via the communication interface IC25.
Connected to US 14.

In this example, the master controller 18 is connected to the tape deck 6.
It also serves as the control for tuner 7. Further, the tape deck 6 control portion of the master controller 18 also controls the autochanger 5. Slave units 200-1 to 200
, are also connected to the communication BUS 14 via communication interface ICs 25 to 31.

FIG. 5 shows a master unit 200 and a slave unit 2.
A specific example of the connection state with 00 is shown below. As shown in FIG. 5, the master unit 200 and slave unit 200 are connected by a communication BUS 14. The communication BUS 14 uses twisted pair wires consisting of two wires. The communication data DT sent and received via the communication BUS 14 is sent to the master unit 2.
00 and the communication interface IC25 of the slave unit 200 and -D communication interface IC31.

The communication interface IC 25 is separated into a communication driver/receiver 32 and a communication control IC 33, and similarly the communication interface IC 31 is separated into a communication driver/receiver 35 and a communication control IC 36. In this regard, in the past, they were provided integrally within 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 with high current driving ability. The same applies to the communication driver/receiver 35 and communication control IC 36.

As described above, by separating the communication interface IC 25 into the communication control IC 33 and the communication driver/receiver 32, it becomes possible to cope with changes in the transmission medium of the communication BUS 14. For example, in the example of FIG. 5, a twisted pair wire is used as the communication BUS 14 for differential transmission, but as shown in FIG. 6, when using the optical communication cable 40 as the communication BLiS 14, the communication driver/ By using the electrical/optical converter 38 in place of the receiver 32, this can be handled without changing the other configurations. Furthermore, malfunctions occurring in the master unit 200 are 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 3
In many cases, only the communication driver/receiver 32 needs to be out of order, and it is advantageous in terms of maintenance, as it is easy to restore the status quo by replacing only the communication driver/receiver 32. In particular, in-vehicle AV
In the case of a system, there are many opportunities for noise generated from the engine system of a car to mix in, so this is effective.

In addition, from the viewpoint of IC manufacturing, it is easier to manufacture and it is more cost-effective to separate the IC into CMOS transistor and bipolar transistor ICs, which have different manufacturing processes, than to configure the Bi-CMO8 IC.

In addition, although the above explanation was about the communication interface IC 25, other slave units 200-+ to 200-+
The communication interface ICs 26 to 31 of 200-n are similarly separated into a communication control IC and a communication driver/receiver.

Transmission Format of Communication Data DT Next, the transmission format of communication data DT used in the present invention will be explained.

FIG. 7 shows an example of the transfer format of communication data DT. As shown in FIG. 7, communication data DT includes master address data MA indicating the address of master unit 200, slave unit 200 . ~200-. , message length data N1 indicating the message length of data D, classification data TP indicating the type of data D, and data D indicating the transfer content.

The structure of data D is the content of communication data DT, that is,
It differs depending on the classification data TP, and can be roughly divided into three types of format configurations. As shown in FIG. 10, the first format is a format for connection confirmation, the second format is a format for keys, display data, etc., and the third format is a format for sending the result of check sum C8. It is. Furthermore, the format for connection confirmation is to send the communication data DT to the slave unit 200. -200-n to the master unit 200 and vice versa. Note that in FIG. 10, in the format of keys and display data, all of the data configurations from physical status data PS to logical mode data LM are the same, so illustration is omitted.

The classification data TP is placed at the beginning of the communication data DT,
This is a data area representing the type of data D following the classification data TP. The classification data TP is composed of major classification data and minor classification data. The major classification data represents the type of data D, as shown in FIG. Regarding bit allocation, when the entire classification data TP is 8 bits, the upper 4 bits are allocated. As shown in FIG. 9, the minor classification data is mainly used to identify the format of data D.
The lower 4 bits are assigned.

As shown in FIGS. 11 and 12, the physical address data PA is a communication address for specifying the communication interface ICs 25 to n 31 of each master unit 200 to slave units 200 to 200 on the communication BUS 14. The master unit 200, slave units 200, ~20
This is an address indicating 0-n. Of this physical address data PA, the physical address data PA that specifies the master unit 200 is always fixed. Basically, one physical address data PA is assigned to one unit. FIG. 14 shows an example in which physical address data PA is assigned in association with the unit configuration of FIG. 4. In FIG. 14, the physical address data PA is also set in the master controllers 18 to 24, but this means that one master controller 18 has the tape deck 6,
This example takes into consideration the case where two functional elements of the tuner 7 are connected. In a combination in which one controller has one function, physical address data PA and logical address data LA are used, as in slave controllers 19 to 24.
are the same address.

Physical status data PS is stored in master unit 200, slave unit 200 . ~200 status information n regarding the unit, and the functional address of the unit (i.e.
This data indicates the number of logical address data (LA) to be described later.

As shown in FIG.
This is data indicating the functions of the unit 00-n (ie, tuner, tape deck), and is assigned to each function.

The number of logical address data LA is equal to the number of functions handled by the controller determined by the physical address data PA, and L
A, LA2, etc. are added, so it is not a fixed number. FIG. 14 shows an example in which logical address data LA is assigned in association with the unit configuration of FIG. 4.

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

The listener address data LN indicates the address of the destination (listener) that receives the communication data DT.

Logical status data LS represents the state of the function corresponding to each logical address LA.

Logical mode data LM represents the operating state (mode) of the function corresponding to each logical address.

The checksum data C8 is error detection data added to improve the reliability of the data D.

Communication operation In the AV system explained above, mask unit 2
The operation of n when communication data DT is communicated between h200-1 to h200-200 and units h200-1 to 200 will be described below.

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

That is, the connection confirmation sequence in the present invention can be broadly divided into a communication sequence SEQ when the power is turned on (ACC switch ON), and a communication sequence SEQ during the power supply period (normal operation).

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

“After each slave detects that the power is turned on, it accesses the master and requests connection confirmation.

The master treats the accessed slaves as connected slaves, and after a predetermined period of time has elapsed, provides information to each slave. (2) Also, communication sequence 5EQ2 during the power supply period
is slave unit 200. ~200-n dropout processing sequence SEQ, and new slave unit 2
The basic algorithms are as follows (see FIGS. 16(a) and 16(b) for detailed algorithms).

(2-1,) Processing sequence when dropped 5EQ3 "Each slave makes a connection confirmation request to the master at regular intervals. In response, the master always provides the latest connection information. Slave without connection confirmation request For BUS
It is assumed that the item has fallen from above, and the necessary internal processing is performed, and the latest connection information to that effect is provided to each slave.'' (2-2) Processing sequence when joining 5EQ4 ``Power supply O
If a slave whose connection has not been confirmed suddenly requests a connection confirmation during connection confirmation at time N, it is assumed that the slave has participated, performs the necessary internal processing, and sends a message to each slave. Provide (up-to-date) connection information. ” In other words, the communication sequence 5EQ during the above power supply period
2, the master unit 200 is configured as shown in FIG. 17(a).
As shown in , the connection confirmation cycle T.

(for example, every 5 seconds) slave unit 200-t ~ 2
Connection confirmation request information from 00 Self-n of D
Detecting the presence or absence of a REQI declaration (
Figure 17(b)). The connection confirmation request information D is the connection confirmation cycle T. If the master unit 200 is accessed at the timing EQI timing within the
Figure 7 (C)).

Here, the confirmation time T of the connection request information set in the master unit 200. is set to "5 seconds", and the master unit 200 checks each slave unit 200-1 to 200- at this confirmation cycle time Tc.

Receive and verify connection information from. In contrast, slave unit 200. ~200-n's connection request information transmission cycle time is "2 seconds", and the master unit 200's confirmation time is slave units 200-200.
The transmission period is set to be at least twice as long as 1-n. Therefore, each slave unit 200. Even if the transmission timing of the connection request information from ~200-Il is different, it will be confirmed within one of the confirmation times, so each slave unit 200-1
It is not necessary to set the time according to the angle of ~200°. Therefore, the timer only needs to be set for one time, and the storage area of the memory (RAM) used for the timer can be effectively utilized.

Now, if the slave unit 200-1 is newly connected, the master unit 200 connects at time t2.
The slave unit 200 confirms its participation in the AV unit and registers it. Further, when the connection of the slave unit 200-1 is confirmed, the master unit 200 transfers information regarding other slave units connected to the communication bus 14 to the slave unit 200-1.
(Fig. 17(e)).

On the other hand, in the case of slave unit 200-2, FIG.
As shown in f), connection confirmation request information D is accessed in a cycle before time t1, and in this case, the slave unit 200-2 is confirmed (FIG. 17(g)). However, time t and t
The connection confirmation request information D is not accessed in the period between 2 and 2 (EQ2(f) in FIG. 17). In this case, the master unit 200 at time t
The slave unit 200. is assumed not to fall out of the AV system (Fig. 17 (h)) Fig. 17 (i
) is the slave unit, 200, . 2 is confirmed, the master unit 200 sends the slave unit 200.
Indicates the status of the reply.

In this way, during normal operation, the master unit 20
0 is the connection confirmation cycle T. Since the connection is periodically checked every time, it is possible to know whether the slave units 200-1 to 200 have dropped out or joined.

n Next, a specific example is shown in FIG. Figure 18 shows TV/F
This figure shows an example of a connection confirmation sequence when the slave unit accesses its own AV system between a slave unit including an M tuner and a master unit to confirm connection to its own AV system.

Now, in FIG. 18, the slave unit issues communication data DT1 and transmits it to the master unit via the communication BUS 14 in order to request connection confirmation (self-report). At this time, the communication data DT sets its own physical address data PA to "123H" (H is hexadecimal hexadecimal),
The physical address data PA of the destination master unit is “
100H", and logical address data LA = 05 and logical address data LA2 = 07 indicate that the slave unit has a configuration including a TV tuner and an FM/AM tuner (see Fig. 13). This communication According to data DT, master unit M has PA=123H.
This registers that a device with the functions LA 1 = 05 and LA 2 = 07 is connected to the communication BUS 14, and henceforth this device will be handled as a member of the AV system. When the communication data DT1 is transmitted, the master unit returns return data RDT1 to the slave unit to indicate that it has received the communication data DT. Next, in order to inform the newly connected slave unit of the constituent members of the AV system, system connection information DT2 is transmitted to the slave unit side.

The slave unit that has received this system connection information DT2 returns return data RDT2 to the master unit side to confirm reception. Next, after a predetermined period of time has elapsed, the slave unit again transmits communication data DT of a connection confirmation request (self-report) to the master unit. In the case of an in-vehicle AV system, the connection confirmation request communication data DT1 is sent again after a predetermined period of time has elapsed.
This is because the N10FF depends on the ON10FF of the ACC switch, so 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, they can be combined in any combination. Communication data DT can be sent to any destination.

Although the above operation example describes an example of communication between a slave unit and a master unit, communication is possible between other slave units as well.

In addition, by separating the format of the communication data DT and assigning addresses to each unit into the physical address PA and the logical address L as described above, even if the physical address PA is unknown, the logical address L
If A is clearly set, it is possible to connect a new unit, and communication between the new unit and the already connected unit is possible.

That is, as shown in FIG. 19, it is assumed that a new slave unit 200 is connected to the communication BUS 14. In this case, even if the physical address data PA of the slave unit 200 is not expected and physical address data PA = 101, if the function is "display function", it is already registered in the slave unit 200. Since the same function exists with the logical address data LA=01, it is possible to access the logical address data LA, so that the slave unit 200 can be connected. This will contribute to improving the expandability of the AVm system.

〔Effect of the invention〕

As described above, according to the present invention, the slave device self-reports connection request information to the master device via the communication bus at a predetermined period, but the time interval for receiving the connection request information from the master device is determined by the connection request information. Since the transmission period of the 1 is small (both are set to twice or more, the probability that the connection request information will be received within the reception time interval is high. It is no longer necessary to set the reception time to match the transmission timing of the request information, and only one timer is required, which allows for miniaturization of the device configuration and effective use of the RAM storage area.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the principle of the present invention, Figure 2 is a power supply system diagram of the AV system, Figure 3 is an overall configuration diagram of the AV system, Figure 4 is a block diagram of the control network of the AV system, and Figure 5 is a diagram of the control network of the AV system. 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. , Figure 8 is an explanatory diagram showing the contents of classification data (major classification), Figure 9 is an explanatory diagram showing the contents of classification data (minor classification), East Figure 10 is an explanatory diagram showing the basic data format, Figure 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. 13 is an explanatory diagram showing an example of a logical address, and FIG. 14 is an explanatory diagram showing an example of physical address and logical address assignment. Block diagram, Fig. 15 is a flowchart showing the communication sequence when power is turned on, Fig. 16 is a flowchart showing the communication sequence during the power supply period, Fig. 17 is a timing chart for checking the connection state of the slave unit, Fig. 18 19 is an explanatory diagram showing an example of communication operation, and FIG. 19 is an explanatory diagram when an additional slave unit is connected. ADH...Address data B...Communication BUS C8...Check sum data D...Data DT...Communication data LA, LA, ~LAll...Logical address data M
...Master device PASPA, ~PAn...Physical address data PS.
・Physical status data S1~S, ・・
Slave device TP...Classification data To...Connection confirmation cycle 101...Car battery 102...ACC switch 103...AV system 200...Master unit 200-t~200□...Slave unit ...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 section 35...Communication driver/receiver 36...Communication control IC 37...Controlled section 38...Electronic/optical converter 39...Electronic/optical converter Applicant Agent Yasushi Ishikawa Younger brother Figure 1 AV system conductive RID Figure 2 Nani 7D base'j! =7t-Ma-bu 乍first-order dress (7) Fake 11 Figure 11 O-Yuko Ko-Address Ita) Figure 12 Category 1-Address Ita 11 Figure 13+J3L prison weight Kai 1-Ki no S ν Piece of the unit] Quimin finamard of the B snoring θ of imagination,
Figure 18

Claims (1)

[Claims] One master device and one or more slave devices are connected to the same communication bus, and the slave device self-reports its own connection request information to the communication bus to the master device at a predetermined period. In the data communication system, the master device checks the connection request information at a time interval that is at least twice the transmission cycle for self-reporting the connection request information from the slave device. Characteristic in-vehicle data communication system.