JPH04160936A - Data communication method in on-vehicle communication network - Google Patents

Abstract

PURPOSE:To make it possible to put a relevant onboard communication network in an operable state without issuing polling when the master unit is recovered by continuously sending connection request information to a communication bus until receiving an answer of receiving confirmation information from the master unit periodically even when the network is enters the power consumption mode. CONSTITUTION:When answer of connection information from the master unit 200 is ceased, each slave unit 200-1-200-n, when a predetermined detecting period of time passes, enters the low power consumption mode. However, after that, each slave unit 200-1-200-n automatically switches its own operation mode from the power consumption mode to the mode of issuing connection confirmation request information periodically or at arbitrary timing and repeats answering connection confirmation information. This repeat operation is continues until receiving answer of connection confirmation information from the master unit 200. This retry action enables the AV system to be completely recovered.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a data communication method in a vehicle-mounted communication network, and in particular to a data communication method suitable for use in a connection network of a vehicle-mounted AV (audio-visual) system. Concerning communication methods.

[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 establishes a master-slave relationship by giving priority status to one of the controllers, making that controller the master, and making the remaining controllers slaves, and when the master collects data from the slaves, it always This is a method in which the master side accesses the slave side.

According to this conventional polling method, when a master sends communication data to a slave to access it, 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, start command =
ON data) is added and sent and received on the communication bus.

By the way, in a bus-based network, as mentioned above, there is always one master on the communication bus.

If this master fails for some reason,
Polls will no longer be sent out on the communication bus. In this case, if the slave detects that there is no polling sent for a certain period of time, it determines that the master is abnormal, stops its own operation, and then enters a low consumption mode to reduce power consumption and remains on standby. do. Next, when the master returns one day or a new master is connected, the master side sends polling to access each waiting slave device.

[Problem to be solved by the invention]

In the above-mentioned conventional connection network, especially in the case of an in-vehicle AV system, the AC connected to the engine switch
Turn on the C switch (car accessory power supply switch)
Since the power supply enters the ON10FF state every time 10FF, it is necessary to check the connection status of the slave devices that constitute the network each time. In this case, according to the polling method, the master device must access each slave device to check the connection every 08:00 of the ACC switch, which places an extremely heavy burden on the master device. For example, if the address of the slave device is 12 bits, if the connection is confirmed by serial polling of the master device, a maximum of 4096 accesses will be required.

In addition, in the case of the polling method, in order for the master device to access the slave device, the master device must register the addresses of all slave devices on the communication bus, and additional slave devices that are not registered must be registered. The communication bus cannot be accessed in any way, and even if it is physically or electrically connected to the communication bus, it may not function. In order to function reliably, it is necessary to allocate a unique address to the additional slave device and perform a new registration procedure.

In order to solve this problem, if a method is adopted in which the slave device accesses (self-reports) the master device to request a connection confirmation, if part of the master device drops out of the system for some reason, When the system returns to normal operation, there is a possibility that the system may not return to normal. Furthermore, if this state is left unattended, the power consumption of the slave device will be wasted.

The purpose of the present invention is to reduce power consumption and ensure system operation when the master is restored after the master has dropped out in a network where the slave checks its own connection to the master. An object of the present invention is to provide a data communication method in a communication network.

[Means to solve the problem]

According to the present invention, in order to solve the above problems, FIG.
), one master device (M) 7 and one or more slave devices (S.

~S) are connected to the same communication bus (B), and each slave device (S, ~5Il) sends its own connection confirmation request information (D) to the master device (M) in advance. , after receiving the connection confirmation information EQ (D), the master device (M) EQ returns reception confirmation EQ information (RDT) for the connection confirmation information (D) to the slave device (S, ~Sn). A data communication method in an in-vehicle communication network, wherein the slave devices (81 to Sn
), as shown in FIG. 1(b), the master device (M
) is characterized in that when it detects that the reply of reception confirmation information (RDT) has been interrupted for a certain period of time, it puts itself into a low power consumption mode.

[Effect]

According to the present invention, as shown in FIG. 1(b), the slave device (S, ~511) performs self-report EQ of connection confirmation request information (D) to the master device (M) (STEPI). ). Next, the slave device (Sl-
8n) determines whether there is a reply of reception confirmation request information (RDT) (STEP 2).

If there is a reply (YES), 5TEP3 to 5TEP6
Process. If there is no reply (NO), it is determined whether the time set by timer 1 has elapsed (STEP 7), the operation is temporarily halted (HALT), and the power saving mode is entered (STEP 9).

Then, after the predetermined time of timer 3 has elapsed, (STEPI
OLYES) EQ (STEPI) issues connection confirmation request information (D) again and retries the access.

〔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 if the CD player 8 is 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. ~2QC1--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 designed to control both the tape deck 6 and the tuner 7. Further, the tape deck 6 control portion of the master controller 18 also controls the autochanger 5. Each slave controller 19-24 built in slave units 200-1-200-n is similarly connected to communication BUS 14 via communication interface IC25-31.

FIG. 5 shows a master unit 200 and a slave unit 2.
A specific example of the connection state with 00 is shown below.

n As shown in FIG. 5, the master unit 200 and the slave unit 200 are connected by a communication BUS 14. As shown in FIG. 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 the communication interface IC31 of the D communication interface.

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. Communication driver/receiver 35, communication control I
The same applies to C36.

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 shown in FIG. 5, a twisted pair wire is used as the communication BUS 14 for differential transmission, but as shown in FIG. By using an electric/optical converter 38 instead of 32, this can be handled without changing the other configurations. Furthermore, malfunctions that occur in the master unit 200 are largely due to disturbance noise mixed in from the communication BUS 14, and even if an excessive signal gets mixed in for some reason, it is often only the communication driver/receiver 32 that malfunctions. /Receiver 3
This is advantageous in terms of maintenance, as it is easy to return to the current state by replacing only 2. This is particularly effective in the case of in-vehicle AV systems, since there are many opportunities for noise to be mixed in from the engine system of the vehicle.

Also, from the perspective of IC manufacturing, it is easier to manufacture and cost-effective to separate into CMOS transistor and bipolar transistor ICs, which have different manufacturing processes, than to use a Bi-CMO3Ic configuration. .

In addition, although the above explanation was about the communication interface IC 25, other slave units 200. ~2
The communication interface ICs 26 to 31 of 00-1l 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 . It consists of slave address SA indicating the address of ~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 differs depending on whether the communication data DT is transferred from the slave units 200-1 to 200-11 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, if 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 data for specifying communication interface ICs 25 to n 31 of each master unit 200 to slave units 200-1 to 200 on the communication BUS 14. address of the master unit 2001 and slave units 200-1 to 200-2.
This is an address indicating 00. Of this physical address data PA, the physical address data PA that specifies the master device M is always fixed. 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 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 is because one master controller 18 has two tape decks 6 and a tuner 7, like the master unit 200. This takes into consideration the case where functional elements are connected. In a combination in which one controller has one function, the physical address data PA and the logical address data LA have the same address, as in slave controllers 19-24.

The physical status data PS is status information n regarding the unit of the master unit 200 and slave units 200-1 to 200, and is the functional address (i.e.,
This data indicates the number of logical address data (LA) to be described later.

As shown in FIG.
This data indicates the functions of the unit in question (i.e., tuner, tape deck), and is assigned to each function. The number of logical address data LA is determined by the number of functions handled by the controller determined by the physical address data PA. The number is not fixed because it is added like LA 5 LA 2, etc. 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
00 and slave unit 200. The operation of n when communicating communication data DT between n and 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 is broadly divided into a communication sequence SEQ when the power is ON (ACC switch ON), and a communication sequence 5EQ2 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 Figures 15 (a) and (b) for the detailed algorithm).
After N is detected, access is made to the master and a connection confirmation request is made.

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, the communication sequence SEQ during the power supply period
includes a processing sequence 5EQ3 when slave units 200-+ to 200 drop out and a processing sequence 5EQ4 when n new slave units S join, and their basic algorithms are as follows. (The detailed algorithm is shown in Figure 16 (a)
), (b)).

(2-1) Processing sequence at the time of dropout 5EQ3 "Each slave makes a connection confirmation request to the master at regular intervals. In response, the master always provides the latest connection information. (2-2) Processing sequence at the time of participation 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. (2-3) Processing sequence when the master unit 200 falls off The above sequences SEQ-8EQ4 are all based on the assumption that the master unit 200 is healthy, but if the master unit 200 falls off due to some reason.
may stop functioning. In that case, the connection information (slave unit 20
It also includes return data etc. that are returned in response to connection confirmation request information from 0-1 to 200 degrees. ) will no longer be replied to. Therefore, each slave unit 200
, ~200-. enters low consumption mode when a predetermined detection period has elapsed. However, after that, each slave unit 200-1 to 200- automatically switches its operating mote from the consumption mode to the connection confirmation request information issuance mode periodically or at any timing, and reissues the connection confirmation request information. Send repeatedly. This repeated operation is performed until connection information is returned from master unit 200. This retry operation allows the AV system to be reliably restored. Conversely, the AV system cannot be started unless this repeated operation is performed.

The above processing sequence when the master unit 200 falls off is shown in FIG.

Next, a specific example is shown in FIG. Figure 17 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. 17, the slave unit issues communication data DT 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 has its own physical address data PA as "123H" (H is hexadecimal hexadecimal),
The physical address data PA of the destination master unit is “
100H", and the logical address data LA s = 05 and logical address data LA 2 = 07 indicate that the slave unit has a configuration including a TV tuner and an FM/AM tuner (see FIG. 11). .By this communication data DT1, the master unit 200
registers that a unit with the functions LA=05 and LA2=07 is connected to the communication BUS 14 at PA=123H, and from now on, this unit will be treated as an AV system constituent member. When the communication data DT1 is transmitted, the master unit returns return data RDT 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. This system connection information D
The slave unit that has received T2 returns return data RDT2 to the master unit to confirm reception.

Then, after a predetermined period of time has elapsed, the slave unit again sends the communication data DT of the connection confirmation request (self-report).

is sent to the master unit. In the case of an in-vehicle AV system, the connection confirmation request communication data DT is sent again after a predetermined period of time has passed, when the power supply is ON10F.
Since F depends on 0N10FF of the ACC switch,
This is because 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 LA as described above, even if the physical address PA is unknown, the logical address LA can be used.
If it is clearly set, it is possible to connect a new unit, and communication between the new unit and the low-connection unit is possible.

That is, as shown in FIG. 18, 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 contributes to improving the expandability of the AV system.

〔Effect of the invention〕

As described above, according to the present invention, the connection confirmation of each slave device to the communication bus is performed by self-report from each slave device, and the slave device self-reports the connection confirmation request. It is possible to save power by detecting that no reply of reception confirmation has been received for a certain period of time and waiting in power saving mode. Furthermore, even if the power saving mode is entered, connection confirmation information is periodically sent out on the communication bus until reception confirmation information is returned from the master device. As a result, when the master device is restored, it is possible to put the network into operation without sending polling from the master device side. Even if the new master device fails, the slave devices continue to send connection information in the same way, so the network can be operated reliably.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a power supply system diagram of the AV system, Fig. 3 is an overall configuration diagram of the AV system, Fig. 4 is a block diagram of the control network of the AV system, and Fig. 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 physical address, and Fig. 14 is an explanatory diagram showing an example of physical address and logical address assignment. Block diagram, Figure 15 is a flowchart showing the communication sequence when the power is turned on, Figure 16 is a flowchart showing the communication sequence during the power supply period, Figure 17 is an explanatory diagram showing an example of communication operation, and Figure 18 is an addition. A block diagram when a slave unit is connected, and FIG. 19 is a flowchart showing a processing sequence when a master unit is dropped. ADR...Address data B...Communication BUS C8...Checksum data D...Data DT...Communication data LA, LA1-LAll...Logical address data M.
...Master device PA, PA1 to PAn river physical address data PS...
Physical status data S1 to SIl...Slave device TP...Classification data 101...Car battery 102...ACC switch 103...AV system 200...Master unit 200, ~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 part 35...Communication driver/receiver 36...Communication control IC 37...Controlled part 38...Electrical/optical converter 39...Electrical/optical conversion Applicant Yasuo Ishikawa (a) This issue of EF's Fukuri and the Ministry of Foreign Affairs Figure 1 (b) Ozurou's doorwork T theory B Monthly Figure 1 AV System's electricity dripping Figure 2 AV system frost 1) Wholesale and non-distribution software 2nd layer 4th section Figure 8 TP) Y-')I(DI)
Mshi4N(DN) ruttonfη-(CS
Nona-7D Base 1F-)-Matt Figure 10 Physical Address Excerpt)) Figure 1I Oda Tsuki 1 Ryo Dress Ita) Figure 19 of the father prisoner Danbi sequence of the next time Kuunit defection-1

Claims (1)

[Claims] 1. One master device and one or more slave devices are connected to the same communication bus, and each slave device sends its own connection confirmation request information to the master device in advance. transmission, and after receiving the connection confirmation request information, the master device returns reception confirmation information for the connection confirmation information to the slave device, the data communication method in the in-vehicle communication network comprising: A data communication method in an in-vehicle communication network, characterized in that the device puts itself into a low power consumption mode when it detects that the reply of reception confirmation information from the master device has stopped for a certain period of time. 2. In the data communication method in an in-vehicle communication network according to claim 1, the slave device periodically transmits the connection confirmation information to the master device even after the low power consumption mode. Communication method.