JP2000124927A - On-vehicle data communication equipment and on-vehicle data communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain effective utilization of a communication line and to prevent communication waiting or data erasure. SOLUTION: Concerning respective electric devices 13a-13c, when transmitting nonregular data signals such as operation instruction signals, the nonregular data signals are always transmitted to a second communication line for data exchange and when transmitting regular data signals, first of all, the level of communication load of a first communication line for data exchange is discriminated. When the communication load of the first communication line for data exchange is light, the first communication line for data exchange is selected and the regular data signals are sent out. When the communication load is heavy, on the other hand, the second communication line for data exchange is selected and the regular data signals are sent out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle data communication device and an in-vehicle data communication method for mutually transmitting digital data between a plurality of devices in an automobile.

[0002]

2. Description of the Related Art Along with the recent technological development, various technological advances have been made in the field of automobiles such as passenger cars.
In particular, the development of electronics technology has been remarkable, and with this, the configurations of various control systems of vehicles have become diversified. As described above, when a large number of electrical devices are mounted in each automobile, digital data needs to be mutually transmitted between these electrical devices.

[0003] In a conventional automobile, in order to improve the communication performance between each electrical device, for example, Japanese Patent Application Laid-Open No. Sho 62-3 (1987) has been proposed.
As can be seen in Japanese Patent No. 6940 (see FIG. 4), a main main unit is used to adjust communication timing between the main control unit (central unit) 1 and a plurality of electrical units (terminal units) 2a to 2c. By adding not only a communication line (transmission / reception data transmission line) 3 but also a sub-communication line (control signal path) 4 which is separately wired and transmitting / receiving a control signal through the sub-communication line 4,
There was a method for controlling communication on the main communication line 3.
Here, a periodic data signal (periodic data signal) is transmitted and received between each of the electrical devices 2a to 2c using the main communication line 3, while a single control signal for an arbitrary operation instruction of the operator is The transmission and reception were performed exclusively through the sub communication line 4.

[0004]

In the above conventional method,
Since only one main communication line 3 actually communicates the regular data signal, high-speed communication is difficult when the communication is congested.

In general, when transmitting and receiving a periodic data signal, for example, a frequency signal during a seek operation of a radio receiving station is periodically transmitted to an audio information display panel unit every 50 ms, or audio information is transmitted from a CD reproducing unit. When a CD playback time signal or the like is periodically transmitted to the display panel unit every 50 ms, or when 50 ms
There is a case where a power window raising / lowering signal is periodically transmitted every time, and a case where temperature information data of an air conditioner (air conditioner device) is periodically transmitted every 50 ms. If these plural types of periodic data signals are communicated at timings shifted in time, the communication load on the main communication line 3 does not increase so much.

However, a plurality of types of periodic data signals as described above may be simultaneously communicated on the main communication line 3 depending on circumstances. At this time, the communication load on the main communication line 3 increases linearly. Normally, signals communicated on the main communication line 3 such as periodic data signals are simple binary data in which a high or low state appears, and therefore these signals cannot be transmitted simultaneously.

FIG. 5 is a flowchart showing the operation of waiting for the main communication line 3 to become empty. When the data transmission process is started in step S01, first, the high / low state of the main communication line 3 is detected at a fixed time pitch (for example, every 100 μs) (step S02), and the low state is kept for a certain period (for example, 1 ms). If they are detected continuously (step S0
In 3), since it can be determined that the communication load on the main communication line 3 is low, the periodic data signal is transmitted as it is (step S0).
4). On the other hand, if the high state appears at least once within a certain period (for example, 1 ms) in step S03, the processes of step S02 and step S03 are repeatedly performed.
The communication waits until the communication load on the main communication line 3 becomes low.

As described above, when the degree of the communication load is large, it becomes difficult to communicate other data from each of the electrical devices 2a to 2c, and a communication wait often occurs.
In a severe case, there is a possibility that a situation such as loss of data may occur.

Here, the above-mentioned periodic data signal includes an up-and-down signal which is continuously given from the power window control unit until the door window is in the front open state or the fully closed state. The data signal is
It is often the case that communication is simultaneously made with a plurality of electrical devices 2a to 2c installed at a plurality of places in the automobile, for example, near the front and rear seats. While these periodic data signals are being transmitted and received, the operator often does not receive any other control signals. However, in the related art, even when the control signal is not transmitted at all and the communication on the sub communication line 4 is not performed at all, as described above, the communication load on the main communication line 3 is extremely increased, and the communication waits. In some cases, the effective use of the sub communication line 4 was not achieved. That is, the communication efficiency as a whole cannot be said to be good in spite of requiring a large installation space for the arrangement of the sub communication line 4.

It is an object of the present invention to provide a vehicle-mounted data communication apparatus and a vehicle-mounted data communication method that can improve communication efficiency by effectively utilizing a communication line, and can prevent communication waiting and data loss. .

[0011]

Means for Solving the Problems In order to solve the above problems,
The present invention is an in-vehicle data communication device for transmitting / receiving a periodic data signal and an irregular / irregular data signal between at least a plurality of electrical devices in an automobile, wherein the electrical devices are mutually connected. The first and second data transmission / reception communication lines are connected in parallel by a first data transmission / reception communication line and a second data transmission / reception communication line, and the respective electrical devices determine the magnitude of the communication load of the first data transmission / reception communication line. A communication load determination processing unit, and communication for selectively switching a communication line related to transmission of the periodic data signal and the irregular data signal to the first data transmission / reception communication line and the second data transmission / reception communication line A line switching unit, wherein the communication line switching unit always transmits the irregular data signal to the second data transmission / reception communication line when transmitting the irregular data signal. At the time of transmitting the periodic data signal,
When the communication load determination processing unit determines that the communication load of the first data transmission / reception communication line is small, the first data transmission / reception communication line is selected and the periodic data signal is transmitted. When the load determination processing unit determines that the communication load of the first data transmission / reception communication line is large, the second data transmission / reception communication line is selected and the periodic data signal is transmitted.

Here, the irregular data signal is, for example, an operation instruction signal relating to an arbitrary operation performed by an operator using one electrical device.

[0013]

FIG. 1 is a diagram showing a vehicle-mounted data communication device according to a first embodiment of the present invention. As shown in FIG. 1, this in-vehicle data communication device uses two data transmission / reception communication lines 11 and 12 to control all of the electrical devices 13a to 13a.
13c and the main controller 14 are connected, and one of the data transmission / reception communication lines (first data transmission / reception communication line) is connected.
11 is used as a main communication line for transmitting and receiving data such as a periodic data signal, while the other communication line for transmitting and receiving data 12 (second communication line for transmitting and receiving data) is used as a communication line for transmitting and receiving control signals. As well as the first through the second data transmission / reception communication line 12.
When the communication load of the data transmission / reception communication line 11 is increased, the communication line 11 is used as a sub-communication line for communicating a data signal such as a periodic data signal that could not be communicated on the main communication line 11.

As the electrical equipment 13a to 13c, for example, a meter unit, an air conditioning unit (air conditioner unit), an air conditioning instruction switch unit (air conditioner instruction switch unit), a power window unit, a power window switch unit,
A body unit, a CD reproducing unit, a CD display unit, and the like are applied, each of which is equipped with a CPU, a RAM, a ROM, and the like, and performs a predetermined process of signal data (hereinafter, referred to as a “microcomputer unit”). A communication control IC 22 for transmitting and receiving signals to and from the data transmission / reception communication lines 11 and 12 for signal processing in the microcomputer unit 21; and the communication control IC 22 and the data transmission / reception communication lines 11, And a transmission / reception unit 23 for exchanging signals with the transmission / reception unit 12.

Here, the microcomputer unit 21 is provided for each electric device 1
The predetermined functions 3a to 13c include, for example, various gauges for a meter unit, drive control of a predetermined air conditioning mechanism by inverter control for an air conditioning unit, and communication via the data transmission / reception communication lines 11 and 12. It has a function of performing data processing on various periodic data signals and control signals (irregular data signals). The periodic data signal and the control signal are generated and communicated by the microcomputer unit 21 by including therein bibliographic data such as a transmission source ID and a transmission destination ID.

The communication control IC 22 is a multi-protocol serial communication interface circuit having an asynchronous or synchronous transmission protocol for interfacing with the data transmission / reception communication lines 11 and 12, as shown in FIG. The communication protocol control unit 22a that converts the signal format of various signals between the main communication line and the first data transmission / reception communication line 11 as the main communication line is congested during communication of the periodic data signal. And a communication path determination processing unit 22b for automatically determining that the transmission path of the data signal (periodic data signal and control signal) is connected to the first data transmission / reception communication line 11 and the second data transmission / reception communication line 12. And a communication line switching unit 22c for switching.

The communication protocol control section 22a converts the signal from the microcomputer section 21 into a signal format suitable for communication on the data transmission / reception communication lines 11 and 12, and outputs the signal to the communication load determination processing section 22b, as described above. And a function of converting a data signal provided from the data transmission / reception communication lines 11 and 12 through the transmission / reception circuits 23a and 23b of the transmission / reception unit 23 into a digital format suitable for data processing in the microcomputer unit 21. .

The communication load determination processing unit 22b recognizes the state of the communication line control unit 22a when the communication protocol control unit 22a generates a "waiting for communication line vacancy" during signal transmission. Is determined to be increasing. Specifically, immediately before the transmission of the periodic data signal to the first data transmission / reception communication line 11 through the communication line switching unit 22c and the transmission / reception unit 23 described later, the high / low state of the first reception terminal RX1 of the transmission / reception unit 23 is set. When a low state is detected and a low state is detected continuously for a fixed number of clocks, it is determined that "communication is possible". On the other hand, when a high state is detected even once in a certain period, the first data transmission / reception communication line is used. 11 determines that “the communication load is high” and outputs the fact to the communication line switching unit 22c.

The communication line switching unit 22c always selects and connects the communication line for transmission to the second data transmission / reception communication line 12 when transmitting the control signal, and determines the communication load when transmitting the periodic data signal. According to the determination result from the processing unit 22b, the communication line for transmission is changed to the first data transmission / reception communication line 11 and the second data transmission / reception communication line 1
2, the communication load determination processing unit 2
When it is determined that 2b is "communicable", it is switched to the first data transmission / reception communication line 11, and when it is determined that "the communication load is high", it is switched to the second data transmission / reception communication line 12. ing.

As shown in FIG. 2, the transmission / reception unit 23 includes a first transmission / reception circuit 2 connected to the first data transmission / reception communication line 11.
3a and a second transmission / reception circuit 23b connected to the second data transmission / reception communication line 12. In each case, power supply V
The signal transmission PNP transistors Q11 and Q21 connected to the emitter cc and the switching NPN transistors Q12 and Q22 for switching ON / OFF of the signal transmission PNP transistors Q11 and Q21 are connected in two stages. The configuration includes zener diodes D11, D12, D21, and D22 as voltage circuits.

The collectors of the NPN transistors Q12 and Q22 are connected to the power supply Vcc and to the bases of the PNP transistors Q11 and Q21.
The emitters of the N-transistors Q12 and Q22 are provided. Then, the emitters of the PNP transistors Q11, Q21 are connected to the respective data transmission / reception communication lines 11, 12 through the connection lines 11a, 12a. Thus, when the signal applied from the output terminals TX1 and TX2 of the communication line switching unit 22c to the bases of the NPN transistors Q12 and Q22 becomes high, the NPN transistors Q12 and Q22 turn on and the PNP transistors Q11 and Q21 are turned on. When the base is switched to low, the PNP transistor Q11,
Q21 is turned on and connected to the power supply Vcc to switch from a low state to a high state.

Each PNP transistor Q11, Q2
1 is connected to the receiving terminals RX1 and RX2 of the communication protocol control unit 22a via Zener diodes D11, D12, D21 and D22, which are connected to each other in pairs. Connected, and when signals are given from the respective data transmission / reception communication lines 11, 12, the diodes D11, D12, D
The signal is input to the communication protocol control unit 22a through the communication terminals 21 and D22. Here, the anodes of the diodes D12 and D22 are grounded via the resistors R1 and R2, and the high / low state of the receiving terminals RX1 and RX2 is switched depending on whether or not a current flows into the resistors R1 and R2. ing.

The Zener diodes D11 and D12 of the first transmitting / receiving circuit 23a and the communication protocol controller 2
2a is connected to the input terminal of the communication load determination processing unit 22b, and thereby the communication load determination processing unit 22b
The high / low state of the first data transmission / reception communication line 11 can be determined by b.

The main control device 14 is installed in the instrument panel of the vehicle and switches the power of all the electric devices 13a to 13c, etc., and like the electric devices 13a to 13c, A microcomputer section 21 for performing a predetermined intrinsic function; a communication control IC 22 for transmitting and receiving signals to and from the data transmission / reception communication lines 11 and 12 for signal processing in the microcomputer section 21;
And a transmission / reception unit 23 for transmitting and receiving signals to and from the data transmission / reception communication lines 11 and 12. Each element 21
For details of the electronic devices 13a to 13
Since this is the same as 3c, detailed description is omitted.

The operation of the vehicle-mounted data communication device having the above configuration will be described. Here, for simplicity of description, the first electrical equipment 1
Reference numeral 3a denotes an air-conditioning instruction switch unit that can be arbitrarily operated by an operator, the second electric device 13b is an air-conditioning unit driven by operation of the first electric device 13a, and the third electric device 13c. Is the second electrical equipment 13b
It is assumed that the display unit is a display unit that displays a driving state (for example, room temperature information, air volume information, and the like) in the (air conditioning unit) on a liquid crystal panel or the like, and a series of operations in which an operator performs an air conditioning operation will be described.

First, the first electrical equipment 13a is operated by the operator.
When an arbitrary operation related to an air-conditioning instruction such as room temperature adjustment or air volume adjustment is performed on the (air-conditioning instruction switch unit), a control signal is generated by the microcomputer unit 21 in the first electrical equipment 13a (air-conditioning instruction switch unit). Then, after bibliographic data such as a transmission destination ID is added, the control signal is transmitted to the second data transmission / reception communication line 12 through the communication control IC 22 and the transmission / reception unit 23.

At this time, the communication line switching unit 22c in the first electrical equipment 13a (air conditioning instruction switch unit) initially selects the second data transmission / reception communication line 12 for transmission of the control signal. A control signal is transmitted to the second data transmission / reception communication line 12 through the second data transmission / reception communication line 12.

The first electrical equipment 13b (air conditioning unit) receives a control signal relating to the air conditioning operation from the first electrical equipment 13a (air conditioning instruction switch unit). At this time, the second data transmission / reception communication line 12
The control signal obtained through the transmission / reception unit 23 is received by the communication protocol control unit 22a in the communication control IC 22, and the microcomputer unit 21 performs predetermined data processing. Adjust the room temperature and air volume. Then, information (for example, indoor temperature information, air volume information, and the like) indicating the driving status of the second electric device 13b (air conditioning unit) at this time is generated as a periodic data signal, and the third electric device 13c (display unit) is generated. To send a periodic data signal to

At this time, the data transmission / reception communication lines 11, 1
The selection of 2 is performed by the communication line switching unit 22c of the communication control IC 22 in the second electric device 13b (air conditioning unit).

That is, as shown in step S11 in FIG. 3, when the communication line switching unit 22c first sends a periodic data signal to the first transmission / reception circuit 23a, the communication load determination processing unit 22b firstly sets a constant data signal. At the time pitch (for example, every 100 μs), it is detected whether the first receiving terminal RX1 of the first transmitting / receiving circuit 23a is in a high or low state (step S12). When the low state is continuously detected for a certain period (for example, 1 ms) in the reception state from the first reception terminal RX1 (step S13), the communication load of the first data transmission / reception communication line 11 is low. Therefore, the communication load determination processing unit 22
b is determined to be “communicable”, and the communication line switching unit 22c sends a regular data signal to the first data transmission / reception communication line 11 (step S14). Then, the third electrical equipment 13
c (display unit), based on the periodic data signal obtained through the first data transmission / reception communication line 11,
The predetermined data processing is performed on the information regarding the air-conditioning operation in the electrical equipment 13b (air-conditioning unit), and the information is displayed on a liquid crystal panel or the like.

However, when such a periodic data signal is communicated, operations such as power window and CD playback are often performed simultaneously. In this case, a predetermined periodic data signal is generated according to the function of the first data signal. It is transmitted and received on the transmission / reception communication line 11. In this case, the communication load of the first data transmission / reception communication line 11 increases,
The high state of the data transmission / reception communication line 11 appears several times within a certain period (100 μs). In such a case, the communication line for transmitting the periodic data signal is changed from the first data transmission / reception communication line 11 to the second data transmission / reception communication line 12 as follows.

That is, in the process of step S13, the high state of the first receiving terminal RX1 is maintained for a certain period (1 m
If it is detected once or more in s), it is determined that the "communicable" state could not be determined, and the number is counted (step S15), and the processing from step S12 is repeated again. In this step S15, if the communication load determination processing unit 22b cannot determine the “communicable” state a plurality of times (for example, 10 times) consecutively, the bus wait state frequently occurs. Proceeding to step S16, the communication load determination processing unit 22b detects whether the second reception terminal RX2 of the second transmission / reception circuit 23b is in a high or low state at a constant time pitch (for example, every 100 μs). I do. This is output to the communication line switching unit 22c. At this time, the communication line switching unit 22c receives the determination result in the communication load determination processing unit 22b, and connects the transmission / reception unit 23 for transmission from the first transmission / reception circuit 23a to the second transmission / reception circuit 23b. Switch.

In step S17, if the high state of the second receiving terminal RX2 is detected once or more within a certain period (1 ms) in the receiving state from the second receiving terminal RX2, the second data Similarly, the transmission / reception communication line 12 is "in a state where the communication load is high".
The processing from step S12 is repeated again. On the other hand, if the high state of the second reception terminal RX2 is not detected at all in the fixed period (1 ms) in step S17, the communication load of the second data transmission / reception communication line 12 can be determined to be low. Then, a periodic data signal is transmitted to the second data transmission / reception communication line 12 through the second transmission / reception circuit 23b and the connection line 12a (step S18). Since the second data transmission / reception communication line 12 normally performs only one-shot control signal communication, it is generally considered that the communication load is unlikely to become too high.

Here, the third electrical device 13c (display unit) receives a periodic data signal from the second electrical device 13b (air conditioning unit) obtained through the second data transmission / reception communication line 12, Predetermined data processing is performed on the information related to the air conditioning operation in the second electrical device 13b (air conditioning unit), and the information is displayed on a liquid crystal panel or the like.

As described above, in this embodiment, when the communication load on the first data transmission / reception communication line 11 increases, this is automatically determined, and the next periodic data signal to be transmitted is transmitted to the first data transmission line 11. Is transmitted to the second data transmission / reception communication line 12 without being transmitted to the data transmission / reception communication line 11, so that the second data transmission / reception communication line 12, which has a relatively light load, can be effectively used to make the whole. Communication efficiency can be improved, and communication waiting and data loss can be prevented.

In the above embodiment, a signal relating to an arbitrary operation by the operator has been described as a control signal. However, the present invention is not limited to this, and generally includes all signals transmitted irregularly. However, as described above, if an operation instruction signal relating to an arbitrary operation that is transmitted only by chance is transmitted to the second data transmission / reception communication line 12, the second data transmission / reception communication line 1 can be transmitted.
Since the communication load of the second data transmission / reception communication line 11 can be kept relatively small at all times, the second data transmission / reception communication line 12 can save the periodic data signal for communication when the communication load of the first data transmission / reception communication line 11 increases. This is advantageous.

In the above embodiment, the electrical equipment 13
Although only the communication between a to 13c has been described, it goes without saying that the same applies to the communication between each of the electrical components 13a to 13c and the main control device 14.

[0038]

According to the first and third aspects of the present invention, when transmitting an irregular data signal, each electric device always transmits the irregular data signal to the second data transmission / reception communication line. When transmitting the periodic data signal, the communication load of the first data transmission / reception communication line is determined, and when the communication load of the first data transmission / reception communication line is small, the first data transmission / reception communication line is transmitted. A communication line is selected and a periodic data signal is transmitted. On the other hand, when the communication load of the first data transmission / reception communication line is large, a second data transmission / reception communication line is selected and a periodic data signal is transmitted. Therefore, the overall communication efficiency can be improved by effectively utilizing the second data transmission / reception communication line having a relatively light load,
Waiting for communication, data loss, etc. can be prevented.

In particular, according to the second and fourth aspects of the present invention, an operation instruction signal relating to an arbitrary operation that is transmitted only by chance is transmitted to the second data transmission / reception communication line. The communication load of the second data transmission / reception communication line can always be kept relatively small, and when the communication load of the first data transmission / reception communication line increases, the periodic data signal is transmitted to the second data transmission / reception communication line. There is an effect that communication can be performed by saving the information.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an in-vehicle data communication device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of each electrical device in the on-vehicle data communication device according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of the in-vehicle data communication device according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional in-vehicle data communication device.

FIG. 5 is a flowchart showing the operation of a conventional in-vehicle data communication device.

[Explanation of symbols]

 11, 12 Data transmission / reception communication line 13a to 13c Electrical device 14 Main control device 21 Microcomputer unit 22 Communication control IC 22a Communication protocol control unit 22b Communication load determination processing unit 22c Communication line switching unit 23 Transmission / reception unit 23a, 23b Transmission / reception circuit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toshiyuki Sonoda 1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi F-term in Harness Research Institute, Inc. (reference) 5K032 AA01 AA03 BA06 DA11 DB03 DB24 5K048 BA02 BA08 BA42 DC04 EB02 HA04 HA06

Claims (4)

[Claims] 1. An in-vehicle data communication device for transmitting / receiving a periodic data signal and an irregular / irregular data signal between at least a plurality of electrical devices in an automobile, wherein each of the electrical devices is A first data transmission / reception communication line and a second data transmission / reception communication line wired in parallel with each other and connected in parallel, wherein each of the electrical devices determines the magnitude of the communication load of the first data transmission / reception communication line A communication load determination processing unit that selectively switches a communication line for transmitting the regular data signal and the irregular data signal to the first data transmission / reception communication line and the second data transmission / reception communication line A communication line switching unit, wherein the communication line switching unit always transmits the irregular data signal to the second data transmission / reception communication line when transmitting the irregular data signal. In the transmission of the periodic data signal, when the communication load determination processing unit determines that the communication load of the first data transmission / reception communication line is small, the first data transmission / reception communication line is selected and While transmitting a periodic data signal, when the communication load determination processing unit determines that the communication load of the first data transmission / reception communication line is large, the communication data determination processing unit selects the second data transmission / reception communication line and sets the periodic data An in-vehicle data communication device for transmitting a signal. 2. The in-vehicle data communication device according to claim 1, wherein the irregular data signal is an operation instruction signal relating to an arbitrary operation performed by an operator using one electrical device. An in-vehicle data communication device, characterized in that: 3. An in-vehicle data communication method for transmitting / receiving a periodic data signal and an irregular / irregular data signal between at least a plurality of electrical devices in an automobile, wherein the electrical devices are: A first data transmission / reception communication line and a second data transmission / reception communication line, which are wired in parallel with each other, are connected in parallel. In each of the electrical devices, when the irregular data signal is transmitted, the irregular data signal is transmitted. Is always transmitted to the second data transmission / reception communication line. When the periodic data signal is transmitted, the magnitude of the communication load of the first data transmission / reception communication line is determined, and the first data transmission / reception communication line is determined. When the communication load of
The data transmission / reception communication line is selected and the periodic data signal is transmitted, and when the communication load of the first data transmission / reception communication line is large, the second data transmission / reception communication line is selected and the periodical data signal is transmitted. An in-vehicle data communication method comprising transmitting a data signal. 4. The in-vehicle data communication method according to claim 3, wherein the irregular data signal is an operation instruction signal relating to an arbitrary operation performed by an operator using one electrical device. An in-vehicle data communication method comprising: