JPH11232241A - Method and device for data communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily secure the identity of data in circulating data like a ring. SOLUTION: Data Da and initial data DcO are DMA transmitted (S1) by the 1st transmission strart of a 1st microcomputer(MC), a 2nd MC DMA transmits (S2) its own data Db and the data Da and a 3rd MC DMA transmits (S3) its own data Dc and the data Db to the 1st MC. Then the data Da stored in a RAM and the newest data Dc are DMA trnsmitted (S4) by the 2nd transmission start of the 1st MC and the 2nd MC DMA transmits (S5) the data DB, Da to end initial processing. Consequently proper data are stored in respective MCs and the differences of data are not generated between respective MCs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data communication method and apparatus, and more particularly to a data communication method and apparatus for circulating data by performing data communication between a plurality of central processing units such as CPUs.

[0002]

2. Description of the Related Art In recent years, a vehicle is equipped with a plurality of electronic control units (hereinafter referred to as ECUs).
Each of the CUs controls an electronic control device mounted on the vehicle. When the control of the department in charge is complicated, this ECU may be configured with a plurality of arithmetic processing units (hereinafter, referred to as CPUs) to share control with each CPU.

When an ECU is composed of a plurality of CPUs, E
Since data used as a CU must not be different for each CPU, data communication must be performed between a plurality of CPUs to make the data uniform within the ECU.

For this reason, a data communication system has been proposed in which at least three data communication devices including a CPU are connected in a ring configuration, data belonging to each CPU is held in each CPU, and the data is circulated. (See Japanese Patent Application Laid-Open No. H08-214018). In this data communication system, when relaying data to each data communication device and circulating the data in a circular manner for communication,
At the same time, by enabling a plurality of transmission / reception states of communication data to exist between the data communication devices, each data communication device shortens the data reception interval and enables highly accurate and reliable data communication. .

[0005]

However, in the conventional system, data consistency may not be ensured. For example, each CPU before circulating holds data belonging to itself, but data belonging to other CPUs hold initial values. Therefore, during the circulation,
There are times when the initial value is circulated, and data identity may not be ensured.

An object of the present invention is to provide a data communication method and apparatus capable of easily ensuring data identity when data is circularly circulated in consideration of the above facts.

[0007]

According to a first aspect of the present invention, there is provided a data communication method for transmitting data belonging to its own central processing means and data belonging to another central processing means. Communication data including data obtained by updating data belonging to its own central processing unit to the latest data is exchanged between at least two central processing units having a storage area for storing and connected in a ring.
Circulate twice.

According to a second aspect of the present invention, there is provided the data communication method according to the first aspect, wherein after the data is circulated, a rule for the communication data is determined based on the communication data, and the communication data is defined by the determined rule. Is circulated.

According to a third aspect of the present invention, there is provided the data communication method according to the second aspect, wherein the rule of the communication data is:
The data format is a data format representing an array of all data related to a control device in charge of each of the central processing units.

According to a fourth aspect of the present invention, there is provided the data communication method according to the second aspect, wherein the rule of the communication data is:
The communication data includes data belonging to its own central processing unit and communication data containing only data belonging to its own central processing unit used by another central processing unit.

According to a fifth aspect of the present invention, there is provided the data communication method according to the third aspect, wherein each of the central processing means identifies a control device in charge and changes a data format based on the identification result. It is characterized in that it is determined.

According to a sixth aspect of the present invention, there is provided the data communication method according to any one of the first to fifth aspects, wherein:
Each of the central processing units corresponds to at least an engine control function, a transmission control function, and a chassis control function.

The data communication apparatus according to the present invention has a storage area for storing data belonging to its own central processing means and data belonging to other central processing means, and is connected in a ring. A plurality of central processing means, and a circulating means for circulating communication data including data obtained by updating data belonging to the central processing means to the latest data at least twice between the plurality of central processing means. , Is provided.

According to an eighth aspect of the present invention, in the data communication apparatus according to the seventh aspect, after the data is circulated, the data communication apparatus further comprises a determining means for determining a rule of communication data based on the communication data. The communication means is circulated by the circulating means according to the rules defined in the above.

According to a ninth aspect of the present invention, in the data communication apparatus according to the eighth aspect, the rule of the communication data is:
The data format is a data format representing an array of all data related to a control device in charge of each of the central processing units.

According to a tenth aspect of the present invention, in the data communication apparatus according to the eighth aspect, the rule of the communication data is such that the data belonging to its own central processing unit in the communication data is replaced by another central processing unit. It is characterized in that communication data including only data belonging to its own central processing unit used by the processing unit is determined.

According to an eleventh aspect of the present invention, in the data communication apparatus of the ninth aspect, each of the central processing means identifies a control device in charge and determines a data format based on the identification result. It is characterized by.

According to a twelfth aspect of the present invention, in the data communication apparatus according to any one of the seventh to eleventh aspects, each of the central processing units has at least an engine control function and a transmission control. And a chassis control function. According to the first aspect, communication data is circulated among a plurality of central processing units. The plurality of central processing units are connected in a ring, and each has a storage area for storing data belonging to its own central processing unit and data belonging to other central processing units. Therefore, the data to be circulated includes data belonging to its own central processing means and data belonging to other central processing means. In this cycle, in the first cycle, the data belonging to its own central processing unit is the latest data, but may have already been updated by other central processing units.
Therefore, communication data including data obtained by updating data belonging to its own central processing unit to the latest data is circulated at least twice. After being cycled twice this way,
The identity of the communication data, that is, the data belonging to all the central processing units, is ensured.

After the communication data is circulated, the identity of the data is ensured by all the central processing means. However, by simply circulating all the data belonging to the central processing means, it is possible to reduce the amount of data to be circulated. This leads to an increase in load and load. Therefore, as described in claim 2, after the circulation, the communication data rule is determined based on the circulated communication data, and the communication data is circulated according to the determined rule. Thereby, the circulated communication data becomes a fixed form, and it is possible to suppress an unnecessary load increase such as mixing of unnecessary data and data discrimination.

It is preferable that the communication data rules use a data format representing an array of all data related to a control device assigned to each of the central processing units, as described in claim 3. By using the data format representing the data arrangement, it is easy to specify the data to be used for the control device in charge of each of the central processing units.

Further, the rule of the communication data is as defined in claim 4.
In the communication data, data belonging to its own central processing means can be defined as communication data containing only data belonging to its own central processing means used by another central processing means among the communication data. . By doing so, it is possible to suppress an increase in data without circulating data used only by its own central processing unit.

The data format can be predetermined, but when the determined data format is used, unnecessary items may be included. In this case, unnecessary data portions are circulated as communication data. Be inefficient. Therefore, as described in claim 5, it is preferable that each of the central processing units identifies a control device in charge and determines a data format based on the identification result. By doing so, it is possible to determine the optimum items to be circulated, and it is possible to suppress an increase in data amount and an increase in load.

Among the vehicle controls, the engine control function, the transmission control function, and the chassis control function include:
The computational load is enormous, and one central processing means takes charge of it, but the load increases, but since they are related, they must exchange data with each other. Therefore,
As described in claim 6, each of the central processing units can correspond to at least each of an engine control function, a transmission control function, and a chassis control function. By doing so, the engine control function, the transmission control function, and the chassis control function can be operated with a small amount of data and with a reduced calculation load.

[0024] The data communication method can be realized by a data communication device according to claim 7. That is, the data communication apparatus according to the present invention has storage areas for storing data belonging to its own central processing means and data belonging to other central processing means, and is connected in a ring. A plurality of central processing means, and a circulating means for circulating communication data including data obtained by updating data belonging to the central processing means to the latest data at least twice between the plurality of central processing means, It has.

[0025] The data communication apparatus may further include a determination unit that determines a rule of the communication data based on the communication data after the circulation, as described in claim 8.
Communication data according to the rules determined by the determining means can be circulated by the circulating means. Further, as described in claim 9, as the rule of the communication data, it is possible to adopt a data format representing an array of all data related to a control device in charge of each of the central processing units, As described in claim 10, data belonging to its own central processing means among communication data is determined as communication data containing only data belonging to its own central processing means used by another central processing means. be able to. Further, each of the central processing means identifies a control device in charge as described in claim 11,
The data format can be determined based on the identification result. When the data communication device is applied to a vehicle, each of the central processing units includes at least an engine control function, a transmission control function, and a chassis control function. Can be made to correspond.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In the first embodiment, one electronic control unit (hereinafter, referred to as an ECU) mounted on a vehicle is provided with a central processing unit that controls each of an engine control function, a transmission control function, and a chassis control function. The present invention is applied to a case where a microcomputer having a CPU (hereinafter, referred to as a CPU) is configured to share the same.

As shown in FIG. 1, an ECU 10 of the present embodiment as a data communication device includes a first microcomputer 12 in charge of an engine control function, a second microcomputer 14 in charge of a transmission control function, and a chassis control. There is provided a third microcomputer 16 which is in charge of the function, and each is configured to be connected in a ring shape. The first microcomputer functions as a main control device in charge of engine control, and has a control terminal 12 for connecting to a device for engine control.
A, an output terminal 12B for connecting to another microcomputer and outputting data, and an input terminal 12C for connecting to another microcomputer and inputting data.

The second microcomputer 14 functions as a person in charge of the transmission control, and has a control terminal 14A for connecting to a device for the transmission control, and is connected to another microcomputer to output data. Terminal 14B for connection to another microcomputer and an input terminal 14C for data input. Further, the third microcomputer 16 functions as a controller for the chassis control.
Control terminal 16 for connecting to equipment for chassis control
A, an output terminal 16B for connecting to another microcomputer and outputting data, and an input terminal 16C for connecting to another microcomputer and inputting data.

These microcomputers 12, 14, 16 are
The output terminal 12B of the microcomputer 12 and the input terminal 14C of the second microcomputer 14, the output terminal 14B of the second microcomputer 14 and the input terminal 16C of the third microcomputer 16, the output terminal 16B of the third microcomputer 16 and the input terminal of the first microcomputer 12 12C,
Are connected, and data can be exchanged in a ring.

As shown in FIG. 2, the first microcomputer 12
The microcomputer comprises a microcomputer comprising a CPU 20, a RAM 22, a ROM 24, and an input / output port (I / O) 30 connected to the control terminal 12A. Each of the microcomputers is connected by a bus 32 so that commands and data can be exchanged. I have. The bus 32 has a direct memory access device (hereinafter, referred to as a DMA device) 26 connected to the output terminal 12B for data transmission and an input terminal 12B.
A DMA device 28 for data reception connected to C is connected. These DMA devices 26 and 28 are devices that enable direct access to a memory (the RAM 22 in the present embodiment). In FIG. 2, for simplicity of explanation, the DMA device 2 responsible for data transmission and data reception is used.
6 and 28 are configured separately, but these DMA devices 2
As is well known, one of the direct memory access controllers (DMAC) can be used for the devices 6 and 28.

In this embodiment, a case will be described in which a DMA for directly accessing a memory is used. However, a serial communication unit that enables communication by serial data may be provided to perform the serial communication. In addition, each of the above R
The OM stores a processing routine described below.

Since the second microcomputer 14 and the third microcomputer 16 have the same configuration as the first microcomputer 12, their description is omitted.

Next, the operation of the present embodiment will be described. After executing the initial processing (initial processing), the first microcomputer 12, the second microcomputer 14, and the third microcomputer 16
Data communication for executing each function is performed, and each function is executed (normal processing). In the present embodiment, in the initial processing, data is transmitted to all microcomputers by circulating the data. The first microcomputer 1
2. In the second microcomputer 14 and the third microcomputer 16, a memory area is secured as follows.

As shown in FIG. 5, the communication data to be circulated is composed of data Da belonging to the first microcomputer 12, data Db belonging to the second microcomputer 14, and part of data Dc belonging to the third microcomputer 16, and the data Da. , Db, D
c is stored in the RAM of each of the first microcomputer 12, the second microcomputer 14, and the third microcomputer 16. Each microcomputer secures a memory area in the order of data belonging to its own microcomputer, data belonging to a microcomputer to be subjected to DMA reception, and data belonging to a microcomputer to be subjected to DMA transmission.

That is, in the first microcomputer 12, the data D
a, an area M1a for storing data Dc, and an area M for storing data Db.
1b, a memory area is secured in the order of 1b. Similarly, in the second microcomputer 14, an area M2b for storing data Db,
A memory area is secured in the order of an area M2a for storing the data Da and an area M2c for storing the data Dc, and the third microcomputer 16 has an area M3c for storing the data Dc and an area for storing the data Db. M3b,
A memory area is secured in the order of the area M3a for storing the data Da.

In each of the above areas, a readable / writable area and a readable only area are predetermined for each microcomputer. That is, basically, the data belonging to the own microcomputer needs to be updated to the latest data by reading and writing by the own microcomputer, but need not be changed by another microcomputer. In the example of FIG. 5, in the first microcomputer 12, an area M1a for storing its own data Da is a readable / writable area, and in the second microcomputer 14, its own data D is stored.
An area M2b for storing b and an area M3c for storing its own data Dc in the third microcomputer 16 are readable and writable areas. Another region, namely region M
1c, area M1b, area M2a, area M2c, area M3
b, the area M3a is an area where DMA is possible but only reading is possible from each microcomputer.

As data stored in each of the above areas, there is an option setting of each CPU. For example, data indicating the presence or absence of traction control, data indicating whether the transmission is an automatic mission or a manual mission, data indicating the presence or absence of an automatic cruise control, 2WD /
There is data representing 4WD, which can be determined based on the level of the adjust port or the like. There is also a learning value such as the fully closed position of the throttle.

Next, the initial processing executed by each microcomputer will be described. As shown in FIG. 3, in the first microcomputer 12,
Initial DMA activation processing is executed. Step 10
At 0, an initial value stored in the ROM in advance as transmission data is set in the RAM. Instead of using the initial value stored in the ROM, a value determined in the activation process may be set. In the next step 102, DMA transmission / reception is permitted. That is, data communication by DMA is set to be possible.

In the next step 104, the DMA reception completion interrupt processing is permitted. That is, a setting is made to enable the execution of interrupt processing when data has been received by DMA. The interrupt processing (not shown) is a flag indicating that reception has been completed when data has been received by DMA. Is set. In the next step 106, DMA reception activation and standby are performed. This step 106 is performed after the data can be received by the DMA and the other microcomputers 14 and 16
This is to wait for a sufficient time until the preparation for is completed.

In the next step 108, the first DM
A transmission start is executed. That is, the initial value set in the RAM is transmitted by DMA. This initial value is transmitted to the second microcomputer 14. In the next step 110,
The determination as to whether or not the transmission is completed is repeated until the transmission is completed. When the transmission is completed, the process proceeds to the next step 112 to determine whether or not the flag has been set. Repeat the judgment of whether or not
Wait until reception is completed. When the DMA reception is completed, the result in step 112 is affirmative, and the process proceeds to step 114.

When the DMA reception is completed, the first
In the microcomputer 12, data received by DMA is stored in RAM
Has been written to. As a result, the latest data is stored in the RAM.

In the next step 114, it is determined whether or not DMA transmission to the second microcomputer 14 is possible. This determination is made, for example, by a transmission request (RT
It can be determined by referring to whether S) is set or reset. If the DMA transmission to the second microcomputer 14 is possible, the result in step 114 is affirmative, and in the next step 116, the second DMA transmission activation is executed.

As shown in FIG. 4, the second microcomputer 14 executes an initial process. In step 120, an initial value previously stored in the ROM as transmission data is set in the RAM. Instead of using the initial value stored in the ROM, a value determined in the activation process may be set. In the next step 122, DMA transmission / reception is permitted. That is, data communication by DMA is set to be possible.

In the next step 124, DMA reception completion interrupt processing is permitted. In this interrupt processing (FIG. 12), D
A flag indicating that the MA reception has been completed is set (step 150), and in the next step 151, the third microcomputer 1
Then, it is determined whether or not the DMA transmission to the third microcomputer 16 is possible.
A transmission is started and the interrupt processing is ended.

In the next step 128, the first DM
A reception start is executed, and in the next step 130, D
It is determined whether or not the MA reception has been completed. When the DMA reception is completed, the result in step 130 is affirmative, and the process proceeds to the next step 134.

When the DMA reception is completed, the second
In the microcomputer 14, the data received by the DMA from the first microcomputer 14 is written in the RAM. As a result, the latest data of the first microcomputer 14 is stored in the RAM.

The first transmission start in the reception completion interrupt processing is performed by using the data stored in the RAM of the second microcomputer 14 as D
Transmit by MA. This data is stored in the third microcomputer 1
6 is sent. When the execution of the first transmission start in the reception completion interrupt processing is completed, the second DMA reception start is executed in the next step 134, and the next step 13 is executed.
At 6, it is determined whether or not the DMA reception has been completed.
When the DMA reception has been completed, the result in step 136 is affirmative, and this routine ends.

When the DMA reception is completed (step 13)
In the case of (Yes in 6), in the second microcomputer 14, the data received by the DMA from the first microcomputer 12 is written in the RAM. As a result, the latest data of the first microcomputer 12 and the third microcomputer 16 is stored in the RAM.

Since the initial processing in the third microcomputer 16 is the same as the processing in the second microcomputer 14, the description is omitted.

Next, the first microcomputer 12 and the second microcomputer 1
The flow of data transmitted and received between the fourth and third microcomputers 16 by DMA will be further described.

As shown in FIG. 6, the first microcomputer 12
In the first transmission start, communication data consisting of data Da belonging to itself and data Dc0 belonging to the third microcomputer 16 among data stored in the RAM is transferred to the DMA.
Transmit (S1). Since the data Dc0 has not been DMA-received from the third microcomputer 16 at this time, the initial value is used. The second microcomputer 14 is the first microcomputer 1
The communication data from the second microcomputer 2 is received, and the communication data including the data Db belonging to itself and the data Da belonging to the first microcomputer 12 among the data stored in the RAM is DMA-transmitted to the third microcomputer 16 (S2). Similarly, the third microcomputer 16 receives communication data from the second microcomputer 14 and converts communication data including data Dc belonging to itself and data Db belonging to the second microcomputer 12 from data stored in the RAM. DMA transmission is performed to the first microcomputer 12 (S3).

Next, at the second transmission start-up, the first microcomputer 12 stores its own data Da stored in the RAM and the latest data Dc belonging to the third microcomputer 16.
The communication data consisting of (received in S3) is transmitted by DMA (S4). After the transmission ends, the first microcomputer 12 ends the initial processing (initial processing). Second microcomputer 14
Finishes the initial processing (initial processing) by receiving the communication data from the first microcomputer 12, and executes the data Db among the data stored in the RAM as a normal processing.
And the communication data consisting of the data Da
DMA transmission is performed (S5). The third microcomputer 16 is a second microcomputer.
Upon receiving communication data from the microcomputer 14, the initial processing (initial processing) is completed, and RA processing is performed as normal processing.
The communication data including the data Dc and the data Db among the data stored in M is DMA-transmitted to the first microcomputer 12 (S6).

As described above, in the present embodiment, in the initial processing, appropriate data is stored in each microcomputer, so that the processing in each microcomputer does not become unstable due to a data difference.

[Second Embodiment] Next, a second embodiment will be described. Although the case where one communication data is circulated has been described in the above embodiment, this embodiment circulates two communication data. In the present embodiment, since the configuration is the same as that of the above-described embodiment, the same portions are denoted by the same reference numerals and detailed description thereof will be omitted.

Next, an initial process executed by each microcomputer will be described. As shown in FIG. 7, in the first microcomputer 12,
The initial DMA activation process is executed, and the set initial value is transmitted (the first D
MA transmission activation, steps 100 to 108), which are transmitted to the second microcomputer 14. When the transmission is completed and the DMA reception is completed (steps 110 and 112), since the latest data received by the DMA has been written to the RAM, RA
The data stored in M is sent to the second microcomputer 14 again.
A transmission (start of second DMA transmission, step 11)
4, 116).

In the next step 140, the second DM
The determination is repeatedly made as to whether or not the transmission is completed until the A transmission is completed. When the transmission is completed, the determination in step 140 is affirmative, and in the next step 142, it is determined whether or not the DMA transmission to the second microcomputer 14 is possible. . Second microcomputer 1
When the DMA transmission is possible to step S4, the result in step 142 is affirmative, and in the next step 144, the start of the DMA transmission of the second data is executed, and this routine ends.

The initial processing executed by the second microcomputer 14 and the third microcomputer 16 is the same as the processing shown in FIG.

Next, the flow of data transmitted and received by the DMA between the first microcomputer 12, the second microcomputer 14, and the third microcomputer 16 in the present embodiment will be further described.

As shown in FIG. 8, the first microcomputer 12
In the first transmission start, the data Da belonging to itself
Then, communication data including the initial value data Dc0 belonging to the third microcomputer 16 is transmitted by DMA (S1). The second microcomputer 14 receives the communication data from the first microcomputer 12 and converts the communication data including the data Db belonging to itself and the data Da belonging to the first microcomputer 12 into the third microcomputer 16.
DMA transmission is performed (S2). Similarly, the third microcomputer 16
Receives the communication data from the second microcomputer 14 and transfers the communication data consisting of the data Dc belonging to itself and the data Db belonging to the second microcomputer 12 to the first microcomputer 12 by DMA.
It transmits (S3).

Next, at the second start of transmission, the first microcomputer 12 stores its own data Da stored in the RAM and the latest data Dc belonging to the third microcomputer 16.
The communication data consisting of (received in S3) is transmitted by DMA (S4). Then, when the second microcomputer 14 becomes ready to receive, the DMA-transmitted communication data (S4) is again DMA-transmitted (S4a). After the transmission of the communication data is completed again, the first microcomputer 12 ends the initial processing (initial processing). The second microcomputer 14 has a first microcomputer
Upon receiving communication data from the microcomputer 12, the initial processing (initial processing) is completed, and RA processing is performed as normal processing.
The communication data including the data Db and the data Da among the data stored in M is DMA-transmitted to the third microcomputer 16 (S5). Then, the communication data including the communication data received by the DMA is DMA-transmitted to the third microcomputer 16 (S5a). The third microcomputer 16 is the second microcomputer 14
Receiving the communication data from the CPU, the initial processing (initial processing) is completed, and the communication data composed of the data Dc and the data Db among the data stored in the RAM as a normal processing is DMA-transmitted to the first microcomputer 12. And again D
The communication data including the communication data received by the MA is DMA-transmitted to the first microcomputer 12.

As described above, in the present embodiment, two communication data can be simultaneously circulated, so that the sense of receiving the communication data can be shortened and the reliability of the communication data can be improved.

[Third Embodiment] Next, a third embodiment will be described. In the present embodiment, the form of communication data used for normal processing, that is, the format, is determined using communication data circulated in the initial processing. Note that, in this embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description is omitted.

In this embodiment, as shown in FIG. 10, the first microcomputer 12, the second microcomputer 14, and the third microcomputer
A memory area for the microcomputer 16 is secured. That is, an area F1a (F2a) for storing data Da belonging to the first microcomputer 12, an area F1b (F2b) for storing data Db belonging to the second microcomputer 14, and data Dc belonging to the third microcomputer 16 are stored. RAs of the microcomputer in the order of the areas F1c (F2c)
It is assumed that a memory area is secured in M.

FIG. 9 shows a flow of data transmitted and received by the first microcomputer 12, the second microcomputer 14, and the third microcomputer 16 in the present embodiment.

At the first start of transmission, the first microcomputer 12 DMA-transmits communication data including data Da0, Db0, and Dc0 belonging to all microcomputers among the data stored in the RAM (S11). Data Da
0 is option setting information for controlling devices belonging to the first microcomputer 12, and includes, for example, data indicating the presence or absence of auto-cruise control. Data Db0
Is information on option settings for controlling devices belonging to the second microcomputer 14, such as 2WD / 4WD setting information and data indicating the presence or absence of an autodiag. The data Dc0 is information on option settings for controlling devices belonging to the third microcomputer 16, and includes, for example, data indicating the presence or absence of auto-cruise control and data indicating the presence or absence of diagnosis.

Prior to the first transmission start, a general-purpose port (I / O port) or the like is connected to the CPU in each microcomputer.
It is assumed that a process of writing each option setting determined in the above to the RAM has been executed. Therefore, when the first transmission is started by the first microcomputer 12, the first transmission is started.
Communication data including each option setting determined by the CPU of the microcomputer 12 is transmitted.

The second microcomputer 14 receives the communication data from the first microcomputer 12, and receives the data Da0, Db0, Db belonging to all the microcomputers of the data stored in the RAM.
The communication data composed of c0 is DMA-transmitted to the third microcomputer 16 (S12). Similarly to the first microcomputer 12, the second microcomputer 14 executes a process of writing each option setting determined by the CPU from the general-purpose port (I / O port) or the like to the RAM before the DMA transmission.
Therefore, when DMA transmission is performed by the second microcomputer 14, communication data including each option setting determined by the CPU of the second microcomputer 14 is transmitted.

Similarly, the third microcomputer 16 receives the communication data from the second microcomputer 14, and the data Da0, D0 belonging to all the microcomputers of the data stored in the RAM.
The communication data consisting of b0 and Dc0 is DMA-transmitted to the first microcomputer 12 (S13). Even the third microcomputer 16 has the second
As in the case of the microcomputer 14, before the DMA transmission, a process of writing each option setting determined by the CPU from the general-purpose port (I / O port) or the like to the RAM in the microcomputer is executed. For this reason, when DMA transmission is performed by the third microcomputer 16, communication data including each option setting determined by the CPU of the third microcomputer 16 is transmitted.

Next, the first microcomputer 12 is connected to the third microcomputer 1
After receiving the communication data from DMA 6 and checking the option setting of each CPU by referring to the communication data received by DMA, the transmission / reception data format is determined as follows.

As shown in FIG. 10, for example, the region F1a
Represents data Da (c) common to the first microcomputer 12,
The first option setting data Da (1) and the second option setting data Da (2) can be stored. The area F1b includes common data Db (c) relating to the second microcomputer 14 and data Db of the first option setting.
(1) The second option setting data Db (2) can be stored. Similarly, the area F1c is configured to be able to store common data Dc (c), first option setting data Dc (1), and second option setting data Dc (2) for the third microcomputer 16. .

In the normal processing, common data Da (c), Db (c), and Dc (c) for each microcomputer may be used. However, option setting data cannot be used, or May not. Therefore, in such a case, it is not efficient to circulate communication data including option setting data.

For this reason, in the present embodiment, after checking the option setting of each CPU with reference to the communication data received by DMA, the transmission / reception data format from which unnecessary items are deleted is determined. In the example of FIG.
4, the second option setting data Db (2) and the third option setting data Db (2).
Data Dc of the second option setting of the microcomputer 16
The case where (2) is unnecessary is shown. These data Db
(2), a communication data format from which Dc (2) is deleted. That is, the communication data format is a segment F for storing data Da (c) and Da (1) belonging to the first microcomputer 12 from the area F1a.
In the area F1b, the area F1b is a segment F2b reduced to store only the data Db (c) and Db (1) belonging to the second microcomputer 14, and the data Dc (c) and Dc (Dc) belonging to the third microcomputer 16 from the area F1c. 1) is determined by the segment F2c which is reduced to store (1).

By doing so, only the data required by each microcomputer can be used as communication data, so that the data amount can be reduced and the communication load can be optimized and suppressed.

Next, at the second transmission start, the first microcomputer 12 sets the transmission / reception data format determined above (Fs1), and communicates the latest data Da0, Db0, and Dc0 stored in the RAM. D
MA transmission is performed (S14). After the transmission ends, the first microcomputer 12 ends the initial processing (initial processing). The second microcomputer 14 receives the communication data from the first microcomputer 12 by DMA, sets the received transmission / reception data format (Fs2), and stores the data Da stored in the RAM.
The communication data consisting of 0, Db0, and Dc0 is DMA-transmitted to the third microcomputer 16 (S15). After the transmission is completed, the second microcomputer 14 ends the initial processing (initial processing) and shifts to normal processing.

Next, the third microcomputer 16 ends the initial processing (initial processing) by receiving the communication data from the second microcomputer 14, but the third microcomputer 16
The communication data from the microcomputer 14 is received by DMA, the received transmission / reception data format is set (Fs3), and the communication data consisting of the data Dc and the data Db among the data stored in the RAM as a normal process is transmitted to the first microcomputer. Then, DMA transmission is performed.

As described above, in this embodiment, in the initial processing, a format belonging to each microcomputer, that is, a format that determines only option settings such as setting values of connected devices and the like is set. The data amount can be reduced, and the communication load can be optimized and suppressed. Further, since the data format is determined in the initial processing, the initial data can be made general-purpose, and each microcomputer can have a common configuration.

Note that the format of the communication data is not limited to the above-described configuration, and the degree of freedom can be increased as described below. As shown in FIG. 11A, the first microcomputer 12
Area F3a for storing data Da belonging to
An area F3b for storing data Db belonging to the microcomputer 14 and an area F3c for storing data Dc belonging to the third microcomputer 16 are secured. In the present embodiment, the area F3a for storing the data Da is a data area for a transmission request to the first microcomputer 12;
An area F3b for storing b is a data area for a transmission request to the second microcomputer 14, and an area F3c for storing data Dc is a data area for a transmission request to the third microcomputer 16. .

Each area contains data D for each type of transmission request.
a (0) to Da (i), Db (0) to Db (m), Dc
It is divided into a plurality of cells to store (0) to Dc (n). For example, as shown in FIG. 11B, the transmission request type data Da (0) belonging to the first microcomputer 12 includes a plurality of flags represented by “1” with transmission request or “0” without transmission request. The format is continuous, and a plurality of transmission requests can be determined. From this format, that is, by referring to the flag of "1" with transmission request, as shown in FIG. 11 (3), a data format at the time of normal processing consisting of only the one with transmission request is determined.

That is, in the first DMA transmission, each microcomputer writes a transmission request to another microcomputer and transmits the request to the next microcomputer. Then, in the second DMA transmission, the transmission / reception data format is set with reference to the contents of the transmission request to all the microcomputers, and the format of the DMA communication in the normal processing is determined.

By doing so, for example, even if the data (option data) requested by the third microcomputer 16 to be transmitted to the first microcomputer 12 is increased, if the data is registered in the area F3a in advance, Data can be obtained only by changing the processing of the three microcomputers 16. It is also possible to optimize the communication data according to the required options.

Although the above embodiment has been described with reference to the case where the processing routine is stored in the ROM and executed, the floppy disk FD as a recording medium can be inserted into and removed from the input / output unit (for example, the input / output port 30). The above-described processing routine may be executed from the floppy disk FD by connecting a floppy disk unit (FDU) and using the FDU to read and write the floppy disk FD. That is, the processing routine may be recorded in advance on the floppy disk FD without storing the processing routine in the ROM, and the processing program recorded on the floppy disk FD may be executed via the FDU. Further, a large-capacity storage device (not shown) such as a hard disk device may be connected, and the processing program recorded on the floppy disk FD may be stored (installed) in the large-capacity storage device (not shown) and executed. . As recording media, there are optical disks such as CD-ROMs and magneto-optical disks such as MDs and MOs.
When these are used, a CD-ROM device, an MD device, an MO device, or the like may be used instead of the FDU or further.

[0083]

As described above, according to the present invention, communication data including data obtained by updating the data belonging to its own central processing unit to the latest data is circulated at least twice, so that the communication data is identical. Can be secured.

After the communication data has been circulated, the communication data to be circulated is determined by defining the rules for the communication data based on the circulated communication data. There is an effect that unnecessary load increase such as data discrimination can be suppressed.

Further, since a data format representing an array of all data relating to the control device in charge of each of the central processing units can be used in the communication data rules, the control in each of the central processing units can be used. Data to be used for the device can be easily identified,
This has the effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a data communication device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a first microcomputer.

FIG. 3 is a flowchart illustrating a flow of an initial process executed by a first microcomputer according to the first embodiment;

FIG. 4 is a flowchart illustrating a flow of an initial process executed by a second microcomputer.

FIG. 5 is an explanatory diagram for explaining a storage state of communication data circulated between the microcomputers.

FIG. 6 is a timing chart showing a flow of data transmitted and received between the microcomputers of the first embodiment by DMA.

FIG. 7 is a flowchart illustrating a flow of initial processing executed by a first microcomputer according to a second embodiment;

FIG. 8 is a timing chart showing a flow of data transmitted and received by DMA between microcomputers according to the second embodiment.

FIG. 9 is a timing chart showing a flow of data transmitted and received by DMA between microcomputers according to the third embodiment.

FIG. 10 is an image diagram for explaining a format of data transmitted and received by a DMA between respective microcomputers according to the third embodiment.

FIG. 11 is an explanatory diagram for explaining increasing the degree of freedom in the format of communication data in the third embodiment.

FIG. 12 is a flowchart showing a flow of a DMA reception interrupt process executed by a second microcomputer.

[Description of Signs] 10 ECU 12 First microcomputer 14 Second microcomputer 16 Third microcomputer

Claims (12)

[Claims] 1. A plurality of central processing units, each having a storage area for storing data belonging to its own central processing unit and data belonging to another central processing unit, and connected in a ring. A data communication method of circulating communication data including data obtained by updating data belonging to its own central processing unit to the latest data at least twice. 2. The data communication method according to claim 1, wherein a rule for communication data is determined based on the communication data after the circulation, and the communication data is circulated according to the determined rule. 3. The data communication according to claim 2, wherein the communication data rule is a data format representing an array of all data related to a control device in charge of each of the central processing units. Method. 4. The communication data rule includes a communication that includes data belonging to its own central processing unit among the communication data and only data belonging to its own central processing unit used by another central processing unit. The data communication method according to claim 2, wherein data is determined. 5. The data communication method according to claim 3, wherein each central processing unit identifies a control device in charge and determines a data format based on the identification result. 6. The central processing means includes at least an engine control function, a transmission control function,
The data communication method according to any one of claims 1 to 5, wherein the data communication method corresponds to each of a chassis control function and a chassis control function. 7. A plurality of central processing units each having a storage area for storing data belonging to its own central processing unit and data belonging to another central processing unit and connected in a ring, And a circulating means for circulating communication data including data obtained by updating the data belonging to the central processing means to the latest data at least twice between the central processing means. 8. The communication device according to claim 1, further comprising a determining unit that determines a rule of the communication data based on the communication data after the circulation, and circulating the communication data according to the rule determined by the determining unit. The data communication device according to claim 7, wherein: 9. The data communication according to claim 8, wherein the communication data rule is a data format representing an array of all data related to a control device in charge of each of the central processing units. apparatus. 10. The communication data rule is as follows: data of the communication data belonging to its own central processing unit is
9. The data communication apparatus according to claim 8, wherein communication data including only data belonging to its own central processing unit used by another central processing unit is determined. 11. The data communication apparatus according to claim 9, wherein each of said central processing means identifies a control device in charge and determines a data format based on the identification result. 12. The apparatus according to claim 7, wherein each of said central processing means corresponds to at least an engine control function, a transmission control function, and a chassis control function. The data communication device according to claim 1.