JP2008254484A - On-vehicle communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle communication system in which each ECU is provided with a function of backing up data memorized in the non-volatile memories of other ECUs which are different among ECUs. <P>SOLUTION: The on-vehicle communication system 10 is provided with: a plurality of electronic control units 20 connected to each other through a multiple communication wire bus 11. The respective ECUs have: a re-writable non-volatile memory 22 having a conservation area of the self-data and a conservation area of backup data for memorizing vehicle information of the other electronic control unit connected by the bus 11; and a processing part 24 for emitting instruction for transmitting the self-data preserved at the first activation to the other ECU and instruction for transmitting the self-data to the other ECU at re-writing of the self-data, and memorizing the backup data received from the other ECU in the conservation area of the backup data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle communication system, and in particular, in an in-vehicle communication system including a plurality of electronic control units connected to each other via a bus for multiple communication lines, each electronic control unit is connected to another electronic control unit. It is provided with a backup of the data in the nonvolatile memory of the unit.

2. Description of the Related Art In recent years, a vehicle-mounted communication system has been adopted in which a plurality of electronic control units (ECUs) that control vehicle-mounted electrical components are connected via a multiplex communication bus and communicate with each other.
The nonvolatile memory of each ECU stores various set values and vehicle identification information for controlling electrical components at the time of factory shipment. For example, when an in-vehicle communication system is used in a vehicle diagnostic apparatus, an in-vehicle device ECU such as an engine ECU that performs vehicle diagnosis or a communication ECU that communicates with an external management center side has a unique number such as a manufacturing number. Vehicle identification information is stored. When the on-vehicle equipment ECU performs vehicle diagnosis, the communication ECU that has received the diagnosis result via the bus transmits the vehicle identification information together with the diagnosis result to the external management center.
However, when replacing the ECU itself in which the vehicle identification information is stored due to a failure of the ECU or the like, the vehicle identification information must be stored again in the newly connected ECU, which increases the number of work processes. .

Japanese Patent Application Laid-Open No. 11-255079 (Patent Document 1) proposes a vehicle electronic control device in which the same vehicle identification information is stored in a plurality of ECUs connected to a bus.
When the ECU is replaced due to a failure or is newly connected to the bus, when the ECU does not store the vehicle identification information, a request for transmitting the vehicle identification information is issued to another ECU connected to the same bus. The newly connected ECU stores the vehicle identification information received from the other ECU in a nonvolatile memory.
In this way, even if the vehicle identification information is not stored in the newly connected ECU, it can be received and stored from another ECU, so that it is not necessary to store the vehicle identification information before attaching to the vehicle.

  However, in Patent Document 1, a plurality of ECUs store vehicle identification information commonly used by each ECU, but store vehicle information such as initial setting information individually set in each ECU. It is not a thing. For this reason, even when an abnormality occurs in the nonvolatile memory of the ECU and the vehicle information cannot be used, there is a problem that the vehicle information cannot be received from another ECU.

In addition, when a failure occurs in which communication is interrupted because the nonvolatile memory cannot be accessed, even if vehicle identification information is received from another ECU, it cannot be written to the nonvolatile memory, and the ECU uses the vehicle identification information. There is a problem that can not be.
Further, Patent Document 1 does not describe how to deal with data in the nonvolatile memory that is destroyed and becomes erroneous data, and is connected to the ECU when the ECU uses the destroyed erroneous data. There is a problem that the electrical equipment malfunctions.

JP-A-11-255079

  The present invention has been made in view of the above problems, and in an in-vehicle communication system including a plurality of ECUs connected to each other via a bus for multiple communication lines, each ECU is non-volatile of other ECUs. In addition to providing backups of different data for each ECU stored in the memory, each ECU restores its own data to prevent malfunction of the ECU even if an abnormality occurs in the nonvolatile memory of each ECU Is an issue.

In order to solve the above problems, the present invention is an in-vehicle communication system including a plurality of electronic control units connected to each other via a bus for multiple communication lines, and each of the electronic control units includes:
A rewritable nonvolatile memory having a storage area for own data for storing vehicle information including its own initial setting information and a storage area for backup data for storing the vehicle information of another electronic control unit connected by the bus. A storage unit comprising:
A command to transmit the own data to be saved to the other electronic control unit at the first start-up and a command to send the own data to the other electronic control unit at the time of rewriting the own data, and another electronic control A processing unit for storing the backup data received from a unit in a storage area of the backup data;
An in-vehicle communication system is provided.

According to the above-described configuration, when all the electronic control units of the in-vehicle communication system are activated for the first time such as at the time of factory shipment, or when the own data of the electronic control unit is rewritten by connecting the diagnosis etc., each electronic control The unit transmits its own data stored in its own storage area of its own non-volatile memory to other electronic control units, and receives backup data which is data of other electronic control units from other electronic control units. It is stored in the backup data storage area of its own non-volatile memory.
For this reason, each electronic control unit can mutually memorize | store the data of the non-volatile memory of all the other electronic control units connected to the bus as backup data.

  The own data stored in the nonvolatile memory of the electronic control unit is vehicle information set individually for each electronic control unit, and the other electronic control unit stores the own data as backup data. Therefore, even when an abnormality occurs in its own nonvolatile memory and its own data cannot be used, it can receive and use its own data from another electronic control unit.

  The processing unit of each electronic control unit includes a memory check unit that performs a memory check of a non-volatile memory in which the own data is stored. When an abnormality is detected in the memory check unit, It is preferable to rewrite the received own data with the own data stored in the nonvolatile memory.

As an abnormality of the non-volatile memory, the processing unit can read data from the non-volatile memory. However, when an abnormality occurs in which the data content is destroyed and erroneous data is generated, the memory check unit detects the abnormality. At this time, the processing unit issues a request for transmitting own data to the other electronic control unit, receives the own data, and overwrites the received own data in the storage area of the own data in the nonvolatile memory.
In this way, the electronic control unit receives its own data whose data content is not destroyed from another electronic control unit and stores it in the nonvolatile memory, so that it can restore its own data in the nonvolatile memory. . In addition, since the electrical component connected to the electronic control unit is not controlled using erroneous data, malfunction of the electrical component can be prevented.

The storage unit of each electronic control unit includes a volatile memory,
It is preferable that the processing unit issues a request for transmission of own data to the other electronic control unit and stores the received own data in the volatile memory when an abnormality occurs in which the own data cannot be read from the nonvolatile memory.

In processing such as normal control of electrical components, the processing unit once writes the data content of the nonvolatile memory into a volatile memory that can be accessed at high speed, and performs processing using the data in the volatile memory.
Here, as an abnormality of the nonvolatile memory, when an abnormality occurs in which the nonvolatile memory main body breaks down and communication is interrupted, data cannot be read from the nonvolatile memory and written to the volatile memory. Therefore, a request for transmitting own data is sent to the other electronic control unit, and the processing unit stores the received own data in the volatile memory.
In this way, even when an abnormality occurs in which the non-volatile memory is interrupted, the processing unit stores the own data stored in the volatile memory by storing the own data received from another ECU in the volatile memory. It can be used to continue control of the electrical components.

  The processing unit of each electronic control unit transmits its own data to be transmitted to the other electronic control unit with a version number, and receives the own data received based on the transmission request of its own data to the other electronic control unit. It is preferable to store the own data with the latest version number among the data.

Since the self-data is attached with a version number and transmitted to other electronic control units, each electronic control unit sends a version together with the received self-data when making a request to send data to other electronic control units. A number can be received. Further, when the own data is received from a plurality of other electronic control units, the electronic control unit can select and save the data having the latest version number.
Further, when each electronic control unit makes a transmission request for its own data to another electronic control unit, it may first issue a transmission request to transmit only the version number of its own data. The electronic control unit having the latest version number among the received version numbers can be selected and a transmission request for own data can be made.

It is preferable that the processing unit of each electronic control unit sets in advance the priority order of the other electronic control units to which the data is requested to be transmitted.
If there is a plurality of own data with the latest version number among the own data received based on the transmission request to the other electronic control unit, the electronic control with a higher priority is referred to by referring to the preset priority. The own data transmitted from the unit can be saved.

It is preferable that the priorities are determined in advance in the order of increasing free capacity of the nonvolatile memory or in the order of short communication paths from the own electronic control unit.
In the case where the priority order is the order in which the free space of the nonvolatile memory is large, the data can be accurately read from the nonvolatile memory.
Moreover, when the priority is set to the order in which the communication path is short from the own electronic control unit, it is possible to reduce the risk that the own data cannot be received due to the disconnection of the bus.

As described above, according to the in-vehicle communication system of the present invention, when all the electronic control units of the in-vehicle communication system are activated for the first time, such as at the time of factory shipment, or the own data of the electronic control unit is subjected to diagnosis or the like. When connected and rewritten, each electronic control unit sends its own data from its non-volatile memory to other electronic control units, and also receives backup data from other electronic control units from other electronic control units and stores them. Therefore, each electronic control unit can mutually store the data in the nonvolatile memory of all the other electronic control units connected to the bus as backup data.
In addition, when an abnormality occurs in the non-volatile memory, the processing unit can send a request to transmit the own data to the other electronic control unit, receive the own data, and use the own data. Control of the electrical component can be continued, and malfunction of the electrical component can be prevented.

Embodiments of the present invention will be described with reference to the drawings.
1 to 8 show a first embodiment of the present invention.
The in-vehicle communication system 10 of the present invention includes a plurality of electronic control units (ECUs) 20 connected to each other via a bus 11 for multiple communication lines. In this embodiment, three ECUs 20A, 20B, and 20C are provided. It has.
Each ECU 20 transmits its own data in its own EEPROM 22 to the other ECU 20, receives backup data of the other ECU, stores it in its own EEPROM 22, and provides data backup for each other.

The configuration of the ECU 20 will be described using the ECU 20A as an example. The ECUs 20B and 20C have the same configuration as the ECU 20A.
The ECU 20 </ b> A includes a microcomputer 21, an EEPROM 22 that constitutes a rewritable nonvolatile memory in a storage unit, and an input / output circuit 23.
The microcomputer 21 is connected to the bus 11 via the input / output circuit 23, and transmits / receives its own data and backup data to / from other ECUs 20B and 20C connected to the bus 11.
Here, the own data indicates vehicle information including its own initial setting information, and the backup data indicates vehicle information including initial setting information of the other ECU 20 and vehicle information received from the other ECU 20.

The EEPROM 22 is connected to the microcomputer 21 and has a storage area 22a for own data and a backup data storage area 22b for storing vehicle information of other ECUs 20B and 20C connected by the bus 11, as shown in FIG. ing.
In the ECU 20A, the data storage area 22a is an ECUA_DAT area, and the backup data storage area 22b is an ECUB_DAT area and an ECUC_DAT area.
The EEPROM 22 has an area 22c for storing the version number of its own data and an area 22d for storing the version numbers of the backup data of the other ECUs 20B and 20C. In the ECU 20A, the area 22c for storing the version number of its own data is an ECUA_VERSION area, and the area 22d for storing the version number of backup data of the other ECU 20 is an ECUB_VERSION area and an ECUC_VERSION area.

The microcomputer 21 includes a CPU 24 that constitutes a processing unit, a RAM 25 that constitutes a volatile memory of a storage unit, a ROM 26, and an input / output port 27.
The CPU 24 issues a command to transmit its own data to be saved to another electronic control unit, and stores the backup data received from the other electronic control unit in the backup data saving area 22b.
Further, when the own data of the EEPROM 22 is abnormal, a request for sending own data is issued to the other electronic control unit, and the own data stored in the other ECUs 20B and 20C is received.

Further, the CPU 24 includes a memory check unit 24 a of the EEPROM 22. The memory check unit 24a adds the memory contents from the first address to the last address of the EEPROM 22, and determines that the EEPROM 22 is normal if the checksum value as the addition result matches the reference value. A checksum operation is performed to determine that there is.
Further, the CPU 24 calculates the free capacity of the EEPROM 22 and transmits it to the other ECU 20, receives the free capacity information of the EEPROM 22 of the other ECU 20 from the other ECU 20, and requests the transmission request of its own data from these free capacity information. The priority order table 31 of the ECU 20 is determined.

  As shown in FIG. 3A, the RAM 25 receives an ECU_MEMORY area 25a for receiving and storing the free capacity of the other ECU 20, a MEMORY_LIST area 25b for storing a priority table 31 obtained from the free capacity of all the ECUs 20, An OLD_CHECKSUM area 25c for storing a checksum value immediately after the ECU 20 is activated and serving as a reference value for memory check, a NEW_CHECKSUM area 25d for storing a checksum value calculated after the calculation of the OLD_CHECKSUM area 25c, and an EEPROM 22 The same data as the own data stored in the own data storage area 22a is stored, and a BACKUP_DAT area 25e that is accessed when the CPU 24 uses the own data is provided.

In addition, in the ECU_MEMORY area 25a, as shown in detail in FIG. 3B, in the case of the ECU 20A, the free capacity of the other ECUs 20B and 20C is stored. In the case of the ECU 20B, the free capacity of the ECUs 20A and 20C is stored, and in the case of the ECU 20C, the free capacity of the ECUs 20A and 20B is stored.
Further, the MEMORY_LIST area 25b stores a priority table 31 in which the ECUs 20 connected to the in-vehicle communication system 10 including the ECU 20 are arranged in descending order as shown in FIG. is doing.
The ROM 26 stores application programs and the like for the operation of the CPU 24.

Next, the operation of the in-vehicle communication system 10 of the present invention will be described.
First, an outline of the operation at the time of starting of the ECU 20 will be described using the ECU 20A as an example with reference to the flowchart of FIG.
In step S10, a checksum value is calculated. The memory check unit 24a of the CPU 24 calculates a reference value for the checksum value used for the memory check.
In step S11, the priority table 31 is created. The ECU 20A issues a request for transmitting information on the free capacity of the EEPROM 22 to the other ECUs 20B and 20C, and creates the priority order table 31 so that the ECU 20 with the large free capacity of each ECU 20 has priority.

In step S12, the data version number is acquired. The version number of the own data stored in the EEPROM 22 of the ECU 20A is transmitted to the other ECUs 20B and 20C, and the version number of the backup data is received and stored from the other ECUs 20B and 20C.
In step S13, backup data is acquired mutually. The ECU 20A transmits its own data to the other ECUs 20B and 20C, receives backup data of the other ECUs 20B and 20C, and stores them in the EEPROM 22.

Details of the steps will be described.
FIG. 5 is a flowchart showing details of calculation of the checksum value in step S10. The calculation of the checksum value is performed by the CPU 24 of each ECU 20 after each ECU 20A, 20B, 20C is activated.
In step S20, after the ECU 20 is activated, the memory check unit 24a of the CPU 24 calculates a reference value for the checksum value used for the memory check.
In step S21, the calculated checksum value is written in the OLD_CHECKSUM area 25c of the RAM 25.

FIG. 6 is a flowchart showing details of creation of the priority order table 31 in step S11.
In step S31, the ECU 20A transmits a request for transmitting the free space information of the EEPROM 22 to the other ECUs 20B and 20C.
In step S32, the ECUs 20B and 20C receive the transmission request.
In step S33, the ECUs 20B and 20C check the free capacity of the EEPROMs 22B and 22C.
In step S34, the ECUs 20B and 20C transmit the free capacity information to the ECU 20A.

In step S35, the ECU 20A receives the free space information of the EEPROM 22 from the ECUs 20B and 20C.
In step S <b> 36, the ECU 20 </ b> A confirms whether or not free space information has been received from all the ECUs 20 connected to the bus 11. If not received, step S36 is repeated. If received, the process proceeds to step S37.
In step S37, the CPU 24 of the ECU 20A compares the received free space information of the EEPROM 22 of the other ECUs 20B and 20C and the free space information of the ECU 20A, and assigns priorities to the priority table 31 in descending order of free space.
In step S38, the table shown in FIG. 3C is stored in the MEMORY_LIST area 25b of the RAM 25.
In step S39, the priority table 31 is transmitted to the other ECU 20.

In step S40, the ECUs 20B and 20C receive the priority table 31 from the ECU 20A.
In step S41, the ECUs 20B and 20C store the received priority order table 31 in the MEMORY_LIST area 25b of the RAM 25.

Since the priority table 31 is created from the free capacity information of the EEPROM 22 of each ECU 20, the same priority table 31 is created regardless of which ECU 20 is created.
In the present embodiment, only the ECU 20A creates the priority table 31 and transmits it to the other ECUs 20B and 20C. The ECUs 20B and 20C store the priority table 31 created by the ECU 20A in the RAM 25, but the ECU 20B or the ECU 20C The priority order table 31 may be created and transmitted to another ECU 20.
Alternatively, the ECUs 20A, 20B, and 20C may issue a transmission request for the free space information in the EEPROM 22 to create the priority table 31 and transmit it to the other ECUs 20. In this case, each time the ECU 20 receives the priority table 31 from the other ECU 20, it overwrites the priority table 31 in the MEMORY_LIST area 25b and uses the last transmitted priority table 31.

  Further, the priority order table 31 may be determined so that priority is given to an ECU having a short communication path from its own ECU, instead of obtaining from the free space of the EEPROM 22. In this case, since the priority order table 31 differs depending on each ECU, the priority order table 31 is stored in advance in each ECU at the time of factory shipment.

  FIG. 7 is a detailed flowchart of the operation of mutually acquiring the version numbers in step S12. Although FIG. 7 illustrates an example in which the ECU 20A transmits the version number, the ECUs 20B and 20C perform the same operation as the ECU 20A, and the ECUs 20A, 20B, and 20C store the version numbers of the other ECUs 20 with each other. ing.

In step S50, the ECU 20A reads the version number of its own data in the EEPROM 22 from the ECUA_VERSION area, which is the area 22c for storing the version number of its own data, and transmits it to all other ECUs 20B and 20C.
In step S51, the ECUs 20B and 20C receive the version number from the ECU 20A.
In step S52, the ECUs 20B and 20C store the version number of the ECU 20A in an ECUA_VERSION area, which is an area 22d for storing the version numbers of other ECUs as viewed from the ECU 20B and 20C.

  FIG. 8 is a detailed flowchart of the operation of mutually acquiring backup data in step S13. FIG. 8 illustrates an example in which the ECU 20A transmits its own data to the other ECUs 20B and 20C. However, the ECUs 20B and 20C perform the same operation as the ECU 20A, and the ECUs 20A, 20B, and 20C mutually communicate with each other. The backup data is stored.

In step S60, the ECU 20A reads the own data in the EEPROM 22 from the ECUA_DAT area, which is the own data storage area 22a, and transmits it to all the other ECUs 20B and 20C.
In step S61, the ECUs 20B and 20C receive data from the ECU 20A (backup data when viewed from the ECUs 20B and 20C, and own data when viewed from the ECU 20A).
In step S <b> 62, the ECUs 20 </ b> B and 20 </ b> C store the data of the ECU 20 </ b> A in the ECUA_DAT area of the EEPROM 22.

  According to the above-described configuration, according to the in-vehicle communication system 10 of the present invention, when all the ECUs 20 of the in-vehicle communication system are first started up such as at the time of factory shipment, or the own data of the ECU 20 is connected to a diagnosis or the like. Each ECU 20 transmits its own data stored in its own EEPROM 22 to the other ECU 20 and stores backup data of the other ECU 20 from the other ECU 20, so that each ECU 20 is connected to the bus 11. Data in the EEPROM 22 of all other connected ECUs 20 can be stored as backup data.

Note that the rewritable nonvolatile memory is not limited to the EEPROM 22, and may be a mask ROM, PEPROM, EPROM, flash memory, or the like.
In the present embodiment, a plurality of ECUs 20 are connected to one bus 11 and exchange data with each other. However, backup data is exchanged between the ECUs 20 connected to other buses 11 via a gateway. Transmission and reception may be performed.

FIG. 9 shows a second embodiment of the present invention.
The second embodiment is a case where the contents of the data in the EEPROM 22 are intentionally rewritten after the ECUs 20 constituting the in-vehicle communication system 10 in the first embodiment have each stored the backup data in the EEPROM 22. Is the action. The EEPROM 22 can be rewritten by a dealer or the like by connecting a diagnosis or the like.
As an example, a case where the data in the EEPROM 22 of the ECU 20A is rewritten will be described with reference to the flowchart of FIG.

In step S70, new data is overwritten in the ECUA_DAT area which is the storage area 22a of the own node of the EEPROM 22 of the ECU 20A.
In step S71, the version number of the ECUA_VERSION area, which is the storage area 22c for the version number of its own data in the EEPROM 22, is incremented by one.
In step S72, when the memory check unit 24a of the CPU 24 periodically performs a memory check, the memory check operation is stopped.

Steps S73 and S74 are the same operations as steps S10 and S11 of the first embodiment.
In step S73, since the data is rewritten in the EEPROM 22 of the ECU 20A, the checksum value serving as the reference value for the memory check is calculated again.
In step S74, since the free capacity of the EEPROM 22 of the ECU 20A has also changed, the priority table 31 is created using the new free capacity information of the ECU 20A.
In step S75, the ECU 20A transmits a new version number to the other ECUs 20B and 20C. Note that the version numbers may be received from the other ECUs 20B and 20C as in step S12 of the first embodiment.
In step S76, the ECU 20A transmits new own data to the other ECUs 20B and 20C. Note that the data of the ECUs 20B and 20C may be received from the other ECUs 20B and 20C as in step S13 of the first embodiment. By step S76, the new data of the ECU 20A is also stored in the other ECUs 20B and 20C, and the backup data is mutually acquired.
In step S77, the periodic memory check stopped in step S72 is resumed.

According to the above configuration, even when the ECUs 20 constituting the in-vehicle communication system 10 have each stored the backup data of the EEPROM 22, the data of the EEPROM 22 is automatically rewritten. Therefore, the backup data can be stored again between the ECUs 20.
In addition, since another structure and an effect are the same as that of 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the present embodiment, the processes after step S71 are performed immediately after the EEPROM 22 of the ECU 20A is rewritten with new data in step S70. However, steps S71 and S72 may be performed after rewriting the EEPROM 22 with new data in step S70, and the processing after the checksum calculation in S73 may be performed after the engine is started.

FIG. 10 shows a third embodiment of the present invention.
In the third embodiment, data can be read from the EEPROM 22 after the ECUs 20 constituting the in-vehicle communication system 10 in the first embodiment have stored the backup data of the EEPROM 22, respectively. This is an operation in the case where an abnormality in which data contents are destroyed and erroneous data is generated due to noise mixing or a malfunction at the time of resetting of the ECU 20 or the like.
As an example, the case where the data in the EEPROM 22 of the ECU 20A is destroyed will be described with reference to the flowchart of FIG.

  In step S80, the memory of the EEPROM 22 is checked. The memory check unit 24a of the CPU 24 of the ECU 20A periodically performs the checksum calculation of the EEPROM 22, stores the checksum value in the NEW_CHECKSUM area 25d, and compares it with the value in the OLD_CHECKSUM area 25c that is a reference value. If the values in the NEW_CHECKSUM area 25d and the OLD_CHECKSUM area 25c do not match, it is determined that an abnormality has occurred in the EEPROM 22 and the process proceeds to step S81. If the values match, the EEPROM 22 is normal and step S80 is repeated.

In step S81, the ECU 20A requests the other ECUs 20B and 20C to transmit own data. The own data of the EEPROM 22 of the ECU 20A is stored in the ECUA_DAT area of the other ECUs 20B and 20C.
In step S82, the ECUs 20B and 20C receive a data transmission request from the ECU 20A.

In step S83, the ECUs 20B and 20C transmit the data of the ECU 20A stored in the ECUA_DAT area of its own EEPROM 22 to the ECU 20A together with the version number stored in the ECUA_VERSION area.
In step S84, the ECU 20A receives its own data and version number from each ECU 20B, 20C.
In step S85, the CPU 24 of the ECU 20A compares the version numbers received from the ECUs 20B and 20C, and determines whether or not the latest version numbers have been received from the plurality of ECUs 20. If it is received from a plurality of ECUs 20, the process proceeds to step S86, and if the latest version number is received from only one ECU 20, the process proceeds to step S87.

In step S86, the priority order table 31 is referenced from the MEMORY_LIST area 25b of the RAM 25, and the ECU 20 having the highest priority order is identified among the plurality of ECUs 20 that have transmitted the latest version number.
In step S87, the received own data is overwritten in the ECUA_DAT area of the EEPROM 22 and stored.

According to the above configuration, even when the data content of the EEPROM 22 is destroyed and becomes erroneous data due to noise mixing, a malfunction at the time of resetting the ECU 20, etc., the backup data is received from the other ECU 20 and the EEPROM 22. Thus, normal data can be restored to the EEPROM 22.
In addition, since another structure and an effect are the same as that of 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 11 shows a fourth embodiment of the present invention.
In the fourth embodiment, after the ECUs 20 constituting the in-vehicle communication system 10 in the first embodiment store the backup data of the EEPROM 22 with each other, the main body of the EEPROM 22 breaks down and the data is read from the EEPROM 22. This is an operation when an abnormality that cannot be performed and communication is interrupted occurs.
As an example, a case where the CPU 24 of the ECU 20A is disconnected from the EEPROM 22 will be described with reference to the flowchart of FIG.

In step S90, the CPU 24 periodically communicates with the EEPROM 22 to detect whether or not a failure has occurred. If the CPU 24 cannot access the EEPROM 22 and cannot communicate, the process proceeds to step S91. If no failure is detected, step S90 is repeated. Note that the CPU 24 may detect the occurrence of a failure of the EEPROM 22 when the vehicle body collides.
In steps S91 to S96, the ECU 20A receives the own data of the ECU 20A from the other ECUs 20B and 20C, and determines the ECU 20 that has transmitted the own data to be stored from the version number and the priority table 31. Steps S91 to S96 are the same as steps S81 to S86 of the third embodiment, and thus the description thereof is omitted.

In step S97, the own data transmitted by the ECU 20 is stored in the BACKUP_DAT area 25e of the RAM 25.
In step S98, the set value of the predetermined function performed by the CPU 24 is restored on the RAM 25 using the own data stored in the BACKUP_DAT area 25e.

According to the above configuration, even when the EEPROM 22 main body fails and data cannot be read from the EEPROM 22 and an abnormality occurs that interrupts communication, the backup data of the EEPROM 22 is received from another ECU 20 and stored in the RAM 25. Thus, the CPU 24 can read the setting values stored in the EEPROM 22 conventionally from the RAM 25, and the CPU 24 can execute a predetermined function.
In addition, since another structure and an effect are the same as that of 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows 1st Embodiment of the vehicle-mounted communication system which is this invention. It is explanatory drawing of a structure of EEPROM. (A) is explanatory drawing of a structure of RAM, (B) is a block diagram of ECU_MEMORY area | region of RAM, (C) is a block diagram of the MEMORY_LIST area | region of RAM. It is a flowchart which shows the outline | summary of operation | movement of an electronic control unit. It is a flowchart of checksum value calculation. It is a flowchart of a priority table creation. It is a flowchart of transmission and reception of a version number. It is a flowchart of transmission / reception of own data and backup data. It is a flowchart which shows 2nd Embodiment. It is a flowchart which shows 3rd Embodiment. It is a flowchart which shows 4th Embodiment.

Explanation of symbols

10 On-vehicle communication system 20 (20A to 20C) Electronic control unit 21 Microcomputer 22 EEPROM
22a Self data storage area 22b Backup data storage area 22c Self data version number storage area 22d Backup data version number storage area 23 Input / output circuit 24 CPU
24a Memory check unit 25 RAM
25e BACKUP_DAT area 31 priority table

Claims (6)

An in-vehicle communication system comprising a plurality of electronic control units connected to each other via a bus for multiple communication lines, wherein each electronic control unit is
A rewritable nonvolatile memory having a storage area for own data for storing vehicle information including its own initial setting information and a storage area for backup data for storing the vehicle information of another electronic control unit connected by the bus. A storage unit comprising:
A command to transmit the own data to be saved to the other electronic control unit at the first start-up and a command to send the own data to the other electronic control unit at the time of rewriting the own data, and another electronic control A processing unit for storing the backup data received from a unit in a storage area of the backup data;
An in-vehicle communication system comprising:   The processing unit of each electronic control unit includes a memory check unit that performs a memory check of a non-volatile memory in which the own data is stored. When an abnormality is detected in the memory check unit, The in-vehicle communication system according to claim 1, wherein the transmission request is rewritten, and the received own data is rewritten with the own data stored in the nonvolatile memory. The storage unit of each electronic control unit includes a volatile memory,
2. The processing unit issues a request for transmission of own data to the other electronic control unit and stores the received own data in the volatile memory when there is an abnormality in which the own data cannot be read from the nonvolatile memory. The in-vehicle communication system according to claim 2.   The processing unit of each electronic control unit transmits its own data to be transmitted to the other electronic control unit with a version number, and receives the own data received based on the transmission request of its own data to the other electronic control unit. The in-vehicle communication system according to claim 2 or 3, wherein the self-data with the latest version number is stored among the data.   The in-vehicle communication according to any one of claims 2 to 4, wherein the processing unit of each electronic control unit presets a priority order of another electronic control unit to which the data is requested to be transmitted. system.   6. The in-vehicle communication system according to claim 5, wherein the priority order is determined in advance in the order in which the non-volatile memory has a large free space or in the order in which the communication path is short from the electronic control unit.

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