JP5754316B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an electronic control device including a nonvolatile memory such as a flash memory.

  The use of a rewritable nonvolatile memory such as a flash memory is spreading as a storage medium for storing data used in electronic devices such as computers or electronic control devices (also referred to as ECUs) for vehicles.

  In the flash memory, the write process for setting the erase state to the write state can be executed in units of addresses or bits, but the erase process for changing the write state to the erase state is performed in units of memory cell blocks (sector units). It is performed in a lump and cannot be executed in units of addresses or bits.

  For this reason, in a nonvolatile semiconductor memory device, in general, when all or a part of data already written in a predetermined memory cell block (hereinafter sometimes simply referred to as “block”) is updated, After executing the write process to write the data in the memory cell block (also called the update destination memory cell block) that has been batch erased, the batch erase process to erase the update source memory cell block storing the pre-update data in a batch The data update process to be executed is being executed.

  Therefore, by determining whether or not writing to the flash memory is necessary, it is possible to suppress unnecessary writing to the flash memory by determining execution of writing to the flash memory, improving processing time and writing. A flash memory control method that can improve reliability by reducing the number of times has been devised (see Patent Document 1).

JP 2007-304920 A

  In the configuration of Patent Document 1, it is assumed that an initial value such as zero is uniformly written for all areas of the flash memory. In other words, there is no write suppression for individual write target data in the flash memory during normal operation of the device, and even if the write data is compared with the value initialized using a uniform initial value, the number of writes can be suppressed. There is a problem of not becoming.

  Against the background of the above problems, an object of the present invention is to provide an electronic control device that can more efficiently suppress writing to data to be written to a flash memory.

Means for Solving the Problems and Effects of the Invention

An electronic control device for solving the above problems includes a flash memory that stores a data ID that identifies data and a data value that is the value of the data, and a data ID that is stored in the flash memory at a predetermined write timing. A data writing unit that writes data values in association with each other, a representative value ID corresponding to each data ID is determined, a representative value storage unit that stores a predetermined representative value for each representative value ID, and each data ID A data management information storage unit for storing data management information indicating which of the corresponding data value and the representative value is used as a value corresponding to the data ID, and when the data writing unit writes the data value, For each data ID, when the data value to be written and the representative value are the same, the comparison unit for comparing whether or not the data value to be written is the same as the representative value. A write control unit that represents a representative value use state in which a representative value is used as a value corresponding to the data ID, and suppresses writing of the data value corresponding to the data ID to the flash memory by the data writing unit; It is characterized by providing.

  With the above configuration, it is possible to suppress writing to individual write target data in the flash memory during the normal operation of the apparatus other than when initial values are written (that is, when the flash memory is initialized), and overwriting of individual data is possible. The amount of data that cannot be written to the flash memory can be suppressed.

  In addition, the representative value in the electronic control device of the present invention is determined to have a higher frequency of obtaining the data value.

  With the above configuration, if a value having a higher appearance frequency is used as a representative value as the data value, the number of opportunities for writing to the flash memory is increased, so that writing of the data value to the flash memory can be more efficiently suppressed.

  In the electronic control device of the present invention, a plurality of data IDs are associated with the representative value ID.

  With the above configuration, the storage area of the representative value can be reduced.

  In the electronic control device of the present invention, when the data value to be written is changed to a value different from the representative value at the write timing, the write control unit assigns the data ID to the flash memory by the data writing unit. The suppression of the writing of the corresponding data value is canceled, and the data management information storage unit indicates that the data value stored in the flash memory is used as the value corresponding to the data ID for the data management information corresponding to the data ID. Use data values.

  With the above configuration, writing to the flash memory can be performed only when the data value changes to a value different from the representative value, so that the amount of data written to the flash memory can be suppressed.

  Further, the electronic control device of the present invention, when the data management information represents the data value use state, when the data value is changed to the same value as the representative value at the write timing, the write control unit Is used as a representative value use state, and writing of the data value corresponding to the data ID to the flash memory by the data writing unit is suppressed.

  With the above configuration, when the data value changes to the same value as the representative value, writing the representative value to the flash memory can be prevented.

The electronic control device of the present invention further includes a data value reading unit that reads a value of data corresponding to the data ID at a predetermined reading timing, and the data value reading unit indicates that the data management information indicates the representative value use state. When representing, the representative value of the representative value ID corresponding to the data ID is read from the representative value storage unit.

  With the above configuration, the latest and appropriate data (that is, the representative value) corresponding to the data ID can be read.

  The electronic control device of the present invention further includes a data value reading unit that reads a data value corresponding to the data ID at a predetermined reading timing, and the data value reading unit indicates that the data management information indicates a data value use state. Sometimes, the data value corresponding to the data ID is read from the flash memory.

  Also with the above configuration, the latest and appropriate data (that is, the data value) corresponding to the data ID can be read.

The block diagram which shows the structure of an electronic controller. The figure which shows the structural example of a representative value memory | storage part. The figure which shows the structural example of a data management information storage part. The figure which shows an example of the data storage area in flash memory. The flowchart explaining a data writing suppression process. The flowchart explaining a data read-out process. The figure which shows another example of a structure of a representative value memory | storage part. The figure which shows another example of a structure of a data management information storage part.

  The electronic control device of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a configuration example of an electronic control device (hereinafter referred to as “ECU”) 1 of the present invention. The ECU 1 is used for controlling in-vehicle devices such as vehicle engine control and air conditioner control. The ECU 1 includes a CPU 10, a ROM 11, a RAM 12, and a flash memory 13. The CPU 10 executes various control functions of the ECU 1 by executing control programs stored in the ROM 11 or the flash memory 13. The RAM 12 temporarily stores various data generated when the CPU 10 executes the control program.

  The ECU 1 includes an input I / F 14 for obtaining data from a sensor 16 such as a rotation sensor or a temperature sensor or receiving data from another ECU, and an actuator such as a motor or a solenoid. 17 includes an output I / F 15 for outputting an operation control command value to 17 or transmitting data to another ECU.

  The flash memory 13 includes, for example, one or more known memory cell blocks, and stores data necessary for the operation of the ECU 1. The CPU 10 performs batch erasure processing in units of memory cell blocks, a storage area unit of a predetermined address number or a bit unit for the flash memory 13 according to the operation state of the ECU 1 or the data storage state of each memory cell block of the flash memory 13. And the like, and control such as data update processing in units of memory cell blocks.

  With the above configuration, the ECU 1 calculates an operation control command value based on the data acquired from the sensor 16 or another ECU and the operation state of the actuator 17 and outputs the operation control command value to the actuator 17.

FIG. 2 shows a configuration example of the representative value storage unit 11 a in the ROM 11. In the representative value storage unit, a corresponding representative value is stored in advance for each representative value ID. Any of the following is used as the representative value. In this embodiment, the data ID is the same as the representative value ID, and the data ID and the representative value ID have a one-to-one relationship. In this embodiment, the data value is a hexadecimal number having a data length of 1 byte.
A value having the highest appearance frequency among data values obtained in the processing calculation by the CPU 10.
Default value: a fail-safe value that is determined for each data ID, and is substituted when, for example, a data value obtained by processing calculation by the CPU 10 is not included in a predetermined range. Or the value at initialization.

FIG. 3 shows a configuration example of the data management information storage unit 12a in the RAM 12. The data management information storage unit stores, for each data ID, data management information indicating which one of the representative value of the ROM 11 or the data value stored in the flash memory 13 is used as the data value. . Since the data management information storage unit has a relatively high frequency of rewriting, it is desirable to set an area in the RAM 12 that can be rewritten in address units or bit units.
Representative value (representative value usage state): The representative value of the corresponding representative value ID stored in the ROM 11 is used as the data value corresponding to the data ID.
Data value (data value use state): The data value stored in the flash memory 13 is used as the data value corresponding to the data ID.

  FIG. 4 shows an example of the data storage area 13 a in the flash memory 13. Data is stored in association with a data ID and a data value. In the data of the data IDs 0, 2, and 5, data values are written, but the data values are not used because the above-described data management information does not represent the data value use state.

  Since the flash memory 13 cannot be erased or overwritten in address units or bit units, when the stored data is updated or when new data is added, the flash memory 13 is sequentially added to this empty area. For example, when the data value of data ID1 changes from 0x01 to 0x10, new data is stored in a free area after the data storage area of data ID7.

  The flash memory 13 may be provided with a backup area 13b of the data management information storage unit 12a of the RAM 12. Prior to this, when the operation of the ECU 1 is stopped, the contents of the data management information storage unit 12a are copied to the backup area 13b (after the batch erasure). Then, when the operation of the ECU 1 is started (for example, at the initial time), the data is read from the backup area 13b and returned to the data management information storage unit 12a. Of course, since overwriting of the backup area 13b cannot be performed in units of addresses or bits, it is desirable that the memory cell block including the backup area 13b is different from the memory cell block including the data storage area 13a.

  The data write suppression process included in the control program stored in the ROM 11 and executed by the CPU 10 will be described with reference to FIG. First, for example, it is determined whether or not the data write timing has arrived as when the data value of certain data has changed as a result of the calculation by the CPU 10. That is, the data write suppression process is performed at a timing other than the initialization of the flash memory. The data calculation result is temporarily stored in the RAM 12, for example.

  When the data write timing does not arrive (S11: No), the process waits until the data write timing comes. This process may be terminated. On the other hand, when the data write timing arrives (S11: Yes), the data value temporarily stored in the RAM 12 is referred to (S12). Then, the representative value of the representative value ID corresponding to the data ID of the data value stored in the ROM 11 is referred to (S13), and both are compared.

  As a result of the comparison, when the data value is the same as the representative value (S14: Yes), the data value of the data ID is not written to the flash memory 13, that is, the data writing is suppressed (S15). The data management information corresponding to the data ID in the data management information storage unit 12a of the RAM 12 is assumed to represent the representative value usage state (indicated as “representative value ID0” in FIG. 3), and (S16) The process ends.

  On the other hand, when the data value is not the same as the representative value (S14: No), the data management information corresponding to the data ID in the data management information storage unit 12a is referred to (S17). When the data management information indicates the data value usage state (indicated as “data value” in FIG. 3) (S18: Yes), the data value corresponding to the data ID stored in the flash memory 13 is referred to. (S19). Then, these two data values are compared.

  As a result of the comparison, when the two data values are the same (S20: Yes), nothing is done, that is, the data writing is suppressed, and this processing is terminated. On the other hand, when the two data values are different (S20: No), the new data value and its data ID are stored in the flash memory 13 (S22), and this process is terminated.

  That is, in the above configuration, when the write data value changes to a value different from the representative value at the write timing, and when the corresponding data value already stored in the flash memory is equal, the write control unit The writing of data values to be written to the flash memory by the data writing unit is suppressed.

  On the other hand, when the data management information represents not the data value use state but the representative value use state (S18: No), the data management information represents the data value use state (S21). Then, the new data value and its data ID are stored in the flash memory 13 (S22), and this process is terminated.

  A specific example of the above-described data writing suppression process of FIG. 5 will be described with reference to FIGS. The data value of the data ID0 in which the data management information (see FIG. 3) of the data management information storage unit 12a of the RAM 12 is the representative value ID0 (that is, the representative value usage state) is 0x05 of the representative value ID0 as a result of the calculation. When 0x80, which is different from FIG. 2), the data management information is rewritten with the data value (that is, the data value use state). Further, since the data value already stored in the flash memory 13 is 0x00 (see FIG. 4), which is different from the new data value, the data ID: 0 and the data value: Write 0x80. Further, when the data of data ID 0 is not written, a new area is secured and written.

  In general, in flash memory, data is written from the beginning of the memory cell block, so when a plurality of data with the same data ID is stored, the data stored behind the memory cell block is read out. Yes.

  In addition, the data value of the data ID2 in which the data management information (see FIG. 3) in the data management information storage unit 12a is the representative value ID2 (that is, the representative value use state) is 0xAA ( When the value becomes 0xCC different from that shown in FIG. 2, the data management information is rewritten to the data value (that is, the data value use state). At this time, the data value already stored in the flash memory 13 is 0xCC (see FIG. 4), which is the same as the new data value, and therefore writing to the flash memory 13 is not performed.

  Further, the data value 0x7F of the data ID3 in which the data management information (see FIG. 3) of the data management information storage unit 12a is the data value (that is, the data value usage state) is 0x80, which is the same as the representative value as a result of the calculation. When this happens, the data management information is rewritten to the representative value ID3 (that is, the representative value usage state). At this time, writing to the flash memory 13 is not performed.

  A data reading process included in the control program stored in the ROM 11 and executed by the CPU 10 will be described with reference to FIG. This process is executed when a condition for reading a data value is satisfied, such as when the CPU 10 reads a data value necessary for performing various calculations.

  First, the data management information corresponding to the data ID to be read in the data management information storage unit 12a of the RAM 12 is referred to (S31). Next, when the data management information indicates the representative value use state (S32: Yes), the representative value corresponding to the data ID stored in the ROM 11 is read (S33), and this process is terminated. . On the other hand, when the data management information represents not the representative value use state but the data value use state (S32: No), the data value corresponding to the data ID stored in the flash memory 13 is read (S34). ), This process is terminated.

  The specific example of FIG. 6 will be described with reference to FIGS. Since the data management information (see FIG. 3) represents the representative value usage state, the data of data ID 0 is read as 0x05 (see FIG. 2) stored in the ROM 11. In addition, since the data management information (see FIG. 3) indicates the data value use state, the data of the data ID 4 is read as 0x00 (see FIG. 4) stored in the flash memory 13.

  FIG. 7 shows another example of the configuration of the representative value storage unit 11a of FIG. In this case, a representative value is shared by a plurality of data IDs. Thereby, the area | region of the representative value memory | storage part 11a can be decreased. In the example of FIG. 7, there is no one-to-one relationship as shown in FIG. 2 between the representative value ID and the data ID, and a representative value and a data ID using the representative value are associated with each representative value ID. Yes. When the data length of the data value is a 1-byte hexadecimal number, the number of representative values is 256 at the maximum regardless of the number of data (data ID).

  For example, the data IDs 0 to 2 are associated with the representative values of the representative values ID0 to 2, respectively. The data IDs 3, 5, and 7 are associated with the representative value 0x80 of the representative value ID10. The data IDs 4 and 6 are associated with the representative value 0x12 of the representative value ID11.

  FIG. 8 shows the configuration of the data management information storage unit 12a in the configuration of FIG. The data IDs 0 to 2 are the same as in FIG. 3, but the data ID 5 indicates that the representative value 0x80 of the representative value ID10 is used.

  7 and FIG. 8, the data write suppression process and the data read process are the same as those in FIGS. 5 and 6, respectively.

  The present invention can also be applied to an electronic control device used other than a vehicle.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

1 ECU
10 CPU (data writing unit, comparison unit, write control unit, data reading unit)
11 ROM (Representative value storage)
12 RAM (data management information storage unit)
13 Flash memory

Claims (7)

A flash memory that stores a data ID that identifies data and a data value that is a value of the data;
A data writing unit for writing the data ID and the data value in association with the flash memory at a predetermined write timing;
A representative value ID corresponding to each data ID is determined, and a representative value storage unit that stores a predetermined representative value for each representative value ID;
Said each data ID, any corresponding said data value to said representative value storing data management information indicating whether to use as a value corresponding to the data ID data management information storage unit,
A comparison unit that compares whether the data value to be written and the representative value are the same when the data writing unit writes the data;
When the data value to be written and the representative value are the same, the data management information represents a representative value use state in which the representative value is used as a value corresponding to the data ID, and the data writing unit A write control unit that suppresses writing of a data value corresponding to the data ID to the flash memory by
An electronic control device comprising:   The electronic control device according to claim 1, wherein the representative value is determined more frequently among values obtained by the data value.   The electronic control device according to claim 1, wherein a plurality of the data IDs are associated with the representative value ID. At the time of writing, when the data value to be written is changed to a value different from the representative value,
The write control unit cancels suppression of writing of the data value corresponding to the data ID to the flash memory by the data writing unit;
The data management information storage unit sets the data management information corresponding to the data ID to a data value use state indicating that the data value stored in the flash memory is used as a value corresponding to the data ID. The electronic control device according to any one of claims 1 to 3. When the data management information represents the data value use state, at the time of the writing, when the data value is changed to the same value as the representative value,
5. The write control unit according to claim 4, wherein the write control unit suppresses writing of a data value corresponding to the data ID to the flash memory by the data writing unit with the data management information as the representative value use state. Electronic control device. A data reading unit for reading a value of data corresponding to the data ID at a predetermined read timing;
6. The data reading unit according to claim 1, wherein when the data management information indicates the representative value usage state, the data reading unit reads a representative value of a representative value ID corresponding to the data ID from the representative value storage unit. The electronic control device according to claim 1. A data reading unit for reading a data value corresponding to the data ID at a predetermined read timing;
6. The electronic control device according to claim 4, wherein the data reading unit reads a data value corresponding to the data ID from the flash memory when the data management information indicates the data value use state.

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