JP2008146521A - Automobile electronic controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automobile electronic controller capable of utilizing effectively a memory capacity of a flash memory, and capable of storing efficiently data. <P>SOLUTION: The data in an area with the data already written are brought into the same value, or into a condition rewritten as FFh, when the data are written into the flash memory, and the writing of the data by the same writing start address is performed more than once. The data (for example, 1 byte data) having a size smaller than the minimum writing size (for example, 128 bytes) is thereby stored densely in the writing area. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an automotive electronic control device, and more particularly to a data writing technique for a nonvolatile memory capable of electrically erasing and writing data.

Japanese Patent Application Laid-Open No. 2004-228561 discloses an automotive electronic control device that includes a rewritable flash memory in block units and controls a predetermined control target mounted on the vehicle according to a control program stored in the flash memory.
JP 2000-257502 A

As described above, since the flash memory can be rewritten in units of blocks, writing in units of blocks is performed even when data having a size smaller than the blocks in units of rewriting is written. If the write start address is shifted and data is written, there is a problem in that the use efficiency of the memory capacity is poor.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an automotive electronic control device that can effectively use the memory capacity of a flash memory and can efficiently save data.

Therefore, according to the first aspect of the present invention, when data is written to a nonvolatile memory capable of electrically erasing and writing data, updating of data in an area where data has already been written is prohibited and the same writing is started. Data writing is performed a plurality of times with an address.
According to the above-described invention, after the first data write to the nonvolatile memory (for example, the flash memory) based on the predetermined write start address, the second data write is the same based on the same write start address. Block writing is performed, but data updating (rewriting) of the area where data is first written is prohibited, and data is written to the remaining area of the same block. By repeating such a writing process, a plurality of data is packed and stored in the same block.

Therefore, even when data is written to the nonvolatile memory in units of blocks and the size of data to be written is smaller than the block size, the data can be written using the memory capacity effectively.
The invention described in claim 2 is characterized in that data updating is prohibited by rewriting the same data in an area where data has already been written.

According to the above invention, when writing to the same block a plurality of times based on the same write start address, the same data as that at the time of the first write is written in the area where data has been written so far. .
Therefore, even if the same block is repeatedly written, the data in the area where the data has already been written is stored as it is, and new data is sequentially written in the remaining area.

According to a third aspect of the present invention, the last address of the written data is stored, and an area where data has already been written is specified based on the last written address.
According to the above invention, every time data is written, the final address of the data in the write is stored, and the area from the write start address to the final address is specified as an area where data has already been written.

Therefore, even if the data size varies, the area where data has been written so far can be reliably identified.
The invention described in claim 4 is characterized in that the size of data to be written at one time is fixed, and an area where data has already been written is specified from the number of times of writing.
According to the above invention, since the size of the data to be written is fixed, the result of multiplying the data size by the number of times of writing is the total size of the data written so far, and the total size of the written data from the write start address The area of only minutes is the area where data has been written so far.

Therefore, if the data size is fixed, it is possible to easily specify the area where data has been written so far.
The invention according to claim 5 is characterized in that index data is attached to write data, and an area in which data has already been written is specified based on the index data.

According to the above invention, index data (index information) is attached to each data to perform writing, and individual write data is discriminated from the index data, thereby specifying an area where data has been written so far.
Therefore, by reading the index data, it is possible to reliably specify an area where data has already been written.

Embodiments of the present invention will be described below.
FIG. 1 shows a configuration of an engine control unit (ECU) 1 as an automobile electronic control device according to an embodiment.
The engine control unit 1 is for controlling fuel injection and ignition in the vehicle engine, and is a flash memory 2, a RAM 3, and a microcomputer 4 that are nonvolatile memories capable of electrically erasing and writing data. It is comprised including.

The microcomputer 4 includes a CPU, a built-in RAM, a timer, an A / D converter, an SCI, and the like, and executes various programs stored in the RAM 3 and the flash memory 2.
The storage area of the flash memory 2 is divided into a block A and a block B.
The block A is a write data storage area where data is written.

On the other hand, the block B is an area where data is not updated, and is composed of an area for storing a flash writing program, an area for storing an application program, and an area for storing constant data.
The flash write program is a program for controlling erasing / writing of data in the write data storage area.

The application program is a program for controlling the engine mounted on the vehicle, and inputs and calculates detection signals from various sensors 7 for detecting the on / off signal of the ignition switch 8 and the operating state of the vehicle engine. It has a function of processing and outputting a fuel injection control signal, an ignition control signal, and the like.
In the constant data storage area, various constant data (threshold value, coefficient, etc.) necessary for engine control and the like are stored.

On the other hand, the flash writing tool 5 as an external tool is detachably connected to the engine control unit 1 via the communication line 6.
The flash writing tool 5 is provided with a flash memory 5a, and data stored in the flash memory 5a is transmitted to the engine control unit 1 to write data to the flash memory 2. It is like that.

That is, the flash writing tool 5 is a tool for rewriting data stored in the block A of the flash memory 2.
The flowchart of FIG. 2 shows the rewriting process of the block A of the flash memory 2 by the engine control unit 1.
First, in step S100, the application program stored in block B is executed to control the engine normally.

In the next step S110, it is determined whether or not the ignition switch (IGSW) 8 has been turned off.
If the ignition switch (IGNSW) 8 is in the ON state, the process returns to step S100 to continue execution of the application program.
On the other hand, when the ignition switch (IGNSW) 8 is turned off, the process proceeds to step S120, where it is determined whether or not a flash memory rewrite request signal is output from the flash writing tool 5.

If a rewrite request signal is output from the flash writing tool 5, the process proceeds to step S130.
In step S130, the write data transmitted from the flash writing tool 5 is stored in the buffer.
In the next step S140, a write control program is executed in order to write the data transmitted from the flash writing tool 5 to the data storage area (block A) of the flash memory 2.

The processing contents of the write control program are shown in the flowchart of FIG.
First, in step S200, a write start address is set, and in the next step S210, it is determined whether or not all values in the write area are FFh (erase state).
If all the values in the write area are FFh, it is the first data write, so the process proceeds to step S230, and the data write process to the flash memory 2 is executed.

On the other hand, if all the values in the writing area are not FFh, and the writing is performed for the second time or later, the process proceeds to step S220, where an area where data has already been written is specified, and the written area is masked for writing. After performing the setting to perform the process, the process proceeds to step S230, and the data writing process to the flash memory 2 is executed.
In step S240, it is determined whether or not the data writing is completed, and the processes in steps S200 to S230 are repeated until the writing is completed.

Here, details of the data writing process in step S230 will be described with reference to FIG.
The write process shown in FIG. 4 is an example in which 1-byte data is written, and the minimum write size (minimum area where writing is performed in one write operation) is 128 bytes.
First, all values in the data storage area of the flash memory 2 are initialized as FFh (initial value) (see FIG. 4A).

In the first data write, data designated in the first byte (“01” in FIG. 4) is written, and FFh is written in the remaining 127 bytes (see FIG. 4B).
Subsequently, in the second data write, the write start address is kept the same as the previous time, the data update of the first 1 byte is prohibited, and the designated data (second 1 byte) is designated (see FIG. 4). "02") is written, and FFh is written in the remaining 126 bytes (see FIG. 4B).

The prohibition (masking) of data update of the first 1 byte is performed by rewriting the same data or by setting the write data to “FFh” and not rewriting the flash memory 2.
In the third data write, the write start address is kept the same as the previous one, the data update in the first 1 byte and the second 1 byte is prohibited, the specified data is written in the third 1 byte, and the rest FFh is written in the 125 bytes.

By repeating the above process, 1-byte data is sequentially packed and stored in one block, which is the minimum write size of 128 bytes.
When all data writing to the first 128 bytes is completed, the writing start address is shifted by 128 bytes, and data writing to the next 128-byte area is executed in the same manner.

  As described above, the update operation of the area where data has been written up to the previous time is prohibited, and the operation of writing new data to the next address of the area where the update is prohibited is performed multiple times at the same write start address. By doing so, data (1 byte in this embodiment) smaller than the minimum write size (128 bytes in this embodiment) can be written and written, and the capacity of the flash memory 2 can be used efficiently. be able to.

Here, to which address data update is prohibited and to which address the specified data is written can be determined by storing the last address where the data has been written, and in units of 128 bytes from which the last address is written As a block, it can be determined whether or not to move to the next block.
Note that the size of data to be written does not necessarily have to be constant as long as the last address where data has been written is stored.

Further, when the size of the write data is fixed as in the present embodiment, the multiplication result of the number of times of writing and the data size indicates the size of the area where data has already been written.
Therefore, instead of storing the last address where data was written, the number of times of writing is counted and stored, and the size of the area where data has already been written based on the counting result of the number of times of writing and the data size stored in advance. Then, the address (capacity) is calculated, and the address where the designated data is to be written next can be specified.

Furthermore, by adding index data to the data to be written, it is possible to specify an area where data has already been written (address for writing designated data next time).
For example, when the data size is constant, index data of a certain size is attached before or after the data, and this index data is incremented for each writing.

  In this case, since the writing position of the index data is specified in advance, the data at the address position where the index data should be written is verified, and the smallest address among the addresses storing the values that are not recognized as the index data is selected. It can be specified as the address next to the area where data has already been written and the address for writing the next designated data.

Further, as index data, write start position information, write end position information, and the like can be attached to the data.
Further, instead of starting to write data from the beginning of one block of 128 bytes, it is possible to write data from the back side of the block and shift the writing position sequentially forward.

In this embodiment, the minimum unit for writing is 128 bytes and the data size is 1 byte, but it is obvious that the present invention is not limited to these sizes.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.
6. The automobile electronic device according to claim 5, wherein the data has a fixed size, and the index data is a fixed size added before or after the data and is incremented for each writing. Control device.

According to the above invention, since the sizes of the data and the index data are constant, the address position where the index data is written is specified in advance when writing data in a narrow manner.
Therefore, by reading the data at the address position where the index data is written and determining whether or not the data that is recognized as the index data is written, the extent to which the data has been written, that is, the data has already been written. Area can be identified.

The block diagram of the electronic controller for motor vehicles in embodiment. 6 is a flowchart showing a main routine of a write process to the flash memory in the embodiment. 6 is a flowchart showing a subroutine of a writing process to the flash memory in the embodiment. The figure which shows the mode of the write-in for every write frequency in embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine control unit, 2 ... Flash memory, 3 ... RAM, 4 ... Microcomputer, 5 ... Flash writing tool, 6 ... Communication line

Claims (5)

An electronic control device for an automobile equipped with a nonvolatile memory capable of electrically erasing and writing data,
Electronic data control for automobiles, wherein when data is written to the non-volatile memory, data update is prohibited in an area where data has already been written, and data is written multiple times at the same write start address apparatus. 2. The electronic control apparatus for an automobile according to claim 1, wherein the data update is prohibited by rewriting the same data in an area where data has already been written. 3. The automobile electronic control device according to claim 1, wherein a final address of the written data is stored, and an area in which the data is already written is specified based on the final address. 3. The electronic control unit for an automobile according to claim 1, wherein the size of data to be written at one time is fixed, and an area in which data is already written is specified from the number of times of writing. 3. The vehicle electronic control device according to claim 1, wherein index data is attached to the write data, and an area in which the data is already written is specified based on the index data.

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