JP2000057000A - Micro computer with built-in flash memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give information that the number of rewriting times exceeds the number of rewriting guarantee times when rewrite exceeding the number of rewriting guarantee times is executed in a flash memory where program data are stored. SOLUTION: A non-volatile memory 4 storing data 4b on the number of rewriting times on a flash memory 3 and data 4a on the number of rewriting guarantee times on the flash memory 3, a data update means updating data 4b on the number of rewriting times on the flash memory 3, which is stored in the non-volatile memory 4 that is rewritable, based on version information 3b of the flash memory 3, a detection means detecting that the number of rewriting times on the flash memory 3 exceeds the number of rewriting guarantee times by the comparison of data 4b on the number of rewriting times on the flash memory 3 and data 4b on the number of rewriting guarantee times on the flash memory 3, which are stored in the non-volatile memory 4 that is rewritable, and an informing means informing that the number of rewriting times on the flash memory 3 exceeds the number of rewriting guarantee times to outside based on output from the detection means are installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a microcomputer having a built-in flash memory for storing program data (a microcomputer having a built-in flash memory).
It is about.

[0002]

2. Description of the Related Art Both a flash memory for storing data including a program and a writable nonvolatile memory have areas for storing version information of a program, and by comparing the two, a change to a new program is performed. Is disclosed in Japanese Patent Application Laid-Open No. 9-114, in which error detection data is generated, and error check results are reported.
No. 685. According to this technique, every time a program is rewritten, the corresponding version information is updated, so that this version information can be secondarily handled as program data rewrite frequency data.

FIG. 3 shows the configuration of the above-mentioned prior art.

This data processing device (computer)
The configuration mainly includes a CPU 102 mounted on a CPU board 101. In the flash memory 103, version information 104 of the program data is stored together with the program data. Further, the writable nonvolatile memory 105 has a version information storage area 106, in which the version information of the program data is transcribed.

In this method, the version information of the flash memory 103 is compared with the version information stored in the version information storage area 106 of the writable nonvolatile memory 105 to update the content of the flash memory 103. The version information can be detected, and the version information can be handled as data on the number of rewrites of the program data.

[0006]

However, the above-mentioned prior art has the following problems.

That is, in the above-mentioned conventional technique, it is possible to handle the version information of the program data as rewrite frequency data, but it is not possible to know whether the rewrite frequency of the program data exceeds the guaranteed rewrite frequency of the flash memory. There was a problem that it was not possible.

The present invention has been made in view of the above, and while taking advantage of the above-mentioned conventional technology, in a flash memory in which program data is stored, when rewriting exceeding the guaranteed number of rewriting is performed, This is to notify that the number of times of rewriting has been exceeded.

[0009]

According to a first aspect of the present invention, there is provided a microcomputer having a built-in flash memory for storing version information of the program data together with program data. A writable nonvolatile memory for storing the number of times of rewriting of the memory and the guaranteed number of times of rewriting of the flash memory;
Data update means for updating the rewrite frequency data of the flash memory, which is stored in the writable nonvolatile memory based on the version information of the flash memory, and which is stored in the writable nonvolatile memory, Detecting means for detecting that the number of times of rewriting of the flash memory has exceeded the guaranteed number of rewriting by comparing the number of times of rewriting of the flash memory with the number of times of guaranteed rewriting of the flash memory, based on an output from the detecting means; And a notifying means for externally notifying that the number of times of rewriting of the flash memory has exceeded the guaranteed number of times of rewriting.

According to a second aspect of the present invention, there is provided the microcomputer with a built-in flash memory according to the first aspect of the present invention, wherein the writable nonvolatile memory has a guaranteed number of rewrites of the flash memory. The number of times of rewriting of the memory is larger than the guaranteed number of times.

According to the microcomputer with a built-in flash memory according to the present invention, when the rewriting exceeding the guaranteed number of rewriting is performed in the flash memory storing the program data by the above means, the rewriting exceeding the guaranteed number of rewriting is performed. Can be notified that the operation has been performed.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a microcomputer with a built-in flash memory according to an embodiment of the present invention.

In the figure, 1 is a CPU, 2 is a RAM, 3
Denotes a flash memory, and 4 denotes a writable nonvolatile memory. 3a and 3b are program data stored in the flash memory 3 and version information of the program data, respectively.
Are rewrite guarantee count data and rewrite count data stored in the writable nonvolatile memory 4, respectively. 5 is a notification signal output unit, and 5a
Indicates a notification signal output from the notification signal output unit 5. The RAM 2 is used as a work memory or the like during execution of the program data 3a.

Here, the flash memory 3 is optimized for use in a microcomputer, and its guaranteed number of rewrites is about 10 ² to 10 ³ times. Is used, the guaranteed number of rewrites is on the order of 10 ⁵ , so that the number of rewritable times of the writable nonvolatile memory 4 is 10 ² to 10 ³ times that of the flash memory 3. For this reason, as described below, in the writable nonvolatile memory 4, the same number of rewrites as the number of rewrites of the flash memory 3 occurs. However, by using an EEPROM as the writable nonvolatile memory 4, Before the memory 3 becomes unusable beyond the guaranteed rewrite count, the writable nonvolatile memory 4
Is not unusable. Hereinafter, it is assumed that an EEPROM is used as the writable nonvolatile memory 4.

In the above configuration, the version information 3b of the program data 3a to be written to the flash memory 3 for the first time is "1", and every time the program data is rewritten, the version information 3b is changed to "+".
It shall be incremented by 1 ".

Next, the program data 3a includes
An outline of the operation of the rewrite frequency check subroutine of the flash memory 3 is shown in the flowchart of FIG.

First, it is determined whether the version information 3b is "1" (S201), and the version information 3b is determined.
Is "1", the writable nonvolatile memory 4 is initialized (S202).

Next, it is determined whether or not the version information 3b and the rewrite frequency data 4b match (S203). If they do not match, "+1" of the rewrite frequency data 4b is determined. The increment is performed (S204).

Next, the rewriting frequency data 4b is compared with the guaranteed rewriting frequency data 4a (S205). If the rewriting frequency data 4b exceeds the guaranteed rewriting frequency data 4a, a notification signal is output from the notification signal output unit 5. 5a
Is output (S206).

As described above, the number of rewrites of the flash memory 3 included in the program data 3a is checked.
By executing the subroutine, the number of times of rewriting to the flash memory 3 is written to the number of times of rewriting 4b of the writable nonvolatile memory 4, and the number of times of rewriting 4b of the writable nonvolatile memory 4
However, when the number of times of rewriting exceeds the guaranteed number of times 4a, the notification signal output unit 5 outputs the notification signal 5a.

The notification signal 5a is input, for example, as an interrupt signal of the CPU 1, and in the interrupt routine,
CRT or LE via input / output port not shown
It can be used for displaying on an external display device such as D.

Further, as described above, since the rewrite guaranteed number of the flash memory 3 is about 10 ² to 10 ³ times, and rewriting the guaranteed number data, necessary for a writable nonvolatile memory 4 for storing the number of rewriting data Large capacity,
Since 1 to 2 bytes are required for each data area, 4 bytes at most is sufficient. As described above, the above functions can be realized with a small increase in hardware (at low cost), and a highly reliable microcomputer with a built-in flash memory can be provided.

[0024]

As described in detail above, the microcomputer with a built-in flash memory according to the present invention is a microcomputer having a built-in flash memory for storing program data and version information of the program data. A writable nonvolatile memory for storing the number of times of rewriting of the memory and the guaranteed number of times of rewriting of the flash memory;
Data update means for updating the rewrite frequency data of the flash memory, which is stored in the writable nonvolatile memory based on the version information of the flash memory, and which is stored in the writable nonvolatile memory, Detecting means for detecting that the number of times of rewriting of the flash memory has exceeded the guaranteed number of rewriting by comparing the number of times of rewriting of the flash memory with the number of guaranteed times of rewriting of the flash memory, based on an output from the detecting means; And a notifying means for externally notifying that the number of rewrites of the flash memory has exceeded the guaranteed number of rewrites. According to the microcomputer with a built-in flash memory of the present invention, the program Flash memory where data is stored A reliable microcomputer with built-in flash memory that can notify that rewriting has been performed when the number of rewriting operations exceeds the guaranteed number of rewriting operations. Can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram of a microcomputer with a built-in flash memory according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a subroutine for checking the number of times of rewriting of the flash memory.

FIG. 3 is a block diagram of a conventional microcomputer with a built-in flash memory.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 CPU 2 RAM 3 Flash memory 3a Program data 3b Version information 4 Writable nonvolatile memory 4a Rewriting guaranteed number data 4b Rewriting number data 5 Notification signal output part 5a Notification signal

Claims (2)

[Claims] 1. A microcomputer having a built-in flash memory for storing version information of the program data together with the program data, wherein the number of times of rewriting of the flash memory and the guaranteed number of times of rewriting of the flash memory are stored. Writable nonvolatile memory; data updating means for updating the rewrite frequency data of the flash memory stored in the writable nonvolatile memory based on the version information of the flash memory; By comparing the number of times of rewriting of the flash memory stored in the volatile memory with the guaranteed number of times of rewriting of the flash memory,
Detecting means for detecting that the number of times of rewriting of the flash memory has exceeded the guaranteed number of rewriting; and externally notifying, based on an output from the detecting means, that the number of times of rewriting of the flash memory has exceeded the guaranteed number of rewriting. And a microcomputer with built-in flash memory. 2. The microcomputer according to claim 1, wherein the guaranteed number of rewrites of the writable nonvolatile memory is larger than the guaranteed number of rewrites of the flash memory. Microcomputer with built-in memory.