JPH1011366A - Memory replacement detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely detect whether or not a backup RAM is cleared after a program ROM is replaced. SOLUTION: When the program ROM 2 is replaced, the backup RAM 3 is cleared and version data ROMVer of the program ROM 2 is written in the backup RAM 3; when the power source is turned on, the version data ROMVer of the program ROM 2 is compared with version data RAMVer written in the backup RAM 3 and the replacement of the program ROM 2 is detected according to the comparison result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a program ROM mounted on a microcomputer system.
The present invention relates to a memory replacement detection method for detecting replacement of a memory.

[0002]

2. Description of the Related Art A microcomputer-mounted system includes, for example, a one-time microcomputer (OTP).
Or, with a CPU mounted, an external program R
The OM also has an external RAM and the like, and the RAM is backed up by a lithium battery or the like.

In such a microcomputer-mounted system, when the program ROM or OTP is replaced with a new program ROM or OTP and the operation is started with a new program, the data stored in the backup RAM is used for the old program processing. Therefore, if the data is used in new program processing, various problems occur. For this reason, when a new program is started, it is necessary to immediately clear the contents of the backup RAM.

[0004]

However, the microcomputer cannot determine whether the data stored in the backup RAM is old and cannot be used in new program processing, or can be used in new program processing.

[0005] For this reason, after replacing the program ROM, the operator must replace the new program ROM and start the new program, and then, without forgetting to clear the memory of the backup RAM.

When the memory of the backup RAM is forgotten, it is difficult to determine whether or not the memory of the backup RAM is forgotten. Becomes unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a memory replacement detection method capable of reliably detecting whether or not the memory of the backup RAM has been cleared after the replacement of the program ROM.

[0008]

According to a first aspect of the present invention, there is provided a memory replacement detection method for detecting replacement of a first memory mounted on a computer system. A first step of clearing the stored second memory and writing unique data for the first memory to the second memory;
At power-on, the unique data for the first memory and the second
And a second memory for detecting replacement of the first memory based on the comparison result.
And a memory replacement detection method.

With such a memory replacement detection method,
When clearing the memory of the second memory, the unique data of the first memory is written to the second memory, and when the system is powered on, the unique data of the first memory and the unique data written to the second memory are written. Is compared, it is possible to reliably detect whether or not the second memory is cleared from the comparison result.

According to a second aspect of the present invention, in the memory replacement detection method according to the first aspect, the unique data for the first memory is compared with the unique data written in the second memory, and these unique data are different. Then, it is determined that the first memory has been replaced, and a request to execute the memory clear is issued to the second memory. If the respective unique data are the same, it is determined that the first memory has not been replaced.

With such a memory replacement detection method,
When the first memory is replaced, a request to execute the memory clear is issued to the second memory, so that the memory clear of the second memory can be surely executed, and it is possible to prevent forgetting to perform the memory clear.

According to a third aspect of the present invention, in the memory replacement detection method according to the second aspect, when the memory clear of the second memory is performed after the memory clear request for the second memory is performed, Write the unique data to the second memory.

With such a memory replacement detection method,
If the second memory is cleared, the unique data of the first memory is written to the second memory, so that the second memory is surely cleared at the next power-on of the system. Can be detected.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a microcomputer-mounted system to which a memory replacement detection method is applied.

This memory replacement detection method detects the replacement of the program ROM 2 as the first memory mounted on the microcomputer-mounted system 1.
When the program ROM 2 is replaced, the backup RAM 3 serving as the second memory is cleared, and data unique to the program ROM 2, for example, the program RO
M2 version data (ROM version data) R
A first step of writing OMVer to the backup RAM 3 (to be RAM version data RAMVer); and, when the microcomputer mounted system 1 is powered on, the version data ROMVer of the program ROM 2 and the version data RAM written to the backup RAM3.
Ver, and based on the comparison result, program R
A second step of detecting replacement of the OM2.

This memory replacement detection method uses the version data ROM Ver for the program ROM 2 and the version data RA written in the backup RAM 3.
MVer and compare these version data ROMVer
Is different from RAMVer, the program ROM2
Is determined to have been replaced, a request is made to the backup RAM 3 to execute memory clear, and if the version data ROMVer and RAMVer are the same, it is determined that the program ROM 2 has not been replaced.

In this memory replacement detection method, when the memory of the backup RAM 3 is cleared after the memory clear request is issued to the backup RAM 3, the version data ROMVer of the program ROM 2 is written to the backup RAM 3.

Next, the configuration of the microcomputer-mounted system 1 to which the memory replacement detection method is applied will be described. The microcomputer mounted system 1 has C
PU4 is mounted. The program ROM 2 and the backup RAM 3 are connected to the CPU 4 via an address bus 5 and a data bus 6.

The DC power supply 7 for backing up data (RAM data) stored in the backup RAM 3 is connected to the backup RAM 3.
Further, a display drive circuit 9 is connected to the CPU 4 via an I / O port 8, and the display 10 performs a display operation by the operation of the display drive circuit 9.

The CPU 4 has a function of issuing a command in accordance with the ROM replacement detection and corresponding flowchart shown in FIG. 2. When the microcomputer-mounted system 1 is powered on, the version data ROM Ver of the program ROM 2 is read as shown in FIG. Compare the version data RAMVer written in the backup RAM3,
If the version data ROMVer and the RAMVer are different, it is determined that the program ROM2 has been replaced, and a request to execute a memory clear is issued to the backup RAM3.
If Ver is the same, a function is provided for determining that the program ROM 2 has not been replaced.

After requesting the backup RAM 3 to execute memory clear, the CPU 4 issues a backup RA
When the memory clear of M3 is executed, the program ROM2
Version data ROMVer to backup RAM3
, That is, a function of copying the version data ROMVer of the program ROM2 to the backup RAM3.

Next, the operation when the program ROM 2 is exchanged in the microcomputer-mounted system 1 configured as described above will be described with reference to the ROM exchange detection and corresponding flowchart shown in FIG.

When the power supply of the microcomputer-mounted system 1 is turned on, the CPU 4 reads out the program in the program ROM 2 and executes the program.
At this time, in step # 1, the program ROM 2
Version data ROMVer and backup RAM3
Is compared with the version data RAMVer written in the ROM, and if the version data ROMVer and RAMVer are the same, the program ROM 2 is turned off while the power is turned off.
Judge that the exchange was not performed.

In this case, the CPU 4 starts the normal processing, that is, the operation of the program created according to the specifications required for the microcomputer-mounted system 1. On the other hand, the version data ROM Ver of the program ROM 2
And the version data RAMVer written to the backup RAM 3 as a result of the comparison.
If Ver and RAMVer are different, the CPU 4 determines that the exchange of the program ROM 2 has been performed while the power is turned off, and proceeds to step # 2 to inform the backup RAM 3 of the request to execute the memory clear. The signal is issued to the display drive circuit 9 through the / O port 8.

As a result, the display 10 displays a request to execute the memory clear for the backup RAM 3. Then, the CPU 4 proceeds to the next step # 3 and waits for executing a memory clear for the backup RAM 3.

If the key input is not to clear the memory of the backup RAM 3, the CPU 4
Moves to step # 4, and shifts the microcomputer-mounted system 1 in a safe direction. That is, since the program may not operate normally, the control target of the microcomputer-mounted system 1 is switched to a safe mode, and processing necessary for the system such as stop processing is performed.

On the other hand, when a key is input to execute the memory clear of the backup RAM 3, the CPU
In step # 4, the process proceeds to step # 5 to execute memory clear for the backup RAM 3.

Next, the CPU 4 proceeds to step # 6.
As shown in FIG. 3, the version data ROMVer of the program ROM2 is written to the backup RAM3. Thereafter, the CPU 4 starts the normal processing, that is, the operation of the program created according to the specifications required for the microcomputer-mounted system 1.

As described above, in one embodiment,
When the program ROM 2 is replaced, the backup RAM 3
Is cleared, the version data ROMVer of the program ROM 2 is written to the backup RAM 3, the version data ROMVer of the program ROM2 is compared with the version data RAMVer written to the backup RAM 3 when the power is turned on, and the program ROM2 is written based on the comparison result. Exchange detection is performed.
It is possible to detect whether or not the program ROM 2 has been replaced while the power is off.

When the program ROM 2 has been replaced, the display 10 can prompt the user to clear the memory of the backup RAM 3 and automatically clear the memory of the backup RAM 3.

As a result, it is possible to prevent the ROM replacement operator from forgetting to clear the memory of the backup RAM 3, and
Even if the backup RAM 3 is forgotten to clear the memory, the microcomputer mounted system 1 can be shifted to a safe direction.

The present invention is not limited to the above embodiment, but may be modified as follows. For example, the present invention can be applied not only to the exchange of the program ROM 2 but also to the exchange of another memory.

In addition to writing the version data ROMVer of the program ROM 2 to the backup RAM 3, the data may be written to the backup RAM 3 as long as it is data represented as unique data of the program ROM 2.

[0034]

As described in detail above, claims 1 to 5 of the present invention.
According to 3, it is possible to provide a memory replacement detection method capable of reliably detecting whether or not the memory of the backup RAM has been cleared after the replacement of the program ROM.

According to the third aspect of the present invention, the replacement of the program ROM is reliably detected, the execution of the memory clear of the backup RAM is requested, and the memory clear is automatically performed, or the memory clear is prevented from being forgotten. It is possible to provide a memory replacement detection method that can shift the system in a safe direction.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a microcomputer-mounted system to which a memory replacement detection method according to the present invention is applied.

FIG. 2 is a flowchart of ROM replacement detection and corresponding processing.

FIG. 3 is a schematic diagram showing writing of version data of a program ROM to a backup RAM.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... System mounted with microcomputer, 2 ... Program ROM, 3 ... Backup RAM, 4 ... CPU, 5 ... Address bus, 6 ... Data bus, 7 ... DC power supply.

Claims (3)

[Claims] 1. A memory replacement detection method for detecting replacement of a first memory mounted on a computer system, comprising: replacing a second memory mounted on the computer system with a memory when the first memory is replaced. A first step of clearing and writing unique data for the first memory to the second memory; and, when power is turned on, unique data for the first memory and unique data written to the second memory. And a second step of detecting replacement of the first memory based on a result of the comparison. 2. Comparing unique data for the first memory with unique data written to the second memory, and if the unique data is different, it is determined that the first memory has been replaced. 2. The memory according to claim 1, wherein a request is made to execute a memory clear to the second memory, and if the respective unique data are the same, it is determined that the first memory is not replaced. Exchange detection method. 3. When the memory clear of the second memory is performed after the request to execute the memory clear for the second memory, the unique data of the first memory is written to the second memory. 3. The memory replacement detection method according to claim 2, wherein