JP2001034500A - Microcomputer failure diagnosing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microcomputer failure diagnosing device and method realizing the improvement of diagnosing precision by the small number of parts. SOLUTION: This device is provided with a microcomputer 101, a diagnosing circuit 102 arranged in a microcomputer 101, and a timer circuit 104 for measuring the cycle of a diagnostic signal outputted by the microcomputer 101. The diagnosing circuit compares a diagnostic value being the executed result of prescribed diagnosis by the microcomputer with a comparison value being a preliminarily prepared constant, and judges the presence or absence of the failure of the microcomputer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure diagnosis technique, and more particularly to a microcomputer failure diagnosis apparatus and a microcomputer failure diagnosis method which can improve the diagnosis accuracy with a small number of components.

[0002]

2. Description of the Related Art In a conventional system using a microcomputer, it is common to provide a timer circuit for measuring a signal which is output from the microcomputer and has a fixed period in a normal state, and determines a failure based on a change in the period. However, in this system, the operation at the time of the failure of the microcomputer cannot be specified. Therefore, in a system requiring high reliability, two microcomputers operating with the same software as means for guaranteeing the operation at the time of the failure are provided in addition to the above circuit. A dedicated microcomputer is provided to limit the operation when the output signals that should be matched do not match, or to detect a failure of the microcomputer, and by means such as data communication between the two microcomputers,
Failure determination is performed by grasping internal processing operations that are difficult to diagnose from the outside.

Next, a conventional microcomputer failure diagnosis apparatus will be described with reference to the drawings. FIG. 1 is a block diagram of a conventional microcomputer failure diagnosis device 5.
In FIG. 1, reference numeral 5 denotes a microcomputer failure diagnosis device, reference numerals 1 and 2 denote a microcomputer, reference numeral 3 denotes a buffer circuit, and reference numeral 4 denotes a timer circuit. Referring to FIG. 1, a prior art microcomputer failure diagnosis apparatus 5
Is a microcomputer 1 and a microcomputer 2 operated by different software, a buffer circuit 3 to which signals from the two microcomputers 1 and 2 are input, and a cycle of a signal output from the two microcomputers 1 and 2 at a constant interval. Is provided.

Next, a diagnosis procedure using the conventional microcomputer failure diagnosis apparatus 5 will be described. Referring to FIG. 1, first, a first step is executed, and microcomputer 2 transmits a constant prepared in advance through a communication line provided between microcomputer 2 and microcomputer 1. The microcomputer 1 performs a self-diagnosis on the basis of the received constant, and transmits the obtained constant to the microcomputer 2.

Subsequently, a second step is executed. Since a diagnosis value for the transmitted constant is prepared in the microcomputer 2 in advance, the microcomputer 1
Compare whether the value sent from and the diagnostic value are equal. If the result of the comparison is equal, the microcomputer 1 is diagnosed as normal, but if they are not equal, it is diagnosed as a failure, and the microcomputer 2 outputs an inhibit signal (failure signal).

Subsequently, a third step is executed, the microcomputer 2 outputs a signal at regular intervals, and the timer circuit 4 measures the interval time. At this time, if the measured value deviates beyond the threshold value prepared in advance, the timer circuit 4 diagnoses the microcomputer 2 as a failure and outputs an inhibit signal (failure signal).

Then, the fourth step is executed, and the microcomputer 2 invalidates the output of the buffer circuit 3.
When the inhibit signal (fault signal) from the timer circuit 4 is input, the buffer circuit 3 keeps outputting an OFF output that invalidates the input from the microcomputer 1 at all. In this way, the microcomputer failure diagnosis device 5 of the prior art executes self-diagnosis by communication of constants between the microcomputer 1 and the microcomputer 2 and by measuring the period by the timer circuit 4.

[0008]

However, the conventional microcomputer failure diagnosis apparatus 5 has the following problems. First, the first problem is that, although the control itself requires only one microcomputer, another microcomputer is required only for diagnosis, which leads to an increase in the number of parts and an accompanying increase in cost. That is. The second problem is that special software is required for reliably performing communication between the two microcomputers 1 and 2, and further, communication timing adjustment and the like for ensuring the reliability of the software are required. Since a failure diagnosis or the like of a communication line is required, the capacity of the software is increased and the chance of a program error is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a microcomputer failure diagnosis apparatus and a microcomputer failure diagnosis method which realize improvement in diagnosis accuracy with a small number of components. Is to do.

[0010]

SUMMARY OF THE INVENTION The gist of the present invention is a microcomputer failure diagnosis apparatus which realizes improvement in diagnosis accuracy with a small number of parts, and has a built-in diagnosis circuit for self-diagnosis. Microcomputer and
A buffer circuit that outputs an external signal in accordance with the signal of the microcomputer; and a timer circuit that measures a time period of a signal that the microcomputer outputs at regular intervals. The diagnosis circuit performs a predetermined diagnosis by the microcomputer. And a diagnostic value as an execution result of the microcomputer is compared with a comparison value as a constant prepared in advance to determine whether or not the microcomputer has a failure. . According to a second aspect of the present invention, there is provided the microcomputer failure diagnosis apparatus according to the first aspect, wherein the diagnosis circuit is built in the microcomputer. The gist of the invention described in claim 3 is that the diagnosis circuit outputs a signal at a constant interval instructing the microcomputer to execute a self-diagnosis, and the diagnostic circuit responds to the signal at a constant interval from the timer. 3. The microcomputer failure diagnosis apparatus according to claim 1, further comprising a comparator for comparing a diagnosis value, which is a result of the predetermined diagnosis executed by the microcomputer, with the comparison value. The gist of the invention described in claim 4 is a microcomputer failure diagnosis method for realizing improvement in diagnosis accuracy with a small number of components, wherein a diagnosis step for self-diagnosis executed on the microcomputer side, A timer step of measuring a time period of a signal output at a constant interval, wherein the diagnosis step compares a diagnosis value which is a result of execution of a predetermined diagnosis by the microcomputer with a comparison value which is a constant prepared in advance. And a step of determining whether there is a failure in the microcomputer. The gist of the invention described in claim 5 is that the diagnosis step includes a timer step of outputting a signal at regular intervals instructing the microcomputer to execute a self-diagnosis, and a timer step of outputting a signal at regular intervals from the timer step. 5. The microcomputer failure diagnosis method according to claim 4, further comprising a comparison step of comparing a diagnosis value, which is a result of the predetermined diagnosis executed by the microcomputer, with a comparison value, which is a constant prepared in advance. Exists. The gist of the invention according to claim 6 is that the diagnostic step transmits the comparison value to the microcomputer at a constant interval from the timer step in response to a signal and sets the diagnostic value in the comparison step. A microcomputer fault diagnosis method according to claim 5, comprising one step. The gist of the invention according to claim 7 is that the microcomputer executes a self-diagnosis based on the received comparison value, and furthermore, the microcomputer executes a diagnosis value as comparison data obtained as a result of the self-diagnosis. 7. The method according to claim 6, further comprising a second step of transmitting to the microcomputer. The gist of the invention according to claim 8 is that the diagnostic step receives a diagnostic value sent from the microcomputer,
The diagnosis value is set in the comparison step, the diagnosis value is compared with the comparison value using the comparison step, and when the diagnosis value is equal to the comparison value, the microcomputer is diagnosed as normal. 8. The microcomputer failure diagnosis method according to claim 7, further comprising a third step of diagnosing the microcomputer as a failure and outputting a failure signal when the diagnosis value is not equal to the comparison value. Exist. The gist of the invention described in claim 9 is:
The microcomputer outputs a signal at regular intervals,
The timer circuit measures an interval time of a signal at a fixed interval from the microcomputer, and when the measured value of the interval time is shifted beyond a predetermined threshold value prepared in advance, the timer circuit is activated. 9. The microcomputer failure diagnosis method according to claim 8, further comprising a fourth step of diagnosing the microcomputer as a failure and causing the timer circuit to output a failure signal. The gist of the invention according to claim 10 is that the buffer circuit has a fifth step of invalidating an output from the microcomputer in response to the failure signal. Lies in the method of diagnosis.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the embodiment described below are as follows.
By providing a microcomputer, a diagnostic circuit provided in the microcomputer, and a timer circuit for measuring a cycle of a diagnostic signal output by the microcomputer, an improvement in the diagnostic accuracy of the microcomputer can be realized with a small number of components. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram for explaining a microcomputer failure diagnosis apparatus 10 according to one embodiment of the present invention. In FIG. 2, 10 is a microcomputer failure diagnosis device, 101 is a microcomputer,
102 indicates a diagnostic circuit, 103 indicates a buffer circuit, and 104 indicates a timer circuit. Referring to FIG. 2, a microcomputer failure diagnosis apparatus 10 of the present embodiment includes a microcomputer 101 having a built-in circuit for self-diagnosis (diagnosis circuit 102) therein, and a microcomputer 1
The microcomputer 101 includes a buffer circuit 103 that outputs an external signal in accordance with the signal No. 01, and a timer circuit 104 that measures a time period of a signal output from the microcomputer 101 at regular intervals.

FIG. 3 is a block diagram for explaining the diagnostic circuit 102 of FIG. 3, reference numeral 201 denotes a timer, 202 denotes a memory, 203 denotes a buffer, 204 denotes a buffer, and 205 denotes a comparator. Referring to FIG. 3, the diagnostic circuit 102 includes a timer 201, a memory 202, a buffer 203, a buffer 204, and a comparator 205.

Next, the microcomputer failure diagnosis device 1
Operation 0 (microcomputer failure diagnosis method) will be described. FIG. 4 is a flowchart for explaining a microcomputer failure diagnosis method according to one embodiment of the present invention. Referring to FIGS. 2, 3, and 4, first, the first step is executed and the microcomputer 101
The timer 201 (see FIG. 3) provided in the diagnostic circuit 102 (see FIGS. 2 and 3) incorporated in the diagnostic circuit 102 (see FIG. 2) outputs a signal at regular intervals (step S1 in FIG. 4).
02 (see FIG. 3) in the timer 20
At the same time as the signal from 1 is input, a constant (comparison value) prepared in advance is transmitted to the microcomputer 101 through the buffer 203 (see FIG. 3) (step S2 in FIG. 4), and at the same time, the diagnosis value (comparison data) is transmitted. Comparator 20
5 (see FIG. 3) (step S3 in FIG. 4).

Next, a second step is executed, and the microcomputer 101 performs a self-diagnosis (step S4 in FIG. 4) based on the received constant (comparison value), and outputs a diagnosis value (comparison data) obtained as a result. This is transmitted to the diagnostic circuit 102 (step S5 in FIG. 4).

Next, a third step is executed, and the diagnostic circuit 102 receives the diagnostic value (comparison data) sent from the microcomputer 101 (step S6 in FIG. 4).
Then, the diagnostic value (comparison data) is set in the comparator 205 through the buffer 204 (see FIG. 3),
Compares the diagnostic value with the already set comparison value (step S7 in FIG. 4), and if they are equal (Y in step S7 in FIG. 4), the microcomputer 10
1 is diagnosed as normal, and if they are not equal (N in step S7 in FIG. 4), a failure is diagnosed, and the diagnostic circuit 102 outputs an inhibit signal (fault signal) (step S7 in FIG. 4).
8) Yes.

Next, a fourth step is executed, the microcomputer 101 outputs a signal at regular intervals, and the timer circuit 104 measures the interval time. At this time, if the measured value deviates beyond the threshold value prepared in advance, the timer circuit 104 diagnoses the microcomputer 101 as a failure and outputs an inhibit signal (failure signal).

Next, a fifth step is executed, and when an inhibit signal (fault signal) from the diagnostic circuit 102 and the timer circuit 104 (see FIG. 2) for invalidating the output of the buffer circuit 103 (see FIG. 2) is input. , The buffer circuit 103 keeps outputting an OFF output that invalidates the input from the microcomputer 101 at all. As a result, the microcomputer 101 can perform a self-diagnosis using only one microcomputer 101 and the timer circuit 104.

As described above, according to the present embodiment, the following effects can be obtained. The first effect is that the failure diagnosis of the microcomputer 101 can be performed with a small number of parts. The second effect is that diagnostic accuracy can be improved.

It should be noted that the present invention is not limited to the above embodiments, and it is clear that the above embodiments can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to numbers, positions, shapes, and the like suitable for carrying out the present invention. In each drawing, the same components are denoted by the same reference numerals.

[0021]

Since the present invention is configured as described above, the following effects can be obtained. A first effect is that a failure diagnosis of a microcomputer can be executed with a small number of parts. The second effect is that diagnostic accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional microcomputer failure diagnosis device.

FIG. 2 is a block diagram for explaining a microcomputer failure diagnosis device according to one embodiment of the present invention.

FIG. 3 is a block diagram for explaining the diagnostic circuit of FIG. 2;

FIG. 4 is a flowchart illustrating a microcomputer failure diagnosis method according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Microcomputer failure diagnostic apparatus 101 ... Microcomputer 102 ... Diagnostic circuit 103 ... Buffer circuit 104 ... Timer circuit 201 ... Timer 202 ... Memory 203,204 ... Buffer 205 ... Comparator

Claims (10)

[Claims] 1. A microcomputer failure diagnostic apparatus which realizes improvement of diagnostic accuracy with a small number of parts, comprising: a microcomputer having a built-in diagnostic circuit for self-diagnosis; and an external signal according to a signal of the microcomputer. And a timer circuit for measuring a time period of a signal output from the microcomputer at regular intervals, wherein the diagnostic circuit prepares in advance a diagnostic value that is a result of performing a predetermined diagnostic by the microcomputer. A microcomputer failure diagnosis device configured to determine the presence or absence of a failure in the microcomputer by comparing with a comparison value that is a constant. 2. The microcomputer failure diagnosis apparatus according to claim 1, wherein said diagnosis circuit is built in said microcomputer. 3. A diagnostic circuit comprising: a timer for outputting a signal at a constant interval instructing the microcomputer to execute a self-diagnosis; and a predetermined diagnostic executed by the microcomputer in response to a signal at a constant interval from the timer. 3. The microcomputer failure diagnosis apparatus according to claim 1, further comprising a comparator for comparing a diagnosis value, which is an execution result of the above, with the comparison value. 4. A microcomputer failure diagnosis method for realizing improvement of diagnosis accuracy with a small number of parts, comprising: a diagnosis step for self-diagnosis executed on the microcomputer side; and a signal output from the microcomputer at regular intervals. A timer step of measuring a time period, wherein the diagnosis step compares a diagnosis value, which is a result of execution of the predetermined diagnosis by the microcomputer, with a comparison value, which is a constant prepared in advance, to determine whether a failure has occurred in the microcomputer. A microcomputer failure diagnosis method comprising a step of determining the presence / absence. 5. The diagnosis step includes a timer step of outputting a signal at regular intervals instructing the microcomputer to execute self-diagnosis, and the microcomputer executing the diagnosis step in response to a signal at regular intervals from the timer step. 5. The apparatus according to claim 4, further comprising a comparing step of comparing a diagnostic value, which is an execution result of the predetermined diagnosis, with a comparative value, which is a constant prepared in advance.
The microcomputer failure diagnosis method according to 1. 6. The diagnostic step includes a first step of transmitting the comparison value to the microcomputer at a constant interval from the timer step in response to a signal and setting a diagnosis value in the comparison step. The microcomputer failure diagnosis method according to claim 5, wherein 7. A second step in which the microcomputer executes a self-diagnosis based on the received comparison value, and transmits a diagnosis value, which is comparison data obtained as a result of the self-diagnosis, to the diagnosis process. 7. The microcomputer failure diagnosis method according to claim 6, comprising: 8. The diagnostic step receives a diagnostic value sent from the microcomputer, sets the diagnostic value in the comparing step, and compares the diagnostic value with the comparative value using the comparing step. Executing, when the diagnostic value is equal to the comparison value, diagnoses the microcomputer as normal, and when the diagnostic value is not equal to the comparison value, diagnoses the microcomputer as a failure and outputs a failure signal. 8. The method according to claim 7, further comprising the step of:
The microcomputer failure diagnosis method according to 1. 9. The microcomputer outputs a signal at a constant interval, the timer circuit measures an interval time of a signal at a constant interval from the microcomputer, and a measurement value for the interval time is prepared in advance. 9. The method according to claim 8, further comprising a fourth step in which the timer circuit diagnoses the microcomputer as a failure when the timer circuit deviates beyond a predetermined threshold value, and the timer circuit outputs a failure signal. Microcomputer failure diagnosis method. 10. The microcomputer failure diagnosis method according to claim 9, further comprising a fifth step in which the buffer circuit invalidates an output from the microcomputer according to the failure signal.