JPH10123211A - Method and device for fault simulation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method and the device for fault simulation, which can shorten the processing time by utilizing the result of the simulation when the fault simulation is performed for a circuit, which partially and commonly includes the circuit, whose fault simulation was performed beforehand. SOLUTION: In a step 101, at least one partial circuit indluded in a circuit is recognized, and whether the partial circuit, wherein a corresponding fault dictionary is located, is present or not in the already existing fault dictionary is judged. In a step 106, the fault dictionary is extracted for the partial circuit, wherein the corresponding dictionary is present, and fault simulation is performed only for the partial circuit when the corresponding fault dictionary is not present. In a step 107, the fault detecting rate of the above described entire circuit is obtained by using the result of the simulation obtained by this fault simulation and the extracted fault dictionary with regard to the partial circuit, wherein the fault dictionary is present. These steps are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for simulating a fault, and more particularly to a method and an apparatus for determining a fault coverage of the entire circuit by performing a fault simulation by dividing the entire circuit into several partial circuits. is there.

[0002]

2. Description of the Related Art In recent years, a failure simulation has been widely performed in order to obtain a failure detection rate of a circuit.

A failure simulation is performed for each detection node as follows, for example. When the output terminal of the inverter is a detection node, for example, when the input is logic “0” and the output is logic “0”, this output terminal is short-circuited to the ground terminal, and the fault detection rate is 100%.
Becomes Further, when the input is logic "0" and the output is logic "1", it is considered that the output terminal is normal and the output terminal is short-circuited to the power supply voltage terminal. It becomes 50%.

Conventionally, such a failure simulation has been executed for all partial circuits included in a circuit, and the result has been used to calculate the failure detection rate of the entire circuit.

[0005]

However, there are many cases where the circuit for which a failure simulation is to be executed from now on commonly includes a partial circuit which has been previously subjected to a failure simulation in another circuit. Even in such a case, the results of the previously performed failure simulation cannot be used conventionally, and the failure simulation is performed for all the circuits included in the circuit, and the failure detection rate is calculated. Long processing time was required.

The present invention has been made in view of the above circumstances, and when performing a failure simulation on a circuit partially common to a circuit for which a failure simulation has been performed previously, the processing time can be reduced by utilizing the simulation result. It is an object of the present invention to provide a failure simulation method and a device thereof that can be shortened.

[0007]

A fault simulation method according to the present invention includes a step of recognizing at least one partial circuit included in a circuit to be inspected, and a step of recognizing a fault dictionary which already exists among the recognized partial circuits. Determining whether there is a partial circuit in which a corresponding fault dictionary exists; extracting a fault dictionary for a partial circuit in which a corresponding fault dictionary exists; and determining that there is no corresponding fault dictionary Performing a failure simulation on only the partial circuit for the partial circuit;
Using a simulation result obtained by the failure simulation and a failure dictionary extracted for a partial circuit in which the failure dictionary exists, determining a failure detection rate of the entire circuit.

In another fault simulation method according to the present invention, a step of recognizing at least one partial circuit included in a circuit includes a step of recognizing a fault corresponding to an already existing fault dictionary among the recognized partial circuits. Determining whether there is a partial circuit in which the dictionary exists; and, for a partial circuit in which a corresponding failure dictionary exists, among the detection nodes indicated in the failure dictionary, the circuit includes the partial circuit. Determining whether there is an undetected node in which a failure has not been detected in the connected state, and extracting the failure dictionary for a partial circuit having a corresponding failure dictionary and no undetected node. For a partial circuit having a corresponding failure dictionary and an undetected node, this failure dictionary is extracted, and the undetected node is recognized. A step, and the non-detection node,
Performing a failure simulation only on a partial circuit for which a corresponding failure dictionary does not exist; simulation results obtained by the failure simulation;
Using the fault dictionary corresponding to the partial circuit in which the fault dictionary exists and the undetected node does not exist, and the fault dictionary corresponding to the partial circuit in which the fault dictionary exists and the undetected node exists, the fault of the entire circuit is determined. Obtaining a detection rate.

According to the present invention, there is provided a fault simulation apparatus for determining a fault detection rate, comprising: a recognizing means for recognizing at least one partial circuit included in a circuit; and a fault dictionary corresponding to an existing fault dictionary among the partial circuits. The determination means for determining whether or not there is a partial circuit in which there is, and the partial circuit in which it is determined that the corresponding failure dictionary exists,
Extraction means for extracting the failure dictionary, and, for a partial circuit determined to have no corresponding failure dictionary, failure simulation executing means for performing a failure simulation only on the partial circuit and outputting a simulation result; And a failure detection rate calculation means for calculating a failure detection rate of the entire circuit using the simulation result and the extracted failure dictionary.

According to the present invention, there is provided a fault simulation apparatus for determining a fault detection rate, comprising: first recognition means for recognizing at least one partial circuit included in the circuit; and a fault dictionary which already exists among the recognized partial circuits. The first determining means for determining whether or not there is a partial circuit in which a corresponding failure dictionary exists, and the detection of the partial circuit in which a corresponding failure dictionary is determined to be present in the failure dictionary. A second determination unit that determines whether there is an undetected node in which a failure is not detected in the connection state in which the partial circuit is included in the circuit, and a corresponding failure dictionary exists and the For the partial circuit determined to have no detected node, the extraction means for extracting the failure dictionary and the partial circuit determined to have the corresponding failure dictionary and to determine that no undetected node exists. For the second recognition means for extracting the failure dictionary and recognizing the undetected node, the recognized undetected node, and the partial circuit determined to have no corresponding failure dictionary. Means for performing a failure simulation and outputting a simulation result only; a simulation result that is output; the failure dictionary corresponding to a partial circuit in which a failure dictionary exists and an undetected node does not exist; and a failure dictionary exists. And a failure detection rate calculation means for obtaining a failure detection rate of the entire circuit using the failure dictionary corresponding to the partial circuit in which the undetected node exists.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a procedure of the failure simulation method according to the present embodiment.

First, it is assumed that the circuit for which a failure simulation is to be performed includes some partial circuits. Then, in step 101, it is determined whether or not any of these partial circuits has a failure dictionary. That is, a failure dictionary has been previously performed by performing a failure simulation in another circuit, and whether or not a failure dictionary corresponding to a partial circuit included in the circuit exists in the failure dictionary is determined by determining whether the partial circuit has a failure dictionary. Judge based on the connection status.

If it is determined in step 101 that such a failure dictionary does not exist at all, the process proceeds to step 105, where a failure simulation is performed on all partial circuits.

If it is determined in step 101 that there is a partial circuit included in the circuit and a corresponding failure dictionary exists, the process proceeds to step 102. In step 102, it is determined whether or not the failure dictionary exists and can be used in the failure simulation. This decision
This is performed based on the connection state of the partial circuit in which the failure dictionary exists in the entire circuit.

Here, the case where the failure dictionary exists but cannot be used refers to the case where the connection state of the node is different between that in the circuit concerned and that in which the failure simulation was performed previously. In such a case, it is necessary to proceed to step 103 to recognize a node that has not been detected in the entire circuit.

Furthermore, assuming that a failure may exist for an undetected node as step 104, step 105
Then, the failure simulation is executed for the undetected node.

If it is determined in step 102 that the failure dictionary can be used, the failure simulation is not performed for the partial circuit and the processing in step 10 is performed.
Move to 1.

In step 105, as described above, a partial circuit in which a failure dictionary does not exist, or a failure dictionary exists, but the connection state differs between the circuit and a previously simulated circuit and becomes an undetected node. The failure simulation is executed only for the part.

At step 106, it is determined whether or not the processing has been completed for all the partial circuits included in the circuit. If the processing has not been completed, the process returns to step 101, and if completed, the process proceeds to step 107.

In step 107, a failure detection rate is calculated. For partial circuits for which no fault dictionary exists,
The fault detection rate obtained by the fault simulation performed in step 105 is used, and for a partial circuit that has a fault dictionary and can be used, the fault detection rate indicated in the fault dictionary is used. Further, for the partial circuit that has determined that there is a failure dictionary but there is an undetected node, the failure detection rate indicated in the failure dictionary and the failure obtained by the failure simulation performed in step 105 for the undetected node. Use detection rates. The fault detection rates are integrated, and the fault detection rate is output as step 108.

Here, the details of the processing in steps 101 to 103 will be described in detail below. In step 101, it is necessary to determine whether a corresponding failure dictionary exists for a partial circuit included in the circuit. As shown in FIG. 2, two partial circuits 1 are included in the entire circuit 3 to be subjected to the failure simulation.
And 2 are present. The partial circuit 1 has a configuration as shown in FIG. 3 as a single body, and has four input terminals A and B and four output terminals C, D, E and F.

In step 101, it is first recognized that the partial circuits 1 and 2 exist in the entire circuit 3, and it is determined whether or not a corresponding failure dictionary exists for each of the partial circuits 1 and 2. Here, it is assumed that a failure dictionary corresponding to only the partial circuit 1 exists.

FIG. 4 shows a fault dictionary obtained by performing a fault simulation on the partial circuit 1 alone. At each of the detection times 1000, 2000, 3000, and 4000, a failure simulation was performed with the detection nodes n1 to n4 as targets of failure detection. As a result, the detection times 1000-4
For every 000, a failure was detected from the results output from terminals C, D and F, E, F, respectively.

At step 101, in such a case, it is determined that a failure dictionary corresponding to only the partial circuit 1 among the partial circuits 1 and 2 exists.

In step 102, as described above, it is determined whether or not the failure dictionary as shown in FIG. 4 existing for the partial circuit 1 can be used based on the connection state. The partial circuit 1 when outputting the failure dictionary is in a connected state when it is a single unit as shown in FIG. On the other hand, the circuit 3 incorporating the partial circuit 1 is in the connection state as shown in FIG. 2, and the connection state is different. For this reason, the output terminals E and F from which outputs could be taken out when the failure simulation was performed on the partial circuit 1 are in a state where they cannot be taken out because they are connected to the partial circuit 2.

In such a case, recognition of an undetected node in step 103 is performed as follows. As shown in FIG. 5, in the fault dictionary already existing for the partial circuit 1, the output cannot be taken out from the terminals E and F, so that the detection nodes n3 and n4 are undetected nodes. Here, the output of the detection node n2 cannot be taken out from the terminal F, but it can also be taken out from the terminal D to detect a failure, so that it does not become an undetected node.

As described above, for the non-detected nodes n3 and n4 recognized in step 103, step 1
Assume that a fault may exist at 04. Then, in step 105, a failure simulation is performed only on the undetected nodes n3 and n4 in the partial circuit 1. Since there is no failure dictionary for the partial circuit 2, a failure simulation is performed for all the detection nodes to create a failure dictionary.

According to the present embodiment as described above, among the partial circuits included in the entire circuit, those having a failure dictionary are not subjected to the failure simulation for the existing failure dictionary. By utilizing
The processing time for calculating the failure detection rate can be reduced.

The above-described embodiment is an example, and does not limit the present invention. For example, a circuit does not necessarily include two or more partial circuits, and only one partial circuit exists. If a failure dictionary exists for this partial circuit, the processing time is calculated using the failure dictionary. Can be shortened. For example, only the partial circuit 1 is included in the entire circuit A to be subjected to the failure simulation this time, and the failure simulation is performed on the circuit B including the partial circuits 2, 3,. When there is a failure dictionary for the partial circuit 1, the connection state is different, but the processing time can be reduced by recognizing an undetected node and performing a failure simulation only on that part. .

[0030]

As described above, according to the fault simulation method and apparatus of the present invention, when a fault dictionary exists in a partial circuit included in the entire circuit by a fault simulation that has already been performed, For this partial circuit, the existing failure dictionary is utilized without performing a failure simulation, and only a partial circuit in which no failure dictionary exists or a node in which a failure dictionary exists but is not detected due to a different connection state is newly added. Since the failure simulation is performed, the processing time required for outputting the failure detection rate can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a procedure of a failure simulation method according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a connection state of partial circuits 1 and 2 in a circuit to which the failure simulation method can be applied.

FIG. 3 is a block diagram showing a connection state of the partial circuit 1 alone.

FIG. 4 is an explanatory diagram showing a failure dictionary obtained by performing a failure simulation on the partial circuit 1 alone.

FIG. 5 is an explanatory diagram showing a failure dictionary for recognizing a node which has not been detected due to a difference between the connection state in FIG. 2 and the connection state in FIG. 3 among existing failure dictionaries existing for the partial circuit 1 alone; .

[Explanation of symbols]

 1, 2 partial circuit 3 circuit AF terminal

Claims (4)

[Claims] 1. A failure simulation method for performing a failure simulation on a circuit to be inspected to determine a failure detection rate, comprising: recognizing at least one partial circuit included in the circuit; Determining whether there is a partial circuit in which the corresponding failure dictionary exists in the existing failure dictionary; and extracting the failure dictionary for the partial circuit in which the corresponding failure dictionary exists; Performing a failure simulation only on this partial circuit for a partial circuit having no failure dictionary, and a simulation result obtained by the failure simulation and a failure dictionary extracted for the partial circuit having the failure dictionary. Determining the fault coverage of the entire circuit using Fault simulation method comprising Rukoto. 2. A failure simulation method for performing a failure simulation on a circuit to be inspected and obtaining a failure detection rate, comprising: a step of recognizing at least one partial circuit included in the circuit; Determining whether there is a partial circuit in which the corresponding failure dictionary exists in the already existing failure dictionary; and, for the partial circuit in which the corresponding failure dictionary exists, the detection node of the detection node indicated in the failure dictionary Determining whether there is an undetected node in which a failure is not detected in the connection state in which the partial circuit is included in the circuit; and determining whether the corresponding failure dictionary exists and the undetected node does not exist. For the circuit, the step of extracting the fault dictionary and the sub-circuits for which the corresponding fault dictionary exists and the undetected nodes exist are described. Extracting the failure dictionary and further recognizing the undetected node; performing a failure simulation only on the undetected node and a partial circuit having no corresponding failure dictionary; , A failure dictionary corresponding to a partial circuit in which a failure dictionary exists and an undetected node does not exist, and a failure dictionary corresponding to a partial circuit in which a failure dictionary exists and an undetected node exists. Determining a fault detection rate of the entire circuit using the fault simulation method. 3. A failure simulation apparatus for performing a failure simulation on a circuit to be inspected to determine a failure detection rate, comprising: recognition means for recognizing at least one partial circuit included in the circuit; Of the partial circuits,
Determining means for determining whether or not there is a partial circuit in which a corresponding failure dictionary is present in the existing failure dictionary; and for the partial circuit in which the corresponding failure dictionary is determined to be present by the determining means, Extracting means for extracting a fault dictionary; and fault simulation executing means for performing a fault simulation only on the partial circuit and outputting a simulation result for a partial circuit determined by the determining means to have no corresponding fault dictionary. And a fault coverage calculating means for obtaining a fault coverage of the entire circuit using the simulation result output from the execution of the fault simulation and the fault dictionary extracted by the extracting means. Failure simulation device. 4. A failure simulation apparatus for performing a failure simulation on a circuit to be inspected to determine a failure detection rate, wherein: first recognition means for recognizing at least one partial circuit included in the circuit; First determining means for determining whether or not there is a partial circuit in which a corresponding fault dictionary exists among the existing fault dictionaries among the partial circuits recognized by the means; and For a partial circuit for which it is determined that a corresponding failure dictionary exists, of the detection nodes indicated in the failure dictionary, an undetected node whose failure is not detected in the connection state where the circuit includes this partial circuit. A second determining unit that determines whether there is a failure dictionary, and the first and second determining units determine that a corresponding failure dictionary exists and that an undetected node does not exist. The extracted partial circuits are extracted by the extracting means for extracting the fault dictionary, and the first and second determining means determine that the corresponding fault dictionary is present and the undetected node is present in the partial circuit. A second recognition unit that extracts the failure dictionary and further recognizes the undetected node; a non-detected node recognized by the second recognition unit; and a failure dictionary corresponding to the first determination unit. Fault simulation executing means for performing a fault simulation only on the partial circuit determined not to exist and outputting a simulation result; a simulation result output from the fault simulation executing means; a fault dictionary existing and an undetected node; The fault dictionary extracted by the extracting means corresponding to the partial circuit where Fault detection rate calculation means for obtaining a fault detection rate of the entire circuit using the fault dictionary extracted by the second recognition means corresponding to a partial circuit in which two undetected nodes exist. Characteristic failure simulation device.