JPH0454645A - Inspecting device for one-chip microcomputer - Google Patents

Abstract

PURPOSE:To execute various inspection of an analysis of the failure contents etc., according to the result of its execution by executing only an arbitrary step from an arbitrary address of a built-in program memory of a one-chip microcomputer. CONSTITUTION:Suppose that it is to be checked whether a one-chip microcomputer 30 operates normally when for instance, when the address 1,001 to 2,000 are executed in a control program stored in a built-in program memory 12. A counter 46 executes a count of a clock signal CLK, and finishes a count of a 1,000 portion of a set prescribed count number. In this case, a control part 11a which is executing an instruction of a control program in a memory 12 finishes the read-out execution of the 2,000 address of its control program. The counter 46 overflows, when it finishes a count of a prescribed count number 1,000. In the course of designated address operation, when an output pattern outputted from the computer 30 and an expected value output pattern from a test pattern generator 21 are compared by a comparator 22, whether a failure is generated or not can be checked.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of a testing device for testing a one-chip microcomputer.

(Prior Art) Conventionally, various tests are performed on microcomputers to determine whether the microcomputers are good or bad, analyze the nature of the defects, and the like.

Generally, microcomputers are tested by applying a series of input signal sequences (test patterns) to the device under test and checking the validity of the response output sequence in some way. Various test methods have been considered and put into practical use, such as those that carry out testing by setting the device under test on the testing equipment side, and those that are built into the device itself as a test circuit. . For example, FIG. 2 shows an example of the configuration of an inspection apparatus in which a device to be inspected is set on the inspection apparatus side and inspected.

FIG. 2 is a schematic diagram of a testing system including a conventional one-chip microcomputer testing device.

This inspection system includes a one-chip microcomputer 10, which is a device to be inspected, and an inspection device 20.

The one-chip microcomputer 10 includes a central processing unit (hereinafter referred to as CPU) 11 and a built-in program memory 1.
2, a data memory 13, an input/output circuit 14, and a bus 15 interconnecting them. CPtJll includes a control unit 11a that controls the entire one-chip microcomputer, such as decoding commands of a control program and exchanging signals with each unit, and an arithmetic unit 11b that performs arithmetic operations and logical operations.
, and a register section 11C that temporarily holds data. The built-in program memory 12 has a function of storing a control program for controlling the entire one-chip microcomputer, and is composed of, for example, a ROM. The data memory 13 has a function of storing various data, and is composed of, for example, a RAM.

The inspection device 20 includes, for example, a test pattern generator 21 that generates an input test pattern and an expected value output pattern;
It is comprised of a comparator 22 that compares the output pattern output from the one-chip microcomputer 10 with an expected value output pattern according to an input test pattern, a control section R23 that controls them, and the like.

Next, a case where an inspection is performed using a conventional inspection system will be described.

The inspection of the one-chip microcomputer 10 by the inspection system as described above is carried out using, for example, an inspection program different from the control program, and there are two types of means for doing so, roughly classified as follows.

■ One is to store an inspection program in a memory area provided in advance in the one-chip microcomputer 10, and execute the inspection by giving it from the control unit n23 of the inspection device 120 via a predetermined signal line within the one-chip microcomputer 10. A signal indicating a command causes the control unit 11a to execute the command of the test program to perform the test.

■ On the other hand, in the other case, an inspection program is prepared on the inspection device 20 side, the bus 15 is forcibly changed, and the control section 11a executes the instructions of the inspection program on the inspection device 20 side to perform the inspection. It is something to do.

(Problems to be Solved by the Invention) However, the one-chip microcomputer inspection device having the above configuration has the following problems.

(a) In the case of the method (2) above, a memory area for the test program is required in the one-chip microcomputer 10, so the number of circuit elements and the chip area increase. Furthermore, in this case, when the one-chip microcomputer 10 is shipped as a product, the inspection program remains stored in its memory area. There is a risk that the control unit 11a may end up executing the inspection program due to, for example, noise being placed on the signal line provided for supplying the inspection execution command signal.

(b) In the methods of (1) and (2) above, an inspection program is used when inspecting the one-chip microcomputer 10, so it is possible to analyze the details of the defect by appropriately creating an inspection program. . However,
The control unit 11a performs control based on the instructions of the test program during inspection, and performs control based on the control program in the built-in program memory 12 when used as a product. Comparing the two cases, , control unit 11a
The path for reading the inspection program and the path for reading the control program are different. Therefore, even if a malfunction occurs, such as not being able to obtain a normal output turn, when the one-chip microcomputer 10 is operated using the control program in the built-in program memory 12, the external inspection program will detect the malfunction. There will be cases where this is not possible.

In order to solve the above problems, the applicant of the present application previously proposed a technique described in Japanese Patent Application Laid-Open No. 61-221837.

The gist of the technology described in this document is as follows. That is, an inspection program prepared in advance on the inspection device 20 side is transferred to the data memory 12 on the one-chip microcomputer 10 side at the time of inspection, and the inspection is performed by operating the control unit 11a according to the inspection program transferred to the data memory 12. For example, the inspection program in the data memory 12 is erased after the inspection is completed.

However, although the proposed technique solves the problem (a), the problem (b) still remains unsolved, and the following problems occur. With this proposed technology, inspection can be performed when the program space and data space are in the same area, that is, when the control unit 11a can access the program space and data space via the same signal line. However, this cannot be done if the program space and data space are independent. This is because if the program space and data space are independent, the control unit 11a will not execute the test program in the data space even if the test program is transferred to the data space during testing.

As described above, even with the above proposal, the problems of the prior art described above could not be sufficiently solved.

The present invention solves the problems that the prior art had, while eliminating malfunctions caused by testing when using a one-chip microcomputer as a product, while also solving the problem of not being able to test when the program space and data space are independent. The present invention provides an inspection device for a one-chip microcomputer that solves the problem of failure to detect defects.

(Means for Solving the Problems) In order to solve the problems described above, the present invention provides a built-in program memory storing a control program, a clock generation means for generating a clock signal, and a clock generation means for generating the control program in synchronization with the clock signal. A test pattern is input to a one-chip microcomputer equipped with a control section for executing a program, and memory switching means for switching between the built-in program memory or an external memory and connecting it to the control section. A one-chip microcomputer testing apparatus for executing a corresponding predetermined program and testing the one-chip microcomputer based on the execution result is constructed using the following means.

That is, the inspection apparatus includes at least an external program memory storing a predetermined part of the control program, an address setting means for setting a predetermined address according to the inspection content, and a control section for controlling the external program memory by the control section. a comparison means for comparing an address during program execution with the predetermined address to detect whether they match/mismatch; and when the detection result of the comparison means is a match, a predetermined count number preset according to the inspection content is provided; a counter that performs a counting operation of the clock signal by the predetermined number of counts based on the count setting signal; and a switching signal for the memory switching means based on the outputs of the comparing means and the counter. and a switching signal output means for outputting.

(Function) According to the present invention, the inspection device for a one-chip microcomputer is configured as described above, so that when the comparison means detects address matching, the output of the comparison means causes the count setting means to count the number of addresses. A setting signal is output to the counter, the predetermined count number is loaded to the counter, the counter starts counting the predetermined count number based on the clock signal, and the switching signal output means outputs the predetermined count number to the counter, and the switching signal output means outputs the predetermined count number to the counter, and the counter starts counting the predetermined count number based on the clock signal. A switching signal is output to cause the control section to use the built-in program memory as a program memory. This results in
The control unit executes control based on a control program stored in a built-in program memory.

When the counter finishes counting the predetermined number of counts, a switching signal is output from the switching signal output means to the memory switching means to cause the control unit to use the external program memory as a program memory based on the output of the counter. . Thereby, the control unit executes control based on the program in the external program memory.

Therefore, the above problem can be solved.

(Embodiment) FIG. 1 is a schematic configuration diagram of an inspection system including a one-chip microcomputer inspection device showing an embodiment of the present invention. In the figure, common elements with those in FIG. 2 are given the same reference numerals.

This inspection system includes a one-chip microcomputer 30 to be inspected, and an inspection device 40.

The one-chip microcomputer 30 has a CPU 11 configured similarly to the one-chip microcomputer 10.
, a built-in program memory 12, a data memory 13, and a bus 15, and also includes a clock generation circuit 31, which is a clock generation means, and an input/output circuit 32, which has a memory switching section 32a, which is a memory switching means. The clock generation circuit 31 is a circuit that generates a clock signal CLK, and its output is connected to the CPU II.
It is connected to the inspection device 40 side via the bus 15. The memory switching unit 32a uses the built-in program memory 12 or another external memory as a program memory that stores a program that is actually controlled by the control unit 11a based on an external switching signal S1, for example. It has a function to switch between

The inspection device 40 includes a test pattern generator 21 . Comparator 22 and control circuit 23
It also has an external program memory 41. The external program memory 41 stores programs including, for example, the same control program as the built-in program memory 12, and is composed of a RAM, a ROM, or the like.

The external program memory 41 is connected to the input/output circuit 30 via a line and a bus 42, and is also connected to the input side of a comparison circuit 43 serving as comparison means, and a predetermined address is set on the input side of the comparison circuit 43. An address setting device 44 is connected thereto.

The comparison circuit 43 compares the address appearing on the bus 42 with a predetermined address of the address setter 44, detects coincidence/mismatch between the two based on the comparison result, and outputs an output signal S2 according to the detection result. This circuit is composed of logic gates, etc.

The address setting device 44 has a function of setting a predetermined address according to the content of the test, and is composed of, for example, a DIP switch. A count setting means 45 and a counter 46 are connected to the output side of the comparison circuit 43, as well as a flip-flop 47 serving as a switching signal output means.

The count setting means 45 has a function of outputting a count setting signal S3 indicating a predetermined count number to set the count number of the counter 46 and start counting, and is composed of a count setter 45a and a load circuit 45b. The count setter 45a is configured, for example, by a DIR switch, etc., and is for setting a predetermined count number according to the content of the inspection. This is a circuit for loading a predetermined count number into the counter 46.

The counter 46 is configured to count the clock signal CLK from the clock generation circuit 31 based on the count setting signal S3, and overflow at a predetermined count according to the count setting signal S3.

The flip-flop 47 has a function of outputting a predetermined switching signal S1 to the memory switching unit 32a based on the output of the comparison circuit 43 and the output of the counter 46, and is set by inputting the output signal S2 from the comparison circuit 43. A set terminal S and a reset terminal R that is reset by the output of the counter 46.
and an output terminal Q that outputs a predetermined switching signal S1 in response to set/reset.

Next, the operation when the one-chip microcomputer 30 is tested by the testing device 40 will be described.

Among the control programs stored in the built-in program memory 12, for example, when executing the control program from addresses 1001 to 2000, the one-chip microcomputer 30
When checking whether or not it operates normally, the address setter 44 is set to address 1001 as a predetermined address, and the count setter 45a is set to 1000 as a predetermined count number.

Further, when the counter 46 is not in counting operation, that is, when the comparison result of the comparator circuit 43 is outputting the output signal S2 indicating that the comparison result does not match, the flip-flop 47 outputs the control unit 11a that is controlled based on the external program memory 41. A switching signal S1 for executing the above is set to be output to the memory switching unit 32a.

The control section 11a starts control based on the control program of the external program memory 41 by switching the memory switching section 32a based on the switching signal S1.

At this time, when a predetermined input test pattern set in advance is generated by the test pattern generator 21 and the input test pattern is input to the one-chip microcomputer 30, the one-chip microcomputer 30 perform various actions according to the
As a result of this operation, an output pattern is output from the one-chip microcomputer 30 at a predetermined timing.

In this way, the memory switching unit 3 based on the switching signal S1
When the control unit 11a executes control based on the control program in the external program memory 41 by switching 2a,
On the bus 42, an address appears during program execution by the control unit 11a. This address changes as the program progresses and is input to the comparison circuit 43.

For example, the addresses appearing on the bus 42 change sequentially to 10
01 address, and the address that appears on the bus 42, that is, the address of the control program that the control unit 11a has come to read, matches the address preset in the address setter 44, and the comparison circuit 43 detects both addresses. When a match of the addresses is detected, the comparison circuit 43 outputs an output signal S2 indicating that the comparison result is a match.

In response to this output signal S2, the flip-flop 47 outputs a switching signal S1 that causes the memory switching unit 32a to perform switching, and the load circuit 45b loads the predetermined count number 1000 of the count setter 45 to the counter 46. A count setting signal S3 indicating a predetermined count number of 1000 is output to the counter 46. As a result, the counter 46 starts counting the clock signal CLK by the predetermined count number 1000 loaded from the count setter 45a, and the memory switching unit 32
In step a, the control unit 11a performs switching so that the built-in program memory 12 is used as the program memory. Therefore, the control unit 11a reads the program at address 1001 of the control program in the built-in program memory 12, and thereafter sequentially executes the programs starting at address 100.1 based on the control program in the built-in program memory 12. .

A counter 46 counts the clock signal CLK,
Counting for the set predetermined count number of 1000 minutes is completed. At this time, the control unit 11a, which is executing the commands of the control program in the built-in program memory 12 in synchronization with the clock signal CLK, finishes reading and executing the control program at address 2000. When the counter 46 finishes counting the predetermined number of 1000, it overflows, and its output resets the flip-flop 47, which outputs a switching signal S1 that switches the memory switching section 32a. Thereby, the memory switching section 32a switches the control section 11a and the external program memory 41 so that the control section 11a executes control based on the control program of the external program memory 41.
Perform a switch such as connecting. Therefore, the control unit 11a executes the instructions of the control program in the external program memory 41 starting from address 2001.

In this way, the one-chip microcomputer 30
The control unit 11a controls only the portion of the control program in the built-in program memory 12 between addresses 1001 and 2000 based on the contents of the built-in program memory 12, and controls other addresses based on the contents of the external program memory 41. Control by content. Therefore, when the control unit 11a operates based on the instructions at addresses 1001 to 2000 of the control program in the built-in program memory 12, the output pattern output from the one-chip microcomputer 30 and the test result are determined by the comparator 22, for example. By comparing the expected value ratio cover turn from the pattern generator 21, it is possible to check whether or not a problem occurs.

If the control unit 11a is controlling addresses 1001 to 2000 based on the control program in the built-in program memory 12,
If a problem is detected, in order to specify which part of the instruction from address 1001 to address 2000 is causing the problem to be executed, next, input the address to address setter 43 as a predetermined address. Set the address 1001 and set the predetermined count number 500 to the count setting device 45a.
Set. As a result, in the same manner as in the case of addresses 1001 to 2000, the control unit 11a for addresses 1001 to 1500 is transferred to the built-in program memory 12.
It can be operated based on the control program.

In this case, for example, if the defect cannot be detected,
Furthermore, 15
01 address and a predetermined count number 500 in the count setter 45a. As a result, the control unit 11a
Control is performed based on the control program in the built-in program memory 12 only from addresses 1501 to 2000. If a malfunction is detected at this time, it can be confirmed that the malfunction occurs when the control unit 11a executes the instructions between addresses 1501 and 2000 of the control program in the built-in program memory 12.

Thereafter, by repeating the same operations, the address where the one-chip microcomputer 30 has a problem is identified. Therefore, by analyzing the details of the failure based on the inspection results, it is possible to investigate, for example, defects in the hardware configuration.

This embodiment has the following advantages.

(A) In the present embodiment, the control unit 11a can execute control based on the contents of the built-in program memory 12 by an arbitrary step from an arbitrary address of the control program in the built-in program memory 12. Therefore, it becomes possible to analyze the cause of a defect according to the address of the control program, and a high effect can be expected in inspections such as analysis of defect contents.

(B) In the inspection device 40, the control unit 1
1a uses either the built-in program memory 12 or the external program memory 41 as the program memory, so the external program memory 41 can store the inspection program in addition to the control 10 grams, and the inspection function can be improved.

(C) In this embodiment, since the inspection can be performed without storing the inspection program in the existing data memory 13 of the one-chip microcomputer 30, it is possible to carry out inspection even when the program space and data space are independent. 6. I can perform the inspection without any problems.

(D> In this embodiment, the control section 11a is operated partially based on the contents of the built-in program memory 12, and the inspection is performed by checking for defects during the operation. Therefore, the inspection is performed using an inspection program as in the conventional method. Failure to detect defects due to differences in routes will not occur.

(E) According to the inspection device 40, even when the one-chip microcomputer 30 is used as a product, there will be no problems caused by equivalent inspection.

Note that the present invention is not limited to the above embodiments, and various modifications are possible. Examples of such modifications include the following.

(I> The configurations of the inspection device 40 and the one-chip microcomputer 30 to be inspected in the above embodiment can be modified in various ways.

■ For example, address setter 44 and count setter 4
5a may be configured such that a predetermined address and a predetermined count number are set using a personal computer or the like having a keyboard or the like. Furthermore, the configuration of the flip-flop 47 is merely an example, and is not limited to the illustrated example. For example, something other than a flip-flop may be used as the switching signal generating means. Furthermore, the test pattern generator 21, the comparator 22, and the control circuit 23 are different from conventional ones.
Although the examples are shown as those used when configuring an inspection system inside the shell, the configuration and installation thereof can be changed as appropriate depending on the content of inspection and inspection conditions.

(2) The one-chip microcomputer 30 may be equipped with a memory switching section 32a, for example, but it may be provided in advance in the one-chip microcomputer 30 in order to apply the above embodiment, for example.

Further, the configuration of the chip microcomputer 30 shown in FIG. 1 is merely an example, and the application of the above embodiment is not limited to the example shown.

(II) The testing procedure for testing the one-chip microcomputer 30 and the like using the testing device 40 is not limited to that of the above embodiment. For example, if the outline of the defect is known in advance through a primary inspection or the like set in a manner other than the above embodiments, a control program to be stored in the external program memory 41 may be used to control the built-in program memory 12 based on the outline of the defect. The program may be a predetermined part of the program.

(Effects of the Invention) As described above in detail, according to the present invention, the external program memory, address setting means, comparison means, count setting means, counter, and switching signal output means are provided to realize a one-chip microcomputer. Since the inspection device is constructed, it is possible to execute only an arbitrary step from an arbitrary address in the built-in program memory of the one-chip microcomputer, and the execution results enable various inspections such as analysis of defect contents. Further, it is possible to add an inspection program to the external program memory, thereby improving the inspection function.

Therefore, it is possible to test various one-chip microcomputers without being limited to the configuration of the program space and data space, and it is also possible to eliminate failures such as failure to detect defects, and it is possible to test various one-chip microcomputers when using the one-chip microcomputer. Therefore, it is possible to realize a one-chip microcomputer testing device that does not cause malfunctions due to this.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a one-chip microcomputer testing device showing an embodiment of the present invention, and FIG. 2 is a schematic diagram of a testing system including a conventional one-chip microcomputer testing device. DESCRIPTION OF SYMBOLS 11... CPU, lla... Control unit, 12... Built-in program memory, 30... One-chip microcomputer, 32a... Memory switching unit, 40... Inspection device, 41... External Program memory, 42...
Bus, 43... Comparison circuit, 44... Address setter, 45... Count setting means, 45a... Count setting device, 45b... Load circuit, 46... Counter, 47... Flip frog, Sl... switching signal,
S3...Count setting signal, CLK...Clock signal.

Claims (1)

[Claims] A built-in program memory storing a control program;
A clock generating means for generating a clock signal, a control section for executing the control program in synchronization with the clock signal, and a memory switching means for switching between the built-in program memory or an external memory and connecting it to the control section, In a one-chip microcomputer testing device, the one-chip microcomputer is tested by inputting a test pattern to the one-chip microcomputer to execute a predetermined program corresponding to the control program, and testing the one-chip microcomputer based on the execution result. , an external program memory storing at least a predetermined part of the control program; an address setting means for setting a predetermined address according to the inspection content; and an address during program execution of the external program memory by the control unit. and said predetermined address, and when the detection result of said comparison means is a match, a count setting signal indicating a predetermined count number preset according to the inspection content is sent. a counter that performs a counting operation of the clock signal by the predetermined number of counts based on the count setting signal; and a switching signal that outputs a switching signal to the memory switching unit based on the outputs of the comparison unit and the counter. An inspection device for a one-chip microcomputer, comprising: an output means.