JP2924392B2 - Microcomputer system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcomputer system, and more particularly to a self-test circuit for a microcomputer system.

[0002]

2. Description of the Related Art As shown in FIG.
The AM unit 2, the CPU unit 3, and the input / output circuit unit 4 are interconnected by an internal data bus 5. Conventional self-test methods for microcomputer systems use ROM.
The self-test execution instruction group stored in the section 1 is input to the CPU section 3 via the internal data bus 5, and the CPU section 3 decodes and executes the self-test execution instruction group to execute the self-test of the microcomputer system. Running.

[0003]

However, in the above-mentioned conventional method of self-testing a microcomputer system, the operation of data transfer and execution of an operation instruction within the microcomputer system can be tested, but it depends on external data. There is a serious problem that a self-test on the operation of the microcomputer system is not possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and in the self-test of the microcomputer system, the self-test on the operation of the microcomputer system depending on external data can be executed, thereby improving the effect of the self-test. It is an object of the present invention to provide a microcomputer system which is higher than the conventional self-test of the microcomputer system.

[0005]

A microcomputer system according to the present invention comprises: an instruction code generating means for generating a test instruction code in the system at the time of a self test; and a microcomputer based on information output from the instruction code generating means. Control means for inputting external data from an external terminal and arithmetic means for executing the test instruction code using the external data during a self-test are provided.

[0006]

In the microcomputer system according to the present invention, when executing a self-test depending on external data, the external data input to the external terminal by the external terminal scan signal output from the ROM section is used as an input / output circuit. By taking it into the section, a self-test depending on external data can be executed.

[0007]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a microcomputer system according to a first embodiment of the present invention. The microcomputer system according to the first embodiment of the present invention shown in FIG.
And the input / output circuit unit 4 are connected to each other by an internal data bus 5. Further, an external terminal scan signal 6 output from the ROM unit 1 is input to the input / output circuit unit 4.

FIG. 2 is a detailed block diagram of peripheral circuits of the ROM section 1 and the input / output circuit section 4 in the microcomputer system according to the first embodiment of the present invention shown in FIG. As shown in FIG. 2, the input / output circuit unit 4 and the external terminals 11
Scan registers 7 to 10 are respectively connected between. Also, the scan registers 7 to 10
The external terminal scan signal 6 output from the M unit 1 is connected in series, and the external terminal scan signal 6 is sequentially input from the scan register 7.

Next, the first embodiment of the present invention configured as described above is described.
The operation of the microcomputer system according to the embodiment will be described. In the self-test by the microcomputer system according to the present embodiment, a self-test execution instruction group stored in the ROM unit 1 is transferred to the CPU unit 3 via the internal data bus 5 to execute the self-test. By this self-test, it is possible to test the data transfer and the execution of the operation instruction in the microcomputer system. Further, when executing a self-test depending on external data, the external data input to the external terminals 11 to 14 is taken into the scan registers 7 to 10 by the external terminal scan signal 6 output from the ROM unit 1. In addition, a self test depending on external data can be executed.

Next, a microcomputer system according to a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing a microcomputer system according to the second embodiment of the present invention. The difference from the microcomputer system according to the first embodiment of the present invention shown in FIG.
That is, the scan data generating circuit 15 is provided. RO
The scan data control signal 16 output from the M unit 1 is
The data is input to the scan data generation circuit 15. The scan data generation circuit 15 converts the input scan data control signal 16 into an external terminal scan signal 6 and outputs it to the scan registers 7 to 10. Scan register 7-10
Are external terminals 11 to 14 according to the external terminal scan signal 6.
Imports external data input to From the above,
The microcomputer system according to the second embodiment of the present invention can execute a self-test depending on external data similarly to the microcomputer system according to the first embodiment of the present invention.

In the above embodiment, the states of the external terminals 11 to 14 in the input / output circuit unit 4 are arbitrarily set using serial data. By arbitrarily setting the states of 11 to 14, a self-test depending on external data may be executed.

[0013]

As described above, according to the microcomputer system of the present invention, in the self-test of the microcomputer system, the self-test of the data transfer and the execution of the operation instruction in the microcomputer system and the external data are executed. Self-tests on the operation of the dependent microcomputer system can also be performed. Therefore, according to the microcomputer system of the present invention, the effect of the self-test is higher than that of the conventional microcomputer system, and a highly reliable microcomputer system can be configured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a microcomputer system according to a first embodiment of the present invention.

FIG. 2 is a detailed block diagram of peripheral circuits of a ROM unit 1 and an input / output circuit unit 4 in the microcomputer system according to the first embodiment of the present invention shown in FIG.

FIG. 3 is a block diagram showing a microcomputer system according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing an example of a conventional microcomputer system.

[Description of Signs] 1; ROM section 2; RAM section 3; CPU section 4; input / output circuit section 6; external terminal scan signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06F 11/22-11/26 G01R 31/28-31/30 G06F 15/78 510

Claims (1)

(57) [Claims] 1. An instruction code generating means for generating a test instruction code in a system at the time of a self test, a control means for inputting external data from an external terminal based on information output from the instruction code generation means , Computing means for executing the test instruction code using the external data during a test.