JPH05181696A - Microcomputer system - Google Patents

Abstract

PURPOSE:To improve the effect of a self test by arbitrarily setting the state of an external terminal in an input/output circuit part when executing the self test. CONSTITUTION:The self test is executed by transferring a self test instruction group stored in a ROM part 1 through an internal data bus 5 to a CPU part 3. By this self test, the transfer of data in the microcomputer system or the executing operation of an arithmetic instruction can be tested. Further, when executing the self test depending on external data, the external data inputted to external terminals 11-14 are fetched into scan registers 7-10 according to an external terminal scan signal 6 outputted from the ROM part 1 and therefore, the self test depending on the external data can be executed. Otherwise, it is also available to convert a scan data control signal outputted from the ROM part 1 to the external terminal scan signal 6 by providing a scan data generating circuit.

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 A conventional self-test circuit of a microcomputer system is shown in FIG.
The AM section 2, the CPU section 3 and the input / output circuit section 4 are connected to each other by an internal data bus 5. A conventional microcomputer system self-test method is a ROM
The self-test execution instruction group stored in the section 1 is input to the CPU section 3 through 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. Is running.

[0003]

However, in the above-described conventional microcomputer system self-test method, data transfer and operation instruction execution operation inside the microcomputer system can be tested, but it depends on external data. There is a serious problem that the self-test on the operation of the microcomputer system is impossible.

The present invention has been made in view of the above problems, and in the self-test of the microcomputer system, the self-test of the operation of the microcomputer system depending on the external data can be executed, so that the self-test effect can be obtained. It is an object of the present invention to provide a microcomputer system higher than the self-test of the conventional microcomputer system.

[0005]

A microcomputer system according to the present invention comprises an instruction code generating means for self-test, a data generating means, an input / output circuit section for inputting external data, and this input / output circuit section. Data transfer means for arbitrarily setting the state of the external terminal at the time of executing the self test.

[0006]

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

[0007]

Embodiments of the present invention will now 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. 1 includes a ROM section 1, a RAM section 2, and a CPU section 3.
And the input / output circuit unit 4 are connected to each other by the internal data bus 5. Further, the external terminal scan signal 6 output from the ROM section 1 is input to the input / output circuit section 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 terminal 11
The scan registers 7 to 10 are connected between 14 and 14, respectively. Further, the scan registers 7 to 10 are RO
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 aspect of the present invention constructed as described above
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, the self-test execution instruction group stored in the ROM section 1 is transferred to the CPU section 3 via the internal data bus 5 to execute the self-test. With this self-test, it is possible to test the data transfer and the operation of executing the arithmetic instruction within the microcomputer system. Further, when executing the self-test depending on the external data, the external data input to the external terminals 11 to 14 by the external terminal scan signal 6 output from the ROM unit 1 is fetched into the scan registers 7 to 10. , It is possible to execute self-test depending on external data.

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 section 1 is
It is input to the scan data generation circuit 15. The scan data generation circuit 15 converts the input scan data control signal 16 into the external terminal scan signal 6 and outputs it to the scan registers 7 to 10. Scan registers 7-10
The external terminals 11 to 14 according to the external terminal scan signal 6.
Capture the external data input to. From the above,
The microcomputer system according to the second embodiment of the present invention can execute the self-test depending on the external data, like 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 section 4 are arbitrarily set by using the serial data, but the external terminals in the input / output circuit section 4 are set by using the parallel data. The self test depending on the external data may be executed by arbitrarily setting the states 11 to 14.

[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 performed. A self-test on the operation of the dependent microcomputer system can also be performed. Therefore, according to the microcomputer system of the present invention, the self-test effect is higher than that of the conventional microcomputer system, and it is possible to configure a highly reliable microcomputer system.

[Brief description of 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 section 1 and an input / output circuit section 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.

[Explanation of symbols]

 1; ROM part 2; RAM part 3; CPU part 4; Input / output circuit part 6; External terminal scan signal

Claims (1)

[Claims] 1. A self-test instruction code generation means, a data generation means, an input / output circuit section for inputting external data, and the states of external terminals in this input / output circuit section are arbitrarily set during execution of the self-test. A microcomputer system comprising: a data transfer means for setting.