JPS6011941A - Data processor - Google Patents

Abstract

PURPOSE:To improve the detection factor for defect products without changing a mask pattern of an ROM by delivering an instruction equal to the ROM output from an external input terminal. CONSTITUTION:When a test mode setting terminal 10 is set at a low level, the output of an ROM1 is sent to an instruction register 2 via a switch circuit 9. Then a system has a normal actuation in accordance with a program stored in the ROM1. When the terminal 10 is fixed at a high level, the circuit 9 is switched to send the signal sent from an input/output circuit 5 to the register in place of the output of the ROM1. A tester is connected to input/output terminals 6a and 6b to feed a test pattern. Thus a single chip microcomputer can be actuated based on a test flow supplied from outside.

Description

[Detailed Description of the Invention] [Technical Field 1] The present invention relates to a data processing technology and a technology that is particularly effective when applied to a data processing integrated circuit, such as a one-chip data processing integrated circuit that is not externally expandable. [Used for testing] 7. Concerning effective techniques.

[Background technology]

A 4-bit, non-externally expandable single-chip e-microcomputer (hereinafter referred to as 4-bit
(referred to as single-chip microcontroller) and LS for calculators.
In a data processing integrated circuit such as I (Large Scale Integrated Circuit) or PLA (Programmerful Logic Array) for watches, C1[, R O
A kind of test program (hereinafter referred to as a test flow) consisting of a testing pattern for determining whether a product is good or defective is stored in a part of M (read-only memory). Then, by operating the circuit according to the test flow in this ROM and checking the output by Kl 111, we can judge whether it is operating correctly or not. However, it is nearly impossible to create a complete test flow from design self-help. Therefore, in order to increase the detection rate of defective products, it is often necessary to gradually change the test flow. Therefore, each time the test flow is changed, the
The test patterns to be included in the OM must also be changed, which is very inconvenient. In addition, if we try to create a complete test flow to improve the detection rate of defective products, the number of test patterns that should be stored in the ROM will increase, and as a result, the program area in the ROM that can be used by the user will be reduced. It turns out that there is an inconvenience that the number is reduced.

[Object of the Invention] An object of the present invention is to provide a technology related to the data processing 17F that is cheaper than the conventional technology and has new effects.

Another object of the present invention is to improve the detection rate of defective products without changing the ROM mask when applied to a single-chip data processing integrated circuit that cannot be expanded externally. It's about doing.

Another object of the present invention is to make the ROΔ
It is possible to improve the detection rate of defective products without reducing the program area within the area.

Still another object of the present invention is to provide a data processing integrated circuit (,
The goal is to improve reliability.

Yet another object of the present invention is to provide testing techniques suitable for data processing integrated circuits.

The above and eleven objects and features of the present invention will become clear from the description of the present specification and the flow port drawings. cormorant.

[Summary of the Invention] Representative inventions disclosed in this application will be briefly outlined.

The power of this invention is, for example, external extension h1/na4
In data processing circuits such as bit single-chip microcomputers and dedicated microcomputers (PLA for watches, etc.), when in test mode the external input/output terminal 11 is used as the test terminal (-). By configuring the external input (test pattern) so that it can be exchanged with the output of the built-in ROM, the RO can be input from the external input/output terminal.
Make it possible to give a power equal to M output,
This achieves the above object of improving the detection rate of defective items without changing the mask backing of the ROM.

The present invention will be specifically explained below using the drawings.

〔Example〕

FIG. 1 shows an embodiment in which the present invention is applied to a 4-pin, nodal single-chip microcomputer.

In this embodiment, n0M1 stores programs for operating the system, although not particularly limited thereto.
An instruction register 2 that fetches instructions (codes) read from the rtOMl of
A single-chip system is constructed by an LU (logical operation unit) 3, a RAM for temporarily storing the performance, results, etc. of the ALLT 3 (2) + memory that can be read and programmed at any time) 4, and an input/output circuit 5. The microcontroller is configured. In other words,
The part surrounded by the chain line A in the figure is the song chip microcomputer, which is formed on a single semiconductor substrate -F such as a silicon chip.

The above single-chip microcontroller has input/output circuit 5.
Connect the external bus to (7, this external);
It is not possible to expand the system externally by connecting M, RAM, etc. 9, an address signal is input from the outside (via the input/output circuit 5).
It is not possible to directly access internal ROM1, RAM4, etc.

Therefore, the input/output circuit 5) is connected to external output terminals 6a, 6b, such as pins, provided on the package enclosing the chip, using a K-wire punch ink. According to the flowchart of this external input terminal 6a, data from the connected key input device 7, various settings devices, sensors, etc. can be taken in and stored in the internal RAM 4, and the calculation results in the ALU 3 can be connected to the external input terminal 6h. The displayed information is displayed on a display device 8 such as a liquid crystal display (LCD (7)) or operated by an external control device tf.

In this embodiment, a switching circuit 9 such as a multiplexer is provided between the output side of the ROP 11, for example, ROMI and the instruction register 2, and a switching circuit 9 such as a multiplexer is provided between the output side of the ROP 11 and the instruction register 2. One of them is used as a terminal 10 for setting a test mode. The switching circuit 9 is switched by the signal applied to the test mode setting terminal 10, and the input/output terminal 6
Data input to the input/output circuit 5 is supplied to the instruction register 2 from the input/output circuit 5 a and 6b.

That is, when the test mode setting terminal 10 is set to a low level, for example, the output of the ROM 1 is sent to the instruction register 2 via the switching circuit 9f, and the system (single-chip microcomputer) operates normally according to the program in the ROMI. Perform the following actions. When the test mode setting terminal 10 is fixed at a high level, the switching circuit 9 is switched and the input/output circuit 5 is replaced with the output of the ROMI.
The signal sent from the command register 2 is now sent to the command register 2. Therefore, this single-chip microcomputer can operate according to a test flow supplied from the outside by connecting a tester (testing machine) to the input/output terminals 6a and 6b and inputting a test pattern.

In the above embodiment, the terminal 6bl''i used as an output terminal is placed in an output floating state in the test mode so as not to conflict with the input (test pattern).

Therefore, in the above embodiment, since test patterns can be input into the microcomputer from the outside, it is possible to change the test flow once created midway through to increase the detection rate. (There is no need to change the ROMI mask pattern. In other words, the detection rate can be improved without changing the ROMI mask.)

Moreover, when testing with a limited amount of test flow that is written in a part of ROMI and called repeatedly, it is necessary to newly check the untested part. In this case, the same test flow must be repeated many times to generate a new test pattern, and the retesting time becomes extremely long due to the large number of steps in the test flow that are repeatedly executed.

However, in the above embodiment, a test pattern can be input from the outside, so even when newly checking an uninspected part, a desired test pattern can be input immediately. By increasing the number, it is possible to change the test flow and increase the detection rate, suppressing an increase in the number of steps in the entire test flow, and suppressing an extension of test time.

In addition, when the microcomputer is configured as in the above embodiment, it is used for inspecting the propagation of the ROMI output to the input/output circuit 5, inputting a test pattern, and for inspecting the output bin or switching the N: ROM output. The used test mode setting terminal 10 cannot be inspected using a test pattern input from the outside. Therefore, only the test flow that performs such inspection is stored in the internal ROM 1, and during the test, jump 7 is set to the address where this test flow is stored, and then the test mode setting terminal 10 is set to the normal setting. By returning it to the low level during operation, specific tests such as those described above can be performed.

However, in the microcomputer of the above embodiment, data can only be input from the outside into the instruction register 2 in place of the output from the ROMI in the test mode. It is not possible to input address data from outside to make the system work.

〔effect〕

In a data processing device that cannot be expanded externally, a switching circuit is provided to switch between the output of the internal storage means (ROM) and the input signal from the external input/output terminal, and the switching circuit switches between the output of the internal storage means (ROM) and the input signal from the external input/output terminal, and In a specific state, that is, test mode, it is possible to operate by supplying a signal from the external input/output terminal instead of the output of the -J2 ROM, so the command equivalent to the ROM output is given from the external input/output terminal. As a result, the detection rate of defective products can be improved by successively changing the mask pattern of the ROM to a perfect one that improves the test flow without changing the mask pattern of the ROM.

In addition, a switching circuit is provided to switch between the output of the internal storage means (ROM) and the input signal from the external input/output terminal, and mode setting (based on an appropriate control signal such as fi, a specific state, that is, test mode) is provided. So, instead of the output of the ROM, we made it possible to operate by supplying a signal from the external input/output terminal, so that the same command as the ROM output can be given from the external input/output terminal. The amount of test flow that must be stored in the built-in ROM can be minimized, thereby relatively increasing the program area in the ROM available to the user.

A switching circuit is provided to switch between the output of the internal storage means (ROM) and the input signal from the external input/output terminal, and the ROM is switched in a specific state, that is, in a test mode, based on an appropriate control signal such as a mode setting signal. Since it is possible to operate by supplying signals from external input/output terminals instead of outputs, it is possible to input commands equivalent to ROM output from external input/output terminals, which is the most efficient method. With a good test flow, it is possible to perform a σ) test to detect defective products. This has the effect of suppressing the increase in the number of tests and preventing a significant extension of the test time.

The above-mentioned invention will be explained in detail based on Examples (7), but the present invention is limited to the above-mentioned Examples. It does not mean that Lj can be changed in various ways within the range of not changing.

For example, in the above chip σ) RA Mσ) substitute j+k
(You can also use the register of p7 numbers.

[Field of Application] In the above embodiments, the application of the U-example and 1-(ware invention to a 4-pin single-chip
It can be applied to all data processing collector circuits that have an internal ROM such as T, A, electric, and -medium phase LSIs and are configured not to be externally expandable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention applied to a 4-pitch single-chip microcomputer. 1. Memory means (ROM); 3. ALU (arithmetic logic unit). , 4...RAM (random access memory), 6a, 6b...external input/output terminal, 9...
- Switching means (switching circuit), 10...mode setting terminal. Figure 1 Δ

Claims (1)

[Claims] 1. A data processing device having internal read-only storage means and configured to be non-extendable, and provided with switching means for switching between the output of the storage means and an input signal from an external input/output terminal. . A data processing device that can operate by supplying a signal from an external input/output terminal in place of the output of the storage means in a specific state based on an appropriate control signal.