JPH03125206A - Logic integrated circuit - Google Patents

Abstract

PURPOSE:To simplify the test of a logic integrated circuit IC by inputting the system clock of a microcomputer or the output signal of a 1st oscillation circuit to the clock input of a function circuit. CONSTITUTION:A 1st oscillation circuit 2 and a microcomputer 1 are actuated and a control circuit 9 selects a system clock line 7 of the microcomputer 1 via a control signal line 8. As a result, the microcomputer 1 and a function circuit 4 work synchronously with the circuit 2. At the same time, the signals synchronous with each other are outputted to the outside from the output terminals 3 and 6. Thus the signals received from the terminal 3 of the microcomputer 1 and the terminal 6 of the circuit 4 are synchronous with the output of the circuit 2. Then both the microcomputer 1 and the circuit 4 can be tested in a single timing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microcomputer and a logic integrated circuit having a functional circuit that operates asynchronously with the microcomputer.

BACKGROUND OF THE INVENTION As the degree of integration of integrated circuits increases, a plurality of functional circuits, each having an oscillation circuit that operates asynchronously, are increasingly constructed on a single chip.

A conventional semiconductor integrated circuit having such functions will be described below.

FIG. 2 is a diagram showing the configuration of a semiconductor integrated circuit including a microcomputer and a functional circuit that operates asynchronously with the microcomputer. For convenience of explanation, only one functional circuit is shown. In the figure, 1 is a microcomputer, 2 is a first oscillation circuit for generating a clock for operating the microcomputer, 3 is an output terminal from the microcomputer 1 to the outside of the semiconductor integrated circuit, and 4 is an output terminal from the microcomputer 1 to the outside of the semiconductor integrated circuit. A functional circuit controlled by the computer 1, 5 a second oscillation circuit that generates a clock for operating the functional circuit 4, and 6 an output terminal from the functional circuit 4 to the outside of the semiconductor integrated circuit device.

When performing a functional test of a semiconductor integrated circuit as described above, first, the first oscillation circuit 2 and the microcomputer 1 are tested.
is operated, and the output of the output terminal 3 of the microcomputer 1 is tested at a timing synchronized with the first oscillation circuit 2. Next, the first oscillation circuit 2 and the microcomputer 1, and the second oscillation circuit 5 and the functional circuit 4 are operated,
1 functional circuit 4 at a timing synchronized with the second oscillation circuit 5.
The operation of the functional circuit 4 is tested at the output terminal 6 of the circuit.

Problems to be Solved by the Invention In the above configuration, since the output signals of the microcomputer 1 and the functional circuit 4 are asynchronous, it is necessary to test them individually at two timings, making the test complicated and inefficient. occurs.

The present invention solves the above-mentioned conventional problems, and aims to provide a logic integrated circuit that can simplify testing.

Means for Solving the Problems To achieve this object, the logic integrated circuit of the present invention uses the output of a second oscillation circuit provided for operating the functional circuit to the input of the clock for operating the functional circuit. and,
A control circuit is provided that allows the microcomputer to select either the system clock of the microcomputer that controls the functional circuit or the output of a first oscillation circuit provided for operating the microcomputer.

Effect: With this configuration, it is possible to synchronize the clock of the functional circuit by inputting the system clock of the microcomputer or the output of the first oscillation circuit provided for operating the microcomputer. Testing can be performed at a single timing, increasing testing efficiency.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a logic integrated circuit device in one embodiment of the present invention. In FIG. 1, 1 is a microcomputer, 2 is a first oscillation circuit that generates a clock for the microcomputer 1, 3 is an output terminal from the microcomputer 1 to the outside of the logic integrated circuit device, 4 is a functional circuit, and 5 is a A second circuit for generating a clock for the functional circuit 4.
The oscillation circuit 6 is an output terminal from the functional circuit 4 to the outside of the logic integrated circuit, and these have the same configuration as the conventional example. 7 is the system clock signal line of the microcomputer 1; 8 is the control signal line from the microcomputer 1; 9 is the output of the oscillation circuit 5 and the system clock n7 of the microcomputer 1; 8 is the control signal line from the microcomputer 1; This is a control circuit that has a switching function via line 8.

A method for testing the integrated circuit of the embodiment configured as described above will be described below.

The first oscillation circuit 2 and the microcomputer 1 are operated, and the system clock line 7 of the microcomputer 1 is selected by the ii+ control circuit 9 using the control signal line 8. As a result, the microcomputer 1 and the functional circuit 4 operate in synchronization with the first oscillation circuit 2, and synchronized signals are output from the output terminals 3 and 6 to the outside.

As described above, according to the present embodiment, the signals outputted from the output terminal 3 of the microcomputer 1 and the output terminal 6 of the functional circuit 4 are both synchronized with the output of the first oscillation circuit 2, and a single signal is obtained. The microcomputer 1 and the functional circuit 4 can be tested at the same timing.

In the above embodiment, the system clock line 7 of the microcomputer 1 is input to the functional circuit 4, but the same result can be achieved even if the output signal of the first oscillation circuit 2, which is the basic clock of the microcomputer 1, is input instead. Get results.

Effects of the Invention The present invention provides a microcomputer that operates asynchronously by inputting the system clock of the microcomputer or the output signal of the first oscillation circuit to the clock input of the functional circuit. Synchronized output signals are obtained, and two functions that were previously measured individually can be measured simultaneously, making testing more efficient and time-saving.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a logic integrated circuit according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional logic integrated circuit. 1...Microcomputer, 2...
First oscillation circuit, 3... External output terminal of microcomputer 1, 4... Functional circuit, 5...
. . . second oscillation circuit, 6 . . . external output terminal of functional circuit 4, 7 . . . system clock line of microcomputer 1, 8 . . . Control signal line, 9... Control circuit.

Claims (1)

[Claims] A microcomputer, a first oscillation circuit for generating a clock for the microcomputer, a functional circuit controlled by the microcomputer, a second oscillation circuit for generating a clock for the functional circuit, and a clock for the functional circuit. It is characterized by having a function that allows the microcomputer to selectively control the clock generated by the second oscillation circuit, the system clock of the microcomputer, or the clock generated by the first oscillation circuit as an input. Logic integrated circuit.