JPH0616301B2 - Integrated circuit device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention realizes connection and disconnection between external lead terminals without increasing the number of peripheral circuit parts outside the integrated circuit and enables effective use of the terminals. Integrated circuit device.

2. Description of the Related Art In a conventional integrated circuit, when the same signal is input to different terminals and used, as shown in FIG. 2, an external lead having an external interrupt input circuit 6 of an integrated circuit device 10 is provided. External lead terminal 2 provided with terminal 1 and input circuit 7
Are connected to the outside of the integrated circuit by the external interrupt signal line 11, the external interrupt input circuit 6 reads the change in the signal of the external interrupt signal line 11, and the interrupt processing operation is started in the integrated circuit. The polarity of the signal of the external interrupt signal line 11 is read from the lead terminal 2 through the input circuit 7 to determine whether to continue or stop the interrupt processing operation.

Problems to be Solved by the Invention However, under such a use condition, the external lead terminal 2
Is always externally connected to the external lead terminal 1 by the signal line 11, and can be used only as a monitor of the signal of the external interrupt signal line 11, and cannot perform an input operation independently of the external lead terminal 1. In the case where the external lead terminal 2 is one of the parallel input terminals for 4-bit or 8-bit data, the remaining many parallel input terminals have almost no utility value. Therefore, the external lead terminal 2 is connected to the external lead terminal 1 at an arbitrary period and separated at other periods, and the external lead terminal 2 is separated.
Is also used as one terminal of parallel input terminals for 4-bit or 8-bit data, it is externally connected between the external lead terminal 1 and the external lead terminal 2, that is, the switching means is connected outside the integrated circuit 10. I had to. However, in order to reduce the size and weight of the device, the number of parts on the printed circuit board on which the integrated circuit 10 is mounted increases, which poses a serious problem.

Means for Solving the Problems In order to eliminate the above problems, the present invention provides a switching means between an external lead terminal and an input circuit section inside an integrated circuit.

Operation According to the circuit configuration described above, it is possible to freely connect and disconnect the external lead terminals by controlling the switching means.

Examples The present invention will be described below with reference to examples. FIG. 1 shows an integrated circuit device according to the present invention. The same parts as those in the conventional example shown in FIG. 2 are designated by the same reference numerals. In the figure, 8 is a switching means, and 9 is a control signal line for controlling the switching means 8. First, the signal from the external interrupt signal line 11 is read from the external interrupt input circuit 6 built in the integrated circuit device 10 through the external lead terminal 1, and the integrated circuit device 1
An external interrupt processing operation inside 0, which is determined by, for example, a ROM program, is started. At this time, when the polarity of the signal of the external interrupt signal line 11 is read from the input circuit 7 to continue or stop the external interrupt processing operation executed by the integrated circuit device 10, the control signal line By supplying a control signal to the switching means 8 through 9 and connecting the external lead terminal 1 to the input circuit 7, the polarity of the signal on the external interrupt signal line 11 can be supplied to the input circuit 7. Next, when the external lead terminal 2 is used as a parallel input terminal for 4-bit data together with the other external lead terminals 3, 4, and 5 to supply the polarity of the signal on the signal line 12 for 4-bit data to the input circuit 7, By reversing the polarity of the control signal to the switching means 8 through 9, the external lead terminal 2 is connected to the input circuit 7 and one of the 4-bit data signal lines 12 to 15, for example, the signal of the signal line 12 is transmitted. Can be supplied to the input circuit 7. Here, the polarity of the control signal applied to the control signal line 9 is selected by a program operation of, for example, a ROM incorporated in the integrated circuit device 10.
In the embodiment of the present invention, the switching means 8 is arranged between the two external lead terminals in which the input circuit is arranged, but the invention is not limited to this.
For example, as shown in FIG. 3, a serial data input circuit 16 and a serial data register (FIFO) 17 are provided instead of the external interrupt input circuit 6, and instead of the input circuit 7 provided at the external lead terminal 2. Serial data output circuit 18
Is arranged, the first input data of the series of serial data input from the external lead terminal 1 is supplied again to the serial data input circuit from the serial data output circuit provided in the external lead terminal 2. The switching means 8
Via, the first input data of the input series of serial data can be transferred to the bit of the last input data. That is, it is possible to shift the digit of the input series of data. In this case, the external lead terminal 1 has a function as an input / output terminal.

EFFECTS OF THE INVENTION As described in the above embodiments, the present invention allows the functions of the external lead terminals of the integrated circuit device to be utilized to the maximum extent, and enables various uses without increasing the number of peripheral circuit parts. It enables downsizing, weight reduction, and high functionality of equipment.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an integrated circuit device according to the present invention, and FIG. 2 is a diagram showing a conventional integrated circuit device. FIG. 3 is a circuit diagram of another embodiment of the present invention. 1, 2, 3, 4, 5 ... External lead terminal, 6 ... External interrupt input circuit, 7 ... Input circuit, 8 ... Switching means, 9 ... Control signal line, 10 ... Integrated circuit device, 11
...... External interrupt signal line, 12, 13, 14, 15 ……
4-bit data signal line.

Claims (1)

[Claims] 1. An external interrupt input circuit for receiving an external interrupt signal to perform interrupt processing, an external interrupt signal terminal connected to the external interrupt input circuit, and a control signal for receiving the external interrupt signal terminal and an external device. An integrated circuit device comprising: switch means for switching and connecting any one of the lead terminals to an input circuit.