JPH05127788A - Multi-input circuit for switch signal - Google Patents

Abstract

PURPOSE:To input the data of many switches while decreasing the number of in-use terminals of a parallel interface. CONSTITUTION:The multi-input circuit consists of the parallel interface 1, a CPU 2, and plural hexadecimal switches 3, and the interface 1 and switches 3 are connected by a common data bus 4 and the data output permission signal lines 5 of the switches 3. Then the data output switches 3 are selected with a data output permission signal and the data are inputted and outputted through the common data bus 4. Consequently, the number of in-use terminals of the parallel interface is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch signal multi-input circuit for fetching data of a plurality of switches into a parallel interface controlled by a CPU.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a multi-input circuit for a switch signal of this type fetches data of a plurality of switches 13 into a parallel interface 11 (LSI) connected to a CPU 12, and a parallel interface. The data output terminals of each switch 13 are connected to the switch 11, and the data of the switch 13 can be input by the number of input / output terminals of the parallel interface 11.

[0003]

By the way, in the above-mentioned conventional multi-input circuit for switch signals, only the data corresponding to the number of input / output terminals of the parallel interface LSI can be input, so that it is necessary to increase the number of switches. However, there is a drawback that the number of terminals used in the parallel interface LSI is also increased in proportion to the number of terminals, and the wiring of the printed circuit board is complicated accordingly. And
When dealing with many switches, the number of elements of the parallel interface LSI increases, and there is a drawback that the circuit is enlarged.

The present invention has been made in view of the above problems, and an object thereof is to provide a switch signal multi-input circuit which reduces the number of terminals used in a parallel interface and enables data input of many switches. To do.

[0005]

In order to achieve the above object, a switch signal multi-input circuit according to the present invention is a switch signal multi-input circuit for fetching data of a plurality of switches into an input / output parallel interface controlled by a CPU. In the above configuration, the data output terminal of each switch is connected to a common data bus common to each switch, and the data output permission means for selectively permitting the output of each switch is provided.

Then, if necessary, the data output permission means sends a data output permission signal to the signal line connecting the parallel interface and each switch, and the switch permitting data output through the signal line. The data output permission signal output function is provided, and the switch that receives the data output permission signal outputs the data.

[0007]

According to the switch signal multi-input circuit having the above structure, the data output switch is selected by the data output permission means and the parallel interface and the switch are connected by the common data bus. The data is input using.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a switch signal multi-input circuit according to an embodiment of the present invention.

In the figure, the multi-input circuit according to the embodiment is
An example of a circuit when four hexadecimal switches 3 are provided and the data is input is shown. 1 is a parallel interface, 2 is C controlling the parallel interface 1
It is PU. Set the data to hexadecimal switch 3 and CP
When it is read by U2, data is normally input through the parallel interface 1.

The hexadecimal switch 3 and the parallel interface 1 are connected by a common data bus 4 common to the respective switches 3, and the data output permission signal from the parallel interface 1 is input to the common terminal of each hexadecimal switch 3. The signal line 5 is connected.

That is, one interface terminal is set for output per switch, the output signal is connected to the common of each switch 3, and is used for sending the data output permission signal of the switch 3. Each hexadecimal switch 3
The output of the data is controlled by the CPU 2 via the parallel interface 1.

Therefore, according to the switch signal multi-input circuit according to the embodiment, when the data output permission signal is operated by the CPU 2, the parallel interface 1 circuit is provided with each switch via the common data bus 4 of each switch 3. Three
Enter the data in sequence. That is, by giving a data output permission signal for each hexadecimal switch, the CPU 2 can input data using the common data bus 4.

As a result, the parallel interface L
It is possible to reduce the number of terminals used for SI and input data of more switches to one interface element.

[0014]

As described above, according to the switch signal multi-input circuit of the present invention, the number of terminals used by the interface is reduced when the same number of switch data is input as compared with the conventional circuit. be able to. Therefore, it is possible to reduce and simplify the wiring on the printed circuit board.
Further, when many switches are used, it is possible to use the terminals having the vacant interfaces, so that it is possible to reduce the number of interface elements.

[Brief description of drawings]

FIG. 1 is a block diagram showing a switch signal multi-input circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional switch signal multi-input circuit.

[Explanation of symbols]

 1 parallel interface 2 CPU 3 hexadecimal switch 4 common data bus 5 data output enable signal line

Claims (2)

[Claims] 1. In a switch signal multi-input circuit for fetching data of a plurality of switches into an input / output parallel interface controlled by a CPU, a data output terminal of each switch is connected to a common data bus common to each switch, and A multi-input circuit for switch signals, comprising data output permission means for selectively permitting output of each switch. 2. The data output permission means sends a data output permission signal to a signal line connecting the parallel interface and each switch, and a data output permission signal to the switch permitting data output through the signal line. An output function is provided, and the switch which receives the data output permission signal is caused to output the data.
A multi-input circuit for the switch signal described.