JPH0320814A - Key input control circuit - Google Patents

Abstract

PURPOSE:To miniaturize a circuit and to shorten code conversion time by encoding an input signal with hardware. CONSTITUTION:When a switch 22 is depressed, a RIN2 and a CIN2 go to low potential, and another input goes to high potential. Also, when a current flows on a photocoupler H1 and the switch 22 is returned to its original position, the signal is recovered to the high potential. A pulse generated at a key input detection circuit 2 is passed through a rectifier waveform circuit 6, and interruption is supplied to a CPU, and also, it is supplied to a data holding circuit 4 via a data holding timing circuit 8. A signal outputted from an input key generating part 9 is inputted to a code conversion circuit 1 via an encoder circuit 3. When access to the code conversion circuit 1 is performed, encoded data corresponding to key switch input is outputted to the CPU.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a program control device, and particularly to a key switch code generation input control circuit that is suitable for downsizing a large number of key switch input code generation circuits. [Prior art] The keyboard encoder of the conventional device is
As described in Publication No. 43407, a dynamic scan method is adopted. [Problems to be Solved by the Invention] In the above-mentioned prior art, a scan control circuit is added for converting the code engraved on the key input, and the food conversion is performed using keyma 1-1.
It sequentially outputs M to the second column of the signal and detects which row on the input side received the signal. Therefore, there is a problem that the circuit becomes large-scale and the code conversion processing time is slow.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit whose circuit size is reduced and record conversion time is shortened.

(Means for solving the problem) The above purpose is to connect one end of a two-circuit contact switch arranged on a switch matrix using a dynamic scanning encoding method to a matrix circuit, and to connect a pull-up resistor arranged on each row and each column of the matrix. This is achieved by modifying the input signal directly generated by hardware so that it can be encoded immediately by hardware. Also, since no scan control circuit is required, the circuit can be made more compact. [Function] When the key switch is pressed, Among each row and each column, which are kept at a high potential by a resistor, the corresponding row and column change to a low potential.The current change that occurs at this time is detected by the switch input detection circuit, and the signal status of each row and each column is detected by the signal. The switch input signal is generated by holding , and is encoded directly by the encoder circuit, so the code conversion time is shortened compared to the dynamic scan method.Also, no matter which key switch is pressed, the switch input signal is generated at the part where the current change occurs. A switch input detection circuit is provided, and noise such as chattering in the output signal is removed by the waveform shaping circuit. Since this is used as an interrupt to the CPU, a stabilized signal can be input.

Furthermore, since the scanning control circuit and the like are eliminated and the circuit structure is simple, the mounting space can be reduced. Since the encoder output is input to the memory address and the CPU input code is memory data, the code can be easily changed by rewriting the memory.

〔Example〕

An embodiment of the present invention (key matrix of 5 rows x 5 columns) will be explained below with reference to the block diagram shown in FIG. In Figure 1, 1 is a code conversion circuit, which in this example is a memory. 2
is an address decoder circuit that connects the code conversion circuit output to the CPU data bus through memory access from the CPU. 3 is an encoder circuit which encodes the input signal generated by the switch input and outputs it to the code conversion circuit. 4 is a data holding circuit which holds the input signal using the switch input detection signal and outputs a stable input signal to the encoder circuit 3. 5 is a gate circuit that determines the logic of the input signal. 6 is a waveform shaping circuit for removing noise such as chattering. 7 is a switch input detection circuit that generates a signal no matter which key switch is pressed, and is used as an interrupt signal to the CPU and an input signal holding timing signal. 8 is a data retention signal generation circuit that prevents data from changing while the CPU is reading data. 9 is the input key food generator, which consists of 25 two-circuit contact switches and 10 resistors that pull up each row and each column. Next, we will explain the operation. For example, when switch S22 is pressed, RI
Only N2 and CIN 2 have a low potential, and the other inputs have a high potential. Also, a current is generated in the photocoupler 111, and the output of the switch input detection circuit 4 becomes a low potential. When switch S22 returns to its original state, all of the signals return to high potential. A pulse generated by the key input detection circuit 2 is passed through a waveform shaping circuit 6 to supply an interrupt (IRQ) to the CPU, and is also supplied to the data holding circuit 4 via a data holding timing circuit 8. At this time, the signal output from the input key code generation section 9 is inputted to the data holding circuit IIr4 via the gate circuit N5, and is supplied to the encoder circuit 3 after being taken in by the data holding timing signal. The signal encoded in encoder circuit 3!3 is input to code conversion circuit 1. In this situation, when the code conversion circuit 1 is accessed by the CPU in response to the interrupt request, the coded data corresponding to the key switch input is transferred to the CPU.
Output to U. FIG. 2 shows the output signals of the input key code generator corresponding to each key switch. According to this embodiment, the time required for code conversion can be shortened, and the mounting space can be reduced by making the circuit smaller.

〔Effect of the invention〕

According to the present invention, since the input signal can be directly encoded,
The time between code conversion VFs is shortened. Compared to the direct scan method, there is no need for a scan control circuit, and the size of the control board can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the present invention in practice, and FIG. 2 is an explanatory diagram showing the response of the output Shinchin code to the input of the input key code generation section of the present invention.] ...Code conversion circuit, 2...Ad! 3... Encoder circuit, 4... Data holding circuit, 6... Waveform shaping circuit, 7... Switch input detection circuit, 9... Input key code generation section.

Claims (1)

[Claims] 1. An input key code generation section in which one end of M x N two-circuit contact switches is connected to a matrix circuit of M rows x N columns, and a pull-up resistor is arranged in each row and each column of the matrix circuit, and the code generation section. The signal is passed through a circuit that holds the signal from the key input detection circuit, and a circuit that shapes the waveform of the output signal from the detection circuit, and is used as an interrupt signal to the CPU.
A data holding timing signal is inputted together with the CPU timing signal to a data holding signal generation circuit, and is supplied to the data holding circuit, and an encoder circuit for the held key data is provided at the subsequent stage to reduce the number of signals and for code conversion. 1. A key input control circuit, characterized in that a code can be input to a CPU by inputting it to an address signal of a memory and reading the CPU from the memory.