KR19990065220A - Key input device with key matrix - Google Patents

Abstract

The key input device of the present invention configures decoders and encoders in the input / output ports, respectively, in order to reduce the number of input / output ports of the microcontroller allocated for key input. Since the decoder and the encoder are used, the number of input / output data bits during the key scanning operation is reduced, and the scanning operation of the key matrix can be performed with a small number of input / output ports. In addition, an interrupt method is used to save time due to the key scanning operation. An interrupt is generated in response to a keystroke, which is entered into the microcontroller. When the microcontroller receives an interrupt signal according to a key input, the microcontroller performs an interrupt routine for key scanning.

Description

KEY INPUT APPARATUS HAVING KEY MATRIX

The present invention relates to a key input device, and more particularly, to a key input device using a key matrix.

Microcontrollers are widely used throughout the industry, and their functions are getting better. In the application of such a microcontroller, a key matrix is generally used to perform a corresponding function according to a user's selection. An example is shown in the accompanying drawings, FIG.

Referring to FIG. 1, a key matrix 20 having an 8 * 8 matrix structure is connected to the input ports PA0 to PA7 and the output ports PB0 to PB7 of the microcontroller 10. As such, when the key matrix 20 is connected to the microcontroller 10, the key input operation of the microcontroller 10 is as follows.

First, the microcontroller 10 outputs a signal for scanning the key matrix 20 to the output ports PA0 to PA7 and receives a signal generated in response thereto from the key matrix 20 through the input ports PB0 to PB7. The input signal is judged to determine which key is the currently input key. This operation is performed by the microcontroller 10 periodically to perform a key input operation.

However, such a key input device using a conventional key matrix places a heavy burden on the microcontroller. Because, in general, the microcontroller must perform not only a key input operation but also other control operations, because much of the time is spent in processing the key input. This is especially true when a high speed control operation is to be performed. In addition, when the key matrix has a large number of keys, a problem arises in that a large portion of the input / output ports of the microcontroller must be allocated to the key matrix.

Accordingly, an object of the present invention is to provide a key input device capable of reducing the number of input / output ports of a microcontroller for key input processing as proposed to solve the above-mentioned problems.

Another object of the present invention is to provide a key input device that can reduce the key input processing time.

1 is a circuit diagram showing an example of a conventional key input device; And

2 is a circuit diagram of a key input device according to a first embodiment of the present invention; And

3 is a circuit diagram of a key input device according to a second embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10, 30, 60: microcontroller 20: key matrix

40: decoder 50: encoder

70: logic circuit 80: filter

According to an aspect of the present invention for achieving the object of the present invention as described above, the key input device comprises: a key matrix consisting of a plurality of keys in the form of a matrix; A key input processing unit which scans the key matrix to determine an input key; A decoder configured at an output port of the key input processing unit; Including an encoder configured at the input port of the key input processing unit, the signal output during the key scanning operation of the key input processing unit is decoded by the decoder and input into the key matrix, and in response thereto, a signal output from the key matrix. Is encoded by the encoder and provided to the key input processor.

According to another aspect of the present invention, a key input processing apparatus includes: a key matrix composed of a plurality of keys in a matrix form; Means for generating an interrupt signal according to a key input; And a key input processing unit configured to input the interrupt signal and scan the key matrix to determine an input key.

In this embodiment, the interrupt generating means includes a logic circuit for inputting and outputting the output of the key matrix to provide an interrupt signal to the key input processing section.

In this practical example, a filter for removing noise of the interrupt signal is included.

(Example)

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the case of reducing the number of input / output ports of the microcontroller for key input processing will be described in the first embodiment, and the case of reducing the key input processing time of the microcontroller will be described in the second embodiment. As will be described later, the implementation of these first and second embodiments in parallel can be easily carried out by those skilled in the art.

Example 1

2 is a circuit diagram of a key input device according to a first embodiment of the present invention.

As shown in FIG. 2, a decoder 40 and an encoder 50 are configured between the microcontroller 30 and the key matrix 20. The decoder 40 is connected to the output ports PA0 to PA2 of the microcontroller 30, and the output terminal of the decoder 40 is connected to the key matrix 20. The input terminal of the encoder 50 is connected to the key matrix 20, and the output terminal of the encoder 50 is connected to the input ports PB0 to PB2 of the microcontroller 30. The decoder 40 and the encoder 50 are characterized by the number of matrices of the key matrix 20. For example, when the key matrix 20 is configured with an 8 * 8 matrix, the decoder 40 uses a 3 * 8 decoder, and the encoder 50 uses an 8 * 3 encoder. By using the decoder 40 and the encoder 50 in this way, the conventional input / output port of the microcontroller 30 can be saved much compared with the related art. Even when a decoder and an encoder are used, the key scanning program can be applied to the same program as the conventional one, and only the data for scanning can be changed to suit this.

As such, since the decoder and the encoder are used in the key input device using the key matrix, the number of input / output ports of the microcontroller for key input is substantially reduced. This extra input / output port can be useful for other purposes.

Example 2

3 is a circuit diagram of a key input device according to a second embodiment of the present invention.

As shown in FIG. 3, a key matrix 20 is connected to the input ports PA0 to PA7 and the output ports PB0 to PB7 of the microcontroller 60. A NAND gate logic circuit 70 is connected to the input ports PB0 to PB7 of the microcontroller 60, and a filter 80 is connected to an output terminal of the logic circuit 70 to input an output of the logic circuit 70. The filter is input to the interrupt terminal INT of the microcontroller 60.

The operation of the key input device configured as described above is as follows.

When a key input is generated in the key matrix 20, an interrupt signal is input to the microcontroller 60, and then the microcontroller 60 performs an interrupt routine for performing a key scanning operation. Keystrokes are detected by the execution of an interrupt routine for key scanning. In this manner, the microcontroller 60 does not need to perform a periodic key scanning operation. The key scanning operation only needs to be performed when an interrupt is generated according to the key input. Therefore, it is not necessary to perform an unnecessary operation of performing a key scanning operation regardless of whether a key is pressed or not.

According to the present invention as described above, the number of input / output ports of the microcontroller for key input can be reduced considerably compared with the conventional, and the time required for the key scanning operation is reduced because the periodic key scanning operation is not performed. can do.

Claims (4)

In a key input device: A key matrix in which a plurality of keys are formed in a matrix form; A key input processing unit which scans the key matrix to determine an input key; A decoder configured at an output port of the key input processing unit; Including an encoder configured in the input port of the key input processing unit, The signal output during the key scanning operation of the key input processing unit is decoded by the decoder and input into the key matrix, and in response thereto, the signal output from the key matrix is encoded by the encoder and provided to the key input processing unit. Key input processing device, characterized in that. In a key input processing device: A key matrix in which a plurality of keys are formed in a matrix form; Means for generating an interrupt signal according to a key input; And a key input processing unit which inputs the interrupt signal to scan the key matrix to determine an input key. The method of claim 2, The interrupt generating means And a logic circuit for inputting and outputting the output of the key matrix to provide an interrupt signal to the key input processing unit. The method of claim 3, wherein And a filter for removing noise of the interrupt signal.