JPS6019233A - Keyboard input device - Google Patents

Abstract

PURPOSE:To perform scan searching with a small number of input signal lines by carrying out the key matrix scan search by means of an output signal line of a shift register connected to an output port and an input signal line of an input port. CONSTITUTION:An input line 10 of an input port 9 is pulled up by means of a resistance group 11, and the data and clock signal lines 13 are connected to a shift register 14 from an output port 12. Thus a signal pattern containing only a piece of signal line set at a low level is delivered to an output signal line 15. One of lines 15 (C2j) is successively set at a low level within a range of 0<=j<=m, and the signal pattern supplied to the port 9 is checked at each time. Thus a pushed key can be discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a keyboard input device that performs key matrix scan search.

Conventional configuration and its problems Conventionally, a keyboard input device using keys 71-licune scan search has input port 1 as shown in Fig. 1.
, an input signal line 2 connected thereto, a resistor 3 for pulling up the input signal line, an output port 4, and an output signal line 5 thereof. In this device, when no key is pressed, the input signal line 2 of input port 1 is pulled up, so all signals are at high level. Therefore, only one signal from output capo-1- was set to low level/<
Output the turn to the output line 6Vc. For example, Qlj(0≦
If a signal pattern in which only j≦m) is at low level is output from the decoder 4, then the signal input to the input port 1 is the signal pattern.

If a signal pattern in which Rlj (o≦i≦n) is at a low level is input, it becomes clear that R1 and Cj are short-circuited, that is, that key 6 is pressed. G
However, with this configuration, it is possible to determine which key is being pressed by repeating at high speed the process of sequentially setting the low level one by one when C≦i≦m and checking the input signal pattern of the input board each time. A problem arises in which the number of output ports increases in the device.

Further, FIG. 2 shows a configuration diagram in which the decoder 8 is connected to the output ports to reduce the number of output ports. However, in a device with this configuration, in order to reduce the power consumption of the microcomputer, only when the microcomputer shutdown switch (power down mode) key is pressed,
This causes inconvenience when performing a key matrix scan search.

To use this power-down mode, press the key;
When 6BITI is down, the microcomputer needs information to prompt the return sound from power down mode, and in order to obtain this information, all signal lines on the key drive side, that is, all output signal lines of decoder 8, must be set to low level. When a key is pressed, the pulled-up input signal line and output signal line are short-circuited, and one of the input signal lines must become low level. This sets an external flip-flop through the gate and interrupts the microcomputer. and key matrix
Perform a scan search.

However, the pattern of the output signal from the decoder 8 is such that all the signal lines are at low level, which causes problems even when using this power down mode.

OBJECTS OF THE INVENTION The present invention eliminates all of these conventional drawbacks and reduces ports.
- It is an object of the present invention to provide a keyboard input device that allows key matrix scanning searches using numbers.

Structure of the Invention The keyboard input device of the present invention includes a microcomputer having an input port and an output port, a signal line connected to the input port, a key press detection circuit connected to the signal line, and a pull-out signal line. The two objects are achieved by configuring (by configuring) a resistor used to increase the shift register, a shift register connected to the output port, and an output signal line connected to this shift register.

DESCRIPTION OF EMBODIMENTS The embodiments will be described below. In Figure 3,
In the input port 9, the human input signal line 1° is pulled up using a resistor group 11.

12 is the output signal line), 13 is the output signal line.

The shift register 16, which has an output signal line 16 at 14, is a NOR gate that detects when any key has been operated, and 17 is driven by the output of 16 to send an interrupt to the microcomputer. A flip-flop is used to perform a key matrix scan search.

Next, the operation of this embodiment will be explained.・Input signal line 1
0 is pulled up as described above. Also, a signal is sent to the shift register 14 using the output signal line 13 from the output port 12. This causes the output signal line 16 to output a signal pattern in which only one signal is at a low level.

One of the output signal lines 15, c2j'to≦ko≦m, is set to low level /l/ in order, and by checking the signal pattern input to the input board 9 each time, it is possible to determine which key is being pressed. It is possible to identify.

Here, we will explain how to change the level to 02jf 0616m one by one. Two signal lines for data and clock are connected from the output port 12 to a shift register 14. When no key is pressed,
Shift register 1 to shift low level data as many times as necessary
4 and the output signal line 1 of the shift register 14.
Low level 717 that only corresponds to the required key position of 6.
Outputs an output signal with f and enters power down mode. When a key is pressed, a key press detection circuit consisting of a gate 16 and a flip-flop 17 interrupts the microphone computer to exit the power down mode. First, high-level data is processed n times.
The data is sent to the shift register 14, and then low level data is sent once to cause the initial output pattern of the shift register 14 to be output.

Thereafter, each time the signal pattern of the input port 12 is checked, high level data is input to the shift register 14 to shift the output of the shift register 14. In this way, CZj can be set to low level /I/ one after another.

FIG. 4 shows a circuit diagram of a keyboard input device realized in the case where m=n=8.

In this case, the signal line 19 for data and clock from the output port 18 is connected to the shift register 2Q, which increases the number of output ports compared to the case where the output signal line is directly connected to the output port without using a shift register. can be reduced from 8 to 2. Also, compared to keyboard input devices that use decoders, it has the advantage that a power-down mode can be easily used.

FIG. 6 shows another example of a keyboard input device in which m=n=6, in which a data line and a clock signal line are used as the output signal line 22 from the output port 21. This was realized using a. In this case, when using the power down mode, all signal lines can be set to low level/L/IC using a reset signal.

Effects of the Invention As is clear from the above embodiments, the present invention can reduce the number of votes by using the shift register on all key drive sides in a keyboard input device that performs key matrix scan search. It can also be applied to a keyboard input device using an encoder that uses a power down mode that is difficult to use.

[Brief explanation of drawings]

FIGS. 1 and 2 are respectively diagrams of a conventional keyboard input device, FIG. 3 is a diagram of a keyboard input device according to an embodiment of the present invention, and FIGS. 4 and 6 are more detailed diagrams, respectively. 9 is a configuration diagram of an embodiment. 9...Input boat, 10...Input signal line, 11...Resistor group, 12...Output port , 14... shift 1-register, 16...-
...NARD gate, 17...Flip-flop. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3

Claims (1)

[Claims] A microcomputer having an input port and an output port, an input signal line connected to the input port, a resistor group for pulling up the input signal line, and a detector connected to the input port for detecting key presses. a shift register connected to the output port;
The feature is that it performs a search. Keyboard input device.