JPH0481918A - Key input device - Google Patents

Abstract

PURPOSE:To improve the throughput of a central processor and the processing speed as a system by executing a key sense operation with a hardware being a key sense circuit, and also, executing the key sense operation only at the time when one key switch of a key switch circuit is turned on. CONSTITUTION:A key sense operation is executed by a hardware circuit, and with respect to a host CPU 15, a signal is inputted by code data through a parallel interface. Also, only when one key switch of a key switch circuit is depressed, a key sense operation is executed. In such a manner, an useless interruption to the host CPU 15 is eliminated, and also, a software processing therefor becomes unnecessary, the throughput of the host CPU 15 is improved, and the processing speed as a system is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial application field This invention is used in an information processing device equipped with a CPU,
The present invention relates to a key input device for inputting various information to a CPU.

(B) Conventional technology Conventionally, in this type of key input device, a key sense program is used to constantly detect which key is pressed by performing a key sense operation from the CPU side at predetermined intervals. I have to.

That is, as shown in the flowchart of FIG.
U performs a key sense operation on the key input device (
Step 3: Check if there is any key input (Step 32); if there is no key input, step 35
Wait for a predetermined time to elapse, then perform the key sense operation again and repeat this process. Then, in step 32, if there is a key input, it is determined which input key is pressed down (step 33), and processing is performed according to the pressed input key (step 34). , waits for a predetermined time to elapse (step 35), and after the predetermined time has elapsed, returns to step 31 again to perform a key sensing operation to detect an input key.

(c) Problems to be Solved by the Invention However, in such a conventional key input device, a key sense operation must be performed from the CPU side at predetermined intervals, and the interrupts caused by this require the throughput of the program to slow down. There is a problem that the processing speed of the CPU decreases.

Further, since an interrupt occurs even when the CPU is in a sleep state, there is a problem that unnecessary power consumption occurs.

The present invention was made in consideration of the above circumstances, and the key sensing operation is performed by hardware, and the key sensing operation is performed only when a key is pressed down.
The present invention provides a key input device that reduces the load on the U and also reduces power consumption.

(d) Means for Solving the Problems This invention provides a key switch circuit in which a key switch is arranged at each intersection of a row line and a column line, and a key switch circuit is connected to one of the rows and columns of the key switch circuit. a signal input circuit that inputs a signal to the key switch circuit; a signal detection circuit that detects a signal from the other of the rows and columns of the key switch circuit; and a signal detection circuit that detects a signal from the other line of the key switch circuit; A key sense circuit that performs key sense operation,
A code data generation circuit that generates code data corresponding to the intersection point recognized by the key sense operation of the key sense circuit, and a code that identifies the code data generated by the code data generation circuit and controls the output of the code data accordingly. This key input device consists of a data control circuit and an interface circuit for inputting the output from the food data control circuit to a central processing unit.

(E) Effect According to the present invention, a signal is constantly inputted to either the row or column of the key switch circuit by the signal input circuit, and A signal output from the other line is constantly detected by a signal detection circuit.

In this state, when a signal is detected by the signal detection circuit, that is, when one of the key switches located at each intersection of the key switch circuit is turned on, the key sense circuit detects a signal for the key switch circuit. The key sense operation is performed to recognize which intersection point the key switch is turned on, and the code data generation circuit
Code data corresponding to the recognized intersection point is generated.

After the code data control circuit identifies the code data generated from the code data generation circuit, the output of the code data is controlled accordingly, and the interface circuit allows the output from the code data control circuit to be sent to the central processing unit. is input.

Therefore, the key sense operation is performed by a hardware called a key sense circuit, and the key sense operation is performed only when one of the key switches in the key switch circuit is turned on, so unnecessary interrupts to the central processing unit are avoided. This eliminates the need for software processing, improves the throughput of the central processing unit, and improves the processing speed of the entire system.

(f) Examples Hereinafter, the present invention will be described in detail based on examples shown in the drawings. Note that this invention is not limited to this.

FIG. 1 is a block diagram showing the configuration of an embodiment of the key input device of the present invention.

In this figure, 1 is a key switch circuit in which a key switch is arranged at each intersection of a row line and a column line.

Reference numeral 2 denotes a key strobe signal output circuit, which constantly outputs a strobe signal to all row (or column) lines of the key switch circuit 1.

3 is a key data input circuit, which constantly detects strobe signals from all column (or row) lines of the key switch circuit 1, and when a strobe signal is detected, that is, when there is a key input, A signal to start a scan operation for key sensing is output to the key scan control circuit 4, and input data is transmitted to the input data processing circuit 7 during the scan operation.

The key scan control circuit 4 controls the key scan operation according to the state of input data.

Based on instructions from the key processing setting circuit 14, the key strobe generation circuit 5 controls the timing of sequentially outputting each strobe signal at the time of key input, and also controls the key strobe signal output circuit 2 when there is no key input. By controlling the control, the state of the strobe signal output terminal while the scan operation is stopped is controlled.

Reference numeral 6 denotes a historical data processing circuit, which holds all data input in one scan operation until the next scan operation, and sends the data to the input data processing circuit 7 at the next scan operation.

In order to prevent chattering, noise, etc., the input data processing circuit 7 collates the input data from the key data input circuit 3 with the history data from the history data processing circuit 6, and selects data that is actually valid. It is sent to the code data generation circuit 8 at the subsequent stage.

The code data generation circuit 8 encodes the input key data and sends it to the data identification circuit 9 at the subsequent stage.

The data identification circuit 9 identifies functions specific to the coded key data based on the settings of the key processing setting circuit 14, passes information to the status code generation circuit II, and controls operation signals for each function. .

10 is a repeat operation control circuit, and a data identification circuit 9
Based on the information from the CPU 10, the repeat operation is controlled based on the settings of the key processing setting circuit 14 for the code out of the key having the repeat function.

The status code generation circuit 11 generates a status information code for data input from the data identification circuit 9 and the repeat operation control circuit IO.

I2 is a code-out control circuit, and data identification circuit 9
, receives outputs from the repeat operation control circuit 10 and the status code generation circuit 11, and controls the order in which these code data generated from input data are output.

13 is the host CPU via the parallel interface
15 is a host CPU interface circuit that inputs a signal in the form of code data.

When the key switch of the key switch circuit 1 is turned on, that is, when a key input is performed, the host CPU interface circuit 13 temporarily holds the data input to the host CPU S in an internal buffer, and then transfers the data to the host CPU.
The host CPU 15 generates an interrupt to input data, and also performs arbitration for the host CPU 15 to access asynchronously with the scan operation.

Key processing setting circuit! 4 controls condition settings (repeat time, etc.) for key scanning operations, key repeat operations, etc., based on instructions from the host CPU 15, and generates control signals for each function.

Next, the operation of the embodiment with such a configuration will be explained according to the flowchart shown in FIG.

First, when the key operation is stopped, the key switch circuit 1
A key strobe signal is output to all row (or column) lines (step 21), and when a key input is made (step 22), a key scan operation is started (step 23).

Then, it checks which key is the input key (step 24), generates code data corresponding to that key (step 25), generates an interrupt to the host CPU 15 (step 26), and CPU1
After confirming whether there is a next key input (step 2B), return to step 21 and output the key strobe signal again to the row (or column) of key switch circuit 1. It will be in a state where it outputs to all lines.

In this way, by performing the key sensing operation only when any one key switch of the key switch circuit 1 is pressed down, unnecessary interrupts to the host CPU 15 are eliminated, and software processing for this purpose is also unnecessary. The throughput of the host CPU 15 is improved, and the processing speed of the system is improved.

In addition, since there are no unnecessary interrupts when the host CPU 15 is in the sleep state without processing, the host CPU 15
The operating time of the host CPU 15 is shortened, and the power consumption of the host CPU 15 can be reduced.

Furthermore, by performing the key sense operation in a hardware circuit and inputting the code data signal to the host CPU15 via the parallel interface, the software key sense routine can be simplified. The throughput (processing speed) of the CPU 15 can be improved.

Since the key sensing operation is performed only when the key switch is pressed down, the power consumption of the entire device can also be reduced.

(g) Effects of the Invention According to this invention, the key sense operation is performed by hardware called a key sense circuit, and the key sense operation is performed only when any one key switch in the key switch circuit is turned on. This eliminates unnecessary interruptions to the central processing unit, eliminates the need for software processing, improves the throughput of the central processing unit, and improves the processing speed of the system.

Furthermore, power consumption of the central processing unit and the entire device can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the key input device of the present invention, FIG. 2 is a flow chart showing the operation of the embodiment, and FIG. 3 is a flow chart showing the operation of a conventional key input device. ! ...Key switch circuit, 2...Key strobe signal output circuit, 3...
...Key data input circuit, 4...Key scan control circuit, 5...
...Key strobe generation circuit, 6...History data processing circuit, 7...Input data processing circuit, 8...Code data generation circuit, 9...・Data identification circuit, lO...Repeat operation control circuit, 11...
...Status code generation circuit, 12...Code out control circuit, 13...Host CPU interface circuit, 14...Key processing setting circuit, 15... Host CPU. Figure 1 Figure 1

Claims (1)

[Claims] 1. A key switch circuit in which a key switch is placed at each intersection of a row line and a column line, a signal input circuit that inputs a signal to either the row or column line of the key switch circuit, and a key switch circuit. A signal detection circuit that detects a signal from the other line of a row or a column, a key sense circuit that performs a key sense operation on a key switch circuit when a signal is detected by the signal detection circuit, and a key sense circuit that detects a signal from the other line. a code data generation circuit that generates code data corresponding to the intersection point recognized by the key sense operation; a code data control circuit that identifies the code data generated by the code data generation circuit and controls the output of the code data accordingly; , a key input device consisting of an interface circuit for inputting the output from the code data control circuit to the central processing unit.