JPS61151726A - Key scan system - Google Patents

Abstract

PURPOSE:To detect quickly a depressed key by fetching a scanning in an X direction and depression information from Y direction at the same time to detect a position in the Y direction and using a scan signal based on the position so as to detect the position in the X direction. CONSTITUTION:Scan signals are outputted simultaneously from the X direction to a key input means 3 from a scanning signal output means 12, and whether or not the number of depressed keys is 1 is detected by a depressed key number detection means 13 based on the fetch information from the Y direction of the means 3. When the number of depressed key is 1, the position in the Y direction is stored by a key depressed information detecting position storage means 15 and after the scan direction is changed by a scan direction change means 14, a scan position setting means 16 outputs a scan signal from the Y direction including the position in the Y direction. Whether or not the number of depressed keys is 1 is detected by a depressed number detection means 18 based on the fetch information from the means 3 to the scan signal and when the number of depressed keys is 1, a depressed key information report means 19 reports the information of one depressed key.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a key scanning method for quickly detecting how many keys of a plurality of keys arranged in a matrix are pressed.

[Background of the invention]

FIG. 3 shows a block configuration of an example of a key scan circuit based on software processing.

C shows which key is pressed in the key matrix 3 in which multiple keys are arranged in a matrix.
The PU1 is designed to identify and detect it by software scanning via the PIA2.

Note that 4 in the figure indicates the data bus between the CPU and the PIA. Until now, key scan processing using software processing has been exemplified by "How to use microcomputer circuits" (written by Yoshio Shirato, Japan Broadcast Publishing Association, p147.148). ), one side of the le matrix (for example, tf
It is known to determine whether a down key has been pressed by taking in a key press signal from the opposite direction (for example, the X direction) to a shark that sequentially sends scan signals to columns in the y direction.

Generally, such key scan processing needs to be performed periodically because the time point at which a key is pressed is unknown. Here, the time t' required for key scan processing
ts Let T be the period of the key scan process, and n means that about t/T of the entire software processing time is occupied by the key scan process. However, the key scanning process is not simple, and the more keys there are, the more processing time it takes.1 For example, in devices that operate in real time, such as communication terminals, the key scanning process takes a lot of time. The reality is that the processing power of the software is being adversely affected, such as delays in other processing due to the delay.

If two or more keys are pressed during enlargement f'Lfc, the presses of those keys are invalidated, and the pressed key information is registered in the queue. - indicates the following @KoreK: When sequentially scanning from port Ba to B7, whether there is a key pressed in each scan, and if so, whether two or more keys are pressed. It is to be determined whether Whether two or more keys have been pressed is also determined between scans, but when processing in this way, only one key is pressed and the 9 key is specifically detected, and after all scans are completed, that key is pressed. The key information is registered in the queue.

FIG. 5 shows an example of a configuration in which the above processing is implemented in terms of hardware. First, the scan start position is initialized by the scan start position setting means 5. After that, the scan signal is output from the scan signal output means 6 to the key manual means (key matrix 3).
It is now output to . Detection of the number of pressed keys in response to this scan signal is performed by the pressed key number detection means 7, and if there is only one pressed key in this detection, the pressed key information is stored in the pressed key information storage means 8. Yes 0 After this, the number of scans is determined by the scan number determining means 9, but if all the scans have not been completed, the scan position is changed by the scan position changing means 10, and the above operation is repeated. It is intended to do so. Therefore, the pressed key information storage means 8 stores the pressed key 1 throughout the entire scan.
The key information in the case of
The pressed key information reporting means 117fC is to be reported. Note that the pressed key number detecting means 7 stores the detection results from the scans performed up to that point, and the detection result indicating that the number of pressed keys is 1 is 2.
If the number of keys is obtained, a processing end signal is immediately issued to stop the key scan processing operation. ・If two or more keys are pressed in the same scan, the same process is performed. There is.

As described above, regardless of whether software processing is used or not, the time required for scanning processing generally increases as the number of keys increases, which is particularly problematic when software processing is used.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a key scanning method that can quickly identify and detect which key is being pressed even when there are many keys.

[Summary of the invention]

For this purpose, the misfire 8A focuses on the fact that the process of determining whether a key arranged in a matrix has been pressed is equivalent to searching for a point in a grid on the x-y plane, and Scan signals are not sent sequentially but simultaneously, and press information t-a is included from the y direction, thereby detecting the position of the pressed key in the y direction, and then sending scan signals in the y direction including that position. [Embodiments of the Invention] Hereinafter, the unexploded 8Atl--FIGS. 1 and 2 will be explained.

First, we will explain the key scanning method according to the present invention 'i:/7) 70-, which is implemented by software and is processed in a critical situation.
FIG. 1 shows the flow of the process corresponding to FIG. 4. In this case, Port A of the PIA is set as input, Port B is set as output, and scanning is performed from Port B at the same time. As a result of this simultaneous scanning, if it is considered that there is only one pressed key, that is, Port A, = A.
If press information is captured in any one of 7, P
The input/output settings of ports A and B are reversed, and a scan signal is output from port A after the press information has been captured t'. port for this scan signal.
If press information is obtained for one of B (1 to B), it is assumed that there is only one pressed key, and the pressed key information is registered in the queue. Therefore, the pressed key information is registered in the queue. Detection can essentially be accomplished with two scans, regardless of the number of keys.

FIG. 2 shows a configuration in which the above-mentioned processing is implemented in terms of hardware in the following case. According to this figure, when the processing starts, the scan signal output means 12 outputs a signal to the key human power means 5. Scan signals are output all at once (from one direction), but the number of pressed keys is determined to be 1 by the pressed key number detection means 15 based on the information taken in from the other direction by the key manual means 3.
It is now possible to detect whether or not the When only one key is pressed, the position of that key in the other direction is stored in the key press information detection position storage means 15, and the scan direction is changed by the scan direction changing means 14.
After t, the scan position setting means 16/a outputs a scan signal from other directions including the position in the other direction. The number detection means 18 detects whether the number of pressed keys is 1 or not, or if the number of pressed keys is 1, the pressed key information reporting means 19 detects 91.
When only one key is pressed, information on the next key is reported.

(Effects of the Invention) As explained above and as follows, in the case of the present invention, the pressed key can be specified and detected by two scan processes, and even if the pressed key is implemented by software or hardware. This has the effect that the key can be identified and detected quickly.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the processing flow and configuration of an example of the key scan method according to the present invention implemented in software and hardware, and Figure 3 is a diagram showing the configuration of an example of the key scan method according to the present invention. Figures 4 and 5, which are diagrams showing the block configuration of an example of a scan circuit, show the general process 70- of the key scan process so far and an example of the case where the process is implemented in hardware. FIG. 2... PIA, 3... Key matrix, 12.1
7... Scan signal output means, 13.18... Number of pressed keys detection means, 14... Scan direction changing means %
15...Key press information detection position storage means, 16...
Scan position setting means, 19... Pressed key information reporting means. 1 figure, 2 figure, 31 figure! I

Claims (1)

[Claims] In a key scan method for specifying and detecting which of multiple keys arranged in a matrix has been pressed, a scan signal is simultaneously sent to the key matrix from one direction and pressed information is captured from the other direction. After detecting the position of the pressed key in the other direction, a scan signal is sent from the other direction including the position in the other direction, and the pressed key is detected in one direction by capturing the pressed information from the one direction. A key scan method that detects the location of