JPS58221430A - Method for controlling keyboard - Google Patents

Abstract

PURPOSE:To reduce the load of a CPU, by permitting the generation of polling of the CPU only when a keyboard requests data transmission to the CPU. CONSTITUTION:When a key is not depressed, a keyboard controller 221 does not store data to be transmitted to the CPU 21. When the controller 221 does not store the data to be transmitted, a request line driving means 225 turns a request line 24 off. A request line detecting means 212 detects that the line 24 is off and transmits the detected result to a polling means 211. The polling means 211 detects that a keyboard device 22 does not request data transmission by the signal from the detecting means 212 and inhibits the generation of polling to a serial data transmission line 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a keypad control system that reduces the burden on a CPU.

[Technical background of the invention and its problems]

There are various key gate control methods for serial interfaces, but among them, in devices such as data entry devices (= data omission, etc.) that strongly dislike the inaccuracy of key human data, it is necessary to ensure the accuracy of key human data. , polling from the CPU (keyed control is often performed).

FIG. 1 shows an example.

According to this example, the key controller (KBC121) built into the key gate device 12 scans the key matrix 122, converts the obtained key data into serial data, and transmits the key data via the bidirectional signal line X3. Te CP
Send to UII.

It is characterized in that this sending timing is performed as a response to polling (polling mechanism ZZZ) from the CPU II.

According to this method, by adding a sequence check bit to the polling data, it is possible to prevent key data from being omitted manually, thereby enabling highly accurate keyboard control. However, in this method, in order to cope with the expected key force and to keep up with the maximum input speed of the key operator, the two CPUs must always poll at sufficiently short intervals. Experimentally, in order to follow the maximum input speed of the data entry key operator, the number of polling times of 20 milliseconds (ms) or less is 180,000 times.

However, it is said that the average key operator inputs up to 20,000 keys per hour, and only 11% of the polls issued by the CPU are effective in 2/18. C required to issue the remaining 89% of polls
This has the disadvantage that the processing time of the PU directly becomes an overhead and reduces the processing efficiency of the CPU.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and in key 4-key control where data is transmitted via a bidirectional signal line through which polling and key data are transmitted, the key gate transmits data to the CPU. An object of the present invention is to provide a key bead control method that reduces the burden on the CPU by allowing the CPU to issue polling only when the CPU is requesting the polling.

[Summary of the invention]

The present invention is a key gate control system in which data is transmitted via a bidirectional signal line through which polling and key data are transmitted. A mechanism for detecting the request signal and driving the request signal, a signal line for transmitting the request signal to the CPU, and a mechanism for detecting the request signal and permitting/disallowing polling for the key card are provided. CP only when requesting data transmission
By allowing U to issue polls, the CPU overhead for keyboard polling is reduced.

[Embodiments of the invention]

Hereinafter, this embodiment will be described in detail using FIG. 2 and subsequent figures.

FIG. 2 is a block diagram showing an embodiment of an apparatus in which the present invention is implemented.

In the figure, 21V! , CPU, 22 are key date devices, and both are connected via a serial data transmission line 23 and a request line 24, which will be described later. The serial data transmission line 23 is a bidirectional signal line through which polling and key data are transmitted.

211 is a polling mechanism. Polling mechanism 211
is built in the CPU 2Z and polls the keyboard device 2 and takes in key data in response.

This polling mechanism trx is connected to the keyboard controller 21K via a bidirectional serial data transmission line 23.

The keyboard controller 221 has keys that are connected to the keyboard device 2-2.
It scans the key matrix 222 (scan line 223), detects key data via the return line 224, and transmits it to the CPU 21.

225 is a request line driving mechanism.

The request line driving mechanism 225 detects a data transmission request from the keyboard controller 221 transmitted via a signal line 226 and generates a request signal. The output of the stress line drive mechanism 225 is transmitted via the request line 24 to the request line detection mechanism 212 built into the CCPU 2Z. The presence or absence of the signal is transmitted to the polling mechanism 211 via the signal line 213.

FIG. 3 is a timing chart showing the operation of the present invention. In order from the top, the timings of the signal propagated on the request signal line 2A, the signal P (polling data) and KD (key data) propagated on the serial data transmission line 23 are shown.

Hereinafter, the operation of the embodiment of the present invention shown in FIG. 2 will be explained in detail using the timing chart shown in FIG. 3.

In the embodiment of the present invention, the polling interval is set to 20 milliseconds (FF&
8). That is, the polling mechanism 222 has 20
Attempts to issue a poll every rrLS. Since no key is pressed at this point, the key date controller 221 does not hold data to be transmitted to the CPU 21. The request line driving mechanism 225 turns off the request line 25 when the key date controller 22.I does not hold data to be transmitted. The request line detection mechanism 212 detects that the request line 24 is off, and transmits it to the polling mechanism 211. The polling mechanism 211 thereby learns that the keyboard device 2-2 does not request data transmission, and does not issue polling at this time.

When one key is pressed between time points and ■ (indicated by △ in the figure), the request line drive mechanism 225 detects this and turns on the request line 24. The request line detection mechanism 212 detects this and transmits to the polling mechanism zrr that the keyboard device 22 requests data transmission.

As a result, at time 0, the polling mechanism 211 issues a poll and receives key data for it.

The request line driving mechanism 212 turns off the request line 24 when the keyboard controller 221 finishes transmitting data and detects that there is no more data to transmit. Therefore, no polling is sent out at time ■.

Next, when the 2 keys are pressed at the same time between time points ■ and 0 (marked with a square mark in the figure), the request line 24 is similarly turned off and time 0
A poll is issued.

Since the keyboard controller 221 still holds data to be transmitted even after transmitting the data for this, the request line driving mechanism 225
Continue to hold 4 on. Therefore, a poll is issued even at the moment. After the data for this poll has been transmitted, the request line 24 is turned off and at time [F
], 0. In ■, polling is not issued.

〔Effect of the invention〕

As explained above, the present invention is accurate but has the drawback of heavy CPU overhead due to unnecessary I-ring issuance. By adding
It is possible to realize key gate control that inhibits the issuance of unnecessary polling and reduces CPU overhead while retaining all of its advantages.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a Zoroku diagram showing an example of the configuration of a device for realizing conventional keyboard control, FIG. 2 is a block diagram showing an embodiment of a device for realizing the present invention, and FIG. 5 is a timing chart showing the operation of the embodiment of the invention. 21...CPU, ξ2...Keyboard device, 23.
...Request signal line, 24...Serial data transmission line, 211...Polling mechanism, 212...
・Request line detection mechanism, 221...Key keyed controller, 225 request line drive mechanism.

Claims (1)

[Claims] In keyboard control where data is transmitted via a bidirectional signal line through which polling and key data are transmitted, there is a polling mechanism in which a key polls a single key and receives key data in response, and a polling mechanism that captures key data in response. A request line drive mechanism that detects a transmission request and issues a request signal, and a CPU that transmits this request signal.
and a request line detection mechanism that detects the request signal and transmits it to the polling mechanism, and issues CPU polling only when the key gate requests data transmission from the CPU. A key gate control method characterized by allowing.