SU1282109A1 - Information input device - Google Patents

Abstract

The invention relates to computing and can be used in information input devices of automation systems and computing. The purpose of the invention — a simplification of the device — is achieved by introducing a PLA into it. This provides, in conjunction with other elements of the device, reliable protection against contact bounce and protection from the operator mistakenly pressing two or more keys simultaneously, as well as implementations of the control device operation algorithm with saving the number of required elements of the order of 20-30%. 1 il.

Description

The invention relates to computing and can be used in information input devices of automation systems and computing.

The purpose of the invention is to simplify the device while maintaining high reliability of its operation.

The drawing is a diagram of the proposed device.

The device contains a keyboard 1, a programmable logical 1 and 2 Athens, an element of NOT 3, a generator of 4 pulses, an element of 5 prohibition and counter 6.

The device works as follows.

When you press one of the buttons on the keyboard 1 on one of the outputs of the programmable logic array 2, a signal of the logical 1 appears, distorted by the bounce of the contacts of the buttons.

This signal through the element NO 3 is fed to the reset input of the counter, 6. At the counting input of this counter, through the prohibition element 5, synchronous, pulses are received from the generator L of pulses.

When you click one. the signal permits the counting of pulses, however, the arising interference from bounce (logical O) resets the counter 6 to the zero state. After the end of the bounce, the counter starts working without fail. With the passage of 2 N pulses under the order at the output 2 of the counter, a logical 1 signal appears, cleared of bounce. This signal through the inverter 7 is fed to the control input of the element I, blocking the account, and is also used as a cleared sign of pressing any button on the keyboard, which serves as X2, the input of the code converter built on a programmable logic key. the matrix.

A programmable logic matrix provides the output signals, in accordance with rule Z, Х2п., 10Х ,,. „. ПХ„

2 Oh, f OHP

,, ОХ, пХ2П, ... ОХ „., ОХ (1) Z, s X.OX, {JОХ„

From the above relations it can be seen that a single signal on each of the outputs Zp -Zn appears only when there is a sign X, and when logical 1 is applied to only one

where t t,

from the inputs X ,, ... D „. Therefore, the device is not only protected from contact bounce, but also from erroneously pressing two or more buttons simultaneously.

For proper operation of the bounce protection circuit, the following applies: inequality

 NT-T ,, (2)

the period of the clock pulses from the generator; maximum duration of impulses arising during bounce;

N is the control number chosen from the condition of satisfying inequality (2). When the button is pressed, the output signal Zf |... G is also bounce.

5 t of the first zero signal, the counter is reset to the zero state, the first and subsequent bounce pulses will not affect the output signals, because during even the maximum pulse duration the counter does not have time to fill, i.e. Inequality (2) is not satisfied, and the signal at the output of the counter does not excite-c. Bounce-free signals

Z, -Z are fed to the inputs X, 2п Pr ° of a grammable logic matrix, used as a converter of the unitary code of the keyboard into a binary-decimal code at the outputs of the Z matrix, which serve as outputs of the device.

Thus, the proposed device provides both protection of the keyboard buttons from bouncing the contacts, and protection against the operator pressing two buttons at the same time, while the device

performed with the involvement of the minimum number of elements, and in comparison with the known requires only one pulse generator. In the circuit of the known device, two inputs are provided for connecting two external pulse generators. In addition, the use of a programmable logic matrix allows you to combine in a single functional unit as

The circuitry of the keyboard code converter to the binary-decimal code, and the protection circuit against simultaneous pressing of two keys, as well as part of the circuit for protection against contact bounce.

Claims (1)

Invention Formula A device for entering information containing a keyboard, a pulse generator, an alarm element, a counter, an output of a pulse generator is connected to the direct input of a prohibition element whose output is connected to a counter input of a counter whose output is connected to an inverse input of a prohibition element the purpose of simplifying the device. A programmable logic matrix and a NOT element are entered; the keyboard outputs are connected to information inputs of a programmable logic matrix, whose information outputs are information outputs of the device; logical matrix. i m .Sbixff  ,,.