CN203632650U - Matrix key scanning circuit - Google Patents

Abstract

The utility model discloses a matrix key scanning circuit. Each I/O port and other I/O ports form a key detection module, wherein the key detection module comprises a resistor R, a diode D and a key K; and the I/O port is connected with the anode of the diode D through the resistor D, and the cathode of the diode D is connected with the other I/O ports through the key K. The maximum scanning key number of the scanning circuit is K, and K meets the equation of K=n*(n-1), wherein the n presents the number of I/O ports. The matrix key scanning circuit achieves multi-key detection with a few I/O ports and can save more I/O ports compared with a traditional matrix scanning circuit.

Description

A kind of matrix press-key scanning circuit

Technical field

The utility model relates to button and drives field, more specifically, relates to a kind of process reformed matrix key scanning circuit that adopts the many buttons of a small amount of port driver.

Background technology

At present, small household appliances function is more and more, and the button thereupon using also constantly increases, and causes the I/O port resource of chip in short supply, and this just need to remove to drive multiple buttons with a small amount of port.If by driving the single-chip microcomputer of chip expansion or the more I/O mouths of use, the result causing is that cost rolls up.For the more practical cost of more saving, generally can drive multiple buttons by a small amount of port, existing is to expand by the mode of matrix-scanning.Take 12 buttons as example, matrix-scanning needs 7 I/O mouths, as Fig. 1.

Utility model content

The purpose of this utility model is a kind of matrix-scanning circuit through improvement, is the more practical more cost-effective circuit of one.

The purpose of this utility model is by taking following technical scheme to reach:

A kind of matrix press-key scanning circuit, each I/O port and other each I/O ports form a button detection module, and wherein button detection module comprises resistance R, diode D and button K; Wherein I/O port is connected with the positive pole of diode D by resistance R, and the negative pole of diode D connects other each I/O ports by button K.

Scanning circuit of the present utility model, by a diode of corresponding increase at each button place, can be realized the object of more scanning buttons, and the number of elements that this circuit adopts is few, implements simple and reliable.

Described scanning circuit maximum scan is K by bond number, K=n × (n-1); Wherein n is I/O port number.

Compared with existing key scanning circuit, circuit of the present utility model, not increasing under the prerequisite of I/O port, can be realized more key scans, reaches the effect of the many buttons of scanning with a small amount of I/O port.

figure of description

Fig. 1 is the schematic diagram of existing matrix press-key scanning circuit.

Fig. 2 is the schematic diagram of reformed matrix key scanning circuit of the present utility model.

Embodiment

Accompanying drawing, only for exemplary illustration, can not be interpreted as the restriction to this patent;

For better explanation the present embodiment, some parts of accompanying drawing have omission, zoom in or out, and do not represent the size of actual product;

To those skilled in the art, in accompanying drawing some known features and explanation thereof may to omit be understandable.

Below in conjunction with drawings and Examples, the technical solution of the utility model is described further.

Embodiment:

As Fig. 2, a kind of matrix press-key scanning circuit, each I/O port and other each I/O ports form a button detection module, and wherein button detection module comprises resistance R, diode D and button K; Wherein I/O port is connected with the positive pole of diode D by resistance R, and the negative pole of diode D connects other each I/O ports by button K.Wherein diode D realizes the one-way conduction of button detection module, and every two the I/O ports that make can detect two buttons.Arrange circuit design according to this matrix, can maximum scan press bond number:

K?=?n?×?(n?-?1)

Wherein n is I/O port.

The operation principle of the present embodiment:

First one of them I/O mouth is set to delivery outlet, output low level.Other port is set to bring and draws input port, reads the level state of these ports, presses next be low level, press as high level without button when corresponding ports button.Then be switched to another port output low level, repeat above step and read port level.The information that just can read all buttons after 4 cyclings altogether, adopts the scanning circuit in the present embodiment, adopts 4 I/O ports can realize 12 buttons, and adopts traditional scanning circuit, and realize 12 buttons needs 7 I/O ports.

Above-described execution mode of the present utility model, does not form the restriction to the utility model protection range.Any modification of having done within spiritual principles of the present utility model, be equal to and replace and improvement etc., within all should being included in claim protection range of the present utility model.

Claims (2)

1. a matrix press-key scanning circuit, is characterized in that, each I/O port and other each I/O ports form a button detection module, and wherein button detection module comprises resistance R, diode D and button K; Wherein I/O port is connected with the positive pole of diode D by resistance R, and the negative pole of diode D connects other each I/O ports by button K.

2. matrix press-key scanning circuit according to claim 1, is characterized in that, described scanning circuit maximum scan is K by bond number, K=n × (n-1); Wherein n is I/O port number.

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