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Keyboard scanning circuit and method

A technology of keyboard scanning and scanning method, which is applied in keyboard-like equipment coding, electrical components, electrical digital data processing, etc., and can solve the problems of multiple I/O port resources, small number of I/O ports, occupation, etc.

Inactive Publication Date: 2008-04-16
HONG FU JIN PRECISION IND (SHENZHEN) CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The defect of this keyboard scanning circuit is that it takes up too many I / O port resources.
[0005] In addition, in order to reduce the hardware cost, a large number of small single-chip microcomputers have been released on the market, and the main feature of these small single-chip microcomputers is that the number of I / O ports is small. If the above-mentioned matrix keyboard scanning circuit is used, the limited I / O port resources will be reduced. more nervous

Method used

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  • Keyboard scanning circuit and method
  • Keyboard scanning circuit and method

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Embodiment Construction

[0026] see figure 2 , the keyboard scanning circuit 103 of a preferred embodiment of the present invention includes N+1 row lines L 0 ~ L n , N column lines P 1 ~P n , NxN buttons S 01 ~S n(n-1) , N I / O ports K 1 ~K n , N resistors R 1 ~R n , N diodes D 1 ~D n and a power supply VCC, wherein N is a natural number. N column lines and N+1 row lines are arranged alternately in a matrix to form Nx(N+1) intersections. Among the N+1 row lines, one row line is grounded. Among the Nx(N+1) intersections, there are NxN intersections corresponding to the NxN keys respectively, while no keys are placed at the other N intersections. Among the NxN keys, the first end of each key is electrically connected to the corresponding row line, and the second end is electrically connected to the corresponding column line.

[0027] Line L 0 ~ L n , row line L 0 by key S 01 ~S n(n-1) The first end of the line is electrically connected in sequence, and the row line L 0 grounded. The...

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Abstract

The invention relates to a keyboard scanning circuit, comprising N vertical lines, N*N keys formed by N first horizontal lines and second horizontal lines, N I / O ports (in-out ports), N diodes, N resistors and a power supply VCC. The N vertical lines, N first horizontal lines and second lines are arranged in a matrix manner to form a plurality of cross points. The N*N cross points are arranged in a manner corresponding to the N*N keys. Each horizontal line is connected to an I / O port through a diode; and each second horizontal line is grounded. Each vertical line is connected to the power supply VCC through a resistor in an electric manner. The N first horizontal lines correspond to the N vertical lines respectively; each pair of horizontal line and vertical line corresponding to each other communicate with each other and no key is arranged on the N cross points between the horizontal line and the vertical line. The keyboard scanning circuit is capable to use N I / O ports to scan N*N keys, the structure is simple, I / O port resource is saved and the cost is reduced. Besides, a keyboard scanning method is provided.

Description

technical field [0001] The invention relates to a keyboard, in particular to a keyboard scanning circuit and method. Background technique [0002] The keyboard is the main human-machine dialogue device in electronic products such as computers, PDAs (Personal Digital Assistants), and mobile phones. At present, the functions of electronic products are becoming more and more complete. To complete the control of complex and diverse functions, this requires the keyboard to provide enough keys. From a structural point of view, the keyboard is generally divided into three parts: the shell, the keys and the circuit board. The circuit board is the core of the keyboard, which is located inside the keyboard and consists of logic circuits and control circuits. Among them, the logic circuit of the keyboard provides a matrix arrangement of the keys; the control circuit of the keyboard is divided into a scanning circuit for determining the position of the keys, a coding circuit for gener...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03M11/00H03M11/20G06F3/023
CPCG06F3/023
Inventor 翁世芳李德志
Owner HONG FU JIN PRECISION IND (SHENZHEN) CO LTD
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