Matrix keyboard and scanning method thereof

Abstract

A matrix keyboard circuit comprises N-numbered column lines, N-numbered first row lines, N*N-numbered keys, N+1-numbered elements with resistance, N-numbered diodes and a power supply, wherein the N-numbered first row lines are respectively connected on the power supply by the elements with resistance. The matrix keyboard circuit also comprises N-numbered I / O ports and grounded second row lines, wherein The N-numbered first row lines and the second row lines respectively intersect with the N-numbered column lines to form N*(N+1)-numbered matrix intersecting points; a diode is arranged on the intersecting point of each column line and a first row line corresponding to the column line; the cathode of the diode on one intersecting point is connected with the column line forming the intersecting point and the anode thereof is connected with the row line forming the intersecting point; the N*N-numbered keys are correspondingly arranged on other N*N-numbered intersecting points respectively; and the first end of a key on one intersecting point is electrically connected with the column line forming the intersecting point and the second end thereof is electrically connected with the row line forming the intersecting point. The invention also provides a scanning method of the matrix keyboard circuit.

Description

technical field [0001] The invention relates to a keyboard and a scanning method, in particular to a matrix keyboard circuit and a scanning method thereof. 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. Wherein, the logic circuit of the keyboard provides a matrix arrangement of the keys, and most of the existing matrix keyboard circuits use the I / O port of the single-chip microcomputer to scan the keyboard to control the keys of the keyboard. The existing 4×4 matrix keyboard circuit (such as figure 1 shown), including 4 × 4 keys S arranged in 4 rows and 4 columns 1 -S 16 , 4 resistors R 1 -R 4 , 2×4 I / O ports K 1 -K 8 . By analogy, an N×N matrix keyboard circuit requires 2N I / O ports. In the matrix keyboard circuit, N row lines and N column lines are intersected to form N×N intersection points, and each intersection point is provided...

AI Technical Summary

Problems solved by technology

[0004] In this way, if the above-mentioned matrix keyboard circuit is used, the output terminal will occupy more I / O port lines of the single-chip microcomputer, which will make the limited I / O port resources more tense.

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