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A Keyboard Matrix Scanning System That Saves I/O

A keyboard matrix and scanning system technology, applied in the field of scanning systems, can solve the problems of increasing programming complexity, increasing programming difficulty, adding chips, etc., and achieve the effect of reducing programming difficulty, reducing complexity, and reducing chips

Inactive Publication Date: 2016-04-06
SHENYANG INSTITUTE OF CHEMICAL TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method will not only increase the complexity of programming but also increase the cost of chips
For manufacturers who rely on large quantities and low prices to win, this method is not advisable
The second method is to add a microcontroller chip, but communication between microcontrollers is required, which increases the difficulty of programming

Method used

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  • A Keyboard Matrix Scanning System That Saves I/O
  • A Keyboard Matrix Scanning System That Saves I/O
  • A Keyboard Matrix Scanning System That Saves I/O

Examples

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Embodiment Construction

[0020] The present invention will be described in detail below in conjunction with examples.

[0021] figure 2 It is a 4×5 keyboard matrix scanning circuit diagram of the present invention; 10 diodes are added to the circuit, and only 4 I / Os are needed. Compared with the traditional 4×5 keyboard matrix scanning circuit, the required I / O number is reduced by 5, which is only 44.4% of the conventional circuit. This reduces the I / O considerably for a single-chip microcomputer with a small number of I / O.

[0022] The circuit scans by row: when scanning the first row, let P0.0 be low level, P0.1, P0.2, P0.3 be high level, that is, P0.0=0, P0.1=P0.2 =P0.3=1. If SW11 is pressed, diode D21 is turned on and P0.1 is pulled down. If SW12 is pressed, diodes D22 and D31 are turned on, and P0.1 and P0.2 are pulled down. If SW13 is pressed, diodes D32 and D41 are turned on, and P0.2 and P0.3 are pulled down. If SW14 is pressed, diode D33 is turned on, and P0.2 is pulled down. If SW15...

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Abstract

An I / O-saving keyboard matrix scanning system relates to a scanning system, the system includes a 4×5 metal keyboard matrix or a 5×5 keyboard matrix and a circuit, and its diode circuit includes M I / O scanning M× N keyboard matrix; 4 I / Os are set in the 4×5 keyboard matrix scanning circuit; 5 I / Os are set in the 5×5 keyboard matrix scanning circuit. Initialize first, then start to scan each row, start from the first row, judge whether the first row has a key pressed according to the port value, if any button is pressed, after returning the key value, end the program; in the project of the present invention, the keyboard matrix is ​​carried out control, can reduce the complexity of programming, and save cost by reducing chips. Reduce programming difficulty. Only adding a small amount of diodes in the circuit can realize M I / O scanning M×N (????????????????????????????? ??????????????????? M≤N) keyboard matrix. The circuit structure is simple, the software programming is easy, and it can be widely used in low-cost circuits.

Description

technical field [0001] The invention relates to a scanning system, in particular to an I / O-saving keyboard matrix scanning system. Background technique [0002] In engineering projects, keyboard matrix is ​​often used for control. to a M x N ( ) keyboard matrix, the conventional scanning method requires M+N I / O to perform row scanning and column scanning respectively to determine which key is pressed. In most projects, the microcontroller is often connected with multiple peripherals, such as keyboard matrix, LCD, EEPROM, RFIC, time chip, communication chip, analog-to-digital converter chip, multi-way switch, etc. The keyboard matrix alone occupies M+N I / Os. For microcontrollers with fewer I / O ports, such as 51 series microcontrollers (with 4 I / O ports), the shortage of I / O resources is an unavoidable problem. In order to solve this problem, the designer's first thought is to use a chip to expand the I / O port. However, this method will not only increase the complexity of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F3/02
Inventor 李金凤曹顺汪滢王健张琳琳刘欢郭硕
Owner SHENYANG INSTITUTE OF CHEMICAL TECHNOLOGY