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Key testing circuit

A technology for detecting circuits and keys, applied in the direction of dynamic coding, etc., can solve the problems of recognition into others, misjudgment, etc., and achieve the effects of low production cost, good system robustness, and good key recognition performance

Active Publication Date: 2013-01-02
HUIZHOU DESAY SV AUTOMOTIVE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In the existing button detection circuit, resistors are usually connected in series. When multiple buttons are pressed at the same time, they may be recognized as other buttons due to the voltage division of the resistors, causing misjudgment.

Method used

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Examples

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Embodiment 1

[0021] Example 1, such as figure 1 As shown, a button detection circuit includes a pull-up resistor R, N buttons, and N voltage divider resistors (R 1 , R 2 ,...,R n ), N is a natural number, the N buttons are connected in series with the N voltage dividing resistors one by one, and then connected in parallel. One end of the parallel circuit is grounded, and the other end is connected to the power supply VCC through the pull-up resistor R. The parallel end is also used as a signal The output terminal is connected to the signal processing unit; the voltage dividing resistor R 1 , R 2 ,...,R n The resistance value satisfies: R 1 2 n ; In the button detection circuit, several buttons are pressed at the same time, and among the pressed buttons, the voltage dividing resistor connected in series is at least R i , the resistance value is less than R i and the resistance value closest to R i The voltage divider resistor is R i-1 , the circuit composed of the pressed button i...

Embodiment 2

[0023] Example 2, such as figure 2 As shown, a button detection circuit includes a pull-up resistor R, N buttons, and N voltage divider resistors (R 1 , R 2 ,...,R n ), N triodes (Q1, Q2, ..., QN), N is a natural number, the emitters of the N triodes are all grounded, the collectors are respectively connected to N voltage dividing resistors, and the bases of the triodes are respectively connected to N buttons , the other ends of the N buttons are connected to the resistor R0 and connected to the power supply VCC through the resistor R0; The pull resistor R is connected to the power supply VCC; the voltage divider resistor R 1 , R 2 ,...,R n The resistance value satisfies: R 1 2 n ; In the button detection circuit, several buttons are pressed, and among the pressed buttons, the voltage dividing resistor connected in series is at least R i , the resistance value is less than R i and the resistance value closest to R i The divider resistor R i-1 , the pressed button ci...

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PUM

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Abstract

The invention discloses a key testing circuit. The key testing circuit has the advantages that the key identification performance is good, key circuits of the key testing circuit are in parallel connection, resistance values of all divider resistors are set reasonably, and a single chip microcomputer can judge keys accurately according to different input voltages; the robustness is good, and when a plurality of keyboard keys are pressed at the same time randomly, incorrect judgment is avoided; and the circuit is simple in structure, low in production cost and easy for large-scale production.

Description

technical field [0001] The invention relates to a key detection circuit, in particular to a resistance voltage division type keyboard key detection circuit. [0002] Background technique [0003] The basic principle of the resistor divider keyboard: use resistor divider to obtain different voltages, and the single-chip microcomputer identifies the keys according to the voltage value. When a button is pressed, the button detection circuit generates a fixed voltage value through the voltage dividing resistor and sends it to the A / D port of the microcontroller. By collecting the A / D value, it can be judged which button is pressed. The A / D value of different keys can be set by adjusting the resistance value. [0004] In the existing button detection circuit, resistors are usually connected in series. When multiple buttons are pressed at the same time, due to the voltage division of the resistors, they may be recognized as other buttons, thus causing misjudgment. Contents of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03M11/20
Inventor 孙赛男杨展涛
Owner HUIZHOU DESAY SV AUTOMOTIVE
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