CN201656956U

CN201656956U - A/D type key circuit

Info

Publication number: CN201656956U
Application number: CN2010201064614U
Authority: CN
Inventors: 马鹏杰; 张加亮
Original assignee: Guangdong Oppo Electronics Industry Co Ltd
Current assignee: Guangdong Oppo Electronics Industry Co Ltd
Priority date: 2010-02-01
Filing date: 2010-02-01
Publication date: 2010-11-24
Anticipated expiration: 2020-02-01

Abstract

The utility model discloses an A/D type key circuit arranged in a low power consumption system, which includes a key group and a peripheral circuit comprising a resistor, a diode, a triode and a capacitor. When a key is pressed down, two signals are generated, one is provided to an interrupt port of the system to interrupt the system, the other is provided to an A/D port of the system, the system can judge which key is pressed down according to the acquired A/D value, and the A/D value of each key is set through adjusting R0-RN. The circuit is designed mainly for the low power consumption system which is provided with the A/D port and the interrupt port and comes into the standby state frequently; and when the system comes into the standby state, the A/D is automatically turned off, the standby state can be interrupted no matter which key is pressed down, and then the system is waken up to judge which key is pressed down, so as to play the function of the corresponding key. The utility model is suitable for the low power consumption system, and is energy-saving and environment-friendly.

Description

A kind of A/D formula key circuit

Technical field

The utility model relates to a kind of electronic circuit, particularly relates to a kind of A/D formula key circuit of low-power dissipation system.

Background technology:

At present, A/D (Analog to Digital Converter analog to digital converter, typically referring to is the electronic component of digital signal with analog-signal transitions) the formula button of most of manufacturer production is to realize keypress function by electric resistance partial pressure, system scan A/D value.This A/D formula button has only and keeps A/D scanning always, just can make button that function is arranged, and is not suitable for the low-power dissipation system design.And in low-power dissipation system, require when not having button to press, can turn off A/D, thus reduce system power dissipation, when pressing, button can produce interruption (edge or level), and at this moment open again and read the A/D value, can realize keypress function easily.When system enters dormancy, can only be waken up by interruption, general A/D formula button does not have this function, and existing A/D formula button can not produce interrupt signal when button is pressed generation A/D value.

The utility model content:

The purpose of this utility model is to overcome the deficiencies in the prior art, and a kind of A/D formula key circuit is provided, and produces interrupt signal pressing generation A/D value at button when, satisfies the demand of low power dissipation design.

In order to achieve the above object, the technical solution adopted in the utility model is: a kind of A/D formula key circuit, be arranged in the low-power dissipation system, this circuit is made up of the key groups of parallel connection, each key groups is made up of the button and the diode of series connection, bridge joint one divider resistance between the adjacent key group, the output one tunnel of this circuit via after the diode output output again via being delivered to interruptive port INT behind the peripheral circuit of forming by resistance R A, RB, RC; The A/D value of another road output is connected to the A/D port through bridge joint after divider resistance R1, R0 between button K1 and the diode D1 and anti-shake capacitor C 1.

Can produce two signals when button is pressed, an interruptive port that offers system produces system and interrupts; Which button an A/D port that offers system is judged as by collection A/D value and presses, and the A/D value of each button can be provided with by regulating R0～RN.This circuit is the low-power dissipation system design that A/D port, interruptive port is arranged and need often enter standby, after system enters standby, can turn off A/D, reduce power consumption, press Shi Douke as any one button and produce interruption, waken system, and can judge to which button at once and press, thus realize the function of corresponding button.

The utility model adopts diode D1～DN to isolate different buttons and disturbs, and produces interruption when button is pressed.When needs produce trailing edge/low level and interrupt, can make the triode conducting by NPN type triode Q1, thereby make the interruptive port level by VDD reduce to low level () produce and interrupt.Rising edge/when high level interrupted, the VCC level directly made interruptive port mouth signal be upgraded to high level (adjustable) by low level by diode when the needs generation.

Compared with prior art, the beneficial effects of the utility model are: the first, and when pressing generation A/D value, button can produce interrupt signal, can effectively reduce system power dissipation; The second, when having button to press, can not turn off A/D, do not need A/D always at scanning mode; The 3rd, enter dormancy in system, in the time of can only waking up by interruption, system is waken up from the low power consumpting state of dormancy, and accurately judge button.

Description of drawings:

Fig. 1 is a theory diagram of the present utility model;

Fig. 2 is that the utility model trailing edge/low level is interrupted A/D formula key circuit figure;

Fig. 3 is that the utility model rising edge/high level interrupts A/D formula key circuit figure.

Embodiment:

Design of the present utility model is to overcome the deficiencies in the prior art, and a kind of A/D formula key circuit is provided, and exports the A/D value pressing the generation interrupt signal at button when, satisfies the demand of low power dissipation design.Be elaborated with reference to accompanying drawing below in conjunction with embodiment, so that technical characterictic of the present utility model and advantage are carried out more deep annotation.

A kind of A/D formula key circuit, be arranged in the low-power dissipation system, this circuit is made up of the key groups of parallel connection, each key groups is made up of the button and the diode of series connection, bridge joint one divider resistance between the adjacent key group, the output one tunnel of this circuit via after the diode output output again via being delivered to interruptive port INT behind the peripheral circuit of forming by resistance R A, RB, RC; The A/D value of another road output is connected to the A/D port through bridge joint after divider resistance R1, R0 between button K1 and the diode D1 and anti-shake capacitor C 1.

Theory diagram of the present utility model can produce two signals as shown in Figure 1 when button is pressed, an interruptive port that offers system produces system and interrupts; Which button an A/D port that offers system is judged as by collection A/D value and presses, and the A/D value of each button can be provided with by regulating R0～RN.This circuit is the low-power dissipation system design that A/D port, interruptive port is arranged and need often enter standby, after system enters standby, can turn off A/D, reduce power consumption, press Shi Douke as any one button and produce interruption, waken system, and can judge to which button at once and press, thus realize the function of corresponding button.

For the system that needs trailing edge/low level to interrupt, the button schematic diagram as shown in Figure 2, wherein K1～KN is a N button, R0～RN is the A/D divider resistance, D1～DN is that the general button that prevents interferes with each other diode (as 1N4148), Q1 is NPN type triode (N type semiconductor is based on electronics, the triode of being made up of P type semiconductor of 2 N type semiconductor sandwich), and C1 is the anti-shake electric capacity of A/D.Operation principle is as follows: when button Kx presses, diode Dx conducting, thereby make NPN type triode Q1 conducting, INT (being an instruction that sends interruption to CPU in assembler language) signal becomes low level (being about ground) by high level (VDD), interrupt thereby produce, this moment, divider resistance Rx upper end was communicated with VCC by button, because the existence of other diodes, button can not gone here and there mutually with other buttons, at this moment the voltage of AD_KEY1 network is R0*VCC/ (R0+R1+ ... Rx) (x＞=1), button can accurately be judged by gathering the A/D value by system.RA current-limiting resistance in the circuit diagram, RB are pull-up resistor, and RC is for preventing to disturb resistance.

For needing rising edge/high level as the system of interrupting, the button schematic diagram as shown in Figure 3, wherein K1～KN is a N button, R0～RN is the A/D divider resistance, D1～DN is that diode (as 1N4148) is disturbed in general preventing between button, and C1 is the anti-shake electric capacity of A/D.Operation principle is as follows: when button Kx presses, diode Dx conducting, the INT signal by low level () become high level (VDD), interrupt thereby produce, this moment, divider resistance Rx upper end was communicated with VCC by button, because the existence of other diodes, button can not gone here and there mutually with other buttons, at this moment the voltage of A/D_KEY1 network is R0*VCC/ (R0+R1+ ... Rx) (x＞=1), button can accurately be judged by gathering the A/D value by system.RA, RB are divider resistance in the circuit diagram, and scalable is interrupted the level value (VDD) of high level, and RC is a current-limiting resistance.

Claims

1. A/D formula key circuit, be arranged in the low-power dissipation system, it is characterized in that: this circuit is made up of the key groups of parallel connection, each key groups is made up of the button and the diode of series connection, bridge joint one divider resistance between the adjacent key group, this circuit output end one tunnel via after the diode output output again via being delivered to interruptive port INT behind the peripheral circuit of forming by resistance R A, RB, RC; The A/D value of another road output is connected to the A/D port through bridge joint after divider resistance R1, R0 between button K1 and the diode D1 and anti-shake capacitor C 1.

2. A/D formula key circuit according to claim 1 is characterized in that: described A/D value can be determined by VCC and divider resistance R0～RN.