CN104020263A

CN104020263A - Indoor harmful gas detection system

Info

Publication number: CN104020263A
Application number: CN201410286174.9A
Authority: CN
Inventors: 李丹
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-06-25
Filing date: 2014-06-25
Publication date: 2014-09-03

Abstract

The invention discloses an indoor harmful gas detection system. According to the indoor harmful gas detection system, a carbon monoxide sensor MQ-7 is used as a gas detection module for outputting a simulated signal; signal acquisition, digital filtering processing, and display and alarming control of a measurement result are realized by taking a single chip microcomputer (STC12C5A60S2) as a main controller; an ADC (Analog to Digital Converter) in the single chip microcomputer is used as an analog-digital converter to digitalize a measurement signal, so as to be good for subsequence processing; meanwhile, an LED (Light Emitting Diode) digital tube and an alarm are used for directly analyzing the measurement result. The detection system disclosed by the invention can be used for testing that the concentration of carbon monoxide exceeds a standard state in time and alarming, and has the advantages of high sensitivity, high stability and simple circuit structure.

Description

A kind of indoor harmful gas detection system

Technical field

The present invention relates to carbon monoxide, specifically relate to the detection of carbon monoxide.

Background technology

Along with development and the growth in the living standard of human society, in room air, the kind of various harmful gases and quantity are sharply increasing, liquefied gas, coal gas, ornament materials, coating, electrical equipment, human activity etc. are the main sources of room air pollution, the serious threat mankind's health, therefore designs harmful gas detection system fast and accurately and is necessary.At present, about the research of gas detecting system more and more receives the concern of Chinese scholars, having proposed the detection method of various harmful gases, is wherein to utilize gas sensing array to carry out the method for gas detection more widely.But stable, the reliability of the sensitivity that relevant harmful gas detects and detection system still have much room for improvement.

Summary of the invention

The object of the invention is, for more dangerous room air pollution source carbon monoxide (CO), provides a kind of detection system based on single-chip microcomputer and gas sensor.

The technical scheme that realizes the object of the invention is as follows: a kind of indoor harmful gas detection system, and its hardware components comprises:

(1) single-chip minimum system circuit: adopt single-chip microcomputer STC12C5A60S2 to control the operation of whole measuring system, comprise signals collecting, signal processing, control output; Single-chip minimum system figure, mainly comprises singlechip chip, power pack, crystal oscillating circuit, reset circuit, and all I/O (P0, P1, P2, P3) mouth can be used as control line, data line, address wire this minimum system is extended out;

(2) sensor circuit: select MQ-7 carbon monoxide (CO) gas sensor, this sensor need to apply 2 voltages: heater voltage (VH) and test voltage (VC); Wherein VH is used to sensor that specific working temperature is provided, and VC is for measuring the voltage (VRL) on the pull-up resistor (RL) of connecting with sensor; VC need use direct supply; RL=500 Ω.；

(3) signal conditioning circuit: signal conditioning circuit uses amplifier ADOP7AH to design signal comparator, regulates the input voltage (Vj) of this amplifier forward by adjustable potentiometer R4, and C6 is output filter capacitor.

(4) key circuit: key circuit is mainly made up of spring switch and pull-up resistor, in the time not pressing switch, P1_4, P1_5, P1_7 are in high level state, while bouncing when pushing button, will produce a undersuing, single-chip microcomputer is exactly to identify which button and press by reading different undersuings again;

(5) buzzer circuit: hummer is controlled by a PNP triode, by the base stage of single-chip microcomputer P3_7 mouth control triode, has only ensured in the time of single-chip microcomputer output low level, hummer just can be sounded in conducting;

(6) LED charactron circuit: LED is the common anode utmost point, and low level is lighted corresponding charactron, controls anode by P1 mouth, and P2 mouth carrys out control cathode; Light all charactrons by dynamic display types.

Indoor harmful gas detection system of the present invention adopts carbon monoxide transducer MQ-7 as gas detection module outputting analog signal, realize signals collecting by single-chip microcomputer (STC12C5A60S2) as master controller, the demonstration of digital filtering processing and measurement result, controlling alarm, and use the ADC of single-chip microcomputer inside to make measuring-signal digitizing be beneficial to subsequent treatment as analog to digital converter, omit so independent ADC module, make whole circuit simple and stable, the concentration that detection system of the present invention can be tested carbon monoxide in time exceedes normal condition, and report to the police, have highly sensitive, stability is high, the simple advantage of circuit structure.

Brief description of the drawings

Fig. 1 is single-chip minimum system figure;

Fig. 2 is sensor basic test loop diagram;

Fig. 3 is sensor external circuits figure;

Fig. 4 is signal conditioning circuit figure;

Fig. 5 is key circuit figure;

Fig. 6 is buzzer circuit figure;

Fig. 7 is LED charactron circuit diagram.

Embodiment

A kind of indoor harmful gas detection system, its hardware components comprises:

(1) single-chip minimum system circuit: the operation of the whole measuring system of Single-chip Controlling, comprises signals collecting, signal processing, controls output; Single-chip minimum system figure as shown in Figure 1, mainly comprise singlechip chip, power pack, crystal oscillating circuit, reset circuit, all I/O (P0, P1, P2, P3) mouth can be used as control line, data line, address wire this minimum system extended out.

(2) sensor circuit: selecting is MQ-7 carbon monoxide (CO) gas sensor, and Fig. 2 is the basic test loop diagram of sensor for this reason, and Fig. 3 is sensor external circuits figure.This sensor need to apply 2 voltages: heater voltage (V _h) and test voltage (V _c).Wherein V _hbe used to sensor that specific working temperature, V are provided _cthe pull-up resistor (R connecting with sensor for measuring _l) on voltage (V _rL).This sensor has slight polarity, V _cneed use direct supply.Meeting under the prerequisite of sensor electrical performance requirement V _cand V _hcan share same power circuit.For the performance of good utilisation sensor more, need to select appropriate R _lvalue, gets R _l=500 Ω.

(3) signal conditioning circuit: signal condition is mainly that the signal of MQ-7 sensor output is nursed one's health, and makes its applicable ADC input range scope 0 ~ VCC, and wherein VCC is ADC analog reference voltage, is also the real work voltage of single-chip microcomputer.Use amplifier ADOP7AH to design signal comparator, as shown in Figure 4, regulate the input voltage (Vj) of this amplifier forward by adjustable potentiometer R4, C6 is output filter capacitor, in figure, V_IN is sensor input signal, output signal V_OUT=Vj-V_IN.

(4) key circuit: as shown in Figure 5, key circuit is mainly made up of spring switch and pull-up resistor, in the time not pressing switch, P1_4, P1_5, P1_7 are in high level state, while bouncing when pushing button, will produce a undersuing, single-chip microcomputer is exactly to identify which button and press by reading different undersuings again.

(5) buzzer circuit: as shown in Figure 6, sound the alarm when hummer input low-voltage, control by a PNP triode.By the base stage of single-chip microcomputer P3_7 mouth control triode, only ensure in the time of single-chip microcomputer output low level, hummer just can be sounded in conducting.

(6) LED charactron circuit: as shown in Figure 7, LED is the common anode utmost point, and low level is lighted corresponding charactron, controls anode by P1 mouth, and P2 mouth carrys out control cathode.Native system is lighted all charactrons by dynamic display types.

Claims

1. an indoor harmful gas detection system, is characterized in that its hardware components comprises:

(2) sensor circuit: select MQ-7 carbon monoxide (CO) gas sensor, this sensor need to apply 2 voltages: heater voltage (VH) and test voltage (VC); Wherein VH is used to sensor that specific working temperature is provided, and VC is for measuring the voltage (VRL) on the pull-up resistor (RL) of connecting with sensor; VC need use direct supply; RL=500 Ω;

(3) signal conditioning circuit: signal conditioning circuit uses amplifier ADOP7AH to design signal comparator, regulates the input voltage (Vj) of this amplifier forward by adjustable potentiometer R4, and C6 is output filter capacitor;