Grove – Gas Sensor(MQ2) 氣體感測器 seeed原廠

商品說明

Grove – Gas Sensor MQ2 氣體感測器

Grove – Gas Sensor MQ2 氣體感測器模組能檢測家庭或工業區域的氣體洩漏，檢測的氣體包括異丁烷，液化石油氣，甲烷，乙醇，氫氣，煙霧等。感測器的回應速度快，便於實際的測量。通過板上的電位器調整輸出精度。

特徵

• 快速回應並具備高靈敏度
• 檢測範圍廣
• 穩定，工作壽命長
• Grove 接口

規格參數

出貨清單

• Grove – Gas Sensor(MQ2) x1
• Grove連接線 x1

Documents

• Grove – Gas Sensor MQ2 wiki
• How to choose a gas sensor

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Grove – Gas Sensor(MQ2)

The Grove – Gas Sensor(MQ2) module is useful for gas leakage detecting(in home and industry). It can detect LPG, i-butane, methane, alcohol, Hydrogen, somke and so on. Based on its fast response time. measurements can be taken as soon as possible. Also the sensitivity can be adjusted by the potentiometer.

Features

• Wide detecting scope
• Stable and long lifetime
• Fast response and High sensitivity

Specification

Features

• Wide detecting scope
• Stable and long life
• Fast response and High sensitivity

Specification

Application Ideas

• Gas leakage detection.
• Toys.

Hardware Overview

This is a Analog output sensor. This needs to be connected to any one Analog socket in Base Shield. The examples used in this tutorial makes uses of A0 analog pin. Connect this module to the A0 port of Base Shield.

It is possible to connect the Grove module to Arduino directly by using jumper wires by using the connection as shown in the below table:

The output voltage from the Gas sensor increases when the concentration of gas increases. Sensitivity can be adjusted by varying the potentiometer. Please note that the best preheat time for the sensor is above 24 hours. For detailed information about the MQ-2 sensor, please refer to the data-sheet provided in resource section.

Getting Started

Connect the Grove – Gas Sensor(MQ2) to A0 port as shown in the above picture.

Gas Detection : Basic Example

In this example, the sensor is connected to A0 pin. The voltage read from the sensor is displayed. This value can be used as a threshold to detect any increase/decrease in gas concentration.

void setup() {
  Serial.begin(9600);
}
 
void loop() {
  float sensor_volt; 
  float sensorValue;
 
  sensorValue = analogRead(A0);
  sensor_volt = sensorValue/1024*5.0;
 
  Serial.print("sensor_volt = ");
  Serial.print(sensor_volt);
  Serial.println("V");
  delay(1000);
}

Measurement : Approximation

This examples demonstrates a way to know the approximate concentration of Gas. As per the data-sheet of the MQx sensors, these equations are tested for standard conditions and are not calibrated. It may vary based on change in temperature or humidity.

1.Keep the Gas Sensor in clean air environment. Upload the below program.

void setup() {
  Serial.begin(9600);
}
 
void loop() {
  float sensor_volt; 
  float RS_air; //  Get the value of RS via in a clear air
  float R0;  // Get the value of R0 via in H2
  float sensorValue;
 
/*--- Get a average data by testing 100 times ---*/   
    for(int x = 0 ; x < 100 ; x++)
  {
    sensorValue = sensorValue + analogRead(A0);
  }
  sensorValue = sensorValue/100.0;
/*-----------------------------------------------*/
 
  sensor_volt = sensorValue/1024*5.0;
  RS_air = (5.0-sensor_volt)/sensor_volt; // omit *RL
  R0 = RS_air/9.8; // The ratio of RS/R0 is 9.8 in a clear air from Graph (Found using WebPlotDigitizer)
 
  Serial.print("sensor_volt = ");
  Serial.print(sensor_volt);
  Serial.println("V");
 
  Serial.print("R0 = ");
  Serial.println(R0);
  delay(1000);
 
}

2. Then, open the serial monitor of Arduino IDE. Write down the value of R0 and this needs to be used in the next program. Please node down the R0 after the reading stabilizes.
Replace the R0 below with value of R0 tested above . Expose the sensor to any one of the gas listed above.

void setup() {
  Serial.begin(9600);
}
 
void loop() {
 
  float sensor_volt;
  float RS_gas; // Get value of RS in a GAS
  float ratio; // Get ratio RS_GAS/RS_air
  int sensorValue = analogRead(A0);
  sensor_volt=(float)sensorValue/1024*5.0;
  RS_gas = (5.0-sensor_volt)/sensor_volt; // omit *RL
 
  /*-Replace the name "R0" with the value of R0 in the demo of First Test -*/
  ratio = RS_gas/R0;  // ratio = RS/R0 
  /*-----------------------------------------------------------------------*/
 
  Serial.print("sensor_volt = ");
  Serial.println(sensor_volt);
  Serial.print("RS_ratio = ");
  Serial.println(RS_gas);
  Serial.print("Rs/R0 = ");
  Serial.println(ratio);
 
  Serial.print("\n\n");
 
  delay(1000);
 
}

Now, we can get the concentration of gas from the below figure

According to the graph, we can see that the minimum concentration we can test is 100ppm and the maximum is 10000ppm, in a other word, we can get a concentration of gas between 0.01% and 1%. However, we can’t provide a formula because the relation between ratio and concentration is nonlinear.