Grove Air Quality Sensor v1.3

Features

  • Responsive to a wide scope of target gases

  • Cost efficient

  • Durable

  • Compatible with 5V and 3.3V

!!!Cautions 1. Requires relatively clean air as an initial condition. 2. Long time exposure to highly polluted air can significantly weaken its sensitivity. 3. Coffre-fort et armoire forte:

Usage

With Arduino

As described in Introduction, this sensor performs better in providing qualitative results over a wide scope of target gases. In this demo, we will define 4 statuses for reference in the '.cpp' file. They are:

  • a. air fresh -- indicating a good air condition

  • b. low pollution -- indicating a rather low concentration of target gases exist.

  • c. high pollution(without "Force signal active" message printed on serial monitor) -- you should be aware of the pollution level and consider if some measures could be taken.

  • d. high pollution(with "Force signal active" message printed on serial monitor) -- instant measures should be taken to improve the air quality.

We encapsulated the decision structure in a '.cpp' file. You can find information there on how to modify the thresholds.

Let's try it out!

1.Connect the Sensor to A0 port of Grove - Base Shield.

2.Download the File :AirQuality_Sensor Library.

3.Wait at least 2 minutes after powering on for heat-up of the sensor. Then open the example below by the path: File -> Example ->AirQuality_Sensor->AirQuality_Sensor.

/*
AirQuality Demo V1.0.
connect to A1 to start testing. it will needs about 20s to start
* By: http://www.seeedstudio.com
*/
#include "AirQuality.h"
#include "Arduino.h"
AirQuality airqualitysensor;
int current_quality =-1;
void setup()
{
    Serial.begin(9600);
    airqualitysensor.init(14);
}
void loop()
{
    current_quality=airqualitysensor.slope();
    if (current_quality >= 0)// if a valid data returned.
    {
        if (current_quality==0)
        Serial.println("High pollution! Force signal active");
        else if (current_quality==1)
        Serial.println("High pollution!");
        else if (current_quality==2)
        Serial.println("Low pollution!");
        else if (current_quality ==3)
        Serial.println("Fresh air");
    }
}
ISR(TIMER2_OVF_vect)
{
    if(airqualitysensor.counter==122)//set 2 seconds as a detected duty
    {

        airqualitysensor.last_vol=airqualitysensor.first_vol;
        airqualitysensor.first_vol=analogRead(A0); // change this value if you use another A port
        airqualitysensor.counter=0;
        airqualitysensor.timer_index=1;
        PORTB=PORTB^0x20;
    }
    else
    {
        airqualitysensor.counter++;
    }
}

4.Upload the code.

5.Open serial monitor.

To adjust the thresholds and indicating messages, refer to the decision structure below in the .cpp file.

int AirQuality::slope(void)
{
    while(timer_index)
    {
        if(first_vol-last_vol>400||first_vol>700)
        {
            Serial.println("High pollution! Force signal active.");
            timer_index=0;
            avg_voltage();
            return 0;

        }
        else if((first_vol-last_vol>400&&first_vol<700)||first_vol-vol_standard>150)
        {
            Serial.print("sensor_value:");
            Serial.print(first_vol);
            Serial.println("\t High pollution!");
            timer_index=0;
            avg_voltage();
            return 1;

        }
        else if((first_vol-last_vol>200&&first_vol<700)||first_vol-vol_standard>50)
        {
            //Serial.println(first_vol-last_vol);
            Serial.print("sensor_value:");
            Serial.print(first_vol);
            Serial.println("\t Low pollution!");
            timer_index=0;
            avg_voltage();
            return 2;
        }
        else
        {
            avg_voltage();
            Serial.print("sensor_value:");
            Serial.print(first_vol);
            Serial.println("\t Air fresh");
            timer_index=0;
            return 3;
        }
    }
    return -1;
}

With Raspberry Pi

1.You need to prepare a raspberry pi and a grovepi or grovepi+.

2.You need to completed configuring the development enviroment, otherwise follow here.

3.Connection

  • Plug the sensor to grovepi socket A0 by using a grove cable.

4.Navigate to the demos' directory:

cd yourpath/GrovePi/Software/Python/

To see the code

   nano grove_air_quality_sensor.py   # "Ctrl+x" to exit #
import time
import grovepi

# Connect the Grove Air Quality Sensor to analog port A0
# SIG,NC,VCC,GND
air_sensor = 0

grovepi.pinMode(air_sensor,"INPUT")

while True:
    try:
        # Get sensor value
        sensor_value = grovepi.analogRead(air_sensor)

        if sensor_value > 700:
            print "High pollution"
        elif sensor_value > 300:
            print "Low pollution"
        else:
            print "Air fresh"

        print "sensor_value =", sensor_value
        time.sleep(.5)

    except IOError:
        print "Error"

5.Run the demo.

   sudo python grove_air_quality_sensor.py

Resources

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