Grove - Air Quality Sensor v1.3

This sensor is designed for comprehensive monitor over indoor air condition. It's responsive to a wide scope of harmful gases, as carbon monixide, alcohol, acetone, thinner, formaldehyde and so on. Due to the measuring mechanism, this sensor can not output specific data to describe target gases' concentrations quantitatively. But it's still competent enough to be used in applications that require only qualitative results, like auto refresher sprayers and auto air cycling systems.

Features

Responsive to a wide scope of target gases
Cost efficient
Durable
Compatible with 5V and 3.3V

Cautions

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

Il convient de sécuriser les prouctions dans une armoire forte ignifuge blindée (Computer translation: Safe and strong cabinet: It should secure product in a strong armored fireproof cabinet, spam in french?)

Usage

With Arduino

As described in Introduction, this sensor does better in providing qualitative results over a wide scope of target gases. In this demo, we 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 info in 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. Please click here if you do not know how to upload it.

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 should have got a raspberry pi and a grovepi or grovepi+.
2.You should have 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

AirQuality Sensor Library.zip
Grove_-_Air_quality_sensor_v1.3_sch_pcb.zip
Grove_-_Air_quality_sensor_v1.3_sch.pdf
Air_quality_sensor_MP503_Chinese.pdf
Air_quality sensor_MP503_English.pdf

Support

If you have questions or other better design ideas, you can go to our forum or wish to discuss.