Published August 27, 2018 © GPL3+

LED Air Quality Meter

An air quality meter's light will change based on the air quality value detected. Air quality data will be uploaded to a cloud's dashboard.

BeginnerFull instructions provided1,208

Things used in this project

Hardware components

Wilderness Labs Netduino

LED (generic)

Seeed Studio Grove - Gas Sensor(MQ2)

Software apps and online services

Microsoft Visual Studio 2015

Adafruit IO

Story

Introduction

My original idea was to use the NeoPixel as the indicator of this air quality meter. But I am not able to get a Netduino library to talk to NeoPixel. In order to save time, I decide to use a LED as an indicator.

This is a simple project using a MQ4 gas sensor, together with Netduino 3 WiFi. The LED light will turn on if the gas sensor's value is above certain threshold. To ease my testing, I add a light sensor so that I can turn on and off the LED by changing the resistance.

Step 1: Set Up the Netduino

Follow this get started guide to setup the board. Complete the Netduino Blink app to verify your setup is successful.

Next follow this guide to configure the WiFi network. Build and run the Blinky app to make sure you have the network connected.

Step 2: Add Sensors

Here, I add one MQ4 and one light sensors as shown in the picture below. A schematics diagram is provided at the end of this document. A picture is displayed below.

Step 3: Set Up Adafuit.io

Visit io.adafruit.com. Register an account if you do not have one. Here you set up the Feeds, Groups and Dashboard for this project.

A group with feeds:

The dashboard:

Get your key here:

The live dashboard should show something like below:

Step 4: The Code

For source code, please refer to the two C# files below. The following is the code fragment which posts data (gas and light values) from Netdruino to Adafruit.io.

     protected void MakeAdafruitIOWebRequest(int gasVal, int lightVal)
       {
           Debug.Print("now is " + DateTime.Now);
           var url = "https://io.adafruit.com/api/v2/wesee/groups/my-group/data";
           string data = "{\"feeds\": [ { \"key\": \"light\", \"value\": \"" + lightVal + "\" }, { \"key\": \"mq4\", \"value\": \"" + gasVal + "\" } ] }";
           var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
           httpWebRequest.Method = "POST";
           httpWebRequest.Headers.Set("X-AIO-Key", "X-AIO-Key");
           httpWebRequest.ContentType = "application/json";
           byte[] byteArray = Encoding.UTF8.GetBytes(data);
           httpWebRequest.ContentLength = byteArray.Length;
           // Get the request stream.
           Stream dataStream = httpWebRequest.GetRequestStream();
           // Write the data to the request stream.
           dataStream.Write(byteArray, 0, byteArray.Length);
           // Close the Stream object.
           dataStream.Close();
           var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
           using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
           {
               var result = streamReader.ReadToEnd();
               Debug.Print("this is what we got from " + url + ": " + result);
           }
       }

This makes the web service call:

if (!app.IsRunning) app.Run(gasVal, lightVal);

To test the turning on and off of the LED, I add the photocell light sensor so that I can show the effect by changing the resistance. This is the portion of the code that does the checking:

               if (lightVal > lightThreshold || gasVal > gasThreshold) {
                   led.Write(true); // turn on the LED 
               } else {
                   led.Write(false); // turn off the LED 
               }

Video

Summary

You see, this is a very simple project. The next step will adding AI to it. After collecting enough data, AI can be used to train and build a model where you can do prediction of air quality based on certain features.

Code

using System;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
using System.Threading;

namespace AirQualityMeter
{
    public class Program
    {
        public static void Main()
        {
            App app = new App();

            const int lightThreshold = 95;
            const int gasThreshold = 120;

            // configure an output port for us to "write" to the LED
            OutputPort led = new OutputPort(Pins.GPIO_PIN_D13, false);

            // configure an input port for light sensor
            var light = new SecretLabs.NETMF.Hardware.AnalogInput(Pins.GPIO_PIN_A0);
            light.SetRange(0, 100);

            // configure an input port for gas sensor
            var gas = new SecretLabs.NETMF.Hardware.AnalogInput(Pins.GPIO_PIN_A5);
            gas.SetRange(0, 200);

            int lightVal;
            int gasVal;

            int i = 0;
            while (true)
            {
                lightVal = light.Read();
                gasVal = gas.Read();

                if (!app.IsRunning) app.Run(gasVal, lightVal);

                if (lightVal > lightThreshold || gasVal > gasThreshold) {
                    led.Write(true); // turn on the LED 
                } else {
                    led.Write(false); // turn off the LED 
                }

                // Debug.Print("Looping " + i);
                Debug.Print("light value = " + lightVal);
                Debug.Print("gas value = " + gasVal);

                i++;

                Thread.Sleep(2000); // sleep for 2000ms 
            }
        }

    }

}

using System;
using Microsoft.SPOT;
using Microsoft.SPOT.Net.NetworkInformation;
using System.Net;
using System.IO;
using System.Threading;
using System.Text;

namespace AirQualityMeter
{
    public class App
    {
        NetworkInterface[] _interfaces;


        public bool IsRunning { get; set; }

        public void Run()
        {
            this.IsRunning = true;
            bool goodToGo = InitializeNetwork();

            if (goodToGo)
            {
                MakeWebRequest("http://www.payex.io/");
            }

            this.IsRunning = false;
        }

        public void Run(int gasVal,  int lightVal)
        {
            this.IsRunning = true;
            bool goodToGo = InitializeNetwork();

            if (goodToGo)
            {
                MakeAdafruitIOWebRequest(gasVal, lightVal);
            }

            this.IsRunning = false;
        }


        protected bool InitializeNetwork()
        {
            if (Microsoft.SPOT.Hardware.SystemInfo.SystemID.SKU == 3)
            {
                Debug.Print("Wireless tests run only on Device");
                return false;
            }

            Debug.Print("Getting all the network interfaces.");
            _interfaces = NetworkInterface.GetAllNetworkInterfaces();

            // debug output
            ListNetworkInterfaces();

            // loop through each network interface
            foreach (var net in _interfaces)
            {

                // debug out
                ListNetworkInfo(net);

                switch (net.NetworkInterfaceType)
                {
                    case (NetworkInterfaceType.Ethernet):
                        Debug.Print("Found Ethernet Interface");
                        break;
                    case (NetworkInterfaceType.Wireless80211):
                        Debug.Print("Found 802.11 WiFi Interface");
                        break;
                    case (NetworkInterfaceType.Unknown):
                        Debug.Print("Found Unknown Interface");
                        break;
                }

                // check for an IP address, try to get one if it's empty
                return CheckIPAddress(net);
            }

            // if we got here, should be false.
            return false;
        }

        protected void MakeWebRequest(string url)
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
            httpWebRequest.Method = "GET";

            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                var result = streamReader.ReadToEnd();
                Debug.Print("this is what we got from " + url + ": " + result);
            }
        }

        protected void MakeAdafruitIOWebRequest(int gasVal, int lightVal)
        {
            Debug.Print("now is " + DateTime.Now);

            var url = "https://io.adafruit.com/api/v2/wesee/groups/my-group/data";
            string data = "{\"feeds\": [ { \"key\": \"light\", \"value\": \"" + lightVal + "\" }, { \"key\": \"mq4\", \"value\": \"" + gasVal + "\" } ] }";

            var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
            httpWebRequest.Method = "POST";
            httpWebRequest.Headers.Set("X-AIO-Key", "X-AIO-Key");
            httpWebRequest.ContentType = "application/json";

            byte[] byteArray = Encoding.UTF8.GetBytes(data);
            httpWebRequest.ContentLength = byteArray.Length;

            // Get the request stream.
            Stream dataStream = httpWebRequest.GetRequestStream();
            // Write the data to the request stream.
            dataStream.Write(byteArray, 0, byteArray.Length);
            // Close the Stream object.
            dataStream.Close();

            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                var result = streamReader.ReadToEnd();
                Debug.Print("this is what we got from " + url + ": " + result);
            }
        }

        protected bool CheckIPAddress(NetworkInterface net)
        {
            int timeout = 10000; // timeout, in milliseconds to wait for an IP. 10,000 = 10 seconds

            // check to see if the IP address is empty (0.0.0.0). IPAddress.Any is 0.0.0.0.
            if (net.IPAddress == IPAddress.Any.ToString())
            {
                Debug.Print("No IP Address");

                if (net.IsDhcpEnabled)
                {
                    Debug.Print("DHCP is enabled, attempting to get an IP Address");

                    // ask for an IP address from DHCP [note this is a static, not sure which network interface it would act on]
                    int sleepInterval = 10;
                    int maxIntervalCount = timeout / sleepInterval;
                    int count = 0;
                    while (IPAddress.GetDefaultLocalAddress() == IPAddress.Any && count < maxIntervalCount)
                    {
                        Debug.Print("Sleep while obtaining an IP");
                        Thread.Sleep(10);
                        count++;
                    };

                    // if we got here, we either timed out or got an address, so let's find out.
                    if (net.IPAddress == IPAddress.Any.ToString())
                    {
                        Debug.Print("Failed to get an IP Address in the alotted time.");
                        return false;
                    }

                    Debug.Print("Got IP Address: " + net.IPAddress.ToString());
                    return true;

                    //NOTE: this does not work, even though it's on the actual network device. [shrug]
                    // try to renew the DHCP lease and get a new IP Address
                    //net.RenewDhcpLease ();
                    //while (net.IPAddress == "0.0.0.0") {
                    //	Thread.Sleep (10);
                    //}

                }
                else
                {
                    Debug.Print("DHCP is not enabled, and no IP address is configured, bailing out.");
                    return false;
                }
            }
            else
            {
                Debug.Print("Already had IP Address: " + net.IPAddress.ToString());
                return true;
            }

        }

        protected void ListNetworkInterfaces()
        {
            foreach (var net in _interfaces)
            {
                switch (net.NetworkInterfaceType)
                {
                    case (NetworkInterfaceType.Ethernet):
                        Debug.Print("Found Ethernet Interface");
                        break;
                    case (NetworkInterfaceType.Wireless80211):
                        Debug.Print("Found 802.11 WiFi Interface");
                        break;
                    case (NetworkInterfaceType.Unknown):
                        Debug.Print("Found Unknown Interface");
                        break;

                }
            }
        }

        protected void ListNetworkInfo(NetworkInterface net)
        {
            Debug.Print("MAC Address: " + BytesToHexString(net.PhysicalAddress));
            Debug.Print("DHCP enabled: " + net.IsDhcpEnabled.ToString());
            Debug.Print("Dynamic DNS enabled: " + net.IsDynamicDnsEnabled.ToString());
            Debug.Print("IP Address: " + net.IPAddress.ToString());
            Debug.Print("Subnet Mask: " + net.SubnetMask.ToString());
            Debug.Print("Gateway: " + net.GatewayAddress.ToString());

            if (net is Wireless80211)
            {
                var wifi = net as Wireless80211;
                Debug.Print("SSID:" + wifi.Ssid.ToString());
            }

        }

        private static string BytesToHexString(byte[] bytes)
        {
            string hexString = string.Empty;

            // Create a character array for hexidecimal conversion.
            const string hexChars = "0123456789ABCDEF";

            // Loop through the bytes.
            for (byte b = 0; b < bytes.Length; b++)
            {
                if (b > 0)
                    hexString += "-";

                // Grab the top 4 bits and append the hex equivalent to the return string.        
                hexString += hexChars[bytes[b] >> 4];

                // Mask off the upper 4 bits to get the rest of it.
                hexString += hexChars[bytes[b] & 0x0F];
            }

            return hexString;
        }

    }
}

namespace System.Diagnostics
{
    public enum DebuggerBrowsableState
    {
        Never = 0,
        Collapsed = 2,
        RootHidden = 3
    }
}

Credits

vincent wong

81 projects • 205 followers

LED Air Quality Meter

Things used in this project

Hardware components

Software apps and online services

Story

Introduction

Step 1: Set Up the Netduino

Step 2: Add Sensors

Step 3: Set Up Adafuit.io

Step 4: The Code

Video

Summary

Schematics

Netduino Sensors Adafruit

Code

Program.cs

App.cs

Credits

vincent wong

Comments

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LED Air Quality Meter

LED Air Quality Meter

Things used in this project

Hardware components

Software apps and online services

Story

Introduction

Step 1: Set Up the Netduino

Step 2: Add Sensors

Step 3: Set Up Adafuit.io

Step 4: The Code

Video

Summary

Schematics

Netduino Sensors Adafruit

Code

Program.cs

App.cs

Credits

vincent wong

Comments

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