AirMobile - 28 - Finalizing OpenHAB setup on BBB

It's time to finalize the OpenHAB setup on the BeagleBoneBlack, which will collect and analyze data stored on the AirVantage cloud.

The steps required to complete the installation are

Install web server

A web server is required to serve the files for the web page that shows collected data. I chose lighttpd because it's lightweight and easy to configure.

To install lighttpd, simply type

sudo apt-get install lighttpd

First, let's check that your configuration is ok:

$ lighttpd -t -f lighttpd.conf

Now let's start the server for testing:

$ lighttpd -D -f lighttpd.conf

I edited the config file in /etc/lighttpd/lighttpd.conf

server.document-root = "/var/www/airmobile/pages/" 
server.port = 8082

mimetype.assign = (
  ".html" => "text/html", 
  ".js" => "application/javascript", 
  ".txt" => "text/plain",
  ".jpg" => "image/jpeg",
  ".png" => "image/png" 
)

index-file.names = ( "index.html" )

Then I started the webserver by typing

/etc/init.d/lighttpd start

Copy web page files

AirMobile web files (HTML and Javascript) have been copied to

"/var/www/airmobile/pages"

Copy bindings

The binding bundles developed (namely gpio and iarvantage) needs to be copied to the openhab/addons folder. To create the bundle, right click on the project and select Export. In the Export wizard, select Deployable  plugins and fragments.

In the next step, enter the folder where you want the plugin to be generated and check the options as shown

During the deployment, I experienced a Java ClassNotFoundException. I was not able to completely understand the reason for that exception, and the only way to solve this issue was to create a bundle for each jar the AirVantage binding depends on (okhttp, Gson, scribe and org.json). I created bundle projects by selecting File -> New -> Project -> Bundle and following the wizard steps

Finally, I added the bundles to the Import-Package section of manifest file of the AirVantage binding.

Manifest-Version: 1.0
Bundle-Vendor: openHAB.org
Bundle-Version: 1.6.0.qualifier
Bundle-Activator: org.openhab.binding.airvantage.internal.AirVantageActivator
Bundle-ManifestVersion: 2
Bundle-Description: This is the AirVantage binding of the open Home Automation Bus (openHAB)
Import-Package: 
 com.google.gson,
 com.google.gson.reflect,
 com.squareup.okhttp,
 org.scribe.builder,
 org.json,
 org.apache.commons.lang,
 org.codehaus.jackson,
 org.codehaus.jackson.map,
 org.openhab.core.binding,
 org.openhab.core.events,
 org.openhab.core.items,
 org.openhab.core.library.items,
 org.openhab.core.library.types,
 org.openhab.core.types,
 org.openhab.model.item.binding,
 org.osgi.framework,
 org.osgi.service.cm,
 org.osgi.service.component,
 org.osgi.service.event,
 org.slf4j
Export-Package: org.openhab.binding.airvantage
Bundle-DocURL: http://www.openhab.org
Service-Component: OSGI-INF/binding.xml, OSGI-INF/genericbindingprovider.xml
Bundle-ClassPath: .,
 lib\scribe-1.3.5.jar,
 lib\gson-2.2.4-sources.jar,
 lib\json-20140107.jar,
 lib\okhttp-1.2.1-sources.jar

Define the items and the sitemap

First, a set of items that show the last sensor readings are defined

Number Home_Temperature "Temperature [%.1f]" <temperature> {airvantage="system=AirMobile1,measure=temperature"}
Number Home_Humidity "Humidity [%.0f]" <humidity> {airvantage="system=AirMobile1,measure=humidity"}
Number Home_CO "CO [%.3f]" <co> {airvantage="system=AirMobile1,measure=co"}
Number Home_NO2 "NO2 [%.3f]" <no2> {airvantage="system=AirMobile1,measure=no2"}
Number Home_Dust "Dust [%.0f]" <dust> {airvantage="system=AirMobile1,measure=dust"}
Number Home_AQI "AQI [%.2f]" <gauge>

Second, a set of items that show pollutant levels at a certain location (in this case the location of a public garden where I typically go for a run) are define

Number PB_Temperature "Temperature [%.1f]" <temperature> {airvantage="system=AirMobile1,measure=temperature"}
Number PB_Humidity "Humidity [%.0f]" <humidity> {airvantage="system=AirMobile1,measure=humidity"}
Number PB_CO "CO [%.3f]" <co> {airvantage="system=AirMobile1,measure=co"}
Number PB_NO2 "NO2 [%.3f]" <no2> {airvantage="system=AirMobile1,measure=no2"}
Number PB_Dust "Dust [%.0f]" <dust> {airvantage="system=AirMobile1,measure=dust"}
Number PB_AQI "AQI [%.2f]" <gauge>      

Finally, the item for controlling the servo for the Air Quality Index (see below) indicator is defined

Number Home_Servo "Servo [%.0f]" {gpio="pin:13 name:pwm_test_P8_13.11"}

Define the rule to compute AQI

In order to provide an easy to understand measure of the air quality, I defined a custom Air Quality Index. Unfortunately widely-used Air Quality indexes are based also on measure of the ozone concentration at ground level. Since the Air Mobile does not have a ozone sensor, I defined my own Air Quality index.

The index formula is

  homeAQI = 1 -
((((homeCO - 30.0)/(1000.0-30.0))* 0.4) +
(((homeNO2 - 200.0)/(2000.0-200.0))*0.4) +
(((homeDust-0.0)/(500.0-0.0))*0.2))

The index is basically a weighted average of the percentage of the three pollutants detected by the AirMobile sensor

The value of the index range from 0 (worst air quality) to 1 (best air quality)

The index is calculate by an OpenHAB rule

rule "Home_AQI_Calculation"
when
      Item Home_CO changed or
      Item Home_NO2 changed or
      Item Home_Dust changed
then
  homeCO = Home_CO.state as DecimalType
  homeNO2 = Home_NO2.state as DecimalType
  homeDust = Home_Dust.state as DecimalType

  homeAQI = 1 - ((((homeCO - 30.0)/(1000.0-30.0))* 0.4) + (((homeNO2 - 200.0)/(2000.0-200.0))*0.4) + (((homeDust-0.0)/(500.0-0.0))*0.2))
      postUpdate(Home_AQI, homeAQI)
  
  homeServo = 1500 + (homeAQI * 1000)
  postUpdate(Home_Servo, homeServo)
end

This rule also updates the servo position by converting the index value (from 0 t 1) to a PWM duty cycle value (from 600 to 2400 microseconds). The PWM duty cycle is then posted to the Home_Servo item