Tested on Raspberry Pi Zero.

This git contains:

• python scripts to measure:

  • temperature and humidity using DHT-22 (also known as AM2302) sensor,
  • visible and IR light intensity using TSL2561 sensor,

• cgi python scripts to visualise measurements via web UI (adapted from Building an SQLite temperature logger),

• python script to visualise temperature, humidity and current time on Pimoroni's Unicorn pHAT, an 8x4 RGB LED matrix,

• R notebook to analyse data and create an interactive scatter plot of humidity and temperature

Environmental parameters are recorded in an SQLite database, which requires the entire setup to have an Apache web server and SQLite database installed on the system.

Instructions below assume that:

• the Apache server is running (see below for installation instructions),
• the SQLite database is installed (see below for installation instructions),
• the home directory is /home/pi,
• DHT-22 humidity and temperature sensor is installed (see instructions),
• visible and IR light intensity sensor is installed (see instructions)

Follow steps below to get everything running.

0. Get the repository from hithub:

git clone https://github.com/dmattek/pi-enviro-meas.git

This will create pi-enviro-meas in the folder from which the git command was executed. Note that all paths in scripts assume that the directory is located in /home/pi. Change paths in scripts accordingly if different!

1. Copy CGI scripts to default CGI directory of Apache server:

sudo cp pi-enviro-meas/dht/cgi-bin/webguidht.py /usr/lib/cgi-bin/.
sudo cp pi-enviro-meas/tsl2561/cgi-bin/webguilight.py /usr/lib/cgi-bin/.

2. Copy initialised databases:

sudo cp pi-enviro-meas/dht/data/dhtlog_template.db /var/www/dhtlog.db
sudo cp pi-enviro-meas/tsl2561/data/lightlog_template.db /var/www/lightlog.db

3. Add crontab jobs:

*/10 * * * * /home/pi/pi-enviro-meas/dht/meas/logdbDHT.sh
*/10 * * * * /home/pi/pi-enviro-meas/tsl2561/meas/logdbLight.sh
@reboot /home/pi/pi-enviro-meas/dht/meas/dispDHTonUnicorn.sh 

The result is the measurement of temperature and humidity from DHT-22 sensor logged to /var/www/dhtlog.db, and light intenisty (IR and visible) to /var/www/lightlog.db every 10 minutes. The temperature and humidity are fetched every 10 minutes from the dhtlog.db database and shown along with current time on Unicorn pHAT matrix as colour-coded bars. Environmental parameters can be viewed through web UI by pointing your browser to http://your-pi-address/cgi-bin/webguidht.py and http://your-pi-address/cgi-bin/webguilight.py.

The R notebook, pi-enviro-meas/dht/Rscript/dht_anal.Rmd, analyses data and produces an interactive scatter plot of humidity vs temperature. The document can be knitted into an HTML file dht_anal.html.

Follow the instructions from Run python script as cgi under apache2 server.

Install Apache2 webserver:

	sudo apt-get install apache2 -y

Test Apache installation by typing the address of your Pi in a web browser. You should see a default page headlined by "It works!".

Enable mods in apache2 for cgi:

	sudo a2enmod cgid
	cd /etc/apache2/mods-enabled
	sudo ln -s /etc/apache2/mods-available/cgi.load

The default directory for cgi script is /usr/lib/cgi-bin/.

Test a simple bash CGI script by creating a /usr/lib/cgi-bin/hello.cgi file with the following contents:

	#!/bin/bash
	echo -e "Content-type: text/html\n\n"
	echo "<h1>Bash Script Test</h1>"

Make the script executable:

sudo chmod +x /usr/lib/cgi-bin/hello.cgi

Visit http://pi-address/cgi-bin/hello.cgi; you should see a big bold Hello World text.

Test a simple CGI Python script by creating a /usr/lib/cgi-bin/pytest.cgi file with the following contents:

	#!/usr/bin/python
	
	import cgi
	import cgitb
	cgitb.enable()

	print 'Content-type: text/html\n\n'
	print '<h1>Python Script Test</h1>'

Make the script executable:

sudo chmod +x /usr/lib/cgi-bin/pytest.cgi

Visit http://pi-address/cgi-bin/pytest.cgi; you should see a big bold Python Script Test text.

Run

sudo apt-get install sqlite3