Colour Detection & Filtering System - Arduino Code

This is the Arduino part of the development for my bachelor thesis device that sorts an orange by its ripeness

Installing Dependencies

SSH into the Arduino Yun

ssh root@YourArduinoAddressHere

Before moving with the installations, run an update

opkg update

Install uhttpd - Should already be pre-installed

opkg install uhttpd

Install sqlite3-cli

opkg install sqlite3-cli

Install PHP and relevant libraries - Latest version of PHP as of now is 7

opkg install php7-cli php7-cgi php7-mod-sqlite3 php7-mod-json

Install nano

opkg install nano

Editing the uhttpd configuration file

Do

nano /etc/config/uhttpd

Then add

list interpreter ".php=/usr/bin/php-cgi"

option index_page 'index.php'

Creating the SQLite database

Do

sqlite3 /mnt/sda1/sensor.db

Then create the table

CREATE TABLE "sensor_data" (id INTEGER PRIMARY KEY AUTOINCREMENT, type text, red INTEGER, green INTEGER, blue INTEGER, time DATETIME DEFAULT CURRENT_TIMESTAMP);

Then insert some filler data

INSERT INTO sensor_data (type, red, green, blue) VALUES ('ripe', '150', '20', '20');

Then display the contents of the table

SELECT * FROM sensor_data;

Creating the PHP file that takes in the query

Create the PHP file in the following area

nano /mnt/sda1/sensor.php

Insert this code

#!/usr/bin/php-cli
<?php
$db = new SQLite3('/mnt/sda1/sensor.db');
$query = "INSERT INTO sensor_data (type, red, green, blue) VALUES( '$argv[1]', '$argv[2]', '$argv[3]', '$argv[4]' )";
$db->exec($query);
$db->close();
?>

Creating the PHP file that displays your database results

Create the PHP file in

nano /www/stats/database.php

Type this in

<?php
$db = new SQLite3('/mnt/sda1/sensor.db');
$results = $db->query('select * from sensor_data');
$cols = $results->numColumns();
print "<table width='400'  border='1' cellspacing='0' cellpadding='0'>\n";
print "<tr>";
for ($i = 0; $i < $cols; $i++) {
        print "<th align='left'>".$results->columnName($i)."</th>";
}
print "</tr>\n";
while ($row = $results->fetchArray()){
        print "<tr>";
        for ($i = 0; $i < $cols; $i++) {
                print "<td>".$row[$i]."</td>";
        } //end for
        print "</tr>\n";
}
print "</table>\n";
$db->close();
?>

Your database will be viewed at YourArduinoAddressHere/stats/database.php

Development

Anything in the www folder on your Arduino Yun is your website

mkdir www/stats/

Create an index.php file in stats

<?php
  echo "Hello World, running PHP test!"
?>

Restart the uhttpd server

/etc/init.d/uhttpd restart

Your website should be on your Arduino's Address

Ex: 192.168.1.165/stats/

SQLite3 Commands

To clean up the database

DELETE FROM sensor_data;

To quit SQLite

.quit

Other

This was just created to test the capabilities of the Wi-Fi module on the Arduino Yun

The color detection and sorting device can be turned off by going to YourArduinoAddressHere/arduino/statusfilter/0/

And back on using YourArduinoAddressHere/arduino/statusfilter/1/

Credits

Big thanks to this guide on how to setup a server: https://hackaday.io/project/27905-setting-up-the-linkit-c-cross-compiler/log/71201-wifi-server

Amazing guide for publishing data on the Arduino Yun locally: https://forum.arduino.cc/index.php?topic=309600.0