Java Device I/O at Raspberry PI to Build a Candy Vending Machine

Java Native GPIO Operations
Using Device I/O API

About me…
@jeffprestes
Developer Advocate
Java, PHP, JavaScript Developer

Agenda
 What is not IoT
 What is IoT
 Polymath required skills
 Small history of RaspberryPi
 RaspberryPi Components and slots
 Raspbian – a Debian/Linux to RasberryPi
 Java support to SOC devices
 Java Device I/O
 Lab
 Configure WiFi network (static / dhcp / resolv.conf)
 Upgrade the Raspbian
 Install WiringPi
 Install Java for Embedded devices

This is not IoT… (IMHO)
This is so cool but this is Eletronic!!

And this is not new…
(who has gray hair can say… P)

What is IoT?
Internet
Million of Web
Services
(PayPal, Twitter,
Google, Netflix,
Facebook)
Things
Billions of sensors,
motors, displays,
appliances, toys,
cars, stores, robots
+

And to work with IoT you’re going
to need more skills
You’re going to need to a Polimath
A polymath (Greek: πολυμαθής, polymathēs,
"having learned much")[1] is a person whose
expertise spans a significant number of different
subject areas; such a person is known to draw
on complex bodies of knowledge to solve
specific problems. The term was first used in the
seventeenth century; the related term,
polyhistor, is an ancient term with similar
meaning.
(Source: Wikipedia - http://en.wikipedia.org/wiki/Polymath)

Italian Polymath. What was da Vinci? Scientist?
Engineer? Mathematic? Painter? Sculptor? Musician?
Botanic? Anatomist?
Source: Wikipedia - http://en.wikipedia.org/wiki/Leonardo_da_Vinci

Server Side
Eletronic
(sometimes mechanic
and sculptor on wood or iron)
Client/Desktop
Mobile
(Beacons e Weareables)
Operation Systems

Java Device I/O at Raspberry PI to Build a Candy Vending Machine

History
 Designed in UK, University of
Cambridge, 2006, to be a chip alternative
to computers to students. Also a way to
students rediscover how cool is to work
with Robotic.
It has been projected to educational
purposes but can used in Commercial
ones too.
 Team that have concepted it: Eben Upton, Rob Mullins, Jack Lang and Alan Mycroft
 Raspberry Pi Foundation was created and first alpha boards were tested, 2011
 Sells begins April, 2012
 Model B+ is released in November, 2012
 More than 5 Million already have been sold

Raspbian is an unofficial port of Debian Wheezy armhf with compilation settings
adjusted to produce optimized "hard float" code that will run on the Raspberry Pi.
Note: Raspbian is not affiliated with the Raspberry Pi Foundation. Raspbian was created by a small,
dedicated team of developers that are fans of the Raspberry Pi hardware, the educational goals of the
Raspberry Pi Foundation and, of course, the Debian Project.
Best OS to Raspberry Pi nowadays. If you use Ubuntu, you’re going to feeling in
home. All basic Unix commands works on it and almost all basic server-side too:
Apache, Nginx, PHP, Java, Python, MySQL
Default user: pi / Default password: raspberry
And never forget: sudo apt-get install and be happy :D
To install it in your MicroSD card (Recommend 8Gb or more)
http://www.raspberrypi.org/documentation/installation/installing-images

JDK SE for
Embbeded Devices
Since JDK 7, Java SE SDK for Desktop was ported to ARM chips and
JDK 8 is already available.
As Raspberry Pi is based in a ARM chip and runs over a Linux
distribution you’re able to use Java SE
You can run your favorite Java Application Server or create JavaFX
applications
(you don’t need to learn JME or Python anymore :D!)

Device I/O API
Originally part of Java ME library, The Device I/O project is an open source,
Java-level API for accessing generic device peripherals on embedded
devices based on JavaSE. It’s under OpenJDK project.
https://wiki.openjdk.java.net/display/dio/Main
http://docs.oracle.com/javame/8.0/api/dio/api/index.html

Differences between
Device I/O and PI4J
PI4J is an excellent API, however it’s only for RaspberryPi if you would
need to run your APP into a BeagleBone board will have to rewrite all
GPIO access code.
Device I/O, as other Java API, brings abstraction layer over GPIO access
functionallity saving your time and complexity. Write once run anywhere :D

Differences between
Device I/O and PI4J
Also, GPIO map is different in two APIs, check:
Device I/O PI4J
http://docs.oracle.com/javame/8.0/get-started-rpi/piportsapdx.htm
http://pi4j.com/pins/model-b-plus.html

Device I/O API
Device I/O has a configuration file for each board
The Raspberry PI file is
dio.properties-raspberrypi
It has definitions for each GPIO ports
Thus Device I/O can works with different SoC Computers

Device I/O API
Device I/O requires special JDK permissions to access GPIO
Device I/O comes with gpio.policy file
You can map each Pin you’re planning to use or only:
grant {
permission jdk.dio.gpio.GPIOPinPermission "*:*";
permission jdk.dio.DeviceMgmtPermission "*:*", "open";
};
(okay, don’t do this in production kids)

Thanks.
Jeff Prestes
@jeffprestes
Slideshare.com/jeffprestes
Github.com/jeffprestes
@paypaldev
developer.paypal.com
developers.braintreepayments.com

Configure your wifi credentials:
sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
(file content below)
network={
ssid="iPhone"
psk="43070720"
}
network={
ssid=”<<your-wifi-name-here>>"
psk=”<<your-wifi-password>>"
}
network={
ssid="BoxNet"
psk="hackkitty"
}

Configure your wifi network using static IP:
sudo nano /etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet dhcp
auto wlan0
allow-hotplug wlan0
iface wlan0 inet static
address 192.168.20.218
netmask 255.255.255.0
gateway 192.168.20.1
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet static

Configure your wifi network using DHCP (most used):
sudo nano /etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet dhcp
auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

sudo apt-get update
sudo apt-get dist-upgrade
//Upgrades Raspbian
sudo reboot
//Use Reboot to restart Raspbian safetly
sudo halt
//Use halt to turn off Raspbian safetly

sudo nano /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
//Google DNS servers
Configure the DNS Servers

Wiring Pi
It is GPIO Interface library for the Raspberry Pi. It’s written in C for the
BCM2835 used in the Raspberry Pi.
WiringPi includes a command-line utility gpio which can be used to
program and setup the GPIO pins.

Wiring Pi
$ sudo apt-get install git-core
$ git clone git://git.drogon.net/wiringPi
$ cd wiringPi
$ git pull origin
$ ./build
Installation
$ gpio -v
$ gpio readall
Test

Get back to your user home directory
(in this case you’re using pi user, remember?)
$ cd ~/

Downloading
JDK SE 8 for Embedded
I will have to download it from your computer as you will have to accept
Oracle’s terms and conditions.
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-arm-downloads-2187472.html
Mac and Linux users: use scp to copy the file
$ scp jdk-<version>-linux-arm-vfp-hflt.gz pi@<your-device-
ip>:/home/pi/jdk-<version>-linux-arm-vfp-hflt.tar.gz
(note that I’ve changed the extention
because the downloaded file came only with .gz extention)
Windows users: use WinSCP to do this

Installing
At PI home directory execute:
$ sudo mkdir -p /opt/java
$ sudo chown root:root /opt/java
$ cd /opt/java
$ sudo tar xvzf ~/jdk-<version>-linux-arm-vfp-hflt.tar.gz
Set default java and javac to the new installed JDK.
$ sudo update-alternatives --install /usr/bin/javac javac /opt/jdk-<version>/bin/javac
1
$ sudo update-alternatives --install /usr/bin/java java /opt/jdk-<version>/bin/java 1
$ sudo update-alternatives --config javac
$ sudo update-alternatives --config java
After all, verify with the commands with -verion option.
$ java -version
$ javac -version

Installing
Double check if java version is correct for root too:
$ sudo java -version
$ sudo javac –version
This is important because will you need to run your Java application that access
GPIO with root privileges.

Installing
Define JAVA_HOME environment variable:
$ sudo nano /etc/environment
And add to it:
JAVA_HOME="/opt/jdk-<version>"
Do the same in your bash profile
$ nano ~/.bashrc
And add to it:
export JAVA_HOME="/opt/java/jdk-<version>"
export PATH=$PATH:$JAVA_HOME/bin

Installing
Java Device I/O
You’ll need to download and compile the library in your Raspberry PI.
Device I/O like other OpenJDK projects uses Mercurial to manage their source
code. You must install it into your Raspberry PI
$ sudo apt-get install mercurial
Create a directory to store the source code and compile it
$ mkdir deviceio
Download it
$ cd deviceio
$ hg clone http://hg.openjdk.java.net/dio/dev

Installing
Java Device I/O
Let’s compile it:
$ export PI_TOOLS=/usr
$ cd dev
$ make
After this, let’s install your Device I/O files in your JRE
$ cp -r build/deviceio/lib/*
$JAVA_HOME/jre/lib

Now let’s get started to talk about good things…

Our Lab: Create a Candy
Vending Machine
How it works

Vending Machine

Let’s use Wiring Pi to test the circuits
$ sudo gpio mode 1 output
$ sudo gpio mode 4 output
$ sudo gpio write 1 1
Vending Machine

Copy the dio.jar compiled in your Raspberry Pi to your machine
$ scp ~/deviceio/dev/build/jar/dio.jar <your-
user>@<yourmachineip>:~/dio.jar
Or use yout WinSCP
Add it your Maven local repository
$ mvn install:install-file -Dfile=~/dio.jar -DgroupId=jdk.dio -
DartifactId=device-io -Dversion=1.0 -Dpackaging=jar -
DgeneratePom=true
Open the Netbeans and at Team->Git->Clone Repository
https://github.com/jeffprestes/candies-client-native-java.git
Vending Machine

Copy the jar compiled with Dependencies to home’s directory of pi user.
Now it’s time to edit GPIO permissions in gpio.policy file
Copy it to home directory
$ cp ~/deviceio/dev/samples/gpio/gpio.policy ~/gpio.policy
And content must be like this
grant {
// permissions for using GPIO pin 18 GPIOLEDSample
permission jdk.dio.gpio.GPIOPinPermission ":18";
permission jdk.dio.gpio.GPIOPinPermission "0:18";
permission jdk.dio.DeviceMgmtPermission "GPIO18:18", "open";
permission jdk.dio.gpio.GPIOPinPermission ":24";
permission jdk.dio.gpio.GPIOPinPermission "0:24";
permission jdk.dio.DeviceMgmtPermission "GPIO24:24", "open";
};
Vending Machine

Now, let’s start the machine application
$ sudo java
-Djdk.dio.registry=/home/pi/java/dio/config/dio.properties-raspberrypi
-Djava.security.policy=/home/pi/java/nativegpio/gpio.policy
-jar candies.jar iot.eclipse.org jeffprestes/candies/world machineusa 1883
Where:
iot.eclipse.org is the MQTT server
jeffprestes/candies/world is the queue
machineusa is the client name
1883 is the MQTT broker port
Vending Machine

Vending Machine
To buy
Create a Premier account in PayPal Sandbox
developer.paypal.com -> Dashboard -> Sandbox -> Accounts ->
Create Account
Later, goto candies.novatrix.com.br in your mobile phone and
use this user as a buyer

Java Device I/O at Raspberry PI to Build a Candy Vending Machine

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