Slides from the embedded Java workshop on the last day of the JCrete unconference. Includes instructions for Lego Mindstorms EV3 and Raspberry Pi.

1. JCrete Embedded Java
Hacking
Stephen Chin
Java Technology Ambassador
JavaOne Content Chair
@steveonjava

2. What Runs Java?

3. What Runs Java?

4. Java and 3G in a Tiny Package
> Cinterion EHS5

5. Really Tiny…
27.6mm
18.8mm

6. http://upload.wikimedia.org/wikipedia/commons/3/3d/Cloud_forest_Ecuador.jpg

7. =
Have Java With Your Dessert
Raspberry Pi

8. Pis are Affordable
$35

9. Chalkboard Electronics Touchscreen
 10" or 7" Form Factor
 Connects via HDMI/USB
 Tested with JavaFX 8
 10% Exclusive Discount:
G1F0U796Z083

10. How to Setup Your Pi
> Step 1: Install Linux
> Step 2: Download/Copy Java 8 for ARM
> Step 3: Deploy and Run JVM Language Apps
http://steveonjava.com/
javafx-on-raspberry-pi-3-easy-steps/

11. Electronic Safety!
> Unplug from wall before wiring
> Get rid of static by touching a metal
surface
> Don't touch exposed wires/metal
> Never remove/insert SD Card while
power is on
11

12. What Comes in Your Lab Kit
1. Touch Screen
2. SD Card
3. Keyboard
4. Yellow Box:
 Power Adapter
 LVDS Cable/Board
 Raspberry Pi Model B
 Mini-USB Cable (power)
Please Save All the Packaging for Later

13. Hooking Up the Pi (Part A)
1. Insert the SD Card in to the Pi
 Will appear upside down when looking at the top
of your Pi
2. Insert the HDMI board into the Pi's HDMI
jack
3. Connect the Pi power to the HDMI board
 Use the Micro USB Cable (short one)
13
Important: Connect everything before plugging into the wall

14. Hooking Up the Pi (Part B)
4. Slide the LCD cable into the back of the display
 Side with gold connectors goes up
 Be careful, the connector is fragile!
5. Hook up the USB keyboard
6. Connect the USB end to one of the Pi's USB host ports
 This provides touch input
14
Verify connections and plug into power now

15. Is it Working?
> Should get a bunch of flashing LEDs to indicate booting
 Boot takes approx 30 seconds
> The LCD screen should light up
 Might be dim if the light sensor is obstructed
> And you will should see a Linux boot screen with lots of text

16. Logging In
At the login prompt type your username:
> pi
And enter the password:
> raspberry

17. Running the JavaFX Sample Application
Change directory to the project folder
> cd MaryHadALittleLambda
Run the build script
> ant

18. 18

19. Hacking the Code
Run the nano text editor:
> nano src/sample/MapObject.java
Save your changes:
> Control-O Enter
Exit Nano:
> Control-X
Compile/Run:
> ant

20. Mary Had a Little Lambda Project
> Open-source project to demonstrate lambda features
> Visual representation of streams, filters, and maps
20
https://github.com/steveonjava/MaryHadALittleLambda

21. Stuff to do…
> Changes to MaryHadALittleLambda:
 Change the number of sheep
 Make the rainbow have different colors
 Change the fox size to be fatter/skinnier
 Add new graphics (additional image files under images/extra)
21
camel.png lion.png greendragon.png cow.png Brownbear.png

22. GPIO access

23. Wiring LEDs
> Wire the elements in
series:
 Connect the long end
of the LED to GPIO
 Connect the short end
of the LED to the
resistor
 Connect the resistor
to Ground
To GPIO To Ground
23

24. Using a Breadboard
> Pins are connected
horizontally in the center
> The edges are connect
vertically
> No current passes the
center line
24

25. Pi Cobbler
> Connects your Pi to the
Breadboard
> The white line is Pin 1
> Connect it in the center
top of your Breadboard
25

26. Pi4J
> The samples are located in
/opt/pi4j/examples
> Compile the samples by typing "./build"
> Instructions for running the samples are
printed out at the end of the build
> Pi4j needs root access to use GPIO (use
"sudo")
26

27. ControlGpioExample
27
> Demonstrates Controlling Pins:
 pin.low()
 pin.toggle()
 pin.pulse(duration, blocking)
> Try creating your own pattern!
sudo java -classpath .:classes:/opt/pi4j/lib/'*' BlinkGpioExample

28. Wiring Buttons
> Connect a circuit
across two legs
> While the button is
pressed…
 The legs numbered 1
and 2 are connected
 The legs numbered 3
and 4 are connected
28

29. ListenGpioExample
29
> Demonstrates Listening to a pin:
 addListener(pinListener)
> Change the message/action when
a button is pressed!
sudo java -classpath .:classes:/opt/pi4j/lib/'*' ListenGpioExample

30. BlinkGpioExample
30
> Use LEDs and Buttons together!
sudo java -classpath .:classes:/opt/pi4j/lib/'*' BlinkGpioExample

31. LeJOS
How it works on the EV3

32. The Heart of the EV3
> TI Sitara AM1808
 ARM9, 300Mhz
> 64MB RAM / 16MB Flash
> Analog to Digital Converter
> 4 Motor Ports
> 4 Sensor Ports
> Bluetooth / USB
> MicroSD

33. EV3 Motors

34. EV3 Sensors

35. Color and Light Sensor

36. High frequency
sound waves
Ultrasonic Sensor
Measuring mode Vs Presence Mode

37. Infrared Sensor

38. Remote Control

39. Getting Started with LeJOS
Creating Your SD Card
> Micro SD Card (> 2GB)
> Compatible WIFI adapter
 NetGear WNA1100
 EDIMAX EW-7811Un
> Linux (or a Linux VM)
> Details here:
http://sourceforge.net/p/lejos/wiki/Home/

40. Bluetooth Pairing
> Make sure your Lego is turned on
> Open "Devices and Printers" from the
Start menu
> Click "Add a device"
> Select the Lego brick
> After pairing, right click on the new
device and choose "Connect using" >
"Access point"

41. Eclipse Setup
> Open Eclipse
> Go to "Preferences"
> Click on leJOS EV3
> Change the brick name to
"10.0.1.1"
41

42. Creating a New LeJOS Project
> Go to "File" > "New" > "Project…"
> Choose a LeJOS EV3 Project
42

43. Create a Class File
> Create a new class ("File" > "New"
> "Class")
> Give it a package (e.g. sample)
> Give it a name (e.g. LCDTest)
43

44. Simple LeJOS Application
import lejos.nxt.Button;
import lejos.nxt.LCD;
public class EV3FirstProgram {
public static void main(String[] args) {
LCD.clear();
LCD.drawString("First EV3 Program", 0, 5);
Button.waitForAnyPress();
LCD.clear();
LCD.refresh();
}
}

45. Assemble Brace
Parts you will need Step 1

46. Assemble Brace
Step 2 Completed Brace

47. Build Base
Parts you will need Step 1

48. Build Base
Step 2 Completed Base

49. Assemble Motor
Motor parts Snap them on partially

50. Assemble Motor
Take motor and base And connect them like this

51. Add a Foot
Foot parts Step 1

52. Add a Foot
Step 2 Add the Foot to the Base

53. Add a Foot
Assembled Foot and Base

54. Add a Lock
Lock parts Partially insert the red attachers

55. Add a Lock
Attach the lock Push down the red attachers to secure

56. Construct the Tower
Tower parts Step 1 – push the rod all the way through

57. Construct the Tower
Step 2 Attach the Tower to the Base

58. Construct the Tower
Completed Tower

59. Build the Fan Motor
Fan Motor parts Step 1

60. Build the Fan Motor
Completed Fan Motor

61. Construct the Light Sensor
Light Sensor parts Step 1

62. Construct the Light Sensor
Completed Light Sensor

63. Assemble the Fan Blades
Fan Blade parts Step 1

64. Assemble the Fan
Fan Blade, Light Sensor, and Fan Motor Completed Fan

65. Assembled Wind Turbine
65

66. Wind Turbine Wiring
> Port A – Medium Moto
 Power Fan
> Port B – Large Motor
 Rotate Wind Turbine
> Port 1 – Light Sensor
 Track Ambient Light
66

67. EC: Gear Box Construction
Gear Box parts Step 1

68. EC: Gear Box Construction
Completed Fan with Gear Box

69. Making the Wind turbine turn
public class WindTurbine {
public static void main(String[] args) {
EV3MediumRegulatedMotor fan =
new EV3MediumRegulatedMotor(MotorPort.A);
fan.setSpeed(1500);
fan.setAcceleration(150);
fan.backward();
Delay.msDelay(10000);
}
}

70. Making the Tower spin
public class WindTurbine {
public static void main(String[] args) {
EV3LargeRegulatedMotor base =
new EV3LargeRegulatedMotor(MotorPort.B);
base.setSpeed(80);
base.rotateTo(-90);
base.rotateTo(90);
}
}

71. Checking the Ambient Light
public class WindTurbine {
public static void main(String[] args) {
EV3ColorSensor light =
new EV3ColorSensor(SensorPort.S1);
float[] sample = new float[1];
SensorMode mode = light.getAmbientMode();
mode.fetchSample(sample, 0);
LCD.drawString("Light = " + sample[0], 0, 4);
Delay.msDelay(5000);
}
}

72. Putting it all together…
> Can you write a program that will:
1. Rotate the fan in a circle
2. Check the ambient light while rotating
3. Move back to the brightest angle
4. Spin the fan
http://commons.wikimedia.org/wiki/Wind_generator#mediaviewer/File:Eolienne_et_centrale_thermique_Nuon_Sloterdijk.jpg

73. Stephen Chin
tweet: @steveonjava
blog: http://steveonjava.com
NightHacking Tour
Real Geeks
Live Hacking
nighthacking.com

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