Nowadays, IoT is becoming more and more popular and we can no longer ignore it. However, for a regular Java developer getting started in this area may look a bit complicated. During this talk we'll focus on Rasberry Pi from the perspective of Java and compare available RPi models. How to control GPIO or handle real-world events Java style. Talk about if PWM can be controlled and all other things that can help us to build our own Java IoT project.

1. IOT FROM JAVA
PERSPECTIVE

2. HELLO!
I am Dmytro Panin
Java Senior Developer &
Architect at Levi9.

3. Agenda
▸ What’s IoT?
▸ MCU -> Arduino -> RPi
▸ Pi4J library
▹ GPIO
▹ PWM
▸ Development flow
▸ Demo
▸ Q&A

4. What’s IoT?No one knows exactly :(
IoT is a buzzword

5. “It summed up an important insight—one
that 10 years later, after the Internet of
Things has become the title of everything
from an article in Scientific American to
the name of a European Union conference,
is still often misunderstood.
Kevin Ashton

6. “IoT - The infrastructure of the
information society.
Global Standards Initiative
on Internet of Things

7. Mobile phone
So, is this IoT?

8. PC
What about this?

9. Smart devices
The heart of IoT

10. Types of IoT devices
Smart
devices
Phones PCs

11. 6,400,000,000
Approximate number of IoT
devices worldwide in 2016

12. “640K ought to be enough
for anybody
Bill Gates

13. Number of IoT devices in 2020

14. What’s below software?

15. Microcontroller
Self contained system
▸Microprocessor
▸Read only memory
▸Random access memory
▸Input / output

16. ATtiny2313
Characteristics
▸Processor: 20 Mhz
▸Flash: 2KB
▸SRAM: 128B
▸EEPROM: 128B
LedCube 3x3x3

17. ATmega32
Characteristics
▸Processor: 16 Mhz
▸Flash: 32KB
▸SRAM: 2KB
▸EEPROM: 1KB
LedCube 5x5x5

18. Resolution
Hard to kick off - software developers
aren’t happy
▸Tinkering is required
▸Additional components
▸Fuse programming
▸Programmer device
▸Hard to debug

19. “Arduino is an open-source
electronics platform based on easy-
to-use hardware and software.

20. Arduino UNO
Is a microcontroller board
based on the ATmega328P. It
has a 16 MHz quartz crystal, a
USB connection, a power jack.

21. Arduino Software (IDE)
▸Open source
▸Programming in C
▸Output to console
The IDE makes it easy to write
code and upload it to the
board. It runs on Windows,
Mac OS X, and Linux.

22. Resolution
Easy to start - software developers are happy
▸Many tutorials
▸Strong community
▸No configuration required
▸Upload firmware via USB

23. Are Java devs happy?

24. Raspberry Pi
Based on SoC (System on Chip)
Is a series of credit card-sized
single-board computers.

25. What it has on board?
HDMI
Any display that supports this
technology can be connected to
RPi and work as a PC.
USB
Keyboard, mouse, WiFi dongle,
Bluetooth, RFID readers, Flash
drives...
Networking
Some models have: WiFi,
Bluetooth, Ethernet on board.
GPIO
General-purpose input/output. Is
used to communicate with
various sensors or displaying
status.

26. Raspberry Pi zero
Characteristics
▸Processor: 1GHz
▸RAM: 512MB
▸Micro-SD card slot
▸Mini-HDMI
▸Micro-USB sockets for data
and power
▸65mm x 30mm x 5mm

27. Raspberry Pi 3
Characteristics
▸Processor: 1.2GHz x 4
▸RAM: 1GB
▸Micro-SD card slot
▸Full HDMI port
▸Ethernet port
▸4 USB ports
▸802.11n Wireless LAN
▸Bluetooth 4.1 + BLE

28. Supported Operating Systems
Official
▸Raspbian - based on
Debian (+ lite version)
Third party
▸Ubuntu MATE
▸Snappy Ubuntu core
▸Windows 10 IoT Core
▸RISC OS

29. How to develop Java apps?
for Raspberry Pi

30. Pi4J
Characteristics
▸ GPIO General Purpose I/O
▸ PWM Pulse-Width
Modulation
▸ Access system information
▸ I2C Inter-Integrated Circuit
▸ SPI Serial Peripheral
Interface
▸ UART RS232

31. GPIO (General-purpose input/output )
These pins are a physical interface
between the board and the outside world.
At the simplest level, you can think of
them as switches that you can turn on or
off (input) or that the Pi can turn on or off
(output).

32. Pi4J: Change state of a pin
In this example we will change
the pin’s state in order to light
the LED.

33. Pi4J: Change state of a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
outputPin.setState(PinState.HIGH);
Thread.sleep(1000);
outputPin.toggle();
gpio.shutdown();

34. Pi4J: Change state of a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
outputPin.setState(PinState.HIGH);
Thread.sleep(1000);
outputPin.toggle();
gpio.shutdown();

35. Pi4J: Change state of a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
outputPin.setState(PinState.HIGH);
Thread.sleep(1000);
outputPin.toggle();
gpio.shutdown();

36. Pi4J: Change state of a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
outputPin.setState(PinState.HIGH);
Thread.sleep(1000);
outputPin.toggle();
gpio.shutdown();

37. Pi4J: Change state of a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
outputPin.setState(PinState.HIGH);
Thread.sleep(1000);
outputPin.toggle();
gpio.shutdown();

38. Pi4J: Listen to a pin
In this example the pin is
provisioned as an input, so we
could process when the button
is pushed or released.

39. Pi4J: Listen to a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
inputPin.addListener((GpioPinListenerDigital)(event) -> {
if (event.getState().isLow()) {
System.out.println("Button is pressed");
} else {
System.out.println("Button is released");
}
});
gpio.shutdown();

40. Pi4J: Listen to a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
inputPin.addListener((GpioPinListenerDigital)(event) -> {
if (event.getState().isLow()) {
System.out.println("Button is pressed");
} else {
System.out.println("Button is released");
}
});
gpio.shutdown();

41. Pi4J: Listen to a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
inputPin.addListener((GpioPinListenerDigital)(event) -> {
if (event.getState().isLow()) {
System.out.println("Button is pressed");
} else {
System.out.println("Button is released");
}
});
gpio.shutdown();

42. Pi4J: Listen to a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
inputPin.addListener((GpioPinListenerDigital)(event) -> {
if (event.getState().isLow()) {
System.out.println("Button is pressed");
} else {
System.out.println("Button is released");
}
});
gpio.shutdown();

43. Pi4J: Listen to a pin
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
inputPin.addListener((GpioPinListenerDigital)(event) -> {
if (event.getState().isLow()) {
System.out.println("Button is pressed");
} else {
System.out.println("Button is released");
}
});
gpio.shutdown();

44. Pull-up resistor
Pre logic gate
Pull-down resistor

45. Pi4J: Pin state toggler
In this example the pin’s state
toggles in accordance with the
button.

46. Pi4J: Pin state toggler
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
inputPin.addTrigger(
new GpioToggleStateTrigger(PinState.LOW, outputPin));
gpio.shutdown();

47. Pi4J: Pin state toggler
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
inputPin.addTrigger(
new GpioToggleStateTrigger(PinState.LOW, outputPin));
gpio.shutdown();

48. Pi4J: Pin state toggler
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
inputPin.addTrigger(
new GpioToggleStateTrigger(PinState.LOW, outputPin));
gpio.shutdown();

49. Pi4J: Pin state toggler
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
inputPin.addTrigger(
new GpioToggleStateTrigger(PinState.LOW, outputPin));
gpio.shutdown();

50. Pi4J: Pin state toggler
GpioController gpio = GpioFactory.getInstance();
GpioPinDigitalInput inputPin =
gpio.provisionDigitalInputPin(RaspiPin.GPIO_03,
PinPullResistance.PULL_UP);
GpioPinDigitalOutput outputPin =
gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04,
PinState.LOW);
inputPin.addTrigger(
new GpioToggleStateTrigger(PinState.LOW, outputPin));
gpio.shutdown();

51. PWM (Pulse-Width Modulation)
Pulse Width Modulation, or
PWM, is a technique for getting
analog results with digital
means. Digital control is used to
create a square wave, a signal
switched between on and off.

52. Pi4J: Software PWM
GpioController gpio = GpioFactory.getInstance();
GpioPinPwmOutput pinPwmOutput =
gpio.provisionSoftPwmOutputPin(RaspiPin.GPIO_04);
pinPwmOutput.setPwmRange(100);
pinPwmOutput.setPwm(50);
Thread.sleep(15000);
gpio.shutdown();

53. Pi4J: Software PWM
GpioController gpio = GpioFactory.getInstance();
GpioPinPwmOutput pinPwmOutput =
gpio.provisionSoftPwmOutputPin(RaspiPin.GPIO_04);
pinPwmOutput.setPwmRange(100);
pinPwmOutput.setPwm(50);
Thread.sleep(15000);
gpio.shutdown();

54. Pi4J: Software PWM
GpioController gpio = GpioFactory.getInstance();
GpioPinPwmOutput pinPwmOutput =
gpio.provisionSoftPwmOutputPin(RaspiPin.GPIO_04);
pinPwmOutput.setPwmRange(100);
pinPwmOutput.setPwm(50);
Thread.sleep(15000);
gpio.shutdown();

55. Pi4J: Software PWM
GpioController gpio = GpioFactory.getInstance();
GpioPinPwmOutput pinPwmOutput =
gpio.provisionSoftPwmOutputPin(RaspiPin.GPIO_04);
pinPwmOutput.setPwmRange(100);
pinPwmOutput.setPwm(50);
Thread.sleep(15000);
gpio.shutdown();

56. Pi4J: Hardware PWM
GpioController gpio = GpioFactory.getInstance();
GpioPinPwmOutput pinPwmOutput =
gpio.provisionPwmOutputPin(RaspiPin.GPIO_01);
pinPwmOutput.setPwmRange(100);
pinPwmOutput.setPwm(50);
Thread.sleep(15000);
gpio.shutdown();

57. Development flow?
for Raspberry Pi

58. BlueJ
BlueJ is a development
environment that allows you
to develop Java programs
quickly and easily.

59. BlueJ
A free Java
Development
Environment designed
for beginners, used by
millions worldwide.

60. Executing during development
Compile code

61. Executing during development
Compile code Copy via SCP

62. Executing during development
Compile code Copy via SCP
Execute on
PRi

63. Executing during development
Compile code Copy via SCP
Execute on
PRi
One click action

64. Demo
Jenkins traffic light

65. Virtual IoT
Controlling a real world IoT
traffic light via a “virtual” IoT
device from inside of a
game. The devices are
connected via TCP/IP.

66. Virtual IoT
Vice versa. Controlling a
“virtual” IoT device located
inside of a game using a real
world IoT traffic light.
The devices have a “both
ways” connection.

67. THANKS!
Contacts:
https://www.linkedin.com/in/DmytroPanin/
dmytro.panin@gmail.com
Slides and code:
https://www.slideshare.net/DmytroPanin/
https://github.com/dr-mod/traffic-light/

68. Links
http://pi4j.com/
https://www.raspberrypi.org/
https://www.arduino.cc/
IoT from Java perspective