Wireless Sensor Networks

1. DR. VAISHALI D. KHAIRNAR
TERNA ENGINEERING COLLEGE
Wireless Sensor Networks

2. Wireless Sensor Networks

3. Continue..

4. Main Components of Single Node
Architecture
Communication
Device
Controller
Sensors/
Actuators
Power Supply
Memory

12. Different Types of Sensors
 Live in a World of Sensors. You can find different
types of Sensors in our homes, offices, cars etc.
working to make our lives easier by turning on the
lights by detecting our presence, adjusting the room
temperature, detect smoke or fire, make us
delicious coffee, open garage doors as soon as our
car is near the door and many other tasks.
 All these and many other automation tasks are
possible because of Sensors.
 What is a Sensor
 What are the Different Types of Sensors
 Applications of these different types of Sensors

13. Example
 Simple example of an automated system, which is
possible because of Sensors (and many other
components as well).

14. Real Time Application of
Sensors
 Discuss about Autopilot System in aircrafts. Almost
all civilian and military aircrafts have the feature of
Automatic Flight Control system or sometimes called
as Autopilot.

15.  An Automatic Flight Control System consists of different sensors for
different tasks like speed control, height, position, doors, obstacle, fuel,
maneuvering and many more. A Computer takes data from all these
sensors and processes them by comparing them with pre-designed/pre-
defined values.
 The computer then provides control signal to different parts like engines,
flaps, rudders etc. that help in a smooth flight. The combination of
Sensors, Computers and Mechanics makes it possible to run the plane in
Autopilot Mode.
 All the parameters i.e. the Sensors (which give inputs to the Computers),
the Computers (the brains of the system) and the mechanics (the outputs
of the system like engines and motors) are equally important in building a
successful automated system.

16.  We will be concentrating on the Sensors
part of a system and look at different
concepts associated with Sensors (like
types, characteristics, classification etc.).

17. What is a Sensor?
 Sensor as an input device which
provides an output (signal) with
respect to a specific physical
quantity (input).

18. Example:- LDR or a Light Dependent Resistor. It is a device, whose
resistance varies according to intensity of light it is subjected to.
When the light falling on an LDR is more, its resistance becomes very
less and when the light is less, well, the resistance of the LDR
becomes very high.
Connect this LDR in a voltage divider and check the voltage drop
across the LDR. This voltage can be calibrated to the amount of light
falling on the LDR. Hence, a Light Sensor.

19. List of different types of sensors that are commonly used in
various applications.
 sensors are used for measuring one of the physical properties like
Temperature, Resistance, Capacitance, Conduction, Heat Transfer
etc.
 Temperature Sensor
 Proximity Sensor
 Accelerometer
 IR Sensor (Infrared Sensor)
 Pressure Sensor
 Light Sensor
 Ultrasonic Sensor
 Smoke, Gas and Alcohol Sensor
 Touch Sensor
 Color Sensor
 Humidity Sensor
 Tilt Sensor
 Flow and Level Sensor

20. Temperature Sensor
Temperature Sensors are used everywhere like
computers, mobile phones, automobiles, air
conditioning systems, industries etc.

21. Proximity Sensors
Proximity Sensor is a non-contact
type sensor that detects the presence
of an object. Proximity Sensors can
be implemented using different
techniques like Optical (like Infrared
or Laser), Ultrasonic, Hall Effect,
Capacitive, etc.
Some of the applications of Proximity
Sensors are Mobile Phones, Cars
(Parking Sensors),

22. Ultrasonic Sensor
 An Ultrasonic
Sensor is a non-
contact type device
that can be used to
measure distance
as well as velocity
of an object. An
Ultrasonic Sensor
works based on
the properties of
the sound waves
with frequency
greater than that
of the human
audible range.

23. List of projects based on few of
the above mentioned Sensors.
 Light Sensor – LIGHT DETECTOR USING LDR
 Smoke Sensor – SMOKE DETECTOR ALARM CIRCUIT
 Alcohol Sensor – HOW TO MAKE ALCOHOL
BREATHALYZER CIRCUIT?
 Touch Sensor – TOUCH DIMMER SWITCH CIRCUIT
USING ARDUINO
 Color Sensor – ARDUINO BASED COLOR DETECTOR
 Humidity Sensor – DHT11 HUMIDITY SENSOR ON
ARDUINO
 Tilt Sensor – HOW TO MAKE A TILT SENSOR WITH
ARDUINO?

24. What is IoT?
 The Internet of Things (IoT) is the network
of physical objects—devices, vehicles,
buildings and other items embedded with
electronics, software, sensors, and network
connectivity—that enables these objects to
collect and exchange data.

25. Various Names, One Concept
 M2M (Machine to Machine)
 “Internet of Everything” (Cisco Systems)
 “World Size Web” (Bruce Schneier)
 “Skynet” (Terminator movie)

26. Where is IoT?
 It’s everywhere!
Healthcare
Wearable
Tech

28. Where is IoT?
On your campus…

30. History of Contiki
 Developed by Adam Dunkels of SICS
 First released on March 10, 2003
 Named after Thor Heyerdahl's famous
Kon-Tiki raft
 “Contiki runs on tiny and prehistoric
computers, yet is able to do much of what
we expect from large and modern
computers.”

31. Who uses it?
 Most common application is as an OS
for Networks of Embedded Systems
 Use it as an OS for older and smaller
systems
 Ports for Apple II, Atari, Gameboy, NES,
Commodore 64 and 128

32. What is contiki
 OS acts as resource manager.
 Cheap sensor node.
 Micro-Electro Mechanical System
(MEMS)-based sensor
technology(wireless sensor node is
composed of a microcontroller,
transceiver, timer, memory and
analog to digital converter)


33.  microcontroller operates al low
frequency compared to traditional
processing units
 Contiki is an open source OS for
WSN sensor nodes.
 It is a lightweight and portable OS
written in C language and it is build
around an event-driven kernel.

34.  OS provides preemptive
multitasking that can be used at the
individual process level.
 Contiki configuration consumes 2
kilobytes of RAM and 40 kilobytes of
ROM

35. Architecture

36. Event Driven Kernel
 Kernel is event based making it a
real time OS
 An event triggers the kernel to call the
corresponding event handler
 Functions very similar to TinyOS
 Has its drawbacks, i.e. long running
computations

37. TCP/IP Stack Support
 Implements Dunkels’s own TCP/IP
stack called μIP
 Memory Requirements
 Kilobytes of Program Code
 Hundreds of bytes of RAM
 Allows to connect to networks using
SLIP (Serial Line IP)

38. Dynamic Program Loading
 The Core Code and Program Code
are kept separate in ROM.
 Program Code loaded at runtime.
 Program code can be loaded from
ROM or RAM
 Allows for “Programming” for
networks of sensors

39. Small Memory Requirements
 The base system, providing
multitasking and TCP/IP networking,
can be compiled in about 32 KB
 Smallest system to date uses about
2000 bytes of RAM
 Contiki for its low memory usage in
Embedded

40. Protothreads
 Implemented as an additional library
on top of the event based kernel
 Stackless, lightweight thread
comprised of a single C function using
2 bytes of RAM to record its state
 Adds a layer of abstraction to the
state-machine event based code
usually written, to create a sequential
flow of program code.

41. Event-driven
 Event-driven
(TinyOS)
 Processes do not run
without events
 Event occurs: kernel
invokes event
handler
 Event handler runs
to completion
(explicit return;)
Kernel
Handler
Handler
Handler
Handler

42. Contiki: implementing threads on top
of an event-based kernel
Kernel
Event
Event
Event
Event ThreadThread

43. Contiki Programs
 Contiki Tool-kit (CTK) GUI
 Virtual Network Computing (VNC) Server
 A Web Server
 A Web Browser
 A command line shell.
 A telnet server.
 An FTP client.
 A disk directory file reader.
 A file and disk image downloader utility.
 A simple desktop calculator.

44. Additional Features
 Simulation Support :Contiki provides
sensor network simulations through
Cooja
 Security Support: secure
communication protocol with the name
ContikiSec
 Language Support:Cotiki supports
application development in the C
language


45.  Supported Platforms :Contiki
supports the following sensing
platforms: Tmote, AVR series MCU.

46. IWING-MRF Motes
Radio
transceiver
8-bit AVR Microcontroller
USB Connector
(for reprogramming
and power)
Analog/Digital sensor
connectors
External
battery connector
Digital sensor
connectors

47.  Built from components
 Built-in USB boot loader
 Reprogrammed via USB
 Easy to modify and extend hardware

48.  Processor
 8-bit AVR microcontroller
ATMega88/168/328, 12 MHz
 16KB flash, 2KB RAM
 RF transceiver
 Microchip's MRF24J40A/B/C, 2.4GHz
IEEE 802.15.4
 SPI interface
 External connectors
 6 ADC connectors (can also be used as
TWI)
 Power options
 3 – 3.6 VDC
 USB or 2 AA batteries

49. Mica Motes
 By Crossbow, USA
 MCU:
 Atmel ATMega128L
 Comm: RFM TR1000

50. EYES Nodes
 By Infineon, EU
 MCU: TI MSP430
 Comm: Infineon radio modem TDA5250

51. Btnote
 By ETH Zurich
 MCU:
 Atmel ATMega128L
 Comm:
 Bluetooth

52. ScatterWeb
 By Computer Systems & Telematics
group, Freie Universitat Berlin
 MCU:
 TI MSP 430
 Comm:
 Bluetooth

53. Tmote Sky
 By Sentilla (formerly Moteiv),
USA
 MCU:
 TI MSP430
 Comm:
 Chipcon CC2420
(IEEE 802.15.4)

54. IRIS Motes
 By Crossbow, USA
 MCU: ATMega128L
 Comm: Atmel's RF230 (IEEE 802.15.4)
 3x radio range compared to Tmote
 "Postage-stamp" form factor costs as low as $29
per unit (when purchased in large volumes)

55. IMote2
 By Intel Research
 MCU: PXA271 XScale
 Comm: Chipcon CC2420 (IEEE802.15.4)