IoT Physical Devices and End Points.pdf

Basic building blocks of an IoT Device
• Exemplary Device: Raspberry Pi
• Raspberry Pi interfaces
• Programming Raspberry Pi with Python
• Other IoT devices

1. Unit IV
IoTPhysicalDevices&Endpoints

2. Outline
•Basicbuilding blocksof anIoTDevice
•ExemplaryDevice:RaspberryPi
•RaspberryPi interfaces
•ProgrammingRaspberryPi withPython
•OtherIoTdevices

3. WhatisanIoTDevice
•A "Thing" in Internet of Things (IoT)canbe anyobjectthathasa
uniqueidentifierandwhichcan send/receivedata(includinguser
data)overa network(e.g., smartphone, smart TV, computer,
refrigerator, car,etc.).
•IoTdevicesareconnectedtotheInternetandsendinformation
aboutthemselvesorabouttheirsurroundings(e.g.information
sensedbytheconnectedsensors)overa network(tootherdevicesor
servers/storage) or allow actuation upon the physical
entities/environmentaround themremotely.

4. IoTDeviceExamples
•Ahomeautomationdevicethatallowsremotelymonitoringthe
status of appliancesand controllingthe appliances.
•Anindustrialmachinewhichsendsinformationaboutsitsoperation
and health monitoring data toaserver.
•Acarwhichsendsinformationaboutits locationto acloud-based
service.
•Awireless-enabledwearabledevice thatmeasuresdataabouta
personsuchasthenumberofstepswalkedandsendsthedatatoa
cloud-basedservice.

5. Basicbuilding blocksofan IoT Device
•Sensing
•Sensorscanbeeitheron-boardtheIoTdeviceorattachedtothedevice.
•Actuation
•IoTdevicescanhavevarioustypesofactuatorsattachedthatallowtaking
•actionsuponthephysicalentitiesinthevicinityofthedevice.
•Communication
•Communicationmodulesareresponsibleforsendingcollecteddatatoother
devicesorcloud-basedservers/storageandreceivingdatafromotherdevices
and commandsfromremoteapplications.
•Analysis&Processing
•Analysisandprocessingmodulesareresponsibleformakingsenseofthe
collected data.

6. Blockdiagram of anIoT Device

7. ExemplaryDevice:RaspberryPi
•RaspberryPiis a low-costmini-computerwith thephysicalsize ofa
credit card.
•RaspberryPirunsvariousflavorsofLinuxandcanperformalmostall
tasks thatanormaldesktop computer can do.
•RaspberryPialsoallowsinterfacingsensorsandactuatorsthrough
thegeneralpurpose I/O pins.
•SinceRaspberryPirunsLinuxoperatingsystem,itsupportsPython
"out of the box".

8. ExemplaryDevice:RaspberryPi
•RaspberryPiis a low-costmini-computerwith thephysicalsize ofa
credit card.
•RaspberryPirunsvariousflavorsofLinuxandcanperformalmostall
tasks thatanormaldesktop computer can do.
•RaspberryPialsoallowsinterfacingsensorsandactuatorsthrough
thegeneralpurpose I/O pins.
•SinceRaspberryPirunsLinuxoperatingsystem,itsupportsPython
"out of the box".

9. RaspberryPi

10. LinuxonRaspberryPi
•Raspbian
•Raspbian Linuxis aDebianWheezy port optimizedfor RaspberryPi.
•Arch
•ArchisanArchLinux port forAMDdevices.
•Pidora
•PidoraLinuxisaFedora Linuxoptimizedfor RaspberryPi.
•RaspBMC
•RaspBMC isanXBMC media-center distribution for Raspberry Pi.
•OpenELEC
•OpenELECisafastanduser-friendlyXBMCmedia-centerdistribution.
•RISCOS
•RISCOSisaveryfastandcompactoperatingsystem.

11. RaspberryPiGPIO

12. RaspberryPiGPIO
WhenusingtheRPi.GPIOlibraryinPythonwehavetocall
importRPi.GPIOasGPIO
andthen
GPIO.setmode(GPIO.BOARD)
or
GPIO.setmode(GPIO.BCM)
Whatisthedifferencebetweenthesetwooptions?

13. RaspberryPiGPIO
•TheGPIO.BOARDoptionspecifiesthatyouarereferringtothepinsbythenumber
ofthepinontheplug-i.ethenumbersprintedontheboard(e.g.P1)andinthe
middleofthediagramsbelow.
•TheGPIO.BCMoptionmeansthatyouarereferringtothepinsbythe"Broadcom
SOCchannel"number,thesearethenumbersafter"GPIO"inthegreenrectangles
aroundtheoutsideofthebelowdiagrams

14. RaspberryPiGPIO
•UnfortunatelytheBCMnumberschangedbetweenversionsofthePi1ModelB,and
you'llneedtoworkoutwhichone.SoitmaybesafertousetheBOARDnumbersifyou
aregoingtousemorethanoneRaspberryPiinaproject.
•TheModelB+usesthesamenumberingastheModelBr2.0,andaddsnewpins(board
numbers27-40).
•TheRaspberryPiZero,Pi2B,Pi3B,andPi4BusethesamenumberingastheB+.

15. RaspberryPiGPIO

16. RaspberryPiGPIO

17. RaspberryPiGPIO

18. RaspberryPiGPIO
•IdentificationofthepinnumberingsviaLinuxcommand
•ThereisaLinuxcommandtofindoutwhichnameisforwhichGPIOpin.Soin
thatcase,wedonothavetoworryaboutatutorialoracheatsheettohaveby
oursidetocheckoutthepinnumberingsoftheRaspberryPiallthetime.
•Type the following command in the terminal,
pinout

19. RaspberryPiGPIO

20. RaspberryPiInterfaces

21. RaspberryPiInterfaces
Serial
•TheserialinterfaceonRaspberryPihasreceive(Rx)andtransmit(Tx)pins
forcommunicationwithserialperipherals.
•GPIO14–UARTTx
•GPIO15–UARTRx

22. RaspberryPiInterfaces
SerialInterface-UART
•UART(UniversalAsynchronousReceiver/Transmitter)isaserial
communicationprotocolinwhichdataistransferredseriallybitbybit.
•Asynchronousserialcommunicationiswidelyusedforbyteoriented
transmission.
•Inasynchronousserialcommunication,abyteofdataistransferredata
time.

23. Frame Structure of UART

24. Raspberry Pi UART

25. RaspberryPiInterfaces
SPI
•SerialPeripheralInterface(SPI)isasynchronousserialdataprotocolused
forcommunicatingwithoneormoreperipheraldevices.
•In an SPI connection, there is one master device and one or more
peripheral devices.

26. RaspberryPiInterfaces
•There are five pins on Raspberry Pi for SPI interface.
•MISO (Master In Slave Out) : Master Line for sending data to peripherals (GPIO 9).
•MOSI (Master Out Slave In) : Slave line for sending data to master (GPIO 10).
•SCK (Serial Clock) : Clock generated by master to synchronize data transmission (GPIO
11).
•CEO (Chip Enable 0) : To enable or disable devices (GPIO 8).
•CE1 (Chip Enable 1): To enable or disable devices (GPIO 7).

27. RaspberryPiInterfaces
I2C(InterIntegratedCircuit)
•Itisasynchronousserialprotocolthatcommunicatesdatabetweentwo
devices
•Itisamasterslaveprotocolwhichmayhaveonemasterormanymaster
andmanyslaveswhereasSPIhasonlyonemaster
•Itisgenerallyusedforcommunicationovershortdistance.

28. RaspberryPiInterfaces
I2C(InterIntegratedCircuit)
•TheI2CinterfacepinsonRaspberryPiallowstoconnecthardwaremodules.
•I2Cinterfaceallowssynchronousdatatransferwithjusttwopins–
SDA(I2Cdataline)GPIO2andSCL(I2Cclockline)GPIO3.
•ItisusedinmanyapplicationslikereadingRTC(RealTimeClock),assessingexternal
EEPROMmemoryanditisalsousedinsensormoduleslikegyrometerand
magnetometer.

29. Programming RaspberryPiwith Python
•RaspberryPirunsLinuxandsupportsPythonOutofBoxsoftware.
•Therefore,wecanrunanypythonprogramthatrunsonanormalcomputer.
•GPIOpinsprovidescapabilityonRaspberryPithatmakesusefuldevicesforIoT.
•Awidevarietyofsensorsandactuatorscanbeinterfacedwithraspberrypiusingthe
GPIOpinsandtheSPI,I2Candserialinterfaces.
•Inputfromthesensorsconnectedtoraspberrypicanbeprocessedandvariousactions
canbetaken,sendingdatatoaserver,sendinganemail,triggeringarelayswitch.

30. RaspberryPiExample:
Interfacing LEDandswitchwithRaspberry Pi
•InthisexampleLEDisconnectedtoGPIOpin18andswitchisconnectedtopin25.
•Intheinfinitewhileloopthevalueofpin25ischeckedandthestateofLEDistoggledif
theswitchispressed.
•ThisexampleshowshowtogetinputfromGPIOpinsandprocesstheinputandtakes
action.
•TheactioninthisexampleistogglingthestateofanLED.

31. RaspberryPiExample:
Interfacing LEDandswitchwithRaspberry Pi
fromtimeimportsleep
importRPi.GPIOasGPIO
GPIO.setmode(GPIO.BCM)
#SwitchPin
GPIO.setup(25,GPIO.IN)
#LEDPin
GPIO.setup(18,GPIO.OUT)
state=false
deftoggleLED(pin):
state=notstate
GPIO.output(pin,state)
whileTrue:
try:
if(GPIO.input(25)==True):
toggleLED(pin)
sleep(.01)
exceptKeyboardInterrupt:
exit()

32. Python Program for Sending an Email on Switch Press

33. Python Program for Sending an Email on Switch Press

34. Python Program for Sending an Email on Switch Press

35. Interfacing Light Sensor (LDR) with RPi
•ConnectonesideofLDRto3.3Vandothersidetoa1μFcapacitorandalsotoa
GPIOpin(pin18inthisexample).
•AnLEDisconnectedtopin18whichiscontrolledbasedonthelight-levelsensed.
•ThereadLDR()functionreturnsacountwhichisproportionaltothelightlevel.
•InthisfunctiontheLDRpinissettooutputandlowandthentoinput.

36. Interfacing Light Sensor (LDR) with RPi
•Atthispointthecapacitorstartschargingthroughtheresistor(andacounteris
started)untiltheinputpinreadshigh(thishappenswhencapacitorvoltage
becomesgreaterthan1.4V).
•Thecounterisstoppedwhentheinputreadshigh.
•Thefinalcountisproportionaltothelightlevelasgreatertheamountoflight,
smalleristheLDRresistanceandgreateristhetimetakentochargethe
capacitor.

37. Interfacing Light Sensor (LDR) with RPi
import RPi.GPIOas GPIO
import time
GPIO.setmode(GPIO.BCM)
ldr_threshold= 1000
LDR_PIN = 18
LIGHT_PIN = 25
def readLDR(PIN):
reading = 0
GPIO.setup(LIGHT_PIN, GPIO.OUT)
GPIO.output(PIN, false)
time.sleep(0.1)
GPIO.setup(PIN, GPIO.IN)
while (GPIO.input(PIN) ==Flase):
reading=reading+1
return reading
def switchOnLight(PIN):
GPIO.setup(PIN, GPIO.OUT)
GPIO.output(PIN, True)
def switchOffLight(PIN):
GPIO.setup(PIN, GPIO.OUT)
GPIO.output(PIN, False)
while True:
ldr_reading= readLDR(LDR_PIN)
if ldr_reading< ldr_threshold:
switchOnLight(LIGHT_PIN)
else:
switchOffLight(LIGHT_PIN)
time.sleep(1)

38. Interfacing Light Sensor (LDR) with RPi

39. Interfacing Light Sensor (LDR) with RPi

40. OtherDevices
•pcDuino
•BeagleBoneBlack
•Cubieboard

41. Comparison of Single Board Mini Computers