Raspberry Pi

on successful go through of this complete PPT, the learners can be able to understand the Raspberry PI, Raspberry Pi Interfaces(Serial, SPI,I2C) Programming, Python programming with Raspberry PI with the focus of Interfacing external gadgets
Controlling output Reading input from pins.

1. By
Mr.S.Selvaraj
Asst. Professor(SRG) / CSE
Kongu Engineering College
14ITO01–Internetof Things
Unit IV –IoT Devices (RaspberryPi)

2. OUTLINE
•Introduction to Raspberry PI
•Interfaces (Serial,SPI,I2C) Programming
•Python programming with Raspberry PI with
focus of
–Interfacing external gadgets
–Controlling output
–Reading input from pins
•Connecting IoT to Cloud
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3. Introduction to Raspberry Pi
•What is an IoT Device?
•Basic building blocks of an IoT Device
•Exemplary Device: Raspberry Pi
•Raspberry Pi interfaces
•Programming Raspberry Pi with Python
•Other IoTdevices
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4. What is an IoT Device?
–A "Thing" in Internet of Things (IoT) can be any
object that has a unique identifier and which can
send/receive data (including user data) over a network
(e.g., smart phone, smart TV, computer, refrigerator,
car, etc. ).
–IoTdevices are connected to the Internet and send
information about themselves or about their
surroundings (e.g. information sensed by the
connected sensors) over a network (to other devices or
servers/storage) or allow actuation upon the physical
entities/environment around them remotely
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5. IoT Device Examples
–A home automation device that allows remotely monitoring
the status of appliances and controlling the appliances.
–An industrial machine which sends information aboutsits
operation and health monitoring data to a server.
–A car which sends information about its location to a
cloud-based service.
–A wireless-enabled wearable device that measures data
about a person such as the number of steps walked and
sends the data to a cloud-based service.
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6. Basic building blocks of an IoTDevice
•Sensing
Sensors can be either on-board the IoTdevice or attached to the device.
Actuation
IoTdevices can have various types of actuators attached that allow
taking
actions upon the physical entities in the vicinity of the device.
Communication
Communication modules are responsible for sending collected data to
other devices or cloud-based servers/storage and receiving data from
other devices and commands from remote applications.
Analysis & Processing
Analysis and processing modules are responsible for making sense of
the collected data
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7. Block diagram of an IoTDevice
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8. Exemplary Device: Raspberry Pi
•RaspberryPiisalow-costmini-computerwiththe
physicalsizeofacreditcard.
•RaspberryPirunsvariousflavorsofLinuxand
canperformalmostalltasksthatanormaldesktop
computercando.
•RaspberryPialsoallowsinterfacingsensorsand
actuatorsthroughthegeneralpurposeI/Opins.
•SinceRaspberryPirunsLinuxoperatingsystem,
itsupportsPython"outofthebox"
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9. Raspberry Pi Statusleds
STATUSLED FUNCTION
ACT SDcard access
PWR 3.3V Poweris present
FDX Full DuplexLAN connected
LNK Link/Network activity
100 100 Mbit LANconnected
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10. Raspberry Pi Board
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11. Linux on Raspberry Pi
•Raspbian
–RaspbianLinux is a DebianWheezy port optimized for Raspberry Pi.
•Arch
–Arch is an Arch Linux port for AMD devices.
•Pidora
–PidoraLinux is a Fedora Linux optimized for Raspberry Pi.
•RaspBMC
–RaspBMCis an XBMC media-centerdistribution for Raspberry Pi.
•OpenELEC
–OpenELECis a fast and user-friendly XBMC media-center
distribution.
•RISC OS
–RISC OS is a very fast and compact operating system
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12. Raspberry Pi GPIO headers
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13. RasbianLinux Desktop
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14. Raspberry Pi frequently used
commands
Command Function Example
cd change directory cd/home/pi
cat show file contents cat file.txt
ls list files and folders ls/home/pi
locate search for a file locate file.txt
lsusb list usbdevices lsusb
pwd print name for present working
directory
pwd
mkdir make directory mkdir/home/pi/new
mv move(rename) file mv sourcefile.txt destfile.txt
rm remove file rmfile.txt
reboot reboot device sudoreboot
shutdown shutdown device sudoshutdown –h now
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15. Raspberry Pi frequently used
commands
Command Function Example
grep Print lines matching a patterngrep–r “pi”/home/
df Reportfile system disk space usagedf-Th
ipconfig Configure a network interfaceipconfig
netstat Print network connections, routing
tables, interface statistics
Netstat-lntp
tar Extract/create archive Tar –xzffoo.tar.gz
wget Non-interactive network downloaderWget
http://example.com/filr.tar.
gz
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16. Raspberry Pi Interfaces
•Serial Interface / UART Interface
–Universal Asynchronous Receiver and
Transmitter(UART)
•SPI
–Serial Peripheral Interface (SPI)
•I2C
–Inter-Integrated Circuits (I2C)
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17. Raspberry Pi Interfaces
•Serial
–TheserialinterfaceonRaspberryPihasreceive(Rx)
andtransmit(Tx)pinsforcommunicationwithserial
peripherals.
•SPI
–SerialPeripheralInterface(SPI)isasynchronous
serialdataprotocolusedforcommunicatingwithone
ormoreperipheraldevices.
•I2C
–TheI2CinterfacepinsonRaspberryPiallowyouto
connecthardwaremodules.
–I2Cinterfaceallowssynchronousdatatransferwith
justtwopins-SDA(dataline)andSCL(clockline).
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18. Serial / UART
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19. SPI
•InSPIConnection,thereisonemasterdeviceandone
ormoreperipheraldevices.
•TherearefivepinsonRaspberryPiforSPIinterface.
–MISO(MasterInSlaveOut)–MasterLineforSendingData
totheperipherals.
–MOSI(MasterOutSlaveIn)–SlaveLineforsendingdata
tothemaster.
–SCK(SerialClock)–ClockGeneratedbyMasterto
Synchronizedatatransmission.
–CE0(ChipEnable0)–ToEnableorDisabledevices.
–CE1(ChipEnable1)–ToEnableorDisabledevices.
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20. I2C
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21. 211/12/2021 IoT Devices -Raspberry Pi

22. Raspberry Pi Pin Configurations
•ApowerfulfeatureoftheRaspberryPiisthe
rowofGPIO(general-purposeinput/output)
pinsalongthetopedgeoftheboard.
•A40-pinGPIOheaderisfoundonallcurrent
RaspberryPiboards(unpopulatedonPiZero
andPiZeroW).
•PriortothePi1ModelB+(2014),boards
comprisedashorter26-pinheader.
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23. Raspberry Pi Pin Configuration
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24. Raspberry Pi Pin Configuration
•AnyoftheGPIOpinscanbedesignated(in
software)asaninputoroutputpinandusedfora
widerangeofpurposes.
•Note:thenumberingoftheGPIOpinsisnotin
numericalorder;GPIOpins0and1arepresent
ontheboard(physicalpins27and28)butare
reserved for advanced use.
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25. Raspberry Pi Pin Configuration
•Voltages
–Two5Vpinsandtwo3V3pinsarepresentontheboard,aswellasa
numberofgroundpins(0V),whichareunconfigurable.
–Theremainingpinsareallgeneralpurpose3V3pins,meaningoutputs
aresetto3V3andinputsare3V3-tolerant.
•Outputs
–AGPIOpindesignatedasanoutputpincanbesettohigh(3V3)orlow
(0V).
•Inputs
–AGPIOpindesignatedasaninputpincanbereadashigh(3V3)orlow
(0V).
–Thisismadeeasierwiththeuseofinternalpull-uporpull-down
resistors.
–PinsGPIO2andGPIO3havefixedpull-upresistors,butforotherpins
thiscanbeconfiguredinsoftware.
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26. Raspberry Pi Pin Configuration
•Aswellassimpleinputandoutputdevices,theGPIOpinscanbeused
withavarietyofalternativefunctions,someareavailableonallpins,
othersonspecificpins.
•PWM(pulse-widthmodulation)
–SoftwarePWMavailableonallpins
–HardwarePWMavailableonGPIO12,GPIO13,GPIO18,GPIO19
•SPI
–SPI0:MOSI(GPIO10);MISO(GPIO9);SCLK(GPIO11);CE0(GPIO8),CE1(GPIO7)
–SPI1:MOSI(GPIO20);MISO(GPIO19);SCLK(GPIO21);CE0(GPIO18);CE1
(GPIO17);CE2(GPIO16)
•I2C
–Data:(GPIO2);Clock(GPIO3)
–EEPROMData:(GPIO0);EEPROMClock(GPIO1)
•Serial
–TX(GPIO14);RX(GPIO15)
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27. Raspberry Pi Pin Configuration
•GPIOpinout
–It'simportanttobeawareofwhichpiniswhich.
–Somepeopleusepinlabels(like
•theRasPiOPortsplusPCB,or
•theprintableRaspberryLeaf).
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28. Raspberry Pi Pin Configuration
•Ahandyreferencecanbeaccessedonthe
RaspberryPibyopeningaterminalwindow
andrunningthecommandpinout.
•ThistoolisprovidedbytheGPIOZeroPython
library,whichisinstalledbydefaultonthe
RaspberryPiOSdesktopimage,butnoton
RaspberryPiOSLite.
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29. 291/12/2021 IoT Devices -Raspberry Pi

30. Python programming with Raspberry PI with focus of
-Interfacing external gadgets
-Controlling output
-Reading input from pins

31. Python Programming with Raspberry
Pi
•Python programming with Raspberry PI with focus of
–Interfacing external gadgets
–Controlling output
–Reading input from pins
•GPIO pins on Raspberry Pi that makes it useful device for IoT.
•We can interface a wide variety of sensors and actuators with Raspberry
Pi using the GPIO pins and SPI, I2C and Serial Interfaces.
•Input from the sensors connected to Raspberry Pi can be processed and
various actions can be taken, for
–Instance,
–Sending data to a server
–Sending an email
–Triggering a relay switch
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32. Controlling LED with Raspberry Pi
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33. Components Reuired
•You'll need the following components to
connect the circuit.
•1. Raspberry Pi
2. LED
3. Resistor -330 ohm
4. Breadboard
5. 2 Male-Female Jumper Wires
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34. 341/12/2021 IoT Devices -Raspberry Pi

35. 351/12/2021 IoT Devices -Raspberry Pi

36. Python Code
•import RPi.GPIOas GPIO
import time
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(21,GPIO.OUT)
print "LED on"
GPIO.output(21,GPIO.HIGH)
time.sleep(10)
print "LED off"
GPIO.output(21,GPIO.LOW)
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37. 371/12/2021 IoT Devices -Raspberry Pi

38. Python programming with Raspberry PI with focus of
-Interfacing external gadgets
-Controlling output
-Reading input from pins

39. Controlling LED with Switch on
Raspberry Pi
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40. Components Reuired
•You'll need the following components to
connect the circuit.
•1. Raspberry Pi
2. LED
3. Resistor -330 ohm
4. Breadboard
5. Button / Switch
6. 2 Male-Female Jumper Wires
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41. Components
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42. Switch / Button
•Buttonsareacommoncomponentusedto
controlelectronicdevices.
•Theyareusuallyusedasswitchestoconnect
ordisconnectcircuits.
•Althoughbuttonscomeinavarietyofsizes
andshapes,theoneusedhereisa6mmmini-
buttonasshowninthefollowingpictures.
•Pinspointedoutbythearrowsofsamecolor
aremeanttobeconnected.
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43. Switch / Button
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44. Switch / Button
•Whenthebuttonispressed,thepinspointedbythe
bluearrowwillconnecttothepinspointedbythered
arrow(seetheabovefigure),thusclosingthecircuit,as
showninthefollowingdiagrams.
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45. Switch / Button
•Generally,thebuttoncanbeconnecteddirectlytotheLEDinacircuitto
turnonorofftheLED,whichiscomparativelysimple.
•However,sometimestheLEDwillbrightenautomaticallywithoutany
buttonpressed,whichiscausedbyvariouskindsofexternalinterference.
•Inordertoavoidthisinterference,apull-downresistorisused–usually
connecta1K–10KΩresistorbetweenthebuttonandGND.Itcanbe
connectedtoGNDtoconsumetheinterferencewhenthebuttonisoff.
•UseanormallyopenbuttonastheinputofRaspberryPi.
•Whenthebuttonispressed,theGPIOconnectedtothebuttonwillturn
intolowlevel(0V).
•WecandetectthestateoftheGPIOconnectedtothebuttonthrough
programming.Thatis,iftheGPIOturnsintolowlevel,itmeansthebutton
ispressed.Youcanrunthecorrespondingcodewhenthebuttonis
pressed,andthentheLEDwilllightup.
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46. CIRCUIT Diagram
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47. Experimental Procedures
•Step 1: Build the circuit
•Step 2:Create a Python / C code
•Step 3: Run
sudopython 02_btnAndLed.py
•Now,pressthebutton,andtheLEDwilllightup;
pressthebuttonagain,andtheLEDwillgoout.
Atthesametime,thestateoftheLEDwillbe
printedonthescreen.
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48. Python Code
•#!/usr/bin/envpython
•import RPi.GPIOas GPIO
•import time
•LedPin= 11 # pin11 ---led
•BtnPin= 12 # pin12 ---button
•Led_status= 1
•def setup():
–GPIO.setmode(GPIO.BOARD) # Numbers GPIOs by physical location
–GPIO.setup(LedPin, GPIO.OUT) # Set LedPin'smode is output
–GPIO.setup(BtnPin, GPIO.IN, pull_up_down=GPIO.PUD_UP) # Set BtnPin'smode is input, and pull up to high
level(3.3V)
–GPIO.output(LedPin, GPIO.HIGH) # Set LedPinhigh(+3.3V) to off led
•def swLed(ev=None):
–global Led_status
–Led_status= not Led_status
–GPIO.output(LedPin, Led_status) # switch led status(on-->off; off-->on)
–if Led_status== 1:
•print 'led off...'
–else:
•print '...led on'
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49. Python Code (Contd.,)
•def loop():
–GPIO.add_event_detect(BtnPin, GPIO.FALLING, callback=swLed,
bouncetime=200) # wait for falling and set bouncetimeto prevent the callback
function from being called multiple times when the button is pressed
–while True:
•time.sleep(1) # Don't do anything
•def destroy():
–GPIO.output(LedPin, GPIO.HIGH) # led off
–GPIO.cleanup() # Release resource
•if __name__ == '__main__': # Program start from here
–setup()
–try:
•loop()
–except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the child program
destroy() will be executed.
•destroy()
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50. Interfacing
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51. Applications
•InterfacingaPushButtonwithRaspberryPi
mightnotseemasabigprojectbutit
definitelyhelpsusinunderstandingthe
conceptofreadingfromInputpins.
•Asimilarconceptcanbeappliedtoother
inputdeviceslikedifferenttypesofSensors
–PIRSensor,
–UltrasonicSensor,
–TouchSensor,andsoforth.
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52. Python programming with Raspberry PI with focus of
-Interfacing external gadgets
-Controlling output
-Reading input from pins

53. Interfacing a Light Sensor (LDR) with
Raspberry Pi
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54. Components Reuired
•You'll need the following components to
connect the circuit.
•1. Raspberry Pi
2. Light Sensor (LDR Sensor)
3. Capacitor -1µF
4. Breadboard
5. 2 Male-Female Jumper Wires
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55. Components
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56. LDR Sensor
•Thelight-dependentresistororalsoknownas
theLDRsensoristhemostimportantpieceof
equipmentinourcircuit.Withoutit,we
wouldn’tbeabletodetectwhetheritisdark
orlight.
•Inthelight,thissensorwillhavearesistance
ofonlyafewhundredohms.
•Inthedark,itcanhavearesistanceofseveral
megaohms.
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57. LDR Sensor
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58. LDR Sensor
•Aphotoresistor,orlight-dependentresistor(LDR),or
photocellisaresistorwhoseresistancewilldecrease
whenincidentlightintensityincrease;inotherwords,
itexhibitsphotoconductivity.
•Aphotoresistorismadeofahighresistance
semiconductor.
•Iflightfallingonthedeviceisofhighenough
frequency,photonsabsorbedbythesemiconductor
giveboundelectronsenoughenergytojumpintothe
conductionband.Theresultingfreeelectron(andits
holepartner)conductelectricity,therebylowering
resistance.
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59. CIRCUIT Diagram
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60. LDR Sensor
•InthisimplementationwelearnhowtoInterfacealightSensor(LDR)
withRaspberryPiandturninganLEDon/offbasedontheligh-level
sensed.
•Lookgivenimage,ConnectonesideofLDRto3.3Vandothersidetoa1μF
capacitorandalsotoaGPIOpin(pin18inthisexample).
•AnLEDisconnectedtopin18whichiscontrolledbasedonthelight-level
sensed.
•ThereadLDR()functionreturnsacountwhichisproportionaltothelight
level.
•InthisfunctiontheLDRpinissettooutputandlowandthentoinput.
•Atthispointthecapacitorstartschargingthroughtheresistor(anda
counterisstarted)untiltheinputpinreadshigh(thishappenswhen
capacitorvoltagebecomesgreaterthan1.4V).
•Thecounterisstoppedwhentheinputreadshigh.Thefinalcountis
proportionaltothelightlevelasgreatertheamountoflight,smalleristhe
LDRresistanceandgreateristhetimetakentochargethecapacitor.
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61. 611/12/2021 IoT Devices -Raspberry Pi

62. Experimental Procedures
•Step 1: Build the circuit
•Step 2:Create a Python / C code
•Step 3: Run
sudopython 03_ldrAndLed.py
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63. Importing Packages
•Tobegin,weimporttheGPIOpackagethatwewill
needsothatwecancommunicatewiththeGPIOpins.
•Wealsoimportthetimepackage,sowe’reabletoput
thescripttosleepforwhenweneedto.
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64. Pin Assignment
•WethensettheGPIOmodetoGPIO.BCM,and
thismeansallthenumberingweuseinthisscript
willrefertothephysicalnumberingofthepins.
•Sinceweonlyhaveoneinput/outputpin,we
onlyneedtosetonevariable.Setthisvariableto
thenumberofthepinyouhaveactingasthe
input/outputpin.
GPIO.setmode(GPIO.BCM)
ldr_threshold= 1000
LDR_PIN = 18
LIGHT_PIN = 25
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65. Reading the Light Value
•Next,wehaveafunctioncalledreadLDR()thatrequiresoneparameter,whichis
thepinnumbertothecircuit.Inthisfunction,weinitializeavariable
calledreading,andwewillreturnthisvalueoncethepingoestohigh.
•Wethensetourpintoactasanoutputandthensetittolow.Next,wehavethe
scriptsleepfor10ms.
•Afterthis,wethensetthepintobecomeaninput,andthenweenterawhile
loop.Westayinthisloopuntilthepingoestohigh,thisiswhenthecapacitor
chargestoabout3/4.
•Oncethepingoeshigh,wereturnthecountvaluetothemainfunction.Youcan
usethisvaluetoturnonandoffanLED,activatesomethingelse,orlogthedata
andkeepstatisticsonanyvarianceinlight.
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
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66. Python Code
# Example code Interfacing a light Sensor (LDR) with Raspberry Pi
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
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67. Python Code to Toggle the LED
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)
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68. Interfacing
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69. Applications
•Therearecountlessusesforalightsensorinacircuit.Iwilljust
nameafewthatIthoughtofwhileIwaswritingupthisPPT.
•LightActivatedAlarm–Imentionedthisoneearlier,butyoucan
usetheLDRtodetectwhenitstartstogetlightsoyoucansoundan
alarmtowakeyouup.Iftheprogramandsensorareaccurate,then
youcanhavethealarmslowlygetlouderasitgetslighter.
•Gardenmonitor–Alightsensorcouldbeusedinagardentocheck
howmuchsunacertainareaofthegardenisgetting.Thiscouldbe
usefulinformationifyou’replantingsomethingthatneedslotsof
sunorviceversa.
•RoomMonitor–Wanttomakesurelightsarealwaysturnedoffin
acertainroom?Youcouldusethistoalertyouwheneversomelight
isdetectedwhereitshouldn’tbe.
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70. Problem In This Method
•Thebiggestproblemofthiscircuitisthefactthat
thePidoesn’thaveanyanaloguepins.They’re
alldigital,sowecan’taccuratelymeasurethe
varianceinresistanceonourinput.
•Thislackofanaloguepinswasn’taproblemin
themotionsensortutorialsincetheoutputfrom
itwaseitherhighorlow(Digital).
•Instead,wewillmeasurethetimeittakesforthe
capacitortochargeandsendthepinhigh.
•Thismethodisaneasybutinaccuratewayof
tellingwhetheritislightordark.
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71. Solution
•Ifyouwanttomakealightcontrolledswitch,asinglephotoresistor
mightbeuselesssinceyouwillneedthedigitalsignalaccordingtothe
brightness.Thismoduleisdesignedforthatpurpose.
–usingahighqualityphotoresistor
–workingvoltage:3.3~5V
–output:digitalswitching(LOWorHIGHvoltageonDpin)andanalogsignal
(voltageoutputonApin)
–usingawidevoltageLM393comparatorthathasgoodwaveform
–outputcurrent>=15mA,candirectlylightLED.
–withadjustablepotentiometertoadjustthesensitivity
–hastwoM2.5mountingholes
•Thismoduleisverysensitivetoambientlight,andisverysuitablefor
detectingbrightnessofambientlight.Theoutputsignalcantrigger
RaspberryPi,microcontrollerlikeArduino,orotherdigitalrelay
modules.
•Whentheambientlightintensityislowerthanthepredefined
threshold,theoutputsignalishigh.Whenthelightintensityreachesor
exceedsthethreshold,thesignaloutputislow.
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72. Python programming with Raspberry PI with focus of
-Interfacing external gadgets
-Controlling output
-Reading input from pins

73. Sending an E-Mail on Switch Press
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74. Components Reuired
•You'll need the following components to
connect the circuit.
•1. Raspberry Pi
2. LED
3. Resistor -330 ohm
4. Breadboard
5. Button / Switch
6. 2 Male-Female Jumper Wires
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75. Components
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76. Switch / Button
•Buttonsareacommoncomponentusedto
controlelectronicdevices.
•Theyareusuallyusedasswitchestoconnect
ordisconnectcircuits.
•Althoughbuttonscomeinavarietyofsizes
andshapes,theoneusedhereisa6mmmini-
buttonasshowninthefollowingpictures.
•Pinspointedoutbythearrowsofsamecolor
aremeanttobeconnected.
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77. Switch / Button
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78. CIRCUIT Diagram
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79. How It Is Works
•SendinganemailwiththePiusingPythonisn’tthatdifficult.
•Wearegoingtocreatetheemailcontentincodeandusean
externalemailprovidertoactasthemailserversendtheemail.
•Becauseweareusingcodetogeneratetheemail,wecan
dynamicallycreatethecontentwesendbasedonsensorreadings,
timeofday,orjustaboutanythingelseyoucanimagine!
•InthisexamplewearegoingtouseGoogle/Gmailtoprovideemail
services.
•WewillcreateaGmailaccountspecificallyforthisdeviceandgive
thePipermissiontosendwiththisaccount.
•Donotuseyournormalemailaddress–theemailaddressand
passwordarestoredinplaintextinyourcode!
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80. Set GMAIL Permissions
•ToaccessaGmailaccountusinganexternal
deviceliketheRaspberryPi,permissionfor“less
secureapps”willhavetobeenabled.
•Whenloggedinasyournewemailaccountyou
can jump over
tohttps://myaccount.google.com/lesssecureapps
andenablethissetting.
•SincemostpeoplehaveseveralGoogleaccounts,
justbesureyouareusingtherightaccountwhen
youenablethissetting!
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82. SMTP Library
•Firstwearegoingtostartbyaddinginthe
smtplibraryreference.Thisgivesustheemail
toolswearegoingtoneed.
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83. E-Mail Variables
•Weneedtostoreabunchofinformationfor
sendingoutemailsaswell.
•TheSMTPServerandSMTPportarenotgoingto
change,butbesuretoupdatetheemailaddress
andpasswordinyourcodetomatchthe
credentialsfortheGmailaccountyoucreated
earlier.
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84. How to set up BOARD and GPIO
numbering schemes
•TherearetwokindsofInputandOutputpinnumberingfortheRaspberrypi.Oneisthe
BCMandtheotherisBOARD.Basicallythesepinnumberingsareusefulforwriting
pythonscriptfortheRaspberryPi.
•GPIO BOARD–This type of pin numbering refers to the number of the pin in the plug, i.e,
the numbers printed on the board, for example, P1. The advantage of this type of
numbering is, it will not change even though the version of board changes.
•GPIO BCM–The BCM option refers to the pin by “Broadcom SOC Channel. They signify
the Broadcom SOC channel designation. The BCM channel changes as the version number
changes.
•Note: It is very important to wire the GPIO pins with limited resistors to avoid serious
damage to the Raspberry Pi. LEDs must have resistors to limit the current passing through
them. The motors should not be connected to the GPIO pins directly.
•InRPi.GPIOyoucanuseeitherpinnumbers(BOARD)ortheBroadcomGPIOnumbers
(BCM),butyoucanonlyuseonesystemineachprogram.
•Bothhaveadvantagesanddisadvantages.
•Ifyouusepinnumbers,youdon’thavetobotheraboutrevisionchecking,asRPi.GPIO
takescareofthatforyou.Youstillneedtobeawareofwhichpinsyoucanandcan’tuse
though,sincesomearepowerandGND.
•IfyouuseGPIOnumbers,yourscriptswillmakebettersenseifyouuseaGertboard,
whichalsousesGPIOnumbering.IfyouwanttousetheP5headerforGPIO28-31,you
havetouseGPIOnumbering.IfyouwanttocontroltheLEDonaPicameraboard(GPIO5)
youalsohavetouseGPIOnumbering.
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85. Raspberry Pi Numbering Schemes
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86. How to set up a GPIO port as an input
•Usethefollowinglineofcode…
GPIO.setup(Port_or_pin,GPIO.IN)
•…changingPort_or_pintothenumberoftheGPIOportorpinyou
wanttouse.I’mgoingtousetheBCMGPIOnumberingandport
GPIO25,soitbecomes…
GPIO.setup(25,GPIO.IN)
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87. Reading inputs
•InputsareBooleanvalues:1or0,GPIO.HIGHorGPIO.LOW,
TrueorFalse(thiscorrespondstothevoltageontheport:
0V=0or3.3V=1).Youcanreadthevalueofaportwiththis
code…
GPIO.input(25)
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88. GPIO Pin Assignment
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89. E-Mail Sender
•Next,wearegoingtowritethechunkofcode
thatactuallysendstheemail.
•Thiscreatestheemail,formatsitcorrectly,
createstheconnectiontoGmail,logsin,and
sendstheemail.
•Itisquiteafewlinesofcodesowearegoing
toputitintoacustomClass–thatwaywecan
writethiscodeonce,butcallitanytimewe
wanttosendanemailinourprogram.
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90. Create Headers
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91. Connect To GAMIL Server
•ExtendedHELO(EHLO)isanExtendedSimpleMailTransferProtocol(ESMTP)commandsentbyanemailserverto
identifyitselfwhenconnectingtoanotheremailservertostarttheprocessofsendinganemail.
•Itisfollowedwiththesendingemailserver'sdomainname.TheEHLOcommandtellsthereceivingserveritsupports
extensionscompatiblewithESMTP.
•SSL, TLS, and STARTTLS refer to standard protocols used to secure email transmissions.
•SSL (Secure Sockets Layer) and its successor, Transport Layer Security (TLS),provide a way to encrypt a communication
channel between two computers over the Internet.In most cases, theterms SSL and TLS can beused interchangeably
unless you’re referring to a specific version of the protocol.
•BecauseTLS and SSLare application-layer protocols, senders and receivers need to know that they are beingused to
encrypt emails during transit. That’s where STARTTLS comes into play.
•STARTTLS is an email protocol command that tells an email server that an email client, including an email client running
in a web browser, wants to turn an existing insecure connection into a secure one. (By the way, the use of “TLS” in the
STARTTLS command name does not mean that it only works with the TLS security protocol. It works with SSL too.)
•StartTLShas become the most populare-mail encryption methodamong internet providers, as it facilitates the use of
many different domains and certificates on one server
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92. Login To Gmail
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93. Send Email & Exit
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94. 941/12/2021 IoT Devices -Raspberry Pi

95. E-Mail Contents
•TheClasswewroteinthelaststepsendsouttheemail.
•Theclasstakesthreearguments(piecesofinformationwespecifywhen
weusethecodetosendanemail)andconstructstheemailbefore
sending.
•Thesethreeexternalcomponentsare
–therecipientoftheemail,
–asubjectlinefortheemail,and
–thetextyouwanttohaveinthebodyoftheemail.
•Thesethreepiecesofinformationarestoredinthreevariables(sendTo,
emailSubject,andemailContent).
•Thisway,ourcodeiscapableofsendingemailstodifferentpeople,with
differentsubjectlines,anddifferentemailcontentwithouthavingtowrite
adifferentsenderforeachnewcontact/emailmessage.
•Addthethreevariablesandbesuretosettherecipienttosomewhereyou
wanttoreceiveyourfirsttestemail
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96. E-Mail Contents
•Example
–emailContent= ‘Switch pressed on Raspberry Pi’
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97. Calling the E-Mail Class
•Nowthatwehaveeverythingsetup–sendinganemail
isassimpleascallingtheEmailerClasswiththethree
arguments(sendTo,emailSubject,andemailContent).
•Itwillthencreateandsendtheemailbasedonthose
parameters.
•Sendsanemailtothe"sendTo"addresswiththe
specified"emailSubject"asthesubjectand
"emailContent"astheemailcontent.
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98. Example PYTHON Code for Sending an
Email on Switch Press
•Hereisaquickexampleofthiscodebeing
usedtosendanemailanytimeabuttonis
pressed.
•Totryitout,connectamomentarybuttonto
GPIO17andGND.
•YouwillalsoneedtochangeyourGmail
SenderEmailandPassword,alongwiththe
recipientatthebottom.
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99. Python Code
import smtplib
import RPi.GPIOas GPIO
import time
#Email Variables
SMTP_SERVER = 'smtp.gmail.com' #Email Server (don't change!)
SMTP_PORT = 587 #Server Port (don't change!)
GMAIL_USERNAME = '[email protected]' #change this to match your gmailaccount
GMAIL_PASSWORD = 'yourPassword'#change this to match your gmailpassword
#Set GPIO pins to use BCM pin numbers
GPIO.setmode(GPIO.BCM)
#Set digital pin 17(BCM) to an input
GPIO.setup(17, GPIO.IN)
#Set digital pin 17(BCM) to an input and enable the pullup
GPIO.setup(17, GPIO.IN, pull_up_down=GPIO.PUD_UP)
#Event to detect button press
GPIO.add_event_detect(17, GPIO.FALLING)
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100. Python Code (Contd.,)
class Emailer:
def sendmail(self, recipient, subject, content):
#Create Headers
headers = ["From: " + GMAIL_USERNAME, "Subject: " + subject, "To: " + recipient,
"MIME-Version: 1.0", "Content-Type: text/html"]
headers = "\r\n".join(headers)
#Connect to Gmail Server
session = smtplib.SMTP(SMTP_SERVER, SMTP_PORT)
session.ehlo()
session.starttls()
session.ehlo()
#Login to Gmail
session.login(GMAIL_USERNAME, GMAIL_PASSWORD)
#Send Email & Exit
session.sendmail(GMAIL_USERNAME, recipient, headers + "\r\n\r\n" + content)
session.quit
sender = Emailer()
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101. Python Code (Contd.,)
while True:
if GPIO.event_detected(17):
sendTo= '[email protected]'
emailSubject= "Button Press Detected!"
emailContent= "The button has been pressed at: " + time.ctime()
sender.sendmail(sendTo, emailSubject, emailContent)
print("Email Sent")
time.sleep(0.1)
•Oncetheemailandpasswordfieldsareupdated,runthiscodebyhitting“F5”onthe
keyboard.
•Whenthebuttonisdepressed,anemailshouldbereceivedatthereceivingaddressa
momentlaterwiththetimethebuttonwaspressed.
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102. Interfacing
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103. Demonstration Video
•Video Link
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104. Thank You
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