Building IoT applications

using Raspberry Pi
DR. SHWETA SHARMA
ASSISTANT PROFESSOR
DEPT. OF COMPUTER ENGINEERING
NIT KURUKSHETRA
BASICS

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 2

Cache

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 Locality of Reference
 Principle of Locality
 Tendency of a processor to access the same set of memory locations again and again
 Tendency of the computer program to access instructions whose addresses are near one
another

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 4

 Locality of Reference

 Instruction or data near to the current

memory location that is being fetched,
may be needed soon in the near future

 An Array is cache friendly while linked

list is not

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 Levels of Cache memory

 Data flows from the RAM to the L3 cache,

then the L2, and finally, L1
 When the processor is looking for data to
carry out an operation, it first tries to find it
in the L1 cache
 It then proceeds to find it in L2 and then L3.

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 6

 Shared Cache
 Shared among multiple processing units within a single computer system

 Serving as a common source that can be accessed by multiple processes and machines

 Instead of each core having its own private cache, multiple cores in a multi-core processor
share a common cache

 Lead to efficient memory utilization and improved overall system performance

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 7

 Shared Cache
 Suppose you have a quad-core processor with a shared cache
 Cache is shared among all four cores
 When Core 1 accesses a specific memory location, the data from that location is fetched
into the shared cache
 If Core 2 needs to access the same memory location shortly after, it can benefit from the
fact that the data is already present in the shared cache
 This reduces the time it takes for Core 2 to retrieve the data compared to accessing it
directly from main memory

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 8

 Shared Cache

 Shared cache is beneficial for scenarios where multiple cores need to access the same data,
such as in parallel processing tasks

 It helps reduce cache misses and enhances overall system performance by allowing cores to
share cached data

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Raspberry Pi

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 10

 Introduction to Raspberry Pi
 Developed by Raspberry Pi Foundation
 Launched in 2012
 The name Raspberry Pi was chosen with
“Raspberry” as an ode to tradition of
naming early computer companies after
fruit
 Here, "Pi" is for Python Programming
Language

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 11

 Introduction to Raspberry Pi
 A small single board computer
 Microprocessor
 By connecting peripherals like Keyboard, mouse, display to the Raspberry Pi, it will act as a
mini personal computer
 Used for real time Image/Video Processing, IoT based applications and Robotics
applications
 Slower than laptop or desktop
 Applications: Gaming devices, fitness gadgets, weather stations
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Raspberry Pi Hardware

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 14

 Raspberry Pi Hardware
 CPU: Raspberry Pi 3 uses Broadcom BCM2837 SOC 64-bit quad-core ARM Cortex A53
(ARMv8 CPU) with 512KB shared L2 cache
 Memory: Provided with 1 GB of RAM
 Wi-Fi Support: 802.11n Wireless LAN
 Bluetooth: Supports Bluetooth 4.1 Bluetooth Low Energy (BLE)
 USB Ports: 4-USB ports allow attaching 4 different USB devices- keyboard, mouse, etc.
 Ethernet Port: Standard Ethernet port to quickly setup and access internet. Useful to setup
raspberry pi for the first time without a monitor

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 15

 Raspberry Pi Hardware
 GPIO Pins: Raspberry Pi 3 supports 40 GPIO Pins General Purpose Input Output. These
digital input/output pins can be used to drive LED, Switches, and Sensors etc.
 Full HDMI Port: Support HDMI port (High-Definition Multimedia Interface) which can be
used to quickly connect raspberry pi to HDMI Monitor. With HDMI Cable and Monitor we
can add Screen to Raspberry Pi
 Micro SD card slot: The Micro SD Card will hold the operating system which will boot while
we power on Raspberry Pi 3

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 Raspberry Pi Hardware
 Audio/Video: Combined 3.5mm audio jack and composite video
 Display interface (DSI): enable us to interface Display Module
 Camera interface (CSI): enable us to interface Camera Module
 Graphics Support: Video Core IV 3D graphics core for advance graphics capabilities.

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 17

 Raspberry Pi vs. Arduino
 Raspberry Pi is a single board computer with Microprocessor whereas Arduino is
considered as Microcontroller unit
 The Raspberry Pi can run an OS (Linux Distribution) and also consumes more power. Since
Arduino is microcontroller device it has no operating system and can only run a single
program

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 18

 OS for Raspberry Pi
 Raspberry Pi Foundation officially provides Debian based Raspbian OS
 Provides NOOBS OS for Raspberry Pi
 NOOBS: New Out Of the Box Software and is an easy to use bootloader for the Raspberry
Pi
 Using NOOBS, users can easily install numerous operating systems to Raspberry Pi
 Users can even use NOOBS to install multiple operating systems to Raspberry Pi and to also
boot from them

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 19

 OS for Raspberry Pi
 Users can install several Third-Party versions of OS like Ubuntu, Archlinux, RISC OS,
Windows 10 IOT Core, etc.
 Raspbian OS is official Operating System available for free to use
 This OS is efficiently optimized to use with Raspberry Pi

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 OS for Raspberry Pi
 Raspbian have GUI which includes tools for Browsing, Python programming, office, games,
etc.
 SD card (minimum 8 GB recommended) to store the OS (operating System)
 Provides access to the on-chip hardware i.e. GPIOs for developing an application. By
accessing GPIO, users can connect devices like LED, motors, sensors, etc. and can control
them too

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 Versions of Raspberry pi models
1. Raspberry Pi 1 Model A
2. Raspberry Pi 1 Model A+
3. Raspberry Pi 1 Model B
4. Raspberry Pi 1 Model B+
5. Raspberry Pi 2 Model B
6. Raspberry Pi 3 Model B
7. Raspberry Pi Zero

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 Versions of Raspberry pi models
Raspberry Pi 2 Raspberry Pi 3
Features Raspberry Pi Model B+ Raspberry Pi zero
Model B Model B
System-on-a-Chip BCM2835 BCM2836 BCM2837 BCM2835
CPU ARM11 Quad Cortex A7 Quad Cortex A53 ARM11

Operating Freq. 700 MHz 900 MHz 1.2 GHz 1 GHz

RAM 512 MB SDRAM 1 GB SDRAM 1 GB SDRAM 512 MB SDRAM
250MHz Videocore
GPU 250 MHz Videocore IV 400 MHz Videocore IV 250MHz Videocore IV
IV
Storage micro-SD Micro-SD micro-SD micro-SD
Ethernet Yes Yes Yes No
Wireless WiFi and Bluetooth No No No

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 Connect Raspberry Pi
 Check the slot on the underside
of your Raspberry Pi to see
whether an SD card is inside
 If no SD card is there, then
insert an SD card with Raspbian
installed (via NOOBS).

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 Connect Raspberry Pi
 Install Rasperry Pi OS on your SD card with the Raspberry Pi Imager (if not pre-installed)
 https://www.raspberrypi.com/software/

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 Connect Raspberry Pi
 Find the USB connector end of
your mouse’s cable
 Connect the mouse to a USB
port on Raspberry Pi (it doesn’t
matter which port you use)

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 Connect Raspberry Pi
 Connect the keyboard in the
same way

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 Connect Raspberry Pi
 Connect the screen to the single
HDMI port (Raspberry 3)

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 Connect Raspberry Pi
 Connect the Pi to the Internet via Ethernet
 Use an Ethernet cable to connect the
Ethernet port on the Raspberry Pi
 Or use wireless connectivity

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 Connect Raspberry Pi
 If the screen has speakers, then Raspberry Pi
can play sound through these
 Or connect headphones or speakers to the
audio port

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 Connect Raspberry Pi
 Plug the power supply into a socke
 Connect it to Raspberry Pi’s USB power port
 Users will see a red light on Raspberry Pi and
raspberries on the monitor.
 Raspberry Pi then boots up into a graphical
desktop

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Communicate Raspberry Pi

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 Programming on the Raspberry Pi

LED Blinking

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 Programming on the Raspberry Pi
touch led.py

from gpiozero import LED

from signal import pause
led = LED(4) #Create an instance of LED called led. Set the GPIO pin to 4

led.blink() #Call the .blink() method on led

pause() #add a call to pause() to make sure the program doesn’t exit:

python3 led.py

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 34

Thank You!

DR. SHWETA SHARMA, DEPT. OF COMPUTER ENGINEERING, NIT KURUKSHETRA 35