Giang Tran

Home Automation System Using Raspbeery-Pi Through Web Application

Metropolia University of Applied Sciences

Bachelor’s Degree

Electronics

Thesis

21 March 2021

Abstract

Author(s) Title

Giang Tran

Home Automation System Using Raspberry-Pi Through Web Application

Number of Pages Date

33 pages + 2 appendices

21 March 2021

Degree Bachelor's Degree

Degree Programme Electronics

Specialization option

Instructor(s) Anssi Ikonen, Senior Lecturer

This thesis aims to clarify home automation's history, the sensors' theoretical framework and

introduce a simple, low-cost home automation system operating on Raspberry-Pi. The end

goal is to show the simplicity and cost-efficiency of building home automation in the current

modern-day.

The thesis presents the hardware and software needed to construct mentioned home

automation system. It introduces NodeJS as a back-end server as well as a data logger.

ReactJS is used to shape the User Interface and display the server's data on the front-end.

The Raspberry-Pi serves as a controller for the system by storing the server and the main

program itself. Testing is done at the end to prove that the prototype works as intended.

The result is a prototype of a low-cost home automation system with essential functionalities

such as motion-detecting, flame-detecting, temperature and humidity measurement.

Abstract

Keywords Home Automation, Raspberry Pi, Sensors, Programming, React.js, Node.js.

Contents

Terms, Acronyms, and Definitions

1 Introduction 1

2 Milestones of Home Automation 1

2.1 The Start of Home Automating Ideas 1

2.2 The Future of Home Automation 2

2.3 Examples of Home Automation's Applications 2

2.3.1 Lighting in Home Automation 2

2.3.2 Doors in Home Automation 3

2.3.3 Thermometers in Home Automation 3

2.4 Smart Home Downsides and Risks 3

3 Theoretical Study of Home Automation System 3

3.1 Sensors 4

3.1.1 PIR Structure 7

3.1.2 The Lens of the PIR Sensor 10

3.2 The Controller of the System 13

3.2.1 Introducing Raspberry Pi 14

3.2.2 Raspberry Pi Programming Languages 14

3.2.3 GPIO 15

3.2.4 Linux Operating System 16

4 Building a Cost-efficient Home Automation 17

4.1 Hardware 18

4.1.1 Temperature and Humidity Sensor 18

4.1.2 Motion Sensor 20

4.1.3 Flame Sensor 22

4.1.4 Raspberry Pi 24

4.2 Software 25

4.2.1 Express Server Using NodeJS 25

4.2.2 REST API 25

4.2.3 Raspberry Pi Programming 26

4.2.4 Building a Web App Using ReactJS + ReactJS Hooks 27

4.3 Testing the Prototype 28

4.3.1 Test Plan 28

4.3.2 Testing the PIR Motion Sensor 28

4.3.3 Testing the Flame Sensor 29

4.3.4 Testing the Temperature and Humidity Sensor 30

4.3.5 Testing Conclusion 30

4.4 The Project's Budget 31

5 Discussion 32

6 Conclusion 32

References 34

Appendices

Appendix 1. ExpressJS Server Code

Appendix 2. Raspberry Pi Main Program

Terms, Acronyms, and Definitions

AI Artificial intelligence or automated intelligence

API Application programming interface

ARM Advanced RISC Machines

DOM Document Object Model, defines the logical structure of HTML and XML

documents and the way a document is accessed and manipulated.

GPIO General Purpose Input Output

HDMI High-Definition Multimedia Interface

I2C A synchronous, multi-master, multi-slave, packet-switched, single-ended,

serial communication bus

IFTTT If This, Then That, a service that allows a user to program a response to

events in the world of various kinds.

IR Infrared sensor

IoT Internet of things

JFET Junction-gate field-effect transistor

JS JavaScript

JavaScript A programming language that conforms to the ECMAScript specification

NodeJS An open-source, cross-platform, back-end JavaScript runtime

environment

OS Operating System

OTP One time programmable

PIR Passive infrared sensor

Python An interpreted, high-level, and general-purpose programming language

REST Representational state transfer

RaspPi Raspberry Pi, a series of small single-board computers

ReactJS An open-source, front-end JavaScript library for building user interfaces or

UI components.

SPI Serial Peripheral Interface

USB Universal Serial Bus

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1 Introduction

By definition, home automation is building automation for a home, called a smart home

or smart house. A home automation system will control lighting, climate, entertainment

systems, and appliances. It may also include home security, such as access control and

alarm systems. When connected with the Internet, home devices are an essential

constituent of the Internet of Things. (1.) Home automation is the world's new trend. It

offers a lot to humanity, and its pros outweigh its cons in many ways.

The Digital Revolution marked a new era for humankind. Almost everything is now

digitalized and automated. Thanks to robots' and Ais' assistance, people's quality of life

increases significantly over time. A home is a place where people spend most of the time

feeling comfortable and protected from unwanted visitors. With the help of technology, it

can be transformed into a smart home to provide further convenience and security.

This document aims to study the background of Home Automation technology, have a

detailed look at sensors, especially PIR sensors, and demonstrate the simplicity in

building an elementary home automation system using Raspberry Pi.

2 Milestones of Home Automation

2.1 The Start of Home Automating Ideas

Within a few hundred years, humans have had a giant leap in digital development.

Engineers shrunk down the computer from the size of a room to a small, carriable

suitcase.

From the early 1900s, the first home appliances, ranging from the clothes iron to

electrical washing machines, were invented in the Industrial Revolution. Though they

were not "smart," they lent a hand in improving life quality. A few decades later, in the

1930s, inventors introduced automated homes and intelligent appliances concepts. The

idea was indeed found fascinating by the spectators.

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In 1966, ECHO IV (2) was invented as the world's first home automation system.

Although it was never marketed, it showed the progression and desire towards building

a home automation system.

The 1980s saw the growth of automated technology in garage doors, temperature

control, et cetera. Though the technology appears to be subtle, it follows humankind to

the current date.

Finally, the world started a whole new millennium of smart devices in the year 2000.

Smart appliances, smartphones, especially, have been more advanced and affordable

for people worldwide. (3.)

2.2 The Future of Home Automation

The definition of IoT is required in order to understand how home automation works.

"Internet of Things" is an umbrella term used for all technologies that enable connecting

a device to the Internet. Such systems depend on the collection of data. The data is then

used to monitor, control, and transfer information to other devices via the Internet. It

allows specific actions to be automatically activated whenever certain situations arise.

(4.) As a simple example, a smart fire alarm will push an urgent notification to the user if

it detects an unwanted ongoing fire situation.

By applying the same concept to our homes and appliances, we can effortlessly create

an IoT-powered smart home. Nowadays, almost all smart devices allow us to control

them using an app interface or voice control. Big companies are using and developing

voice-controlled personal AI assistants such as Google's Google Assistant, Amazon's

Alexa, and Apple's Siri.

2.3 Examples of Home Automation's Applications

2.3.1 Lighting in Home Automation

Lighting plays a vital role in one's living routine. While switching a light on and off seems

lightweight and straightforward, repeating in at certain times every day tends to be

tedious. With IFTTT enabled, the lights can respond differently to each different situation.

For example, a light will turn off in the daytime and turn on during nighttime without user

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interaction. It can also be programmed to turn on only if there are people nearby and turn

off automatically when the area is empty.

2.3.2 Doors in Home Automation

Doors are a way for us to protect our privacy. In that sense, they can be integrated with

face-recognition to guard against any unwanted visitors. They can also keep a log of

activity to monitor who has been tampering with the user's private space. Nonetheless,

they can be implemented together with the lighting solution to save electricity and reduce

CO2 emission, for instance, the lights turn on when the door opens, and they will turn off

after some given time.

2.3.3 Thermometers in Home Automation

A thermometer is one of many great tools to be implemented into a smart home. It

measures the indoor temperature and, perhaps, adjusts the air conditioner to match the

user preferences. There are many other ways that the intelligent system can actively

adapt itself to our personalized settings.

2.4 Smart Home Downsides and Risks

Although the mentioned benefits are significant, we cannot deny the main drawbacks of

using a smart home: security and data breach. No matter how secured a smart device

is, there is always a risk that it can be hacked into or tampered with by hackers. In which

case, a data breach is inevitable as the third party gathers information of the user's

conversation or personalized environment. The more devices the system has to manage,

the more maintenance it needs to ensure no security breach and data exposure.

For the smart home to work uninterruptedly, a stable internet connection is a

requirement. Without it, the system cannot send and retrieve its data to the user and,

therefore, nullify the system's benefits. (5.)

3 Theoretical Study of Home Automation System

The document has clarified some milestones in the timeline of home automation

development throughout the years. However, what are the fundamental elements of the

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system? The following section covers the essential elements needed for the home

automation complex to be functional in detail.

3.1 Sensors

A sensor is a device, module, machine, or subsystem whose purpose is to detect events

or changes in its environment and send the information to other electronics, frequently a

computer processor. A sensor is always used with other electronics. (6.)

Sensors are widely used in everyday applications. They become so common that we

do not even recognize that they are there, and we take them for granted. For instance,

people's smartphones for mundane work are composed of many sensors, such as

ambient light sensors, accelerometers, and gyroscope sensors. Sensors are almost

always digital. They are accepted widely in temperature measurement, smoke

detection, fire detection, and many more use cases.

Sensors react to changing physical conditions by altering their electrical properties.

Therefore, most artificial sensors rely on electronic systems to capture, analyze and relay

information about the environment. In short, a sensor converts surrounding property such

as heat, light, and sound into electrical signals. These signals are usually converted into

binary code that a computer can process. (7.)

Electronic sensors are divided into two types: Analog sensors and digital sensors.

Analog sensors turn data from the environment into an analog signal, while digital

sensors convert physical data to a digital signal. Analog sensors are more accurate

than their digital counterparts simply because digital signals are limited to a finite set of

possible values, while analog has an infinite set of values.

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Figure 1 Analog vs. Digital Signal (8)

Both analog and digital signals are superb for transferring information. Both have

different benefits and downsides. As shown in Figure 1, an analog signal is depicted by

a sine wave shape representing physical measurement, whereas square waves draw a

digital signal. While analog signals can have an infinite set of values, digital signals are

stuck with either HIGH or LOW as their most basic form. On the contrary, high-bit

digital signals can have as much as 2 to the power of bit count different configurations

to represent the information; for instance, 224 sets for a 24-bit digital signal. (8.)

Based on their fundamental differences, noise can reduce the analog measurement

accuracy. Digital signals' accuracy depends on a variety of different concepts. First of

all, the number of states available. The total number of states can reach 2n, where n is

1, 2, 3…. What is next is how many times the signal is sampled during the conversion

step. The more times, the more accurate the result would be. Nevertheless, the bitrate.

The bitrate is the amount of information recorded every time the signal is sampled. In

that sense, a higher bitrate means more information recorded and hence, more

accuracy. (8.)

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A sensor must always obey the following rules: Firstly, it must be sensitive to the

measured property. Secondly, it must be nonreactive to other properties that are likely

to be encountered in its application. Lastly, it must not influence the measured property.

(6.) For example, a temperature measuring sensor must be sensitive to the temperature

changes in the surrounding environment. Besides, its operation should not create heat

that affects the environment in any way.

Most sensors use waves likes ultrasonic waves or infrared waves to detect objects and

changes in their environment. They have an energy source inside that allows them to

emit radiation to their target. The radiation is reflected by the object and detected by the

sensor. This kind of sensor is considered to be active sensors. (7.)

Passive sensors do not send out radiation or waves. They detect radiation emitted from

other objects, such as heat or thermal infrared radiation. (7.) Let us take an in-depth look

into one of the most common passive sensors, the PIR sensor. For a quick look at the

PIR sensor, see the following Figure 2.

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Figure 2 Typical PIR representation (9)

A typical PIR sensor usually presents a white plastic "hat" covering the sensing window

underneath, together with three pins. These pins are usually Ground, Supply Voltage,

and Output Signal pins.

3.1.1 PIR Structure

The IR sensor is sheltered within an airtight metal container, improving accuracy against

noise, temperature, and humidity. On top of the metallic container goes the silicon-coated

IR-transmissive material protecting the fundamental core sensing element. The two

sensors are located inside the container. (9.) The illustration is below in Figure 3.

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Figure 3 PIR Structure (9)

The sensing parts are made of pyroelectric material, meaning it is sensitive to

temperature. In an ambient environment, it generates no voltage. However, if there are

any changes in temperature in said environment, a voltage is generated temporarily. In

that sense, the motion created by an IR source translates into the voltage created by the

material.

Figure 4 Cross-sections of PIR with two sensing elements (9)

Figure 4 shows two sensing elements position of a PIR sensor. Usually, a PIR sensor

has two or four sensing parts; each part acts as an "eye" monitoring different areas. Two

sensing elements can only detect horizontal motions, while four elements can detect

both horizontal and vertical.

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Figure 5 Internal PIR diagram (9)

Figure 5 illustrates that the two sensing elements are wired in an inverted serial, meaning

one part's positive is connected to the other's positive (or vice versa). This way of wiring

achieves two things. Firstly, the IR coming from surfaces in a still environment does

cause the pyroelectric materials to create voltages. However, the voltages generated are

equal and in a reverted direction. In this case, they cancel each other out. Secondly,

when an IR source comes to the field of view of one of the two elements, one of the

sensing elements creates more voltage than the other due to IR exposure. The voltage

difference at the JFET transistor gate leads to a voltage pouring to the drain port. The

illustration is shown below in Figure 6.

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Figure 6 PIR working mechanism Illustration and output result (9)

While being idle, the PIR detects steady IR waves from the walls and ambient

environment to its two mentioned slots. When an IR source, for example, emitted from

humans or animals, passes by, it intercepts one of the slots in the PIR sensor. The event

causes a positive differential between the two halves. When the IR source leaves the

active area, the process happens in reverse, meaning the PIR instead produces a

negative differential. (9.)

3.1.2 The Lens of the PIR Sensor

On the first look, the 'hat' of PIR sensors appears to be a cheap small plastic piece attach

on top of a PIR sensor. Although small and low-cost, it plays a significant role in

complementing the sensor's functionality. The lens impacts the width, range, detecting

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pattern effortlessly. It is made of multiple scattered Fresnel lenses, named after a French

physicist Augustin-Jean Fresnel. (10.)

The Fresnel lenses are usually seen in imaging, illuminating and on stage. Its design

allows the construction of lenses with a large aperture and short focal length without the

mass and volume of material that a lens would require in the conventional design (see

Figure 7). In short, a Fresnel lens does almost the same thing as its Plano-convex lens

counterpart, with the leverage of being more lightweight. It can be made much thinner

than an equivalent conventional lens, and in some cases taking the form of a flat sheet.

(10.)

The Fresnel lens is likely to be made of glass on staging and illuminating due to the heat

generated. However, the PIR sensor lens can be made of plastic because it does not

heat up during operation.

Figure 7 Fresnel lens versus Plano-convex lens (10)

The detecting area is two parallel rectangles, as seen in the sensor's cross-sections

depicted in Figure 4. In most use cases, a broader and larger detecting area is preferred,

and that is where the lens is needed. The small, thin, and moldable plastic lens acts as

a camera lens: it condenses an extensive area into a compact one, in this case, the

silicon-coated window. Although this may add unwanted distortion, the downside is

neglectable for the mentioned benefits.

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Figure 8 Light condensed by Fresnel lens (10)

Figure 8 shows the Fresnel lens serving as a conventional lens to increase the sensing

element range significantly.

Figure 9 Macro shot shows the inside of the dome lens (10)

Figure 9 features the inside the 'hat' of the PIR sensors. In there, various Fresnel lenses

are responsible for dividing the detection zone into many smaller rectangle zones. It is

preferred to have many small but scattered detection zones than one big one. (9.)

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Figure 10 Scattered PIR detection zones with Fresnel lens (11)

The separated zones (Figure 10) help the sensors to recognize motion from an IR source

more broadly and directionally. As said, if only two elements are presented, the

movement can only be in one direction. Many detection zones mean the movement can

be detected in any orientation. When an IR source comes into the zones, the ambient

temperature changes to body temperature, causing the voltage differences, as

mentioned in the previous subchapter.

3.2 The Controller of the System

A control unit is a must for every home automation system. Its roles are to control and

update the information received from sensor components. Without it, it will be challenging

to handle and customize the data to our wishes.

While a full-size desktop can achieve many things, including operating home automation,

the size and cost are unsuited for such tasks. The control unit is preferred to be cost-

efficient, small yet powerful enough to handle data. Luckily, two noticeable low-cost

pocket-size computers meet the requirements available in the market, being Arduino and

Raspberry-Pi.

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While Arduino is known for its in-depth technical potential, RaspPi is recognized for its

beginner friendliness and Python programming language. As a foundation for the later

demonstration project, let us look more in-depth into the RaspPi.

3.2.1 Introducing Raspberry Pi

The Raspberry Pi (Figure 11) is a credit-card-sized computer that uses the standard

keyboard and mouse. It comes with HDMI ports for monitor display, USB ports for

keyboard and mouse, a 3.5mm port for speakers, and an ethernet port for internet

connection. Its capability is almost limitless, for instance, exploring the Internet, learning

new programming languages, or playing games.

Figure 11 A Raspberry Pi without its cover (12)

3.2.2 Raspberry Pi Programming Languages

RaspPi is recommended to be used with Python programming language due to its

simplicity and beginner friendliness. Of course, any programming language which can

be compiled for ARM v6 can run on the RaspPi. The adaption to new programming

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language from the RaspPi is growing throughout the years. There are numerous

preinstalled languages, for example, Java, C, C++, Scratch, and Python.

3.2.3 GPIO

Raspberry Pi features 40 GPIO pins along the top edge of the device. The pins are

designated to be inputs and outputs for various intents. For details, see the following

illustration in Figure 12.

Figure 12 Raspberry Pi GPIO pins (12)

There are two 5V, two 3.3V, and a handful of GND pins presented on the board. All of

them are unconfigurable. The rest are general-purpose 3v3 pins. These pins can be set

to HIGH (at 3.3V) or LOW (at 0V) as output, or they can be read as HIGH and LOW for

input. (12.)

Besides simple input and output devices, the GPIO pins can be used with a range of

alternative functions. Some are available on all pins, others on specific pins. See the

following functions list (12).

• PWM (pulse-width modulation)

o Software PWM available on all pins

o Hardware PWM available on GPIO12, GPIO13, GPIO18, GPIO19

• SPI

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o SPI0: MOSI (GPIO10); MISO (GPIO9); SCLK (GPIO11); CE0 (GPIO8),

CE1 (GPIO7)

o SPI1: MOSI (GPIO20); MISO (GPIO19); SCLK (GPIO21); CE0 (GPIO18);

CE1 (GPIO17); CE2 (GPIO16)

• I2C

o Data: (GPIO2); Clock (GPIO3)

o EEPROM Data: (GPIO0); EEPROM Clock (GPIO1)

• Serial

o TX (GPIO14); RX (GPIO15).

3.2.4 Linux Operating System

Linux is a family of open-source Unix-like operating systems based on the Linux kernel;

an operating system kernel first released on 17 September 1991 by Linus

Torvalds. Linux is typically packaged in a Linux distribution.

Distributions include the Linux kernel and supporting system software and libraries,

many of which are provided by the GNU Project. Many Linux distributions use the word

"Linux" in their name, but the Free Software Foundation uses GNU/Linux to emphasize

the importance of GNU software, causing some controversy.

Popular Linux distributions include Debian, Fedora, and Ubuntu. Commercial

distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise Server.

Desktop Linux distributions include a windowing system such as X11 or Wayland and

a desktop environment such as GNOME or KDE Plasma. Distributions intended

for servers may omit graphics altogether or include a solution stack such as LAMP.

Because Linux is freely redistributable, anyone may create a distribution for any purpose.

(13.)

Raspbian is a free operating system based on Debian optimized for the Raspberry Pi

hardware. An operating system is the set of basic programs and utilities that make

Raspberry Pi run. However, Raspbian provides more than a pure OS: it comes with over

35,000 packages, pre-compiled software bundled in a friendly format for easy installation

on the Raspberry Pi.

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The initial build of over 35,000 Raspbian packages, optimized for best performance on

the Raspberry Pi, was completed in June of 2012. However, Raspbian is still under active

development, emphasizing improving the stability and performance of as many Debian

packages as possible.

Raspbian is not affiliated with the Raspberry Pi Foundation. Raspbian was created by a

small, dedicated team of developers that are fans of the Raspberry Pi hardware, the

educational goals of the Raspberry Pi Foundation, and, of course, the Debian Project.

(14.)

4 Building a Cost-efficient Home Automation

Next, this document will demonstrate the making of a low-cost home automation system

from hardware installation to software programming. The scopes of this project are:

❖ To measure the temperature and humidity of the environment using DHT11.

❖ To log motions activity detected by Grove PIR Motion Sensor

❖ To log flame activity detected by Grove Flame Sensor

❖ To send all of the measured and collected data to the NodeJS server.

❖ To display the data through a web application

See the diagram below in Figure 13 to have an overall idea of the system design.

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Figure 13 Home Automation dataflow diagram

The three sensors used in this project are all connected to the Raspberry Pi. The NodeJS

server is also running on Raspberry Pi. It is designed in order for the sensors to be on

the same device as the server. The front-end web application then picks up data from

NodeJS and renders it on the website for phones, PCs, or other devices.

4.1 Hardware

4.1.1 Temperature and Humidity Sensor

Grove - DHT11 Temperature & Humidity Sensor is a high-quality, low-cost digital

temperature and humidity sensor based on the DHT11 module (15). The overall look of

the sensor can be seen in Figure 14 below.

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Figure 14 A look at temperature and Humidity Sensor (15)

DHT11 is the most common temperature and humidity module for Arduino and

Raspberry Pi. Hardware enthusiasts favor it for its many advantages, such as low power

consumption and excellent long-term stability. Relatively high measurement accuracy

can be obtained at a low cost. The single-bus digital signal is output through the built-in

ADC, which saves the I/O resources of the control board. (15.)

Its specifications are suitable for the demonstration. Its dimension and weigh fit well with

Raspberry Pi. It operates on 3.3V or 5V, which can be provided from Raspberry-Pi pins.

More detail can be seen in Figure 15 below.

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Figure 15 DHT Technical specifications (15)

Moreover, Grove - Temperature & Humidity Sensor uses the upgraded version of

DHT11. The new version of the DHT11 module replaces resistive humidity components

with capacitive humidity components. The temperature and humidity measurement

range is broader, and the temperature resolution is higher than its previous versions.

(15.) The collected data is sent through pin 17 of the Raspberry Pi and is saved on the

NodeJS server.

4.1.2 Motion Sensor

The Grove - PIR Motion Sensor (Figure 16) can detect infrared signals caused by motion.

If the PIR sensor notices the infrared energy, the motion detector is triggered, and the

sensor outputs HIGH on its SIG pin. The detecting range and response speed can be

adjusted by two potentiometers soldered on its circuit board. The response speed is from

0.3s - 25s, and max 6 meters of detecting range. (16.)

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Figure 16 Grove PIR motion sensor (16)

The Grove - PIR Motion Sensor is an easy-to-use motion sensor with Grove compatible

interface. It can be used as a suitable motion detector for Arduino and Raspberry Pi

projects, for example, in security alarm systems and automatic lighting applications. (16.)

In this project, the Grove PIR motion sensor, shown in Figure 16 is used to detect and

log possible motions. The sensor has the following specifications in Figure 17.

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Figure 17 PIR Motion Sensor Specifications (16)

When the motion is detected, a HIGH output signal is received on pin 14 of the RaspPi.

The RaspPi then sends an API request to the server, asking the server to log to a log

file.

4.1.3 Flame Sensor

The Grove - Flame Sensor (Figure 18) can detect fire sources or other light sources of

the wavelength range of 760nm - 1100 nm. It is based on the YG1006 sensor, a high-

speed and highly sensitive NPN silicon phototransistor. Due to its black epoxy, the

sensor is exposed to infrared radiation. (17.)

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Figure 18 Grove Flame Sensor (17)

The flame sensors will play a crucial part in the fire alarm for this demonstration. Figure

19 below shows its specifications.

Figure 19 Grove - Flame Sensor specifications (17)

Likewise, when there is a flame detected in the field of view, the RaspPi asks the server

to log down the activity and save it to display to the user later on. It is connected through

pin 23.

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4.1.4 Raspberry Pi

Finally, we have the Raspberry Pi in the setup as a central control unit. Data collected

from sensors will be processed and controlled by the Raspberry Pi.

Figure 20 Raspberry model 3B+ (18)

We will use Raspberry Pi model 3B+ (Figure 20). With an upgraded processor boasting

impressive new packaging and improved networking capabilities, the new Raspberry Pi

3B+ has a generally better specification than its predecessor, the Raspberry Pi 3. (19.)

The detailed specifications can be seen in the following Figure 21.

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Figure 21 RaspPi 3B+ Specifications (19)

The RaspPi collects data from the sensors and instructs the server to log it down. It also

serves as a place to store the log files.

4.2 Software

4.2.1 Express Server Using NodeJS

Express is a minimal and flexible Node.js web application framework that provides a

robust set of features for web and mobile applications (20).

A server is crucial for users to communicate with RaspPi, thus communicate with the

sensors. For simplicity, the server will also serve as a database recording the history of

PIR motion and Grove Flame sensor detections.

4.2.2 REST API

REST API has a vital role in the communication of the web app and the server. On the

web app first load, it hits the server and requests the needed information. The server

then returns the information and displays them on the front end.

For this project, several API routes needed to be built, three of which are needed for

flame, motion, and temperature and humidity sensors. One more is needed for the front

end to call whenever it needs a server's data update. The entire program can be found

in Appendix 1.

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4.2.3 Raspberry Pi Programming

After setting up the server, the next needed thing is to program the Raspberry Pi, so it

works as intended. We will create a looping program to check the states of the sensors.

If any sensor is tripped, we will send a REST API call to the server to update the data.

The temperature and humidity sensor continuously gets updated regardless of the other

sensors' activity. See the following flowchart in Figure 22.

Figure 22 In-depth details data flowchart

The loop goes first to check if the motion sensor state has recently changed from LOW

to HIGH. If it does, then RaspPi sends a PUT request to

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localhost:3000/api/motionSensor. Likewise, if the flame sensor is triggered,

RaspPi sends a PUT request to localhost:3000/api/flameSensor. Temperature

and humidity data also get sent to the server if there are any changes. The server will

pick up the PUT requests, log down the activity and data, ready to serve them to the

front-end.

The whole process will be looped every 1 second, ensuring that the server's data is up-

to-date. The server file and the main program will be located on the Raspberry Pi. They

will be initialized after the RaspPi boots, which can be achieved by modifying

/etc/rc.local file. See the Appendix 2 for the Python full program's code.

4.2.4 Building a Web App Using ReactJS + ReactJS Hooks

React is an open-source, front-end JavaScript library for building user interfaces or UI

components. It is maintained by Facebook and a community of individual developers and

companies. React can be used as a base in the development of single-page or mobile

applications. (22.)

There are plenty of documents explaining in-depth how React works. However, it is out

of the scope of this piece of work. In short, developers write "components" for a website

and place them together on a browser's DOM. The website is managed through a state

management system. In simplicity, every time the state changes, the content" re-render"

or refreshes itself, therefore, display the latest information.

When a user opens the website, it first fetches the server's data, updates the

components, and continues to fetches data every 4 seconds afterward, hence making

the components re-render, displaying the newest data. However, the weather is fetched

every 10 minutes from an external source (openweathermap.org) due to the lack of

budget.

A complete front-end code and components can be found in the following URL:

https://github.com/Kyokatarz/thesis-frontend

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4.3 Testing the Prototype

4.3.1 Test Plan

Several tests will be conducted to prove that the system is working as intended:

• Check the motion sensor functionality

o Create movement in front of the PIR sensor and check the motion logs

o Measure the detecting range of the PIR sensor (optional)

o Measure the detecting angle of the PIR sensor (optional)

• Check the flame sensor functionality

o Create a heat source in front of the flame sensor and check the flame logs

o Measure the detecting range (optional)

• Check the temperature and humidity sensitivity

o Create a heat or coolness around the DHT11 sensor and check for

changes in the application

o Increase and decrease environment humidity around the DHT11 and

check for changes in the application

Disclaimer: Fire hazards are not to be taken lightly while conducting the tests. Reproduce

the tests at one's own risks.

4.3.2 Testing the PIR Motion Sensor

In order to test the PIR motion sensor, create a motion in front of it. In this study, a motion

was created by waving in front of the sensor. The application then showed the time when

the motion was detected, as shown in Figure 23.

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Figure 23 Server logs of the most recent movements

Further testing was done to measure the detecting distance and detecting the angle of

the sensor. The sensor is efficient at around 2.7m to 3m. A distance further than that

causes the detection to be unreliable. The sensor can also detect motion around 60

degrees each side from its center, which makes 120 degrees in total. The results seem

to match the specifications in Figure 17.

4.3.3 Testing the Flame Sensor

By creating a fire source and directly pointing the black epoxy of sensor to the fire source

direction, we can test whether the flame sensor is functional. In this case, candles were

used to conduct the test. After doing so, the flame sensor log was checked, as shown in

the following Figure 24.

Figure 24 Flame logs of the most recent activities

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More testing was also done to measure the detecting range of the flame sensor. Based

on the specifications, theoretically, the sensor can detect flame up to 1 meter. However,

while conducting the test, it is found that the sensor efficiently works around 0.75 meters,

further than that seems to give a fluctuating result.

4.3.4 Testing the Temperature and Humidity Sensor

The log in the application seems to show an expected value of the environment

temperature and humidity, as shown below in Figure Figure 25:

Figure 25 Room temperature and humidity (sampled on 16 February 2021)

Further testing was done to test whether the result updates as the temperature and

humidity change. One of the methods is to breathe briefly into the sensor. The warmth

and moisture of a human breath should be sufficient for the sensor to pick up.

Doubtlessly, the temperature rises to 30-32 degree Celsius, and the humidity rises to

95%. The actual humidity may have been even higher than the recorded number, but

due to the sensor technical limit (as shown in Figure 17), it can only read to up to 95%

humidity.

4.3.5 Testing Conclusion

After evaluating the product's results, it is safe to say that the prototype is working as

expected and is now complete. By putting all of the application components together, the

final version of the web application overall look is as following in Figure 26

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Figure 26 Fullscreen screenshot of the final application

The flame log, motion logs and temperature and humidity section are to monitor the

indoor environment. The Weather section is an extra feature to show the outdoor

temperature, making the application more appealing.

4.4 The Project's Budget

The following table from Figure 27 shows the current time market price for the

components needed for this project. Prices tend to be different from site to site.

Component Price (€)

Raspberry Pi 3B+ (18) 44.90

Grove Motion Sensor (16) 6.51

Grove Flame Motion Sensor (17) 5.69

Grove DHT11 Temperature and Humidity Sensor (15) 4.86

Total: 61.96

Figure 27 Price table of the components on 12 February 2021

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5 Discussion

The result proves that it is possible to build an elementary and straightforward working

home automation system from simple components. Nonetheless, the system has

limitations that are yet to be discussed.

It is not easy to match the sensor pulse with the program's delay on the Raspberry Pi

programming. As a result, the data is only collected if the sensor pulses and the delay

are matched. On further testing, it does not seem to affect the outcome. However, it is a

mentionable flaw of the system.

The NodeJS server logging method upon API call is rather primitive and not

performance-optimized. It is functional on a small-scale application such as this one.

However, if it were to scale to be in a more significant project, some refactorings are

necessary.

The front-end application generally looks acceptable. Nevertheless, a more aesthetic

design is always welcomed.

6 Conclusion

The demonstration of a home automation system shows that with fundamental sensors,

a RaspPi, and a basic programming level, one can build a simple home automation and

security system effortlessly.

The project, undoubtedly, has much room for improvement. It can be implemented with

a lightbulb for automated lighting or connect to the phone for immediate warning about

motions and flame. The AI voice assistant technology can also be applied for even more

alleviated using experience. For now, the system only works within the local network.

Perhaps it can be exposed to the Internet for better user monitoring. On the other hand,

although it lacks functionalities compared to a complex home automation system, it is an

excellent base for more advanced applications to be built on top of it.

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To conclude with a thought, technology and science are emerging to a point beyond our

imagination. If 50 years ago, owning a personal computer is senseless, then it might be

true that home automation technology is just beginning to bloom. Smart homes will

indeed become more advanced to assist humanity in their daily living basis.

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Appendix 1

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ExpressJS Server Code

Appendix 1

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Appendix 2

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Raspberry Pi Main Program

Sendrequest.py

Appendix 2

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Main.py