All language subtitles for gfdhjhkjffff

arduino is an open source electronics

platform based on

easy to use hardware and software this

course from ashish will teach you

everything you need to know

to start creating your own electronics

with arduino

and you don't even have to have any

hardware to follow along

hello everyone thank you for joining

this arduino course for beginners

this course is created for people who

have no or very little prior experience

in electronics

and programming so in this course i'm

going to help you get started with your

arduino adventures and by the end of the

course

we will have some basic knowledge of the

most common hardware components

such as breadboard resistor led etc

and their usage in electronic circuits

you will also be able to write arduino

programs on your own

this course is built in such a way that

it would cover

things which absolute beginners face

while understanding the code written by

other creators

while creating this course i've kept in

my mind what problems i had faced

when i started my own journey with

arduino and made it like a course

which i wished i had watched before

starting

anything at all if you don't have an

arduino and other components with you

right now

you can still follow along the course

and get one later

to perform your experiments which you

have in your mind so let's get

started this section will be a quick

overview to practical electronics and

some of the most common electronics

components that we will be using

throughout the course with the arduino

you can always revisit this section if

you find any term confusing or you need

to understand something again

so let us start with electricity i'm

pretty sure that you all must have heard

of this term at least once in your

lifetime

if not let me tell you that electricity

has played a major role in letting you

watch this video on your computer or

your laptop

electricity is a type of energy that can

be built up in one place or flow from

one place to another

when electricity gathers in one place it

is known as static electricity

and electricity when moves from one

place to another

is called current electricity

have you felt a sudden painful jolt when

you brush someone's arm

or crackling sounds when you take off

your sweaters or have you

tried to attract paper bits by a comb

all this happens due to static charges

that were accumulated at a place

believe it or not even the lightning

that happens in the sky

happens due to static electricity so why

does this happen

everything in this universe is made up

of atoms which are made up of protons

and electrons

protons are positively charged and

electrons are negatively charged

in an atom generally the number of

protons and electrons are equal

hence the electric state of atom is

neutral but when some atoms lose their

electrons they become positively charged

and when some atoms gain electrons they

become negatively charged

the short learning which i want you to

take from this lesson

is that similar charges repel and

opposite charges attract each other

as shown in this diagram static

electricity is a very deep topic

and has a separate study called as

electrostatics

which will go beyond the scope of this

course

the other reason i told you about static

electricity is that

the static electric charges in our hands

may damage your electronic components

sometimes

so just make sure you keep your stuff on

hard and solid surfaces

and keep your components back in the

anti-static packets which you got

along with the components current

electricity is the form of electricity

which makes all of our electronic

gadgets work

this form of electricity exists when

charges are able to constantly flow

as opposed to static electricity where

charges gather and remain at rest

current electricity is dynamic charges

are always on the move

we will be focusing on this form of

electricity throughout

the rest of our course so in the next

video we will talk about

voltage which is one of the most

important concepts

for the existence of this current

electricity so i will see you in the

next video

in this video we will learn about

voltage voltage is a force

that makes electrons move through a wire

it is measured in

volts and the symbol is v okay voltage

is also called as

electromotive force or emf which

drives the electrons inside a wire

voltage was named after a scientist

called

alessandro volta so now technically

speaking the voltage is a difference in

electric potential

between two points for example the

difference between

the positive and the negative terminal

of a battery

let's say this battery is of 5 volts so

the potential at this point can be 5

volts and the potential at this point

can be 0 volts

so the potential difference is 5 volts

okay

it can also be 10 volts here and 5 volts

here resulting into a difference of 5

volts it can also be 0 here

and minus 5 here then also the

difference will be

5 volt so this battery provides some

force

on electrons so that they can move

inside a wire

like this you can see these electrons

are moving inside a wire

and and this bulb is glowing now let us

understand

voltage by a water analogy this is a

water tank

and the pressure at the end of the hose

can represent

voltage the water in the tank represents

charge

more the water in the tank the higher is

the charge and

more is the pressure at the end of the

hose we can think of this tank as a

battery

a place where we can store certain

amount of energy and then

release it if we drain our tank a

certain amount the pressure created at

the end of the hose

also goes down right what i mean to say

is we can think of this as a decrease in

voltage like when the flashlights which

use batteries

glow dimmer as the batteries run down

and then there is also a decrease in

amount of water that will flow through

this hose

less pressure means less water is

flowing so we can consider this flowing

water

as current which we will discuss in the

next video

in this video we will learn about

current on a very basic note the rate of

flow of charge is known as current

when electrons move from a negative

terminal to positive terminal of a

battery

they give rise to current the unit of

current is

amperes and the direction in which the

current flows is is the opposite

to the direction of electrons what that

means is

if electrons are moving in this

direction then the current will move in

this direction all right so now on a

more technical note

current is the amount of electric charge

that flows when one coulomb of charge

moves past somewhere in one second and

that current is

one ampere coulomb is the measuring unit

of charge

all right and to measure the current at

any point we can use an ammeter

we can also understand the flow of

current by water analogy

let's say this is a tank filled with

water and this water is flowing due to

potential energy of water which we

learned is called as

voltage in the previous video so here

the size of

hose is acting as resistance a bigger

size hose

offers less resistance and the smaller

size hose offers more resistance

so the path which has

lower resistance more current can flow

through that path

and the path which offers more

resistance less current can

flow through that path okay so here

since the voltage is equal and

resistance is lower in this case

the water flowing here will be more and

the water flowing here will be less

okay so this has given

rise to another term called as

resistance and we will learn about

resistance in

next video but before that i would like

to tell you that there are two types of

current

one is direct current and one is

alternating current in dc current

the flow of electrons stay in the same

direction and the voltage stays

steady with the time as you can see from

the graph

while in ac the flow of electrons change

and the voltage does not stay steady

with time that also you can see from the

graph

don't worry if you could not understand

all this at this moment

at this point you only need to

understand that the current

which you see in your home that is the

current which drives your fans

and other appliances like air

conditioners televisions

etc is known as ac current and the

current which you get from the batteries

or specific power supplies is dc or

direct current the current you get

from your laptop or computer's usb port

is also dc current

and for our course we will be dealing

with the dc current only

if you have understood just this part

you are good to go

so i will see you in the next video now

we will take a look at resistance

the electrical resistance of any

component is a measure of difficulty of

passing an electric current

through that substance with more

resistance in a circuit less electricity

will flow through the circuit

based on this term resistance there is

an electrical component known as a

resistor

a resistor is a device which limits the

flow of a current in a circuit

we may need resistor inner circuits

where we need to drive leds

which require limited amount of current

so that we can prevent it from burning

off

right now if we see the resistance with

the water analogy

we can see this is a pipe and this is

one another pipe

the water can flow easily through this

pipe because it offers less resistance

the flowing water can be

synonymous to flowing current okay and

when there is more resistance

less current will pass through it one

important thing which you would like to

know is

that the current always takes the least

resistive path

for example if you offer two parts for

current to flow

it will try to flow from the least

resistive path out of them

okay so in the next video we will study

the relation between current voltage

and resistance and in upcoming videos we

will also learn

how to identify the value of the

resistor the value

of the resistor is measured in ohms more

the value of resistor

more the resistance it will offer in the

circuit so now i will see you in the

next video

so till now i'm sure that you all must

have inferred that somehow

all these terms are interconnected if

you have then you are absolutely correct

there is a law known as ohm's law which

tells the correlation of these terms

a german physicist george simon ohm

stated

that the electric current flowing

through a metallic wire is directly

proportional

to the potential difference across it

provided

temperature remains the same that means

like i said earlier more the force more

the current

so potential difference is the force

here which we talked about earlier

so mathematically we get voltage v

is equal to the product of resistance r

and

current a or i for that matter

[Music]

if any one of them is unknown we can

find out by doing the math

there's an easy way to find that out

there is a triangle

known as ohm's law triangle

[Music]

we just hide the unknown quantity and we

get

the answer for example if we hide v

so i and r looks in a multiplication

position

so v is equal to i multiplied by r

if we have to find resistance we will

cover up r then v and i

appear in a division like position so r

is equal to v divided by i

then we have i as unknown quantity

then we can do i is equal to v by r

based on the similar reason

this interesting image shows that if we

consider voltage current and resistance

as people

how would they behave the voltage would

keep pushing the current

and resistance would create difficulty

for it to pass

isn't it funny so now let's see how

do we use ohm's law to calculate the

unknown values in a circuit

this is a circuit and this is a very

basic circuit right

and here is the resistance of value 600

ohms

and this is the circuit representation

of a resistance

which is a zigzag line right

here we have a battery which measures 12

volts

and this is the connecting wire so can

you figure out

how much current is flowing in the

circuit right now we will use ohm's law

to find out

okay so here what quantity is unknown

i which is current right so we will be

using i

is equal to v by r so we'll do

12 upon 600 which would be 0.02 amperes

okay so now if we change the value of

our resistance

and make it 6 ohms instead of 600

so can you tell me the new value

we just need to do 12 by 6 now

which would turn out to be 2 amperes all

right

so did you observe that if we reduce the

resistance in a circuit

the current flowing in the circuit

increased earlier it was 0.02 amperes

and now

it is 2 amperes right

now if we change the voltage

of the battery as well let's say 24 so

now the current flowing will be

4 amperes right so we increase the

voltage and reduce the resistance

so the overall current flowing in the

circuit was 4 amperes

so i guess you must be able to see the

relation between voltage

resistance and the current flowing in

the circuit one thing you need to learn

about using resistances in a circuit

is that there are multiple ways we can

use resistances

like we can use them in series we can

use them in parallel

so now i will show you how to use

resistances in series and parallel

if i give you a general idea about

resistances in series in parallel

i would say in a series circuit the

output current of the first resistor

flows into the second resistor and into

the third resistor

therefore the current is the same in

each resistor

while in parallel all the resistors are

connected to each other

in a manner shown here right all the

ends

are connected to each other like this so

now we will look at

series circuit in a bit more detail so

if we look at

the circuit here we can see that three

resistances

r1 r2 and r3 are connected in series

across a battery of a certain voltage

okay we don't know what voltage is that

right now but let's say

that voltage is v right so now since

there is just

one path for current to flow in this

circuit the

value of current flowing in the circuit

would be same let's say

it would be equal to i okay so due to

that

in a series circuit the voltage drop

across each resistor

would be different and interestingly the

sum of v1

v2 and v3 that is the voltage across

each resistor

will be equal to the voltage of the

battery

right let's say if the voltage of the

battery is 12 volts okay

so the voltages which we will get across

these resistances

would add up to 12 and from this circuit

we can create

an equivalent circuit like this where

where the equivalent resistance is the

algebraic sum of

all the resistances which we have used

so let us now see an example

where you can apply this learning right

so here we have a circuit

with five resistances connected in

series

and which are connected across a battery

which measures 9 volts

so what we need to do is we need to find

the equivalent resistance

the current flowing in this circuit and

individual voltages

across each resistance right let's have

our diagram handy with ourself

which we use to remember the ohm's law

so let us first calculate the equivalent

resistance

as i told you to calculate the

equivalent resistance in a series

circuit

we just take the algebraic sum of all

the resistances

right so here

it will be 20 plus 20 plus 20 plus 20

and plus 10 which is equal to 90 ohms

right

now since we have this equivalent

resistance to calculate the current

flowing in the circuit we would use

this formula i is equal to v by r right

the only difference is instead of using

r we will use

r equivalent because we will be using

the equivalent resistance in the circuit

right that would be 9 upon 90 which is

0.1 amperes so now we know

that 0.1 amperes is flowing in this

circuit

so to calculate individual voltages

across the resistances

what we can do we'll use the ohm's law

once again

but this time we will use this formula

we need to calculate v is equal to i

into r

so i is 0.1 and r is 20.

so 0.1 into 20 is 2 volts okay

similarly this will also measure 2 volts

this will also measure 2 volts this will

also measure 2 volts

and this one will be 1 volt because 0.1

into 10

is 1 right so now you notice that

2 plus 2 plus 2 plus 2 and plus 1

is equal to 9 right as we saw earlier as

well

all the voltages also add up to the

voltage of the battery which is 9 volt

all right so this is about series

circuit now we will look at

the parallel circuits so the resistors

are in parallel when one end

of all the resistors are connected by a

continuous wire of negligible resistance

and similarly

other ends are also connected to each

other through a similar wire

since all the resistances in parallel

are connected directly

to the battery you can say the voltage

across all of them

is equal right but unlike the resistors

in series

where there is just one path for current

to flow in parallel circuits

there are multiple paths for resistance

to flow like in the circuit you can see

current has two parts if the current

flowing in the circuit is i

then it will divide into two parts let's

say i1 and i2

if there were more resistances we would

say like i3 and i4 etc

and when that current flows it comes

back and

it adds up and becomes i again and if we

wish to calculate the values of i1 and

i2

again we can use the ohm's law here

right because the voltage

across this resistors is equal to the

battery's voltage

and the value of resistor is also known

so we can calculate i using ohm's law

right

you should remember that v1 and v2 will

always be equal to

v and i will be equal to

i1 plus i2 right

now we can also calculate the equivalent

resistance

this combination of resistors will offer

in the circuit

and to do that there is a very simple

formula

one upon req that is equivalent

resistance is equal to

1 by r1 plus 1 by r2 plus 1 by r3

and so on right so let us see one

example

and let us keep that diagram handy again

right so what we need to do in this

question is

we need to find out the current flowing

in this circuit

and the individual current flowing in

these resistances

right so one approach can be we can find

out the equivalent resistance first

using the formula we just saw let us

place the values inside it

right 1 by req is equal to 1 by 1

plus 1 by 2 plus 1 by 2.

we have just replaced these values by

the values of the resistors

right so now we will take lcm

and which turns out to be 4 by 2

but please note that this is 1 by r

equivalent

all right so to calculate r equivalent

we will take the reciprocal of this

value which would turn out to be

0.5 ohms right so now we have

the equivalent resistance of this

circuit we can simply use

the formula i is equal to v by r v is 3

and r is 0.5

so the answer would be 6 amperes right

so 6 amperes will be flowing in this

circuit

now if we want to calculate the

individual currents in these

resistances what we will do is we will

use

this formula again because v is same

and r is known right so in this resistor

v is three and r is one so in this

resistor three amperes will be flowing

in this resistor

three by two that means one point five

would be flowing right and in this

resistance as well

1.5 amperes would be flowing so now if

we add up

all these currents in these three

resistances

that would come out to be six so again

we verified the things we just studied

and i don't know if you noticed or not

the equivalent resistance

of 0.5 was even lesser than the lowest

of the resistance is used

right so this will always be the case

the equivalent resistances

in the parallel circuits will always

come out to be

lesser than the lowest value of the

resistance in those combinations

all right so this was about parallel

circuits

and now we will see a slightly more

complicated circuit

which involves series and parallel

circuits both

so here we have such a circuit where

resistances

are present in series as well and panel

as well

so now i will tell you how to find out

unknown values

in such kind of circuits right so first

of all

we need to work in sections of the

circuit for example

in this circuit i have taken up this

section we can see that these two

resistances

r3 and r4 are in series right so using

our regular

resistances in series formula which is r

equivalent is equal to r1 plus r2 plus

r3 and so on

right so here are two resistances so we

have just taken some of those two

resistances

which is 10 ohm then in our mind we will

think of it as

one single resistor right which is in

parallel with

this resistance right so now we will use

our parallel formula

which is 1 by r equivalent is equal to 1

by

r1 plus 1 by r2 right

so both of the resistances are of 10

ohms so if you plug the values

in this formula you will get 5 ohms you

can try it on your own right

then we will reduce that circuit in our

mind only

with 5 ohms as a resistance then this

equivalent resistance

is in series with 7 ohm resistor right

again we will use our resistance in

series formula

so the equivalent resistance will turn

out to be 12 ohms

so now let's have our ohm's law formula

handy

right so what we can find out now is how

much current is flowing in this circuit

how we can do that we will use this

formula i is equal to v by

r where v is 24 and r is

12 so we will get 2 amperes

right so now if we want to know voltages

across

each resistance and current flowing in

each resistance

we can work our way backwards now right

so we know two amperes is flowing in

this circuit so we can calculate the

voltages across

these two resistances right so first we

will calculate

across 7 ohm resistor so how will we do

that we'll use v is equal to

i into r i is 2 and r is 7

so we will get 14 volts across this

okay and here we will get

2 into 5 10 volts right so you can see

14 plus 10 is 24 we are satisfying the

things which we have studied so far

now we'll move one step back so we knew

voltage across this resistance

was 10 volts right so in this section

also

the voltage will be 10 volts so now

since this is a parallel circuit in both

of the resistances

voltage will be 10 volts so now we can

calculate

current in this right by using this

formula again

right v is 10 and r is also 10

so 1 ampere would be flowing inside it

the answer would be same for this one as

well

right now if we take one step back again

we'll have to calculate voltage across

these two resistances how will we do

that again we'll use this formula

v is equal to i into r so current was 1

ampere in this

so in this as well it will be 1 ampere

so we know

6 into 1 is 6 volts

and across this one we'll have 4 volts

using the same formula right so we have

all the unknown values

right now since there were so many

values i can understand it must be a

little difficult for some of you to

visualize it

so i have created a circuit to help you

visualize a little

right let's have a look at it so here is

that visualization

so you can see exactly similar circuit

which we saw earlier

and i have written all the values of

current flowing in each resistance

and now i will show you the voltages

across each resistance

let's keep this formula handy as always

now i will show you voltage across each

resistance

it is 14 volts across 7 ohms 6 volts

across 6 ohms

4 volts across 4 ohms and 10 volts

across

10 ohms right so if you have understood

this part

i can say you have understood really

important fundamental

about using resistances in series and

parallel but

you may also find circuits like this

okay

where we have two batteries right in

circuits like these

you cannot simplify the circuits which

we have seen so far

so there are some advanced concepts such

as kirchhoff's law

okay which is used to calculate the

unknown values in the circuit

but that will go beyond the scope of our

course right now so one last thing about

resistances i want to tell you is

identifying the resistance is based on

the color bands

let's have a look at that now

resistances

come with the four or five color bands

denoting the value of resistance

it will offer in the circuit

so you see in this diagram there are

four band

resistors and there are five band

resistors

okay in a four band register the first

band will tell you the first digit

the second band will tell you the second

digit

the third band will tell you the number

of zeros which you need to put after the

first two digits

and the fourth band tells the error

percentage

means it can be that much percentage

above or below

the stated value now see the first band

in this case

is yellow so it the first digit will be

four the second band is violet so the

second digit will be

seven the third band is origin color

so the multiplier will be one thousand

so we get the value of

forty seven thousand and the fourth band

is

gold so that means it will have a

tolerance of plus minus

five percent so the net value of this

resistance is

47 000 ohms

or you can say 47 kilo ohms with the

tolerance of five percent

now we see the five band code okay

the first band tells the first digit the

second man tells you the second digit

the third bank tells you the third digit

fourth band tells you the multiplier

here

and first bank tells you the tolerance

we'll consider this example

first band is orange and color so the

first digit will be three

second band is green so the value will

be

five the third band is black in color

so the third value will be zero

and fourth band is red so the multiplier

will be

hundred till now we get three five zero

and double zero so this is 35 000

and the last band is brown in color so

one percent of tolerance so the net

answer will be

35 kilo ohms with a tolerance of one

percent

you can refer to this chart whenever you

need to find the value of your

resistances

and i understand this might be confusing

at first but with practice

you can understand this very easily in

this section

we will finally take a look at the main

thing most of you must be already

waiting for this section to come up

so this blue colored thing which is

present in your kit is the arduino board

i will tell you what is it what it can

do

and how to start using it finally

but before that i would like to tell you

about some terms which you may

or may not have heard about before

starting this course

so these terms are microprocessor

microcontroller

memory integrated circuits etc

microprocessors are known as a brain of

any computer

they consist of a cpu which stands for

central processing unit

which is responsible for doing all the

computations and calculations which we

need to carry out

they need additional peripherals like

ram and rom in order to function

example of a microprocessor is the cpu

which is being used in your computer

right now

if you go and check the history of

microprocessors you will see the

microprocessors have come a long way

after so many improvements in

developments microprocessors

and graphic processors are used where

there is a need of heavy computational

cycles

like artificial intelligence deep

learning self-driving cars

and high-end robots our daily

applications like playing games

movies browsing internet also requires

our microprocessors

and then there are microcontrollers

microcontrollers are integrated chips

that are basically tiny computers but

are powerful enough to do a lot many

tasks

like controlling motors pumps other

appliances or they can send some sensor

data to internet cloud

control basic displays and even act as

brains of some intermediate level robots

applications are endless trust me the

power requirements of such integrated

chips is very low

and you can even run these chips on

batteries

for days or even months they have all

the peripherals like memory and flash

storage

built on the same chip

[Music]

if we compare microcontroller and

microprocessor

in terms of cost a microcontroller is

far cheaper than a microprocessor

however

microcontroller cannot be used in place

of a microprocessor

and using a microprocessor is not

advised in place of a microcontroller

as it makes the application quite costly

if we compare them in terms of speed if

we say human brain is fast

then microcontroller is faster and

microprocessor is fastest

but please note we are talking in a very

general way this won't be applicable if

you compare an old generation thing with

a new generation thing

as technology advances it won't make any

sense to compare

and also some exceptions are always

there it is really possible that you

or any human may be faster

[Music]

so do you have any guesses in which

category or arduino board will fall

if you said microcontroller then you are

partially right

an absolutely correct answer is that

arduino is a circuit board

which has a microcontroller on it which

act as the heart of that board

the arduino board given to you in your

kit is arduino uno

which uses microcontroller atmega328

there are many more kinds of arduino

boards available with other

microcontrollers

which may be superior or inferior to

atmega328

but arduino uno is just right for our

applications

you may want to pause the video here to

have a look at all these

boards and admire how beautifully they

are made

so arduino is basically a company in

italy which made it really easy for

people to use microcontrollers for their

application

the hardware and software of arduino is

open source which means

one can have access to the files and

even modify them for their own work

since it is open source many other

companies take their design and

manufacture their own versions of

arduino

so it is really easy to clone and modify

the arduino board

[Music]

what makes arduino a beginner-friendly

tool is their easy to use

hardware and software it can be used

even by people

having no technical background

earlier people would have to use very

difficult assembly language to control

their votes

but it is not the case with arduino

as you progress with the course you will

see yourself with how easy and intuitive

this tool is

you will see that uploading the code is

as simple as plugging a usb cable and

clicking upload button

in this video we will see the parts

which make up the arduino board

so this is the diagram of arduino board

which shows the typical components which

are placed on it

so we will begin by the digital pins the

pins which you see

here which are numbered 0 to 13

and some pins have a special symbol like

this

curvy symbol on in front of it which

denotes pwm capability

that means these pins support pwm other

than that

these pins take digital input from

sensors and give digital output

to some of the components all right so

then we move to the built-in led

which is shown by this led

this led by default is connected to pin

number 13. so whenever pin number 13

goes high

this led will turn on and when that pin

goes low

this led will turn off and then

we will see the power led this is the

power led

if this led is turned on that means your

arduino is plugged in

that means it's turned on right now then

we have

the main component the atmega328 chip

it controls all the main functions of

this board

whatever is happening on this board is

due to

this ship then we have

analog pins we have six analog pins on

this board

numbered from a0 to a5

we can connect any analog sensor on

these pins

then we have the power pins these are

the power pins

you can power any component using these

pins but make sure that you don't your

components are not drawing a lot of

current

basic sensors and basic you know

breadboard circuits

are fine with these pins

then we see the power dc jack if you

want to connect

your arduino externally through a dc

jack you can connect it

through this jack the voltage input it

can accept is 7 volts to

12 volts then we have tx and rx leds

these are the tx and rx leds rx means

receive tx means send

transmit okay so whenever these leds are

blinking that means

cardinal board is either communicating

with the computer

or some other another arduino board

then we have the usb jack you connect

your arduino board with your computer

using this jack

then we have the reset button this

button reloads the entire code which is

running on the

arduino board but please note that this

button does not

clears the memory of arduino

here are few technical specifications of

arduino uno

by technical specifications i mean the

information which you look

while buying any item or a computer like

in a computer you see how much disk

space is there

how much ram does it have or processor

it has similarly

arduino being a microcontroller board

has some technical specifications

like it has atmega328 as the main chip

which does all the work it operates at 5

volts

the input voltage which it can accept is

5 to 12 volts

although according to the data sheet of

arduino

the recommended voltage is 7 to 12 volts

and the limits

are 6 to 20 volts so i recommend that

5 to 12 volts is a good enough voltage

to operate

arduino with and then there are

14 digital pins out of which six are pwm

capable

don't worry about pwm right now but just

think having pwm capability is a good

thing

then there are six analog pins which are

used to connect analog sensors to the

arduino

you can understand that these pins are

connected to arduino

through a 10 bit adc an adc is

an analog to digital converter we'll

talk about adc

in further lectures

the i o pins are capable of supplying 40

milliamperes of current

so these pins cannot drive large

appliances or the things which require

more current like motors and it is not

even recommended

that you run motors through arduino but

few leds and most sensors which we use

in this course do not draw very large

amount of current

so these pins are just fine

there is a 3.3 volt pin as well and the

maximum current you can draw from it is

50 milliamperes

and there is a flash memory of 32 kb

which we use

to store all the programs into it 32 kb

must be seeming like a very less amount

but trust me you can store lines

of 1000 even 2000 lines of code in this

and it won't even exceed 10 percent of

the storage

then it have sram of 2kb which is a

volatile memory

or more generally it is similar to ram

on your computer

again it would seem too less and i would

repeat

what i said for the flash memory that it

is more than enough

it also has 1 kb of eep rom which can

store

some variables even after you switch off

the arduino

clock speed is 16 megahertz clock speed

is the speed that microprocessor

executes each instruction

one megahertz representing one million

cycles per second

i understand a lot of information in

this video might have just bounced over

your head

and it's perfectly okay if you don't

understand some portion of it

i would just say don't lose your

motivation and just stick with us

and i promise you you will understand

each and every part

of it by the end of the course if not we

are always here for help

in this section i will tell you about

arduino ide

but before we jump into that first of

all we need to understand what an ide

is a text editor like a notepad

along with the compiler is a bare

minimum requirement to start

coding but wait what is a compiler

compiler is a special program that

processes statements written in a

programming language

and turns them into a machine language

which are basically zeros and ones which

a computer can understand

but unlike text editor an ide which

stands for integrated development

environment

is a software tool which has a lot more

functionality to make programming easier

for the user

it has a built-in text editor and

compiler along with easy to use tools

menus and buttons to compile

run debug analyze

and save the programs

considering arduino they also have one

official ide

which has buttons to verify and upload

the sketches they also have

easy to use menus to select boards and

ports

throughout the course we will be using

the official arduino ide

and for that in the following sections

we will be downloading

and installing the official arduino ide

now i will tell you how to install the

official ide

for that go to any browser and go to

arduino dot cc then click on software

tab

you will find many options here we will

go with the windows installer

click on just download if you don't wish

to donate anything

donations like these help open source

communities to fund themselves

once the download completes

we will click on it and when the

installation starts

click on i agree make sure that all

these boxes

are checked these are the essential

drivers which are required

for your computer to detect and

communicate with the

arduino board right we'll click on next

then we will choose the destination

folder i will go with the default one

and click on install

this process may take some time let's

wait for it

to finish

in my screen it says completed but some

people may get additional prompts to

install those additional drivers

all you need to do is just click on

install on them as well

and then once it is completed for you

click on close and then you will find

the arduino icon

on your desktop then you just double

click on it

and here is your fully functional

arduino ide

window so now we will set up our

computer for uploading our first basic

sketch

there is nothing complicated we need to

do the first step is

we need to plug in an arduino board with

the usb cable given

in the box and once you do that your

computer will automatically detect that

arduino has been plugged in

and it will list it out on a specific

serial port

in windows it is known as a com port

which you need to go

and select using tools go to tools and

then go to port

and you will automatically see a com

port here

it is very likely that you see com3 if

you have plugged your arduino for the

very first time

okay so you will see arduino genuine

uno written over here if you're using

mac

then you will see something like this

forward slash dev

dot forward slash cu dot usb modem this

is the port number

and you will see arduino uno here

instead of adding omega i have tested

with arduino mega that's why it is

showing it

like that but you will see arduino uno

right

if you're using linux you will see

serial port as

power slash dev tty acm0 it is most

likely will find it at

at acm 0. after this step

we are just ready to upload our first

basic sketch

so finally we will be testing our

arduino boards and for that we will be

using the built-in example sketches

so in order to upload our first sketch

we'll go to examples we'll go to basics

and then we'll select the blink sketch

this is the first sketch which will be

uploading

on our arduino board we'll go to tools

we'll select our board as arduino uno

and we'll select

our port as com3 and

then we will go to upload button we'll

click on upload in order to upload the

code

there are more buttons like verify save

open we will talk about these buttons

in upcoming sections but now we'll click

on upload

it will first compile the sketch and

then it will upload the code to the

board

after uploading you will see done

uploading will appear

in the messages done uploading right

and you will see that led is blinking

with this gap of one second

is it blinking right if it is blinking

then congratulations you have done your

first example

at this point the viewers without an

arduino must be feeling a little stuck

but please don't worry i've got you

covered all you need to do

is use an online simulator like

autodesk tinkercad and for that you need

to go to

the website of tinkercad

right this one

and you need to create an account if you

don't have it already

you can choose the option relevant to

you make an account

and after creating your account you will

see a screen like this

all you need to do is click on circuits

and create a new circuit

at this window we need to search

arduino uno r3

and just drag it over here

right so now you have your virtual

arduino board

it will just function exactly like the

actual arduino board

and whatever code i write in official id

in the following videos

you need to write that into this window

right so you will have this window over

here

whatever code i am writing in the

official id you just need to

write that in this area okay so just as

you saw

few moments ago that we tested our

arduino board

so we will now test our arduino board

over here

right so this is the same code which we

wrote over there

only the comments are not here right so

this is exactly the same code

and what we need to do after that is

start simulation

okay so it will be plugged in and

you know we can see the outcome of our

code over here

and in some portions of the video you

will also see that i am

printing out the outputs of some code on

the serial monitor

so the serial monitor in this simulator

is this

right so you will see whatever outputs

i'm showing in the videos you can see

them here

okay so don't worry if you don't have an

arduino at this point you can still

follow along the video so before we move

forward from this point

having the knowledge of a few more

things would be greatly beneficial

things such as breadboard how to make

connections in breadboard

some safety instructions for the arduino

and

some basic terms like input output

sensors analog

digital bit and byte you may want to

revisit this section as well

if you find yourself forgetting about

these concepts as we proceed

all right so let's start with breadboard

is this the first thought which came to

your mind when you heard of breadboard

well that's a perfectly genuine thought

when i stepped in the field of

electronics i myself had this thought

but when i learned that the breadboard

in electronics is a completely different

thing

i had a really big face pump moment

let's discuss this in the comment

section as to why it is called as

breadboard

or from where it got its name we will

just talk

about breadboard in terms of electronics

breadboards are meant to make quick

non-permanent connections between

electronic components

and they are covered with tiny socket

holes which are

connected in rows the breadboard

itself is broken into four sections

there are two inner sections full of

short horizontal rows

and two outer sections with long

vertical rows

if we remove the adhesive which is

present on the back side of the

breadboard we would see

something like this a series of

metal connections do you see that

we'll discuss what this means in a few

moments

but before that i would like to show you

the strip which is connected inside that

it is a single strip which is taken out

from that bright board and it would look

like that

so you see this entire metal piece

so when we make connections on that

you know it is internally connected

automatically

coming back to this if we consider

this row corresponds to this

all right so that means these points

are connected among themselves

automatically

and like these rails are connected

so these points are also connected from

inside

we'll discuss this in detail we'll also

make circuits don't worry about that

if you're wondering what kind of

circuits which we can make on a

breadboard

i would like to tell you that you can

also make your arduino uno

on the breadboard and it would look like

this now we will see

how to use a breadboard we will also

understand the connections

in details all right

so this is our breadboard okay can you

see

all these holes like this

which are getting highlighted in blue

right these are the holes

which i was talking about in the

previous video

okay so i'll now show you how they are

interconnected for example

these points are interconnected the

yellow ones all of these are

interconnected

within themselves right like these all

these points

are connected among themselves but

please note

that this point is not connected to this

point internally

this point is only connected to these

points like can you see

right like this all these points are

interconnected

all right so then we'll see these points

these are the external points all of

these points are interconnected

like this right

like this and like this in some

breadboards there are connection break

at this point so you will just see

that the points are connected only till

here

and these points are connected till here

but this point is not connected to this

point

in some breadboards but in most

breadboards they are all connected

like this can you see that okay

so now i'll tell you if you want to

connect

some two points for example we'll take a

wire

and we'll join this so now

these points are connected among

themselves right

no matter how many wires we join here

these will still stay connected okay

and what if i connect a wire here

then all these points will get connected

you see that

right i think it is really interesting

to see that how easy

it makes for us to make connections on

the breadboard

right so now we'll see how to make a

series connection

right we'll take a resistance

like this okay and we'll place it here

okay now i will take another resistance

and connect it here okay

so now these resistances are in series

now if i make want to make another

resistance which i want to take in

series

i'll place them here

all right now these three resistance are

connected in series

how for example these points were

interconnected

okay and so we connected our resistance

here so that means they are in

a continuous position now similarly

here as well okay i would like to tell

you that some people

make a mistake and to make a series

connection they would go like this

they will place the resistance here

instead of placing it here

right this is a series connection but

this is

no connection at all because these

points are not interconnected

however if we join a wire like this

okay so now these points are

interconnected

okay i hope i am making you myself clear

now we will try to understand a parallel

connection

similarly we'll take resistance

and we'll place it here now since

in parallel connections all of the

points are you know

originating and ending at the same point

and these points are interconnected

so we'll take another resistance and

place it here

so these two resistance are in parallel

now if you want to

take a third resistance as well and

we'll take it and place it here now

these three resistances are

in parallel okay now we want to make a

connection

in which there is a resistance in series

and then there are two resistances in

parallel

we'll try to make that circuit

this is one resistance okay and then

if we make it like this

like this

okay and we take another resistance

and we place it like this okay so what

that is representing

it is one resistance which is in series

with this resistances which are in

parallel among themselves

and then there's another resistance

which is in series with that

okay okay it's all right if you don't

understand what i'm trying to say right

now

we'll understand this with one more

example

so before i begin with my second example

i would like to tell you

a few more things like i told you

in the previous video if we connect a

wire like this

the points become interconnected

but if you take a resistance and connect

it like this

[Music]

so these points are not connected to

these points right because it is a

resistance

you see that in this case these points

are interconnected

but in the case of resistance these

points are not interconnected

now another point which i want you to

notice every connected wire

like this it won't make any sense

as these points are already

interconnected right

so this wire will not make any

difference

so now another thing which i want you to

notice

if we take a resistance and if we place

it like

[Music]

this

like this then also

it won't make any difference because as

we all know the current always takes the

least resistive path

so connecting a resistance like this

won't make any difference because the

current will travel

through the rails only this resistance

will not add any value to the circuit

okay but however if you connect a

resistance like this

then it would make some sense okay how

it will make some sense we will see

[Music]

for example we can connect it like this

and like this

okay so this is a series connection now

these two resistances are in series

but yeah please note that these

resistances

[Music]

are not in parallel

[Music]

but please note that these resistances

are not in parallel

because these points are not connected

okay

now we will begin with our second

example in this example

we will just connect an led with a push

button and a battery

okay so when we press the push button

that led will

blow so we will make a circuit on that

so for that we'll take a push button

circuit first of all

okay this is a push button circuit i'll

tell you about push button circuit

that internally this terminal is

connected to this terminal

okay so automatically this rail will get

connected to this rail

okay like this

and this terminal is connected to this

terminal so these points will also get

interconnected

okay so when you press this button

this terminal gets connected to this

terminal

okay so these points will get connected

when you press

the switch all right then we will take a

battery

let's take this battery this is a simple

battery 3.7 volts

let's place it here this has a positive

terminal and a negative terminal

we'll try to connect it on a rail

let's make this wire as red color

[Music]

and the black wire as

the black one okay in general

electronics

this is also a convention that the red

wire represents positive terminal and

the

black wire represents the negative

terminal okay so now

these and this entire rail okay so now

this entire rail

is positive okay as we have connected

the positive terminal of the battery

here just see that

and this terminal is negative this

entire rail is negative

okay so we will start by placing a

resistor

as we should always connect our

resistance in series

when using a led

replace it like this okay

so that means this point and this point

are interconnected so this resistance is

in series with this switch

and then we'll take one led

this is the led okay

as we all know there is a positive end

and the negative end

of the led so this is the positive end

and this is the negative end we have

connected the negative end to the

resistance

okay to make the led glow we have to

always connect the positive end

of the led to the positive end of the

battery

okay so first of all what we'll do is

we'll take a positive wire

from here right as we know all know this

entire rail is positive

so from any point on this rail we can

take

positive line so we'll take a positive

line from here

and connect it here

this is a general wire so we'll make it

blue all right

and then what we want is we need to

complete the circuit like this

we'll take a black wire from here and

connect it here

okay so this is our circuit

completed whenever we press this switch

this circuit will get completed the

positive

wire will go from here the current will

flow from positive terminal like this

it will flow from resistance and it will

go from circuit and then

to the negative end and back to the

battery

but whenever we release the switch the

circuit will break and the led will stop

glowing

this was the very basic example of a led

in a

breadboard in this video we will discuss

about

some of the safety instructions which we

need to follow while using our arduino

board

the first thing which you need to keep

in your mind is you never have to

connect

any voltage of over 5 volts on any i o

pin

okay any i o pin means any input output

pin

be it the digital pins or the analog

pins you just don't have to connect any

voltage over 5 volts on those pins you

can only use

any voltage over 5 volts to power the

arduino

through v in pin and you cannot connect

any pin

to a voltage over 5 volts okay

next important thing you need to notice

you never have to connect

a 5 volt pin to a ground pin this way

you will short it down

an arduino will turn off the next point

is you have to take care of the polarity

polarity means you cannot connect

positive and negative terminals in

opposite ways what i mean is you cannot

connect a positive pin

to a negative pin of some other

component and vice versa if there is no

polarity management circuit on the

device which you are using it will

simply damage the device one more point

is you have to be careful while using

external power in this course for all

the project the usb power

would be more than enough but still if

you need any external power

you can use it through dc jack or vn

pins

and in that case also please make sure

you don't connect any voltage above 12

volts

although arduino can tolerate up to 20

volts but still

it i advise you that don't use above 12

volts otherwise you will see

unnecessary heating on the arduino board

okay

so these were the main safety

instructions which you need to follow

or you may damage your arduino and while

doing our experiments

i will also tell you about more safety

instructions if they are required

okay so now i will see you in the next

video in this video

i will talk about input and output and

how to understand it with respect to

arduino you may want to revisit this

video when we study pin mode function

it has been taught in arduino

programming section so generally

speaking

input is something which goes inside

an output is something which comes

outside

speaking technically input is some data

or signal which goes into the system

an output is some process information or

signal which comes out of that system

the system may be anything like in our

case the system would mostly be arduino

the sensors would be giving the data to

the arduino an arduino would act on that

data

and give an output based on how you have

programmed it

please bear in mind that input and

output is never absolute

it is always relative to something as

you may have been told in junior classes

that input and output devices are fixed

yes they are fixed but with the

reference to the computer

like a mouse is an input device to the

computer but if we look in the mouse

itself

there would be several more devices like

an optical reader

which takes the movement of the mouse as

input and gives its output

to the chip inside which processes it

and gives the cursor position as output

similarly we have been told that a

printer is an output device

yes it is certainly an output device but

with reference to the computer

now if we see in a printer as well there

is a main controller board which takes

the input signal which is coming out

from the computer and then that

controller takes the decision

that how to move the motors which colors

to select

in order to print the page i hope i am

making some sense to you

now if we see in reference to our course

there are lot many things

and sensors which act as input devices

for the arduino

like these sensors which you can see on

the screen but wait what are sensors

like humans have five senses which help

us get aware of our surroundings and act

accordingly

similarly in electronics sensors help

the controller to take decisions

and give output based on the

environmental data which is given by

them

sensors tell something to the controller

by changing its voltage

a change in voltage is read by the

controller like we see in this image

there is an autonomous car which has n

number of sensors placed on it which are

telling it about the other cars

battery level fuel level humidity level

etc

now i will briefly discuss about these

sensors which you see on the screen

we will also discuss these sensors in

detail when we use these particular

sensors first of all we see is a

rotatory potentiometer

this device would change the resistance

it offers if we rotate the knob

clockwise or anti-clockwise

then we have a momentary push button

switch when we press the switch it will

close the circuit when we

release the switch it will open the

circuit then we have a force sensing

resistor

this resistor changes its resistance

based on the force applied on it

then we have a light dependent resistor

this resistance change its resistance

based on the light falling on it then we

have a triple axis accelerometer

usually we see accelerometers in phones

and gaming devices

okay the basic purpose of the

accelerometer is to get the orientation

of the object

on which it is placed then we have a

joystick

joystick is nothing but a basic input

controller you must have seen it on

on the gaming consoles then we have a

microphone or a sound sensor

it will capture the environmental sound

and noises

we may want to record them or take some

decisions based on that

then we have a touch sensor it will just

see if someone is touching it or not

then we have a rotary encoder

this sensor senses the rotation

basically for example

you can attach this rotary encoder to a

motor shaft and we can see the

rotational speed of that motor

how many rotations it have taken or you

must have seen a rotary encoder in

our volume knobs in your music systems

and we have an ultrasonic distance

sensor

it uses ultrasonic waves like in a sonar

to tell the distance between

the sensor and the object in front of it

then we have a temperature sensor as the

name suggests it will tell the

temperature around it

we have a temperature and humidity

sensor it tells humidity as well along

with the temperature

then we have an infrared sensor this is

basically an obstacle detection sensor

it can tell if an object is there in

front of it or not

then we also have output devices

output devices are those devices that

can convert the output

given by the arduino to some human

readable form

right for example i'll tell you there is

an led which is known as light emitting

diode it will basically

just glow if any pin on arduino is set

to high

and we have an rgb led this is a special

led

it has all the colors uh red green and

blue leds and it can form

n number of colors and we have a buzzer

it will make some sound

if high voltage is given to it it will

make some sound then we have a

loudspeaker

like this general speaker which you have

seen in your mobiles and your laptops

which you know

you play music through and we have an

oled display

it is a full-fledged display you can

just click graphics on it we have lcd

display this is liquid crystal display

you can

display characters on it okay for

example some value of a sensor or

someone's name

etc the seven segment display consists

of seven leds

arranged in a rectangular fashion as

shown

it is used to display numbers on it

for example if we want to display seven

so we will highlight this one this one

and this one

so we will see that seven is appearing

if we want to show zero

then we will highlight these ones

okay and if you want to display eight we

will highlight all of them and it will

look like it is coming on we have a dot

matrix display dot matrix display is an

array of multiple leds okay we can show

even characters on it

you must have seen a dot matrix display

in delhi mid to display

or even you know scrolling displays you

must have seen in front of some shops

which display the shop's name so that is

a dot matrix display then we have a dc

motor it basically

moves clockwise or anti-clockwise if it

is given some voltage across it then we

have servo motor so

this is a special kind of motor we can

stop it at specific angles then we have

a stepper motor a stepper motor is just

like a dc motor

but you know the entire rotation is

divided into equal steps

so like servo motor we can also stop it

at specific angles and

even lift heavier loads we can drive

heavier loads using a stepper motor so

to conclude this video i would like to

say

since we know about input and output

properly now we can easily understand

how arduino interacts with the

environment and we can make some

meaningful projects after knowing this

see you in the next video in this video

we will talk about analog and digital so

to begin with

i would like to tell you that our world

is full of analog information

like the colors we see fragrances we

smell flavors we taste

sounds we hear temperature we feel all

these

have just endless number of values there

can be millions of colors

smells flavors sounds etc this was in a

very general sense

now if we see in the terms of

electronics something which is analog

can have infinite number of values let's

say your wall clock

it can show endless number of time

intervals though

they are not marked on it but yet it

holds the capability

to tell you even smaller fractions of

time while digital is something

with discrete or limited number of

values like a digital clock

that clock can show you limited number

of digits let's say it's 2 pm

or 10 minutes past 2 pm depending on the

precision of that clock

it may still show you seconds but it is

still limited to

some values only so before we move

further we also need to understand one

more term

called as signal signals are used to

convey some information to someone

like these road signs are passing on

some information to us

like that we need to stop or we cannot

park here etc

similarly when we speak we generate a

signal and that signal contains the

information which we want to pass on to

the listener

like i'm speaking right now i'm

generating an audio signal which you can

see on this screen

this is the audio signal which i have

generated with my

voice okay

so this signal passes through my mouth

through air and to your ear

and you make some sense out of it okay

this audio signal is analog in nature

because there are infinite number of

values which are changing

okay in electronics signals are some

time varying quantities which convey

some sort of information

usually that time varying quantity is

voltage

that means with time the voltage changes

okay or sometimes it is also current

but usually it is voltage then those

time varying signals are passed between

the devices in order to send and receive

information

which might be video audio or some sort

of encoded data

usually signals are transmitted through

wires but they can also be passed

through

air wirelessly okay so there is an

entire field of study

which is based just on signals like

digital signal processing

signals and systems there are some

entire subjects based on signals only

okay but for the scope of this course we

will just tell you the required

information

so now there are two types of signals

one is analog signal and one is

digital signal like we just saw that our

sound is a type of analog signal

similarly there can be other analog

signals as well

typically an analog signal would look

like this that means we have plotted

time on the x-axis and voltage on the

y-axis so with time

the voltage is increasing then

decreasing then going into negative part

then increasing this is an analog signal

it is not necessary that it stays

this smooth it can be little messy as

well

like this this is also an analog signal

okay and then there is a digital signal

in digital signals

there are only two discrete values

either it is on or either it is

off where 5 volts represents on and 0

volts represent off so you can see

with time here it is on it is off on off

on

off on and off right now the sensors

and the sensors which we use in our

course will either give

analog signal or either digital signal

and we have to use arduino to read

those signals okay we will see an

example

let's say we have a gaming console here

this is the joystick

this is a device which would give some

analog signal

and these are the buttons and these

devices will give some digital

information so this game machine can be

programmed to read this

state of the joystick for example we can

make a character move

forward when the joystick is moved

forward we can also control the moving

speed of that character for example

if we make the joystick move a little

forward then it will move slow

and if we move it a little more ahead

then it will move faster

but this cannot be the case with the

digital button we can just press the

switch

and tell the character to move forward

we cannot decide the speed we can only

set

one speed there or we can program it to

move forward

fast based on some time okay but we

cannot input

the speed through buttons right so this

joystick is sending some

analog signal into the computer or the

controller which is placed inside this

gaming machine and these buttons

are sending some digital information

like either they are pressed or not

they are on or off okay but this is a

digital signal

i'll give you one more example we have

potentiometer here

and we can move it as a knob

and we have infinite number of values

here we have a switch which is either on

or off

this represents analog and this

represents digital

so whenever we use analog sensor or

component we will use

analog pins of the arduino and we use

digital pins

for digital sensors or components okay i

have given more insights on this topic

in analog read and digital read video in

programming section once you reach there

and watch those videos as well

it will be crystal clear to you and if

not you can just comment down below or

send us a message

in this video we will talk about bit and

buy so basically what is

bit bit is the smallest storage or

memory size which can store a value of

either zero

or either one this box represents a bit

here

okay similarly if eight bits are

combined then it forms

a byte okay so we can say eight bits is

equal to

one byte so one byte can store zero

as the smallest number why because in

that case

all the eight boxes or all the eight

bits

are holding zero inside it as i told you

it can either store zero

or one okay so each box

has a multiplier and we take the value

from this box

and we multiply it with this box okay

and calculate the value here and in the

end we take sum of

all the values so here what will happen

0 multiplied by 2 to the power

0 2 to the power 0 is 1 0 into 0 is 0

0 into this is 0 0 into anything is 0

similarly in all the boxes

we'll get 0 so hence the smallest value

will be

0 and when will be the maximum value

if all the boxes are 1 right so here we

will get

1 into 2 to the power 0 that is 1

and 2 to the power 1 is 2 here we'll get

2

here we will get 4 here we will get 8

here it will be

16 here it will be 32 64 and 128

now if you take a sum of all these value

you can calculate it on your own we will

get

255. now in case if we want to store a

value greater than 255

so now in that case we will have to take

one more bit

aside this so it will become 9 bit

so the 9 bits can store 511 values

and what if we have to store a bigger

number than that then we will add

another bit here as well and it will

become 10 bits so 10 bits will be able

to store

a value till 1 0 2 3. so now what you

have to keep in mind is

you will be needing this information

whenever i say 8 bits 10 bits 12 bits in

the course

so we can only store values up to the

upper limit of that space

okay so this information will be

sufficient for you to carry on the

course

but yeah if you want to know more about

binary math you can just google

binary maths and you will get really

good links from wikipedia and other

websites

and you can just read them if you face

any problem you can always comment down

below

and we will get back to you in this

section i would cover all the essential

programming concepts that you would need

to get working and make projects with

arduino i would like to tell you that

programming is a game of practice

the more you practice the more you get

better at that so i would cover all the

essential topics to get you started and

i will also tell you about concepts as

we progress ahead

so let's get started before we know

about arduino programming we need to

understand what programming is

programming is something which we do to

tell a computer or a controller what to

do

computers don't understand the language

which humans use to communicate with

each other

computers only understand the zeros and

ones so by programming we tell it

what to do in our language and a

compiler or an interpreter converts that

into a language which computer

understands

and the computer finally acts on it so

there are many programming languages

over there

like c c plus plus c sharp python java

etc all of them have their own benefits

and drawback the language which we use

to program the arduino is a mixture of c

and c

plus plus which arduino makers call as

wiring

the best part of this arduino language

is that it is uniform across all

platforms

that means it won't matter if you use

windows mac or linux the output of the

code would be the same

so in the next video we will start to

look at arduino programming in a bit

more detail

so let's start by opening up our arduino

ide

once it opens you would see this window

all right and we see void setup and void

loop is written over here

let's discuss whatever we see on the

screen the first line which we see is

white setup right it says void

then setup then a pair of brackets

then a curly bracket then we have two

forward slashes then it says put your

setup code here to run once

and then we have another curly bracket

so what we have done here is

we have declared a mandatory function

known as setup

and this is how you declare functions in

arduino then we have a curly bracket in

most programming languages

these curly brackets indicate a block of

code this left curly bracket means the

start of the block

and this right bracket shows the end of

the block

whatever code which goes inside this

block belongs to this function

the arduino id would help you recognize

the blocks of codes

when you click on these brackets for

example when you click here

it would highlight this bracket

automatically that means

this is the start of your function and

this is the end of your function

whenever you click here then it would

highlight the ending can you see that

all right then we see these two forward

slashes

these forward slashes mean a single line

command whenever we write a comment

compiler entirely ignores whatever is

written after that

so coming back to void setup this

mandatory function contains

all the lines of code which we want

arduino to run once when it is turned on

or when we press reset button

we'll talk more on this in coming

lectures similarly there is void loop

in this section we write all the code

which we want arduino to run

all the time repeatedly that means

whatever is written in this section

would run until the arduino is switched

off the void loop

runs after void setup so in the next

lecture we would see the blink led

example

which we used to test our arduino in a

little more detail we will understand

each part of that code

so see you in the next lecture so till

now we have understood that the two

functions void setup and void loop

are the bare minimum requirement to run

our code successfully

why are they mandatory i will just show

you in a moment i am removing these

functions

and i'm hitting compile the compiler has

passed us with errors

just read them undefined reference to

set up undefined reference to loop

that means it is expecting that we must

define these functions now i will

bring back these functions now i'll hit

compile once again

now the compiler has successfully

compiled the code so with that we can

say arduino ids compiler

expects these two functions like some

other programming languages expect the

main function

without that we won't be able to run the

code we would get an error as you saw so

now we will see some more concepts in

the blink led experiment

so for that we'll go to files

examples basics and then blink

all right so this is our blink example

this is that same code which you used

to test your arduino so we see a huge

chunk of lines here

this is a block of multi-line comments

like we saw a single line comment in the

previous video we start a multi-line

comment by a forward slash followed by a

star

and then we write whatever we want and

then we end it

by a star followed by a forward slash so

anything which is written in between is

ignored by the compiler you may ask then

why do we write comment the answer is

the comments help us to document the

code and they also help the other

readers of the code to understand what

is done by the author of the code

comments also help the author himself

to recall what he did when he sees his

code at the latest date

since comments are totally ignored by

the compiler not writing them won't make

any difference

for example if i remove this comment

and compile the code it will still

compile and with the comments also it

will run just like that

since these comments don't serve any

technical purpose in the code

most developers develop a habit of not

writing that comment which is certainly

not a good practice it is always advised

to write comments for the reasons which

i have already told so now

i will tell you about the white spaces

and case sensitivity the spaces which

you see here

here here etc like here

here won't make any difference as the

compiler would ignore them like the

comments now what i mean to say by this

is that we can add as many spaces

as we want wherever we want

and the compiler won't say anything to

us

it will still successfully compile the

code

like this all right but what we can't do

is we can't add spaces in between

like this otherwise you will get an

error if you compile now

just see that how many errors we have

got so now you will ask what's the

purpose of white spaces white spaces

basically help us

indent the code it makes it easier for

us to identify the blocks of code

it also makes the code look beautiful

for example

if i write something like this

what do you think this code looks better

or this code looks better obviously this

one

all right so proper indentation is

important

now coming to case sensitivity arduino

language is case sensitive what i mean

by that is

the small character would come as small

and the capital character would come as

capital

you can't interchange that for example

this void cannot be written as

this it will give an error

white does not name a type right in this

pin mode you see we cannot write

pin mode as the spin mode

right then also it will give an error

so same goes for everything what you see

here like this high

cannot be written as high

or anything for that matter you have to

write it exactly like

this don't worry if you find it too

difficult to remember you will get a

hang of it very soon remember what i

told about programming

it is the game of practice it is very

common to mess up so the arduino ide has

built-in provision to help us with that

what i mean to say by that is if you

ever mess up the casing by mistake

you would see that this is no more

coming in orange color

right now it is coming back in orange

color

same goes here so if you ever see that

these critical words are not showing up

in color form you can guess that you

have made a mistake now let's see what

is done here in void setup

it says pin mode led built-in

output this pin mode is a built-in

function which configures the specified

pin to behave either as an input or an

output

this input and output is in reference to

the arduino if something is going into

the arduino through that pin

we would configure it as input or if

something is coming out of arduino

through that pin

it will be output in our case the

built-in led would need some sort of

output from arduino

so we will use output so if we see this

line

in a little more detail we have written

pin mode then there is an open bracket

then we have written led built in then

there is a comma then there is output

then there is bracket close and there is

a semicolon

i won't be surprised if you have not

noticed this semicolon till now

i won't be surprised because it is very

very common to forget this semicolon

this semicolon

marks the end of a statement that means

we are telling the compiler we are done

with the statement

we have finished one line if we remove

the semicolon

we would get an error you see expected

semicolon before this

so back to that what this line means is

we have called

a built-in function called pin mode

which has two arguments

the first argument is the pin number

which we want to configure

and the second argument tells the

configuration which we wanted to act as

this built-in led is connected to pin

number 13 of arduino so we are telling

arduino to set the configuration of pin

number 13

as output okay this is what this line is

doing

also note that this line is written

inside the block of void setup

can you see that right one more thing

which i would like you to note is

this led built in the compiler is

automatically replacing this led built

in

with pin number 13. also note that the

compiler is not changing the led

built-in to 13

magically it has been fed somewhere else

in the arduino libraries

we will talk about libraries in coming

lectures but what i want to say right

now is

this is equivalent to this for those

people who felt a little uncomfortable

when i said

we are calling a function here which has

two arguments

i just want all of those people to know

that we will talk about functions

calling functions arguments of the

functions in a lecture

in which we talk about creating custom

functions then you will be able to

relate what i said here exactly

but for now just understand we use pin

mode function

like this we will have to use it

whenever we have to configure a pin

and using this inside setup means that

we want this function to run

once whenever we turn on the arduino or

reset our arduino

all right so now we will see what we

have done in void loop

the first thing which we see is digital

right when it is led built in

then we have high okay so the digital

right

is an inbuilt function which is used to

manipulate the digital pins

and we can also manipulate analog pins

using digital write if the pin is

declared as output

in setup using pin mode digital write

will write a value of 5 volt if we use

high and to 0 if we use low but do make

sure that you have declared the pin as

output

otherwise you may see unexpected results

then after this line we have

delay the value of 1000 in that as the

name suggests

the function would pause the code here

for a specified amount of time

in our case it is 1000 milliseconds

which is one second

whenever we use delay the entire state

of arduino is preserved and nothing

happens during that time

then we have another digital write which

would write low

to the led built in that means the led

will turn off here the led will turn on

here it will turn off and this another

delay will keep it off

for one second and this entire process

would keep on repeating unless we turn

off the arduino as this is inside

white loop so if we change the value of

this delay to 500

we would see the change in blinking

pattern i would like you to try changing

the value to your desired value

and comment down below if you were able

to see the change now i would like to

tell you

that you can also store this delay value

into an imaginary container known as a

variable we can do that by

writing int my delay

value is equal to 100.

you can also choose some other name over

here there are some rules to deciding

the variable name and you would

gradually get to know those rules

as we progress along the course so now

we can take this value

and replace it here

so now while the arduino is looping on

this code it will take

my delay as 100 instead of some other

value what benefit do we have to use

this

we can change our value to any other

value

like this or this

if we need to change the value instead

of changing here

twice and making our code error prone

we can just change the value here

it will save our time and also make our

code less prone to errors

we can also make our own variable to

define led pin

and we would do that by hint

led pin is equal to 13

and now we will take this led pin and we

will replace it here

right so this code will work exactly

like the earlier code and it would work

flawlessly

the benefit of using our own pin is that

we can change the pin which we want to

use

later for example now i have decided to

use pin number

two instead of pin number 30. so instead

of changing the pin number

from 13 to 2 everywhere i can just

change it to 2 here

so now automatically the compiler will

pick the value of 2

of led pin and replace them here now

some of you must have noticed the way

how i am writing led pin

like small ln and capital p what's the

reason behind that

now since we cannot keep spaces between

our variable names

and led and pin are two different names

so the compiler will throw an error

and some people came up with the

solution that to name variables like

this

we can keep the first character of the

second word capital in order to

differentiate

so now our eyes are able to

differentiate between led and pin

properly

and this technique is known as camel

casing if i have to use more than two

words

what i can do is like this

so now my eyes are able to read my led

pin as three different words

instead of one word but for the compiler

it is just the one word

and now some of you must be wondering

what is int why we have declared it here

right so in the next video we'll talk

about this int

and the other data types variables and

more about

variable scope see you in the next video

so now we will discuss about variables

what exactly are variables

variables are nothing but they are kind

of a virtual containers

which is used by a compiler and we store

some values in those containers

there are different kinds of data which

we can hold in different kinds of

container

for example at your home you store sugar

in some kind of specific container you

store

tea in the tea container oil in the oil

container similarly in programming as

well

we have some sort of containers and

those can store some sort of specific

data

the variables are available in different

sizes and we will be talking about just

the default variables which are used in

the arduino programming

the thing to note here is the bigger the

container the bigger the value it can

store

the first kind of data type which we

will see is int if you can recall

we used in in the previous video when we

declared our led pins and our own

delay values right so int is basically a

container which can hold

integer values and i hope you're aware

what integers are

if not i will just quickly tell you that

the number line is there the whole

numbers from

negative infinity to positive infinity

are all

integers which you can see here in this

video like minus 4 minus 3 minus 2

0 1 2 3 4. the numbers greater than 0

are positive integers and

the numbers less than 0 are negative

integers the default integer which we

use in arduino programming

has a range of minus 32 768

to positive 32 767 right what this means

is the size of integer

can hold these many values if you try to

store value

beyond this range the values will

overflow now i will tell you

how to declare an integer in programming

language

first of all we write int then we name

the variable

like in this case the name of the

variable is value and then we assign a

value to it for example

we have assigned a value of 5 here right

and then a semicolon

we can also assign it like this we write

int then value

and we do not initialize it with any

value if we do not initialize any value

the default value is zero i'm going to

say is if you do not initialize the

variable the default value which it

holds is

0. we will see more about integers in a

moment so before i can demonstrate how

int exactly works in the code i need you

to understand

these three critical functions first one

of them is serial.begin

bracket 9600 bracket close basically

this function enables the serial

communication between arduino

and the computer what serial

communication is

and what these functions are we will

talk in detail

in coming lectures but for now just

understand we

have to write this statement whenever we

want any communication to happen between

the arduino

and the computer then there is

serial.print bracket

semicolon right we use this function

whenever we want to print something on

the serial monitor

we will see serial monitor in a moment

and then we have serial.println

the difference between serial.print and

serial.println is that serial.println

just

adds an additional line after printing

whatever is

ours to print now without any further

delay we'll just see

how integer works so now let's start

afresh

by learning about integers let me open a

new file

all right so i'm declaring my first ever

integer above void setup

like this end my

variable is equal to 5

it is similar to something which we saw

in the presentation when i told you

about integers

now to see the value of my variable i

will start

serial communication with my computer

like this

and now to see the value i will print

the value serial dot println

my variable so now i'll upload the code

it's done uploading and now i will see

the serial monitor

so you see it has printed the value of 5

that means the value of my variable is 5

as we have declared

similarly when i said if we don't

initialize it

the value is 0. we'll upload the code

and see it again

let me name the file first

right if now we have not declared it so

now we will see the value

it says zero so now i will be telling

you about how we can

modify our variables for example

the first thing which we can do is we

will take our variable

and add 2 to it

so first operator which you see is plus

these are arithmetic operators and we

will be discussing more about these

shortly now if you print our variable

serial dot println

my variable

right so the answer would be 2.

so the value of my variable initially

was 0 and now we have added 2 to it

so we have 2 here now for example if we

had initiated it

with 5 so now we will get

7 right okay

as expected now the variable value is 7

right so now we will manipulate it

by subtracting 2 from it

now again we will get 5. let me tell you

that shortcut to open the serial monitor

is

this button and then we will print it

right 5 7 and 5 i hope i am making some

sense

similarly there is a multiplication

operator and a division operator

what we can do is let's say

my variable is equal to my variable

into 5 let's say now we will print my

variable

so what will we get in guesses

we'll get 25 right so 5 was the value of

my variable and we multiplied it by 5 so

we have 25 so now let's divide

my variable by 25 divide by

25 what will we get one right

right we got one now the important thing

which i want you to notice

the integer variable can only hold

integers it cannot hold

fractions for example i'll tell you let

me delete all this code

for example if my variable was 3 right

and what if we divide my variable

by 2 mathematically

the answer should be 1.5 but since

our integer variable can't hold decimal

values so can you guess what will it

print now

it will print one why

because it can only hold integer part of

any decimal the answer was

1.5 but it will pick only the integer

value

so if you want decimal values as well we

will use float and we will soon learn

about float

now there is another interesting

operator known as modulo

it will give us the remainder after

division

let's say my variable is 6 okay

and i want to get the value of the

remainder we will say

my variable

equal to my variable modulo

the symbol of modulo is percentage sign

if we divide 6 by

2 so it will completely divide by 2

right so the remainder will be

0. so if we print my variable we should

get a value of 0

right as expected

if we divide six by three

then also we'll get a remainder of zero

but if we divide six by four we get a

remainder of

two right we will get two here now

as expected now can you guess what if we

divided by

five what remainder will be

we'll get one right as expected

so these were the main arithmetic

operators which we can use

to modify our variables now for example

we have more than one variables in our

code

my second variable

and the value of that is 5. now what we

can do is

now let's see what will we get my

variable plus

my second variable right

so can you guess what will we get we'll

get 11.

right as expected and what if we

subtract it

are we correct absolutely similarly we

can also multiply

what should we get 6 multiplied by 5 is

30 right what another thing which we can

do is we can store

these values here our results are not

getting stored

here they are just being displayed what

if we want to store it

we can take another variable my third

variable

and let's not initialize it okay so what

we can do is

let's take my third variable

okay and let's store the value

of my variable

plus my second value

and let's print the third variable

we should get 11 here exactly

so similarly we can do whatever we want

with the variables

but the most important thing which i

want you to notice is before

using the variable we have to declare it

for example

if we do not declare my third variable

okay and try to do something with it

the compiler will throw us an error my

third variable was not declared in this

scope

all right we'll discuss about scope in

coming videos

just wait for some time you also need to

note that

you have to declare the variable before

using it right

you cannot do this as well for example

you

try to declare your third variable here

right then also you will get an error

you have to declare it before using it

you cannot declare it after using it

right

the last important operator which you

need to know to be comfortable with the

course

is the increment and the decrement

operator there are two types of each

one is post increment and pre-increment

and post decrement and pre-decrement

all right the purpose of increment

operator is to increase the value of

variable by one

and the purpose of decrement operator is

to decrease the value of our variable by

1. i'll show you this by an example we

have

my variable and the value of my variable

is 6. so now

if i take my variable and do

plus plus this plus plus is post

increment operator okay and now if i

print my variable

you will see that we will get 7

right so now if i use

pre-increment operator then also

we'll get the value of 7 see

so now you may ask what is the

difference between post increment and

pre-increment

well there is actually a difference and

you will get to know that difference

when we use

this operator in some expression for

example

let's see it here

if i increment the value of my variable

like this like you see in serial println

then we will get value of 6

right as you can see and the reason

behind this is

in a post increment operator the value

is first used in the expression

and then it is incremented

now if i

use a pre increment operator then we

will see we get

7. so by this we can understand

by pre-increment operator the value is

first incremented and then used in the

expression

similarly there is a decrement operator

if i do

my variable minus minus

will get 5 because my variable was

originally 6

so we decremented it by 1 so hence we

get 5.

i hope this concept was clear to you

this concept will be used multiple times

during our course so if you have any

questions you can comment down below

and in the next video we will look at

the float data type

so now we will look at the float data

type this data type is capable of

holding

decimal places as well like we saw in

the integer it cannot hold decimals

the float can hold decimals as well and

the default float which we use

in arduino programming is precise up to

7 decimal places

let me explain you in a better way like

for example

the number you see here is a real number

it is 863.267

right so in integer if we try to store

this

that would store only 863. it will just

ignore

0.267 so if you want to use

0.267 as well in our memory so we will

use

a float data type so how do we declare

that

we write float then space then the name

of that float

variable in our case it is value equals

to

5.6 or some other value which you want

then a semicolon

you can also start a float uninitialized

like we have done here so let's now see

the demonstration of how float is used

in a programming we will declare the

variable

my float variable is equal to

7.8 for example

let's see right we can see the value

of 7.8 now let's see what happens if we

try to

store 7.8

in an int variable

as i told you in the presentation we'll

get seven

right can you see the difference now now

we will just quickly see

the limitation which we had while using

int variable

that while dividing we could not store

the decimal part

so we will see if we can store that in

float variable or not

let's see it quickly i'll take my float

variable

and i'll divide it by

2 okay and we'll see the my float

variable then

let's comment this statement

all right 7.8 divided by 2 is

3.9 we can use all the operators which

we used in the int variable like plus

minus divide multiply

increment decrement and floats as well

okay

so you can try that on your own and

comment down below if you face any

problem

so now we will take a look at the bool

or boolean data type

they can be used interchangeably right

but we prefer

to use bool so the pool data type

holds one of the two values true or

false

that means if something is true or if

something is

false for example we can declare a

boolean variable

by writing pool then the name of the

boolean variable

in our case it is is tall equals to

true or false we'll take another example

bool is fit is equal to false semicolon

so this way we can declare a boolean

variable but i want you to note is

that one high or true are considered

same

by the id also 0 low

and false are also considered same by id

by id i mean

the arduino ide right and anything other

than 0

is also considered true by the id we'll

look at

what exactly this means in the coding

now let's understand

the boolean variable in the coding we

will initialize it by

writing bool we will then name it and

initialize the value of

say one as i told you

one high

or true all these three hold

the same meaning and similarly zero

low and false

all hold the same meaning if we try to

print the variable

let's see what happens it will print

zero right because false is zero if we

use

low then also it will print zero same

goes for true

if i use true here it will print one

and the other thing which i told you if

you use anything other than

0 that would evaluate to 1 let's see

that also for example i used 78

let's see what happens it still gave 1

okay so that means bool can either store

0 or 1

that's all and what's the purpose of

boolean operator

we check if something is true in the

code we'll see

examples while doing our experiments

shortly i would like to tell you

if we want to check some condition is

true or false or we can initialize our

condition as well if something is true

then only we have to do certain tasks

you will understand more about

boolean data type when we progress in

the course like when we study about

conditionals or when we study logical

operators or when we study

the comparison operators we will now

move on to another data type which is

known as

byte the next data type which we have is

byte

so as the name suggests it is a byte

long data type

it can store up to eight bits of data so

as we all know eight bits equals to one

byte okay

so a byte is just like an integer but

the only difference is

the range is 0 to 255. so if you're sure

that your

variable is not going to exceed 255 you

can always use a byte type

data type so using a byte data type will

save your

arduino memory so we will now see how to

declare a byte

we will write byte space name of the

variable

equals to and the value which we want to

add in that then a semicolon

we can also declare it without

initializing the variable and in that

case

the default value it will store is 0

just like integer

so let's just quickly declare our byte

and let's print it

right so now we will look at our next

data type

which is char which is a short for

character

as the name suggests it can hold a

single character

any character present on the keyboard

for that matter including all the

symbols like comma

question mark numbers like 1 2 3

characters like abc

small caps everything let's see how we

declare a character

we write char space name of the variable

equals to and the character which we

want to use

and that is enclosed in single inverted

commas and then

a semicolon we can also declare our

character like this

as we have seen it many times already

the thing to note about characters is

that it is still stored as a number what

i mean by that

is there is a full ascii table each

character

on the keyboard corresponds to a number

for example you can see

a capital a is 65 and a small a is

97 right similarly you can see the

entire table it contains

all the characters which are present on

the keyboard and each character

has its own number so we'll look at this

in a bit more detail

using our coding all right so we will

declare a character

care my care

is equal to right

now we will print it right

we get an a now if i write 65

which is the ascii value of capital a

you can refer ascii table to verify then

also it will print a

and let's have a look right it printed a

now still these are numbers that means

it should be possible

for us to perform some arithmetic on

that for example

if i take a here and add 1 here

right so what should we get we should

get 66

as expected why because the value of a

was 65 and it added 1 to that

so we get 66 right a char data type

occupies one byte in the memory

okay so i hope you understood the char

data type i can understand if you got

a bit confused with the character

arithmetic don't worry about that right

now

this information is enough to start our

projects

so now we have discussed all the

important data types like end

float char bool byte and you have also

learned

when to use which type of data type so

i'm pretty sure that you won't face any

issues

while performing your experiments

although there are more data types like

arrays and strings which are slightly

more complicated than data types which

we have already discussed

and they would also involve the usage of

loops so we will cover them after

discussing loops

as that would make it easier for you to

understand for now we will move on to

our next topic

which is variable scope and qualifiers

see you in the next video

now since we are familiar with the data

types and what variables are

we can easily understand what is

variable scope and qualifiers

so let's start by understanding what is

scope in many programming languages

including arduino's programming language

it matters where you have declared your

variable

speaking of which we have two kinds of

variables global variables and

local variables a global variable is the

one which can be seen by

every function in the program while

local variables are only visible to the

function

in which they are declared in the

arduino environment any variable

declared outside of a function example

void setup or void loop or any other

custom function

is a global variable so let's start by

understanding that in a proper manner

so what positions would qualify for

writing a global variable

the first position which we see is just

above white setup

the place where my cursor is blinking

right now for example i write

int myvariable

is equal to 6. so in this case my

variable

is a global variable

as i told the global variable is

accessible in all the functions

let's see that by printing my variable

in void setup

right it will print here as well it will

print

in void loop as well let's make an

identifier

so that we can identify in which

function it got printed

serial.println printing in

setup all right and let's differentiate

printing in blue all right

let's have a delay here because it will

print very fast otherwise

okay let's see that now

right printing in setup and printing in

loop

it is printing again and again because

we have written that in loop

as we already know loop function will

run until and unless we turn off the

arduino so that means

my variable could be accessed by white

setup as well as

while loop that means this is a global

variable

now we will see a local variable instead

of declaring it above

void setup let's declare it in void

setup

so now let's try to compile this we

should get an error

why because my variable was not declared

in the scope it is saying

in void loop you did not declare my

variable so i don't know what my

variable is so let's comment out this

line

now it will compile okay it compiles

successfully and it will just print

in setup once right

if we declare my variable

in void loop and just uncomment this

line

now we'll get an error in white setup

because it was declared in void loop but

it was not declared in void setup

you see in void setup my variable was

not declared in the scope

now let's see a consolidated example of

using global and local variables

together

the variable which i declare here is in

my global

variable is equal to 789 so let's

print it here and let's also

print it here okay this one is

accessible to

both white setup and while loop let's

declare a local variable here

and my local variable

is equal to 852. so this is a local

variable and it will be accessible only

to white setup

now let's try to print this

my local variable note that we can use

same names

if we are using a different scope for a

variable for example we can use

my local variable in void loop as well

and we can give it a different value

1 2 3 for example and let's

print this as well so what should be the

expected result when we print my global

variable

it should print 789 and when we print my

local variable when the code is running

in void setup

it should print 852 and when it is

running in while loop it should print

one two three

so let's upload this code

is that as expected let's see printing

in setup it printed my global variable

which is 789 and my local variable which

is

852 right now in printing in loop

it printed my global variable 789 and my

local variable which was

123. so i hope you are clear with the

scope of the variable

when programs start to get larger and

more complex local variables are useful

way to ensure

that only one function has access to its

own variables

this prevents programming errors when

one function modifies the variables used

by other functions

this concept will get clearer to you as

we progress in the course

so now we will look at qualifiers

qualifiers basically define

additional behavior to our variables

there are two main kinds of qualifiers

one is constant and one is static the

constant qualifier is declared by using

const keyword it is a variable qualifier

that modifies the behavior of the

variable

making a variable read-only this means

the variable can be used just as any

other variable of its type

but its value cannot be changed you will

get a compiler error if you try to alter

a value to a constant variable

we will just see by an example we will

declare our variable

constant int my variable

is equal to 5. now my variable is a

constant integer you cannot add anything

to it you cannot subtract anything to it

you just can't alter it

now let's try to alter it let's see what

happens

we got an error assignment of a read

only variable my variable

however you can use constant variables

for doing the math

for example i take another variable here

is equal to my variable into

5 right

since this is not possible we'll remove

it we'll try to

print the value of my second variable

right so can you guess what will we get

we got 25 right because my variable was

5 and we multiplied it by 5 so we got

25.

so you may wonder what purpose do

constant variables

serve in the code well we can use

constant variables wherever we don't

want our variables to change their value

for example there are constants like pi

which is 3.14

and we can have our arduino pins as

constants like if we don't want to

change them in the code

i would also like to tell you that there

is an alternative in c

plus plus language to define our

constant variables

which is hash defined as define is a

useful c plus plus component that allows

the programmer to give a name to a

constant value

before the program is compiled define

constants in arduino don't take up any

program memory space on the chip

the compiler will replace the references

to these constants with the defined

value at the compile time

so let's see this by an example we start

by writing hash

define then the name of the variable

which you want

let's say pi okay and the value of that

variable which you want it can be

anything for that matter it can be an

integer it can be a float it can be a

character

so let's say the value of pi is 3.14

right also note that we don't terminate

the defined lines

by a semicolon we just write this so

whenever we use

pi in our code the compiler will replace

the value which is written next to it

there the compiler won't care if it

makes any sense or not you have to make

sure that it makes sense

okay so now let's declare another

variable

of float type and let's name it area

of circle okay

and let's do the math pi into

r square let's say r is 5 so

right and now let's print the area of

circle

right let's upload it we see

it has automatically picked up the value

of pi from here and

it has done the math and it is giving

the answer to us right

as hash defined doesn't use any memory

in the arduino it is really tempting to

use hash define

but it certainly has some downsides the

compiler will replace

all the references to pi in the code and

you will start facing problems

so it is recommended that you avoid

using hash define so use constant int

in place of hash define unless you are

falling short of memory

so in the next video we'll talk about

the static qualifier

see you in the next video so we will

discuss about static qualifier in this

video

let me just quickly clean up this mess

first because it's looking so

confusing so just observe what's

happening let's declare a variable here

int xyz is equals to

zero let's increment it here and let's

print it let's see what happens

can you see that we initialized it by

zero we incremented by one and then we

printed the value so when the loop

started again

the value would be incremented to two

let me stop this auto scroll

the value will increment to two then

three then four and five

and six and then so on okay it will keep

running

until i stop it

so in this case we have declared xyz as

a global variable but i would like to

tell you that it is not a good practice

to declare many global variables

so we should try that we use local

variables as much as possible

so let's try to use it as a local

variable we will remove it from here

and we will declare it here right we

declared index y

equal to zero then x y z plus one

then we will increment it by one and

then we will print it okay

let's see what difference will it create

can you explain why is this happening

okay we initialize it by zero we

incremented it

we printed it okay and then

it was again initialized to zero then

again it was

incremented by one and then printed so

it will keep on printing one

unless i stop this loop so now we are in

a trouble

if we declare it in loop then it would

reset every time the loop is called

and it is recommended that we don't use

global variables that much so what is

the solution

the solution is that we use a static

qualifier

to do that we will just add static in

front of

our variable what this will do is this

will just initialize it by zero

and it will not reset it to zero every

time the loop is called

let's see if it solves our problem

yup it did solve our problem so using a

static data qualifier is a good way to

preserve

the data of our variables between the

function call i hope it was clear to you

please comment down if you have any

questions see you in the next video

in this video we will look at the

comparison operators

comparison operators are basically some

operators which would tell you if

something which you're trying to compare

is true or not they would return a

boolean value of either true

or false so we have about five or six

comparison operators we will just look

at them

in a moment the first operator which we

have is a lesson operator and is

represented by

a less than symbol then we have a

greater than operator

then we have less than equal to then we

have

greater than equal to then we have equal

to equal to and then

we have not equal right so we have a

total of

six comparison operators we will just

look at them what they exactly mean

let me comment this out first uh let's

have our variables

end variable one right

let's say it is seven and we have int

variable two and it is eight

let's try to compare them variable one

less than variable two as i told you

this operator returns something

which is true or false so what will

happen here is since variable one

is less than variable 2 right so it will

print

1. let's see

so now let's do one thing let us make

this variable 1

as 9. now we should get 0 because this

statement will become false

right as we expected so now can you

guess if i make variable 1 as 8

what will happen let's see

this should return 0 yes why because 8

is not less than 8 okay it is equal to 8

but it is not less than 8.

so we'll talk about this condition very

soon okay now we will have

the greater than operator let's replace

this right and change the variable

to 9 back okay so what do you think it

should return it should return true

because

variable 1 is greater than variable 2 of

course i hope you understood these two

operators

then we have less than equal to we use

it like

this a less than symbol and equal to

symbol this is a less than equal to

operator what this does is it will

return true

if the value on the left side is lesser

than

the value on the right side or it is

equal to the value on

right side you got my point so

previously when i made

variable 1 equal to eight and variable

two also eight it returned

zero but in this case it will return one

because eight is equal to

eight so let's try that

right so similarly a greater than equal

to sign

also works like this you can experiment

this on your own

then we'll look at the equal to equal to

sign equal to equal to sign means

it will compare if some values are equal

or not

it will return true only and only if a

value is exactly equal

in our case we will get one because our

value are eight and eight

we got one if i make it nine for example

we should get zero

then we have a not equal to operator we

use it like

we take an exclamation mark and then i

equal to symbol

this operator will tell you false only

if the two values are equal

okay in all the other cases you will get

a 1 not equals 2 right if some value is

equal to some other value it will say it

is

false because that is equal but if you

take any value

in our case for example variable 1 is 9

and variable 2 is 8 we should get

a 1 because that is true

right so we have covered all the

operators and how they work so you may

be wondering now what is the use of

these operators

in programming well these operators will

help you compare the values for example

you make a project in which you have to

compare the values of the sensors so you

may have to use these operators

right and when you use these operators

you will get some

decision making capability in your code

i would like you to note

one important thing about the equal to

operator many people make a mistake

while using the equal to operator

they use 1 equal to sign instead of 2

equal to signs while 1 equal to sign

is the assignment operator that means

you are assigning a value to a variable

like in this case we have assigned a

value of 9 to variable 1

we have used one equal to sign okay and

when we use

double equals to that means we are

trying to compare something

so to avoid making mistakes i really

recommend that you double check

the operator which you have used i will

talk about this once more

in the control structures when we study

about the if conditional block

and in the next video we will learn

about the logical operators

in this video we will look at logical

operators the concept of logical

operators is very simple we use logical

operators

whenever we want to take decisions in

the code each operand

is applied to some condition which may

be either true or false

we'll just see that in a moment so

basically there are three logical

operators

and operator or operator and a not

operator

so let's see how it works in coding so

the and operator

the and operator is represented by two

ampersand signs

these signs can you see that then we

have or operator and which is

represented by

two straight lines we'll find this

symbol just above your

enter key and then we have a not

operator

it is an exclamation mark that's all

so let's see the and operator so the and

operator expects that all the conditions

which

we are using in it are true in order to

return a true

these operators also return a boolean

value of either true or false

they also operate on boolean values

which is either true or false like i

told you

they work on some conditions please hold

on as i further clarify this

let's start with the and operator let me

just open the cl monitor so that we can

understand it side by side

the first thing which we have written is

the lessons about and operator

it is printed exactly as we have written

it

okay then it is true and true is true

and true is written like this

okay then we have written true which is

the boolean value

then the operator and operator and then

another

boolean value which is again true the

true and true

returns a true and both of the two

conditions are true

then the answer is true for all the

other conditions it is

false for example true and false is

false

false and true is false false and false

is also false

so whenever we use it to take decisions

we tell the compiler

you have to proceed only if both the

conditions are true

okay if they're false you don't have to

proceed okay i hope it is clear

if it is not clear don't worry we will

just understand while we write our main

programs

then we have printed some empty lines so

that we can have a space over here then

we will see

the or operator this is the or operator

it is printing the lessons about

our operator with the or operator even

if one condition is true

then the resultant will be true it will

be false only if

all the conditions are false for example

we can see

true and true is true true and false is

also true false and true is also true

false and false is false right then

again we have printed some lines

so that we can see the gap here then we

will see the not operator the not

operator basically just reverses the

value of the boolean for example

the not of true is we have used the

operator here

and the not of true is false as you can

see it's zero then the not of false is

true

right it has just reversed the values it

is very useful when we write our

conditional blocks

which we will see shortly all right so

let me just

make some changes so that you can

connect it with the comparison operators

which we used earlier

okay so instead of straight away writing

true here let's take

5 greater than 3 which is true right and

instead of writing true here

we can say seven is less than eight

okay both the conditions are true hence

we will also get

true right then also we got true

because both the conditions were true if

we make one condition false

let's say here 8 is less than

5 which is false right so true and false

is

false let's see that

right this is giving false we'll just

quickly look at

our condition let's say both the

conditions are false

let's make false conditions 5 is less

than

2 which is false 4 is greater than

9 which is also false so we should get

right which is this line false and false

is

0. i can understand it can be a bit

confusing for some people but i can

assure you that

once you start writing the codes on your

own you won't face any problem

while using these operators and even if

you still have some problem we are

always there to help you

you can always comment down in the

comment sections so see you in the next

video

we will now look at control structures

so basically till now we have seen

that the code is executed line by line

that means the lines of codes are

executed in the order

in which we have written them for

example we have written some code to

perform action one then we have written

some code to perform

action two then in that case the action

one will happen before

action two when the action do completes

then the action three will take place so

similarly there is a controlled flow of

code where we can decide which parts of

the code we want to execute based on

some conditions we start our code

and then there is a condition that

condition can be anything for that

matter

and based on that condition if it is

true or false we can take some other

actions

let's say we have a switch we'll check

if switch is pressed then we want to

take some action

if it is not pressed we want some other

action to take place and the flow of

code will depend on that condition

either it will go this way either it

will go this way and after completing

that task it will

jump back to the main code execute the

lines which are present in the main code

and then

it will exit so the first control

structure which we will study is

the if statement we will understand

about if statement and we will see how

to use if conditions in our code in the

next video

so let us see the if condition whenever

we write an if statement we write a

condition

along with that let's say we are trying

to use a if block

will take a condition which we want

should be true if it is true

then whatever we write in the if block

will execute and then

it will move on to the statement which

is written just after if statement okay

and it will execute that as well

and then it will exit but if in case it

is false

then it will entirely ignore whatever is

written inside the if block and it will

straight away jump to

the code which is written after if

statement it will execute that

and then it will exit let us quickly

look at the syntax of if statement

let's see this is our code we have

written some statements we write

if then we start a bracket we write our

condition

let's say something greater than

something or if something is true

if something is false if something is

not true anything for that matter i will

put a condition in this bracket then we

close the bracket and then we open up

the curly bracket

then we write all the statements which

we want to execute then we close the

bracket and then we move on to

write more statements in our code so

this is the syntax of if statement

so let us try this in our coding so we

have an example here

we'll write cl dot begin 9600 here so

that we can communicate with the

computer so we will write the first

statement serial.println

this line should print irrespective of

anything and yes this line will print

irrespective of anything

then we will write if true serial dot

println

this line should print

only if the condition

is true please note that we don't use a

semicolon here

let's write another statement

if false serial.print

ln this statement will not print

as the condition is false it is over

and then again we'll write one line

which should execute

irrespective of anything let's say this

only this line

should also print irrespective of

anything

so let's upload this code and see what

happens

so we see this line should print

irrespective of anything this line

should print only if the condition is

true this line should also print

irrespective of anything

did you know that when the condition was

false the block did not execute

let me do one more thing let's see a

block of code

executing let's print one more line here

the second line

right so now this line should also print

there

the second line because it was the part

of this if block so whatever is written

inside this block

it will execute no matter what once the

condition is true but of course

writing true and false exactly like this

does not make any sense right so we have

to

build our conditions let's say if 5 is

greater than 3

then this should execute we'll see the

same result because this evaluates to

true

right so basically we should keep in

mind that a boolean

value should come inside this okay in

this bracket there should be a boolean

value

then only it would be able to take some

decision based on that boolean value so

now we can complicate the condition as

well

like for example and 2 greater than 5

but this is false right like we saw in

the and operator

both the conditions should be true in

order to return true

right but this is true and this is false

so we'll now see that this block of code

will also not execute

let's see right as expected

this line should print irrespective of

anything this line will print anyway

this line will also print anyway so now

let's try to print this line

we'll make this condition true 2 is less

than

5 or 5 is less than 2. this condition is

true because

one of the condition is true right 2 is

less than 5 that is true but 5 is not

less than 2

this is false but in the or condition

one statement has to be true to get the

resultant as true

so this line should print now let's see

yep so we were able to print this line

because we made the condition true

okay so when we will be making our

projects what kind of conditions will we

use we will be using conditions like

the sensor value on the left hand side

should be greater than the sensor value

on the right hand side

then these things should happen so i

think you were able to relate with this

thing

okay now i will tell you another thing

for example i took a bool

many people do mistake in this so let's

start by taking a bool

my bowl is equal to false so now what i

want to do is

i want to print these lines only if my

bool

is true so i'm comparing it if it is

true then only

it should print but this is not true

right because the value of my bool was

false so that's why the resultant was

false

so hence the lines present in this if

block will not execute

now if we write false then it will

execute because it is actually false

so we can see these lines got printed so

now i'll talk about the mistake which

people do

what they will do is they will use one

equal to sign instead of

two signs so what will happen is the

compiler will assign

a value of true to my bool and the

resultant

value of my bool will become one okay

and this block of code will execute

right so the expression which we write

in the if condition

is executed first and then the value of

that thing is taken into consideration

if it is true or false

okay in our case my bool was assigned a

value of true

and then the value of my bool was used

please take care you use

double equals to if you want to compare

the values

now we can do nesting of ifs as well

what nesting means like this is our if

block

we can write more if blocks inside are

the parent if block

let's say we write another if if true

serial dot

print this is nested

if right we can write another if inside

that if

false serial.println

this is another line which will not

execute so this was nesting of if this

is the parent if this is a child if and

this is

a further child of this if right we can

see like this

this is the flow this bracket closes

here and this bracket closes here

for example in any case the parent if is

false

then all the child lifts will never

execute please keep that in mind

i hope you understood this point i'm

pretty sure that you will be able to

understand it in a better way when you

perform your experiments

so in the next video we'll look at the

else statement

see you in the next video now we will

try to understand the else statement

first of all let us look at the flow of

the code

we always write an else statement

preceded by an if statement

let's have a look at the flow of code

when we use an else block

there's an entry of code there is an if

condition if that is true

the body inside the if block is executed

the body inside

the else block is entirely ignored then

it moves on to code after if statement

after executing that code it would exit

in case if it is false it will

straightaway go to

else block and it will execute the code

which is present inside the else block

and it will ignore the code which is

present inside

the if block after executing the else

block it will go to the main code the

code which is written after the

if statement it will execute that and it

will exit before looking at the syntax

of else block let us compare it with

just the if block so this was the if

statement

in if statement if the condition was

true it would execute the body inside

the if block then it will go to the main

code

execute that and then it will exit so

when we use just the if condition

without else that means we don't define

what we want to happen if the condition

which we have specified

is false if it is false it will entirely

ignore the if body and it will jump to

the main code

but in else we define what we want to

happen if something is false so that we

write in the else block so now let us

look at the syntax of else block we

start by writing if

we specify the condition we open the

bracket we write our actions here if the

condition one is true

then we close the bracket and then we

write else

if if we have more than one conditions

for example if you want different sound

levels of an alarm

based on the temperature ranges for

example at a lower temperature an alarm

would ring slowly

and at another condition let's say

another range it will ring a bit louder

and if it exceeds something then we want

it to

ring at the maximum intensity okay so

these things can be controlled

by if and else blocks okay after writing

else if we write condition two if that

condition is true think

b will happen okay and then finally we

write an else

if none of the conditions is true then

the else block will execute

the thing which you need to notice here

is if the condition one is true it will

execute

the thing a and it will straight away

jump to the main code after this

the control won't go in else if it will

go in else if only if the condition one

was false for example the code was

running here

it found that condition one was false so

it will jump and check if condition 2 is

true or false

if it is true then it will do the thing

b if it is also false

then it will go to else block and do the

thing c we will just understand this

with the coding example so here we have

example

for understanding the else statement

let's do this we'll write if true

serial dot print ln my first statement

so you can see the compiler has

automatically considered this bracket

which was originally for void setup

for the if block okay we have to make

sure we are using our brackets correctly

now after closing the if block we will

write

else serial dot println my

else statement all right so now we will

close

the white setup bracket now let us

upload this code okay

so my first statement got printed

because my initial if condition was true

and it will ignore the else block now

let's make it false

now we will see that statement written

in the else block will print let's have

a look

my statement okay we can do the nesting

in if else statements as well

like we saw in the if video like i can

start another if here

if some other condition will write

another task here so we can use

endless if and else and the nesting of

them as well by now you must be feeling

a little bored by just printing the

statements here and there and not doing

any real things so in the next video i

will show you

a small simulation by using if and else

blocks

so see you in the next video so before i

show you that fl

simulation i would like to show you this

comic

just have a look at this comic for like

5-10 seconds

and if you get the joke in this comic i

can say that you have pretty much

understood

the concepts which we have discussed so

far

okay don't worry if you could not

understand this once you finish the part

where i'm teaching

about functions i'm sure you will be

able to understand it really well

so just in case if you could not

understand this i would say that please

complete that section

and then come back to this comic again

and

i'm pretty sure that you will have a

good laugh

okay so now let's move on to that

simulation i was talking about

so as i told you that i will show you a

simulation of fns blocks in the previous

video so i will just show you

that simulation on the left hand side of

the screen you can see a circuit diagram

and on the right hand side of the screen

you can see the code which i have used

to make this simulation the simulation

tool which you see on the left is

autodesk tinkercad

you can do a google search about it if

you want to know more about this i'll

help you in the comment section if you

face any problem with this

every one of you must have performed the

blink example and i have very clearly

explained you the functions which we

used in that like pin mode digital write

and delay so i will assume that you will

not face any problem

understanding this code so let's begin i

have declared temperature as the global

variable and initialize it with 0. in

the void setup i have written

pin number 678 as output as i want to

connect our led to those pins

so in the loop section i've started with

if i'm trying to tell the compiler

if the value of the temperature is less

than 50 and is also greater than 10

that means it lies between 10 to 50. so

i want to

perform this action please note the

values of 50 and 10 are not

inclusive as we have not used the equal

to sign if you want to include those

values you will have to use an equal to

sign

as well you must be remembering less

than equal to operator and greater than

equal to operator right

you can always revisit the videos if you

have any confusion so coming back to

this i've simply written the code to

blink the led which is connected to pin

number six pin number six is this one

that means this led is connected to pin

number six also note that all the leds

which are connected here

are connected to a common ground which

we have connected like this then we have

written

else if that means if the previous if

was not true then check this condition

if temperature is greater than 50

and temperature is less than 70. that

means the temperature range is

51 to 69. so if this condition is true

then we want to blink the led connected

to pin number seven

which is this one pin number seven this

and then finally we have written else if

none of the conditions is true

then do this thing which is blink the

led which is connected to pin number

eight which is this led so let's say

we have temperature is equal to zero

currently we have hard coded this

temperature

but in your projects you may have some

sensors like lm-35

or dht 11 which will return you the real

time temperature of your room and

code will act accordingly but just to

test these conditions will be taking

some arbitrary values

so let's see in which condition will

this zero fall okay

if temperature is less than 50 or

greater than 10 but it is not relying in

this condition

then it is greater than 50 and less than

70

so this is also false so ultimately the

else code should run so let me start the

simulation right you can see

else statement was being executed that

means this led is blinking so now

let's change the value from 0 to 52. so

can you guess what will happen

for the value of 52 okay let's see the

value of 52

is less than 50 which is false so

ultimately this condition will be

discarded

it will check this one then so the

temperature is greater than 50 yes

temperature is less than 70 yes so this

condition is true

so hence the led connected to pin number

7 should start blinking

so let's start the simulation so led

connected to pin number 7

has started blinking pin number seven

okay so let's change the temperature

value to 25 so now this condition will

get true so let's start the simulation

right so this led is blinking so one

small homework for you guys is you have

to comment down below what will happen

if i select the value of 100 we can take

a pause of 5 seconds

and just go and comment down below after

then come back and see the results

so led which is connected to pin number

8 is blinking

why so because 100 will not fall in any

of the conditions so the compiler will

execute

the else statement one interesting thing

which i want you to notice is

that right now we have chosen arbitrary

values but with the sensors you will get

really changing values you may get the

values which are changing so

the arduino will act in the real time

okay if you don't change the value and

the sensor changes that value

and we get different values from that

sensor then the arduino will

automatically check

which condition is true right now and it

will execute that statement

and it happens really fast so with the

real sensor you may see led which is

currently blinking may change very

quickly

for example if you light up a candle

near the sensor then the led which is

blinking may change

and then if you remove the candle then

you may see that the other led may start

blinking depending on the condition

which is currently running

so i hope you are clear with this if you

still have any questions you can always

comment down below or send a message to

us

so we will now take a look at loop

structure which is another kind of a

control structure

in this kind of control structure we

will basically learn how to write

instructions in order to repeat

certain tasks instead of writing code

again and again for doing a certain task

we can

learn how to repeat that task again and

again for example

the void loop function which we use in

arduino is a loop structure

whatever we write in that repeats on its

own but that is

a default loop structure however you may

need something

to repeat itself in a loop as well so

for that

we have loop structures basically we

have three kinds of loop structures

one is for loop the second is while loop

and then

third is do while loop we will look at

them one by one in their dedicated

videos

but before that let us see how it

exactly works so we make the entry to

the code then there is a condition based

on which

we take a decision if it is true then

the certain action which we have defined

will take place and then it will come

back and check the condition again

if it is still true then it will repeat

the action and this will go on and on

until this condition becomes false if it

becomes false

it will break out of that loop and

perform the action 2 which is written

after

the definition of loop after performing

that action

it will exit so in the next video we

will look at how exactly the first

control structure

which is for loop works we will see the

syntax

and we will see how it exactly works in

the coding so see you in the next video

so now let us begin with

the for loop this is the first loop

control structure which is very commonly

used in computer programming

first of all let us know about for loop

this is an entry controlled loop

what this means is the condition based

on which the task will be executed is

checked first

if it is true then only those statements

will be executed

and we use for loop when we know how

many times we need to run a loop

so let us see the syntax of for loop

first of all we write

4 then an open bracket then we

initialize some variable here

that variable will count how many times

the loop has to run

then we write the condition here that

condition can be anything

this condition mostly includes the

variable which we have initialized then

we update

the variable which we have initialized

we close the bracket

then we start a curly bracket we write

all the statements which you want to get

executed

then we write curly bracket let's see

how it is used now let's say

i tell you that you have to write your

name 10 times on the serial monitor

so what will you do serial dot print ln

let's say my name is

ashish so with your existing knowledge

you will take this line

you will write it 10 times and then you

will upload it you'll check on see that

monitor you can see it is getting

printed 10 times so now if i tell you

that you have to type it 100 times

so would you be willing to write it

hundred times i guess no

and some of you may tell that we can

write it in void loop instead

but writing that in void loop would mean

that it would keep printing ashish until

and unless you turn off your arduino

you won't be able to count if it has

printed 100 times you can sit there and

count that but that certainly doesn't

make any sense so for that a for loop

comes to a rescue

let's see how we use it we write for we

declare a variable

int i for example is equal to 0 and we

write a semicolon

then we write a condition here for

example how many times you wanted to run

let's say

i less than let's say we want to print

my name

10 times so let we will write 10 here

and we will update

the condition i plus plus okay we'll now

write serial dot

print ln ashish and now we'll see what

happens

right we can see the arduino printed my

name 10 times

on the screen one two three four five

six seven eight nine and ten

okay we can also add multiple statements

in this block

let's say we can write hello world

okay let's see what happens it will

write ashish hello world ashish hello

world yep as expected

it has repeated all the things 10 times

now what advantage do you have is

now if someone tells you that you have

to write it 20 times

instead of 10 times so instead of

copying pasting that code again

you can just alter 20 here now it has

written it 20 times

now for example i want to use this

declared integer i

in my code serial dot print and then

we can directly use this i here we can

also perform arithmetics on that

for example i can do i plus 2 i plus 5

i minus 5 i divided by 2 anything for

that matter

but please note that the scope of this

variable is just inside this block you

cannot use this declared variable

in other blocks even if you are using it

in some for loop or some

other function the scope of i will exist

only in this

block get my point let's see it will

print 0 to

19 okay

like 0 1 2 3 4 5

6 7 and 19. okay now let's

understand how it was working all right

so whenever we write a for loop

the first step which happens is

initialization this statement is

executed only once when the loop is

entered for the first time

and after this the second step is it

checks the condition

this statement is probably the most

important one it checks to verify

whether or not certain expression

evaluates to true if it is true then the

loop execution continues

then after that if the condition is true

it would move on to execute the

statements as the third step

after executing the statements it will

move on to

the fourth step which is updating the

variable it is typically used to

increment or decrement

some variable after the update the fifth

step is to check the condition

once again if that condition is true

again it will come back to execute the

statements once again then this step

continues again and again until this

condition becomes false the moment the

condition becomes false

it will come out of the loop and start

executing something which is written

after this loop now since you know this

let us understand the code which we

wrote earlier so now let us pay a closer

attention to everything which we have

written i've written for

end i is equal to 0 then a semicolon and

in the condition we have written

i less than 20 that means i

is acceptable till 19 okay

and then we have written i plus plus you

must be remembering that plus plus is

used to increment a variable

by one we have written serial.println

bracket ashish that means

when the value of i is 0 it will print

aashish once then it will print

hello world then it will print the value

of i itself which is 0 right now then

after executing this loop body

it will increment the value by 1 and the

value will become

1 okay when i is 1

it will check if i is less than 20 which

is true it will execute the body once

again

then the value of i will become 2 it is

still less than 20 then again it will

execute the body

so it will continue till 19 but after

executing it for the 19th

time and when the value becomes 20 this

condition will become false the moment

it becomes false it will not execute

these lines

and it will exit out of the loop in case

if we had written

less than equal to 20 then the condition

would have been true

but it would have actually printed it

for 21 times because it is starting from

zero

other thing which we can do is start it

from one instead of zero

it will be equivalent to this but

usually it is recommended that we start

from zero so after knowing this

really easy trick i'm really wondering

if you're wishing

that you knew this trick before when

your teacher gave your punishment so in

the next video we will look at

how to do nesting in for loops

see you in the next video so like we saw

next thing in fl's block we can do

nesting in for loops as well for example

if you want a printer pattern like this

a series of stars there are five columns

with five stars in each row let me just

comment it so that it doesn't create

problem in our code we can simply go

ahead

and write

and we'll write serial dot println and

we'll print five stars

right so let's see what happens when we

upload this

oops we forgot to add a double quote

so now again oh we forgot to write the

name of

variable and i let's see

so it printed a lot of stars but now

what if we want a pattern like this a

staircase type of pattern

let me comment that as well okay so how

will we do that

it's very simple we'll do nesting of for

loops

let's say for enti is equal to zero we

want five rows

okay so we will write five then i plus

plus then we will write another for loop

we will take another variable here and j

is equal to

zero and we'll write condition as j less

than equal to

i and then j plus plus okay and then

we'll write serial dot

print please don't will not write print

ln here because we don't want

it to print in next line so cl.print

and just a single star

and then once this for loops executes

we'll print a new line dot println so

let's see what happens here

okay we got that pattern now i'll

explain you how it worked actually

we took our first for loop we

initialized our integer i

as 0 and we gave a condition i less than

5 that

means it will not run when i exceeds 5

okay or becomes 5 then we wrote another

for loop and we took another variable j

is equal to 0

and j less than equal to i that means in

first iteration the value of

i was zero and the value of j was also

zero okay so here j less than equal to i

that means zero less than equal to zero

this is true and then

j plus plus so it will print a star okay

then the value of j will increase and it

will become

1 so now this statement will become

false because j is 1 and i is still 0

then it will

exit out of this loop and then it will

print a line

then that means after printing one star

it will print another line

okay and then it will come back to this

for loop now

the value of i is 1 is still less than

5 okay and then it will come into this

for loop

so now the value of j is 0 and the value

of i

is 1 okay so 0 is less than

equal to i it is true it will print

a star then again and j will become

1 this condition is still true because 1

is less than equal to

1 right so it will print another star

next to

the previous star so it will print 2

stars let us see in the serial monitor

right after printing this star it will

print this star

then the value of j will become 2 and

then

this condition will become false because

i was still 1

then it will exit out of that loop and

print another line

it will print another line here okay

then i will become

2 then it will go back in this loop and

it will execute

the loop three times 0 1 and 2.

similarly it will

go until and unless this condition also

becomes false

okay so i can understand it must be

really tricky right now

if you just go back and listen to what i

said once again you will understand that

and in case you don't understand you can

always drop a comment or message us

so in the next video we will look at

another kind of loop structure which is

known as a while loop see you in the

next video

in this video we will look at while loop

a while loop is also an entry controlled

loop an

entry control loop is a loop in which

the condition is checked

beforehand before executing the

statements which are written in the

loop body this is the same thing which i

told you for the for loop

all right but the difference between the

while loop and a for loop is

in for loop we know how many times we

want to run the loop but in while loop

we don't know how many times we want to

run the loop it is based

just on the condition if some condition

is true the while loop will

continue to run endlessly and the moment

the condition becomes false

the code control will move out of that

while loop

that condition can be based on some

variable or some external conditions

like some values given by the sensor

let's say we are making a robot

and we are using a distance sensor we

can use a while loop or to move forward

unless the distance is less than some

quantity

and we want to exit out of that by loop

as soon as the distance

gets lesser than that specified value so

that the robot can avoid the collision

from any obstacle in front of it right

there can be many more while loop uses

but we will begin with

the basics we will use our traditional

method of printing variables

on the serial monitor so let's see that

so we have our sketch here

let's use a while loop to print a table

of two

let's say we'll start with an integer

which we will use as a condition

int multiple is equal to one

let's start with 1 while multiple

is less than equal to 10

okay serial dot

print ln multiple

into two okay and let's increment the

multiple

all right let's see if we are able to

print the table of two

oops we forgot to write serial dot begin

always write serial dot begin

whenever you have to communicate with

the computer let's upload that again

right 2 4 6 8 10 12 until 20.

this is a table of two now let's print a

table of a complicated number

let's say 73 yep this is a table of 73

so now let me show you how a while loop

can run endlessly if the condition is

true

let us just make it true directly this

will become

an endless loop right now it will not

just print numbers from one to ten it it

will just print

them endlessly let's use the easy number

so that we can verify

it won't stop at all let's see

look at the speed it is printing all the

even numbers

can you see that let's have a look 2 4 6

8 10 12

14 16 as you know there's no upper limit

to the numbers so it will just go on

endlessly

until the limit of int expires

so i have another example to show you

how a statement controls

a while loop how it prevents the while

loop from running when it is false

and how it initiates the while loop when

it becomes true so in the white setup i

have written serial.begin 9600 to

initiate the communication and then i

have void loop

i have declared a static variable a test

variable which is

going to control our condition i have

defined it as static because

i don't want to reset the value of test

variable with each run uh if you have

any confusion regarding the static part

you can check

the dedicated video which we have made

to explain the static qualifier for a

data type

now while loop we have started the while

test condition greater than five

that means right now the test variable

is zero

as we have not initialized it so zero is

the default value so zero is greater

than 5

that means this is false so this

statement should not execute okay but

in the next line we have written

variable plus that means we want to

increment that variable

the variable value will become 1 and it

will print the value

of the test variable then we are waiting

for one second so that we can observe

the changes which are happening and then

again it will come here

it will see while test variable greater

than 5 that means it is still false

because test variable's value

is 1 right now and it is still false so

it will still not go into

this loop then it will become 3 then it

will become 4 then it will become 5

at 5 also this will not become true

because we have not used the equal to

sign

and when it becomes 6 this condition

will become true

and this will start printing let's see

that

right one two three four

five six and we are in the while loop

now

okay this while loop is repeating

endlessly because we have not specified

any exit condition

and please note while this is in while

loop these statements are not being

executed

the control of code is looping here only

since this loop is looping infinitely

we might want to use some break

conditions we will learn about

break and continue statements in coming

videos but in the next video

there is one more loop which is known as

a do while loop we'll learn about

do while loop in the next video we'll

take a look at the last

loop control structure which is the do

while loop the first thing which i want

to tell you about the do while loop is

it is

very very similar to the while loop it

works exactly like the while loop but

the only difference is

it executes at least once and that is

why it is the exit control loop

in exit control loop the statements are

first executed

and then the condition is checked while

in while loop first the condition was

checked if the condition was true then

the statements would execute

in this first the statement block will

execute and then it will check the

condition

if the condition is false it will exit

out of the loop and not execute those

statements further

and if the condition is true it will go

back and execute the statements once

again

if you look at the flow the first thing

which happens is it executes the

statement block then it checks the

condition

if it is true then it will go back

otherwise it will come out of that loop

a do while loop is also used when we

don't know how many times an action has

to be repeated but

we are sure that it should run at least

once in those cases

we use a do while loop a do while loop

is used where the statement has to

execute once otherwise we won't be able

to take decision for example we are

expecting a user to give us some input

and we want him to give

a positive integer as an input but for

example he is trying to give a negative

input so we can write a do while loop

while the user gives us the negative

input

keep telling him to give us the positive

input and the moment he gives us the

positive input

will break out of that loop okay so let

us see a basic example of using a

do-while loop

like we did earlier we printed a table

of two

we'll again print the table of two using

a do-while loop instead of a while loop

so let us see how we do that we have

initialized a variable known as multiple

and initialized it with

one okay we'll write cl dot begin to

start the communication with computer

so we'll write do then the bracket open

we'll write cl dot printenet multiple

into two then bracket close and

semicolon and then we will

increment the multiple and then we will

write while

multiple is less than equal to ten that

means this condition is true

until the multiple becomes 10 the moment

it becomes 11 this condition will become

false and this

statement will stop executing so we'll

get a table of 2 here

let us see what happens right so we got

a table of 2

2 4 6 8 and then so on till 20.

i have another example for do while loop

so that we can understand how exactly it

works

so in the white setup we have written cl

dot begin 9600 so that we can

communicate with the computer in while

loop i have initialized a static into

variable which is known as test variable

we have written do then we are writing

cl.println this

will print at least once because a do

while loop will execute the statements

at least once so ok we have written this

statement

and we have written a delay of 500

milliseconds so that we can observe what

is happening

otherwise you know serial monitor prints

things really fast so now we have

written while

test variable is greater than 5. while

the test variable is less than 5

this statement should not execute but it

will

execute at least once then we have

written test variable plus plus that

means we are incrementing the value of

text variable

here we are printing the value of test

variable and we have given a delay of

500 milliseconds so that we can

observe what is happening okay so now

when we open the serial monitor

what we will see is that this statement

will execute once then the test variable

will increment

okay and then the value of test

increment will print then it will go

back

into do while loop and print this

statement once again

because in do while loop it has to

execute once at least

then while it will check the condition

it is false then it will come back here

it will increment the variable and it

will

repeat till the test variable becomes

greater than 5

okay the moment it becomes greater than

5 so this do while loop will keep on

repeating

let's see how it happens let us upload

the code first

right this will get printed at least

once and this is printing again and

again

but now just see the loop control didn't

come out of this okay because this

condition is true now it will go back

again

and execute the statement these

statements are not being executed

because

it is still in do while loop so i hope

you understood this

do while loop so now i have a really

interesting illustration

which you can see on the screen to

explain the difference between a while

loop and a do while loop and i think it

is a really good example

to show the difference between the two

every one of you must have seen

the roadrunner show and we see this guy

was using the while loop

while this guy was using the two while

loop let's discuss in the comments

who was using these control loops in a

proper manner

if you remember i told you that we might

have to break out of the loops based on

certain conditions

like for example in an endless loop we

might need to do something

to stop that loop so the break keyword

is used to exit

from a loop by bypassing the normal loop

condition which we have specified

let's see how we do that so this is the

modified version

of the code which we used to print the

table of two okay

this is the regular while loop which is

running okay we are printing

a table of two here and we are

incrementing the multiple here

but now we have specified a break

condition okay

like if multiple is equal to five then

we will write breaking out of the loop

now

and we will break out of the loop by

just using this keyword

let's see what happens all right so we

printed it

till four two 4 6 and 8

and then it breaked out of loop although

it should have run till

10 it should have printed till 20. so if

i comment this break condition

and upload the code again so we got

the entire table so this is the basic

use of breaking out of the loop

now let's see if we are inside an

endless loop

let's say while true this is an endless

loop

we are writing serial dot println

endless loop okay

and we will increment the multiple

multiple

plus plus okay let's say

i want to exit after printing it 10

times

if multiple greater than

10. we'll just break out of it

let's see what happens

okay we forgot to close the white setup

bracket

right if we didn't use this break

statement

it would ultimately keep running

endlessly let's see that

quickly okay can you see that it's

printing endlessly

so i hope you understand we use a break

statement wherever we want to

break out of the loop so in the next

video we will see the continue keyword

and we will also compare the break and

continue keywords

like we saw in the break statement that

whenever we use it

code control instantly moves out of the

loop entirely discarding all the

remaining iterations of the loop

right like we were trying to print

numbers from 1 to 10 and when we used if

our variable is equal to 5 then break

out of the loop so it entirely skipped 6

7 8 9 10 but in some situations we might

want to use the remaining iterations

right so in that case the continue

keyword helps us with that

the continue statement skips the rest of

the current iteration of the loop and it

continues by checking the conditional

expression of the loop and proceeding

with the subsequent iterations

that means it won't skip the rest of the

iterations

let us see how it works so we have void

setup serial.begin 9600 as usual

then we are writing for loop to print

numbers from

0 to 10 right because we have

initialized i with 0 and we have used

less than equal to sign

so that means both the ranges are

inclusive so it will print 0 to 10 and

then we are incrementing the

variable now notice we have used if i is

equal to 5 then continue whenever we use

the continue keyword

it would straight away take us to the

condition pack and it would skip all the

statements which are written after that

so let us see what happens

so we see 0 1 2 3 4 5 is missing

and 6 7 8 9 and 10. so it skipped the

iteration in which i was equal to

5 right but it did not skip the rest of

the iteration if we had used the break

keyword it would have skipped the rest

of the iterations

it stopped at 4 only let me switch back

to continue here again and let me

explain the difference between

the break and continue statement let's

say we write a statement here

serial dot println end of our

for loop this is the end of our for loop

that means after

our for loop completes this statement

should print regardless of anything so

when we use continue

we'll see

the loop was going 0 1 2 3 4 and when

the value became 5

it jumped back to check the condition

okay

so in this way it had to skip this

statement it cannot

execute the statement right so when it

became six again then it will start

printing it again can you see that

and after completing the loop it came

and printed this line

when we use break

then the control will directly come here

whenever the break statement is

encountered

the code control goes directly out of

the loop can you see that after printing

4

it printed end of for loop so we may

have different situations to use

continue and break statement and we have

to make sure we use them correctly

so in the next video we will look at the

last keyword

which is return so see you in the next

video the

return keyboard the return keyword would

probably the easiest thing

to learn right now the only function of

the return keyword is to terminate the

function

no matter what it doesn't take any

conditions it doesn't take any

limitations or anything whenever the

code encounters the return keyword it

would just

terminate the function there are two

ways to use a return

we will be covering the first way to use

the return keyword we will cover the

second way in the coming videos

let us see how we use it in one manner

all right so i have this code written

here okay in the white loop

what i'm trying to do is i'm trying to

print line one line two line three and

line four

okay and then i have a for loop which

prints number from zero to

nine right let's see if it is working

properly

yes it is working as expected line one

nine two nine three nine four and zero

to nine

right so now i want that anything return

beyond this point

should not execute so i'll just write

return so we'll see what happens

it will just print line one and line two

it will go back here and execute this

lines only

anything written after return will not

execute

okay now you may want to remove it from

here

and use it here right let's see what

happens

it will just print zero because when the

value of i was zero

it printed zero then it encountered

return so it will just terminate this

function

and you see that it is not printing one

two three four five six seven eight nine

because return keyboard just terminates

the function

all right so now i will see you in the

next video so the next topic in our

course is

switch case like if statements switch

case controls the flow of programs by

allowing us to specify different code

that should be executed in various

conditions

in particular a switch statement

compares the value of a variable

to the value specified in the case

statements when a case statement is

found whose value

matches that of the variable then the

code in that case statement

is executed so let us see the syntax of

switch case first of all we write switch

then our open bracket then we write the

variable which has to be compared

when we close the bracket then we start

a curly bracket then we write

case space label 1 where label 1 is

the number which has to be compared to

the variable okay then we write

colon note that this is a colon not a

semicolon

okay then we write the statements all

the statements which we want to be

executed

when label1 is equal to the variable we

write those statements

in this block then we write break

semicolon

then we write case another label then

all the statements then we write break

we can write as many labels we want in

our code and the last statement which we

write is default

colon all the statements break when none

of the labels is true then the default

statement is executed

if we don't write default and none of

the statement is true then nothing will

happen

all right so now let us see the flow of

code in switch case here is the switch

conditional statement

then it will see case one if it is true

it will execute the statements written

in that block if it is false

it will check case 2. if it is true then

it will execute the

statement if it is false it will go to

case 3

okay and so on if none of these are true

it will

automatically jump to default and it

will execute the default statements

and after executing one of these

statements the flow will go on to the

statement which is written

after the switch let's see in the coding

right

and the white setup we have written

serial dot begin as usual then i'm

writing int

x is equal to 5 here x is the variable

which we want to be

compared okay then i'm writing switch

then x here because i want

x to be compared then i'm writing case 1

colon

serial dot println choice 1 break

similarly i've written 6 cases now can

you guess what statement will be printed

here since

x is equal to 5 my guess is choice 5

should be printed

because it is not equal to 1 it is not

equal to 2 it is not equal to 3 and so

on

ok so let us see what happens

right as expected it is printing choice

five now if i change

the value of x to let's say

one so now choice one will be printed

right now in case if we don't write

break here

the purpose of writing break here is

that we want to exit as soon as one

condition becomes true

let's say if we don't write break here

so it will continue to execute the

statements

since x is equal to 1 so now it should

print choice one choice two and choice

three

okay because there's another break after

choice three right choice one choice two

choice three

that's the purpose of break now let's

see one more example without break

let me use x is equal to 3

then it will start from here will not

use break here

it should print choice 3 choice 4

and choice 5.

right as expected now the important

thing which you need to notice is

the variable which we use here and the

labels which we use here

should be of int or character type if

you use float or if you use another

array type

it will just throw an error this switch

case is a really handy tool if you want

to write a lot of if else statements

instead of that you can just write case

1 case 2 case 3.

we can also specify ranges in case

statements and how we do that

let's say we want to take a range of 1

to 10. we'll write 1

we'll write three dots and then 10

okay then let's say 11 space

to 20 okay let's say

21 3 dots to 30

then we write 31 space you have to write

a space there okay

if you don't write a space you will get

an error so let's see these cases only

let me write break again okay so now let

us see

three what will happen it will write

choice 1

right now for example if i take 35

it should write choice 4

right so i guess you got an idea how

easy it is

right instead of writing if in else we

can use

switch case so i hope you understood

this topic so i'll see you in the next

video

so at this point we are in a position to

study about the two remaining data types

which are arrays and strings these two

data types are also very commonly used

in the projects which are made using

arduino

so in this video we will look at arrays

an array is a variable which can store

multiple values of same type

let's say we have a compartment of a

defined size which has multiple

containers in it

like this and those containers can store

same kind of

information let's see this by an example

to declare an array

we first write the type of data which we

are going to store in it

let's say int then we write the name of

that array

let's say my array okay and then we

write

a square bracket and we write a number

inside it

that number denotes the size of that

array

okay let's say five so when we write

this the compiler will create a space in

memory where you can store

those five integers okay now let's store

some values in this array to do that we

write equal to

then we write curly bracket and then we

will write five

values which we want to store in it

let's say one two three

four and five semicolon each value

is separated using a comma and each

value inside

an array is known as element of array

okay and each element has an address of

its own

that address is known as an array index

that index starts from zero okay let me

show that to you again

let's say we have an array of size 10 so

0 is the first index and 9

is the last index okay and the value

which is present at that

index is known as element let's see that

again encoding so this is the zeroth

element

and this is the fourth element okay

now let's try to access them how do we

access them serial dot

println my array

and then the value which we want to use

let's say

2 can you guess what will be printed

here tell me

0 1 and 2 so 3 should be printed

so 3 has been printed here for the first

time users it must be really confusing

that why it was started from 0. it is

very simple

because computer counts from 0. while

humans are in a habit of counting from 1

that's why we are finding it a little

confusing now let's

change the values which are present

inside this we'll take bigger and

complicated values

let's say 745 74

259 85 and 421

these are the random values which i have

chosen now if we try to print the second

element

it will print 259 because 259 is present

at

second index okay while zero is this one

first is this one second is this one

third is this one and fourth is

this one now we can alter these elements

as well

directly now let's say i want to change

the value which is present at

second index so we'll write my array

2 is equal to let's say

7 0 6 okay now the value of 259

will be replaced by 706 let's see

let's print that again now it should be

printing

706 right we can alter any value for

that matter

we can do our regular calculations on

array elements as well

let's say i have one variable in

my variable okay

now let's say i want to add some

elements and store that value in my

variable

i will write my array okay 0

plus my array 1

plus my array 2.

okay so now my variable will be holding

the sum of 7 45 74 and 249

not 249 706 because we have altered it

here

so let's try and print my variable you

can check on your calculators

if the answer is correct or not

so the sum of 745 74 and 706 is

15 25 1525 okay

similarly we can also do multiplication

subtraction division etcetera all the

operators can be used here

okay now we can also use elements of

these arrays

in for loops as well now let's use a for

loop to print all the elements

inside my array so how we will do that

for

int i is equal to 0

i less than 5

because size of my array is 5 then i

plus plus okay so now what will we do is

serial dot println my array then i

okay so it should print all the elements

which are present inside this array

so it is here

745 74 706

85 and 421 right you can compare them

here 745 74 706 because we updated the

value here

then we have 85 then we have 421 okay

now can you tell me what will we do if

you want to add 5

to all the elements of my array

okay so now let's say we'll write

for

i is equal to 0 i less than

5 then i plus plus will take my array

i is equal to

my array i write

plus 5

so now 5 will be added to all these

elements

so now 5 has been added so now let's

print this again

if we print this again so now we will

see

5 has been added to all the elements

let's see we are here it is printing

from here right

745 plus 5 is 750 74 plus 5 is 79

then 706 plus 5 is 7 11

85 plus 5 is 90 421 plus 5 is 426

okay this way we have added five to all

the elements now we can take

some of all the elements in the array as

well how will we do that

let's say int sum is equal to zero we

have initialized it by zero and for

int i is equal to zero

i less than five then i plus plus

okay what will we write is sum is equal

to

sum plus my array

i okay and after that we'll just print

sum right it is printing 2 0

5 6. so you can check on your

calculators if these values are

summing up to 2 0 5 6 but just make sure

you don't add these values you add

the new values the new value was 750

79 7 11 90 and 426

these were the new values these okay if

you add these values you will get

two zero five six so now we have learned

about how to use arrays

how to access the values in an array and

how to manipulate those values

what we saw till now in this video were

one-dimensional arrays

that means they just have one dimension

now there can be

multi-dimensional arrays as well like

two-dimensional arrays three-dimensional

arrays

like you can see here this pink box

is a two dimensional array

it has rows as well it has columns as

well

okay and then we have three dimensional

arrays as well

like it has depth as well it has rows it

has

columns and it has depth as well

multiple two dimensional arrays

make three dimensional arrays i just

give you one use case

where two dimensional arrays are used

for example we want to store

the pixel data image pixel data of a

black and white image

okay so we use two dimensional arrays

and let's say we have to store pixel uh

image pixel data

of a colored image which also has rgb

values

so we use a three dimensional array for

that in this video we will talk about

strings strings are basically a sequence

of characters

whatever we write or you can say

whatever messages which we write in our

code

are all strings let us see in the code

the easiest way to spot

strings is that you will find them

written inside double quotes

for example serial dot println

this is my string okay

this is my string is the message which

is going to be printed on the serial

monitor

but in itself this is my string is

a string okay now technically speaking a

string is nothing

but an array of characters and as we

have already studied

arrays it would be really easy for you

to understand so now to declare a string

we write char in the name of the string

which we want

for example i have written str 2 then as

we start

an array by a square bracket and a

number inside it we similarly write it

for string as well now example

i want to write ashish which has a s h i

s h

as characters in it okay and the number

of characters in ashish are

6. okay so what we will do is we'll

always take one additional number

to declare our string because an ending

to the string is denoted by a special

character which is known as a null

character

okay the compiler automatically takes

that into consideration when you write

a string or when you declare a character

array okay

in this case compiler will see okay the

person is trying to declare a character

array

which has these characters so it will

automatically add a null character at

the end so now when we print this line

it will print ash ish on the serial

monitor

okay another way is to declare

that null character explicitly for

example i will write

chart str3 then 7

is equal to ash ish and then

a null character this is the null

character which is denoted by a

backslash and a 0.

this way the compiler identifies that

okay

this string has come to an end okay so

it can differentiate between one or more

strings

without this character there will be

problems the compiler may think that

the another string which is coming after

this string is a part of that same

string there has to be some way

to differentiate between different

sentences okay so that's why we use

a null character which is backslash zero

another way to declare a string is

we write char str4 which is the name of

the string

and then we write square brackets

without a number inside it

the compiler is smart enough to

dynamically allot a number to this

bracket it will see okay the user has

written a string

which has ash ish inside that it will

automatically

allot a memory of seven to this string

because ashish has six characters in it

and including a null character it will

become seven okay we can also write

it like this str five seven ashish

simply in double quotes we don't have to

work this much

it is also okay if you take a larger

memory for a smaller string

but it is not okay to take a smaller

size string let's say five

for a longer okay now you will see it

will only print five characters

and then there is another way we will

talk about it shortly but right now let

me comment this out okay

we'll just upload this code and we will

see what we are getting

all right so this is my string then it

wrote ashish

for this ashish for this ashish

for this again

and it printed it till here okay we

forgot to write

serial dot print ln

for str

right it just skipped the last character

because we didn't give

necessary memory to it so according to

me

this is the best way to start writing

strings because obviously you do not

know how many characters your string

will contain and obviously you don't

want to spend that time

to count those characters right the

compiler is smart enough to calculate

the size

for you okay now there is another way

to write a string which is by using

a string class okay here

let me just comment this out this is

a string class we are up calling a

string class and we have named

str7 inside it and we have just written

whatever we want

inside that let's say ashish and when we

print this

it will straightaway print this ok

what's the benefit of using a class is

that it is a built-in class first of all

and it has a lot of functions inside it

and those functions can be like we can

compare a string

okay easily we're just writing string

name dot

equals if it is equals it will return

true and similarly there are many more

built-in functions inside the string

class for example i can tell you we can

print a character

at a particular sequence for example i

wrote str

and then serial dot println str can

at 0 so it will print a because

at 0 position a is present similarly

there are many more functions

like or starting with ending with and

there is a function like we can convert

the entire

string which is written in lowercase to

uppercase

and vice versa uppercase to lowercase

okay we can convert integers into string

we can convert

strings into integers okay so you may be

needing all these functions

while we perform our experiments strings

are used to contain

information messages or error messages

or any

logs okay we can store them inside

strings

and we can also display strings on our

serial monitor on the lcd display

or any kind of display okay we will now

understand

what are functions a function is a set

of statements that take inputs

and do some specific computation and

produces some output

the idea is to put some commonly or

repeatedly done tasks

together and make a function so that

instead of writing the same code again

and again for different inputs we can

call the function

we'll understand what i just said as we

progress in the video so before anything

else

let us first understand how to identify

a function

in the code whenever we see something

like this like void

name and then there are brackets then

there is a curly bracket then there are

some statements written

and then there is a curly bracket again

this is the basic structure

of a function okay where void is

the return type that means we start

writing a function by telling the

compiler the return type of that

function

where void means that function will not

return

anything now instead of white here we

can use

int boolean or float or anything for

that matter

whatever we want to return from the

function then we write

the name of the function we can name it

whatever we want like we saw

digital write or pin mode they were the

functions

and the name of that function was pin

mode and

digital write and then in the bracket we

write

parameters or some people call them

arguments

if there are no parameters or arguments

to the function we just keep this

bracket

empty or if there are parameters then we

specify those parameters how do we

specify the parameters we will see in

the next video okay

so i'll just basically tell you how do

we call a function now like this

in the blink example we called pin mode

function

to call a function we write the name of

the function along with the

parameters of that function in pin mode

led built in comma output was the

parameter of this function

right similarly we have called digital

right here and the parameters of that

digital right was

led built in comma i these are the two

parameters of digital write

so in the built-in libraries of arduino

pin mode and digital write must be

defined somewhere

that's why arduino is able to understand

what this exactly means

otherwise it won't be able to understand

right okay so it has made us

really easy that arduino guys have

defined this function somewhere

for us okay and we just have to call it

now let me tell you the benefits of

using the functions

the first biggest benefit of using the

function is it helps us to reduce the

code redundancy

what that means is for example we want

to do certain tasks so we may

write the statements again and again

again and again so that would make the

code unnecessarily bigger

so what we can do is we can make a

function and we just call that function

whenever we want to

do that task you will understand this

point better when we write our own

functions

then the functions make the code modular

and reusable

what that means is for example we are

making a robot there must be thousands

of lines to make the robot

go forward so what we can do is we can

make a function to make the robot go

forward and we can use that function

whenever

we want to make robot go forward and you

have written the code to make the robot

go forward so now you are trying to make

another robot

so you can use that same code for the

another robot as well

so that means it became modular and it

became reusable

then the other advantage of using

functions is edit provides abstraction

and aids teamwork for example you're

working in a team of four so one person

can write the code for robot to go

forward one person can write the code to

go backward

one person can write the code to move

right and left and one can

write the code to make the robot jump

okay so once these functions are written

so they can together be used as one code

all right so these are the advantages of

using a function

now in the next video we will learn how

to write our own functions

so you will understand these points in a

better manner so i'll see you in the

next video

so let us now create our very own

function we will create a customized

function

to blink the led okay so let's do this

after void loop we will write void

let's say the name of our function is my

blink function okay since there are no

parameters in this we will leave the

bracket empty now

so let us just cut this code from here

and paste this exactly like this in my

blink function

okay so now we have created

a customized blink function now let's

try to

call this function in void loop

right

this way we have called our function in

the void loop

all right so when we upload this code on

arduino you will see

exactly the same results all right so

let us see this

so let us compare both the codes with

the help of a simulator

all right so we had this code right this

is the same blink code

let's see how it is working right as

expected

the led at pin number 13 is blinking

right so now

let us replace the code which we have

just written

we will just take it as it is

right

so now let's start the simulation

so i hope you got my point about

creating our own functions

but now most of you must be wondering

what's the point of making this

right yeah i agree with you there is no

point of making a function for this

small task right but you will find it

useful

when you're writing really huge programs

or you want to customize this thing

i will show you a customization right

now all right

so now let's say you have more than one

leds which you want to blink in a row

okay so with your existing knowledge

what would you have done

you would have done it like this

so you would have repeated these lines

of codes

and just replaced the pin numbers here

right and then you would have declared

these pins as output right but now what

we can do is

we can make a customized function let us

do that

we are here

so let us now make a new function void

my

custom led right

now what we will do is we'll specify

a parameters in which we can tell the

compiler

led pin number so for that we will write

int pin number

okay so this function is going to accept

one parameter which is pin number right

so now let's do this

we have this code okay

so now instead of led built in we will

write

pin here okay so automatically whenever

we call this function

with the pin specified the compiler will

replace

this pin number with the specified pin

number okay

so let's do this

let us just confirm what pins we have

used

we have used nine seven and two

okay nine seven and two

so let us say int led one is equal to

nine

hint led two is equal to

seven and int led three

is equal to two right

so now we just have to declare all these

pins as output

led one okay

see

all right now we'll just replace them

like this since we have declared them as

output

now what will be do is we'll just take

this function

okay we'll write my custom led with pin

number

led one okay

then again we'll call this function with

led 2 right and again we'll call this

function

and we'll just pass led 3 this time

okay let's see if this compiles or not

yes it compiles successfully now let us

see the simulation of this code

right so we have this code here

let us start the simulation okay can you

see that

yep it's working perfectly

first the led one which is connected to

pin number nine is blinking

and then the led connected to pin number

seven is blinking then

the led connected to pin number two is

blinking so now let us see

one more time what exactly happened here

okay so with the pin mode we have

declared all the leds

led one two and three and i'm sure you

know how to do this we have done this

many times till now

okay so now we have created a function

void

my custom led with a parameter of pin

if you wanted more parameters here we'll

just write comma

and then end let's say

parameter 2 right

so this way we can specify endless

number of parameters in our functions

but since we don't need them we'll not

use them

okay then we have started to define

what this function will do which is it

will blink the led

okay which led will it blink the led

which we have passed as the parameter

okay because we have used pin here for

example if you had

declared number here instead of pin

then you would have used number here

instead of pin

got my point so now since we have

finished declaring our function

now we can use it successfully we'll

just take this function

and we will call it here with the

parameter so now we have called it for

the first time

with led1 now what will happen the

compiler will see

okay a function has been used which is

my custom led

with the parameter led1 so it will see

the value of led 1

which is declared as 9 okay so it will

call my custom led with 9

so the control will go to my custom led

with pin 9

and it will execute it with pin 9. once

it is done executing it will come back

it will see it has been called again

with another

parameter which is led 2 and the value

of led 2 is

7 this time so it will go back and

execute the function again

with the value of 7 all right so this is

the basic concept of

function customization okay so instead

of writing this code again and again

with changed

pin numbers we can just do this so i

think all of you can agree with what i'm

saying right now

right one more thing which needs

emphasis is

i've used void here like i told you we

use void whenever our function

is not returning us anything okay so by

the time you must have realized

void loop and void setup are two

functions of their own

they are the main functions which are

used by the compiler we have discussed

about this

earlier as well so now let us try to

make another kind of function

we'll open a new file

and we will start writing our function

first of all let's write serial.begin

this is the most crucial thing to start

communication with the computer

okay so now let us try to write a

function which would return us something

okay so let's say it will return us an

integer

so we'll write in earlier we wrote void

because we didn't want

it to return something to us if you're

not able to understand what returning

exactly means you will just see that in

a moment

so we'll write in let's say we want to

repeatedly calculate

sums of two numbers okay or let's say

sum of three numbers

so we'll write in sum

okay int a comma int

b comma int c

okay where a b and c are the three

numbers which we want to

take some off all right so now we will

write a curly bracket

and then we will write return a

plus b plus c okay

so whenever we call this function we'll

get a value of a

plus b plus c let's see how we get it in

white loop or void setup you can use

this function

anywhere you want let's say we'll use

this in

white loop okay let's say

we write int let's call it d

okay equals to sum

of 7 comma 8

comma 9 all right

and let's print

the value of d okay

so what should it print the sum of 7 8

and 9

which is 24 right we can use it again as

well

with the different set of values let's

say

we'll make another function int e is

equal to

sum 1

comma 2 comma 3

let's print this

we should get six right

so we're getting six 24 and 6.

it's repeating as we have used it in

while loop so you don't have to worry

about that

okay one thing which i want to tell you

is you can use this function like this

as well

serial dot println

directly in serial print sum

4 comma 5 comma 6 right

just make sure to close all the brackets

here we have closed the bracket of the

function

sum here we have closed the bracket of

serial.println

okay so this is called as calling

function inside a function

this is a very useful thing which we can

do in programming

but first of all let us see the result

if it is working or not

right so we are getting 15 here because

this function call here

is printing its value okay

now we can have more than one functions

in our code now let us declare another

function which would return

a boolean value let's say bool

um now we are making a function to check

if a person is tall or not based on the

height we

enter as the parameter all right so

let's name it

is tall okay

and int height

okay so this function's name is

install and the parameter is height

okay so we'll write if

height is greater than

100 return true

okay

or else return

false okay so this function will just

return true

if the entered height is greater than

100 and if it is less than 100 it will

say

false okay so now you will see how handy

it becomes

when you have to check height of

multiple people okay

so now let's call this in white loop

here we have while loop so let's say

serial dot print ln

is tall let's say

123 okay

now let's just comment out the print

statements so that they don't interfere

okay this function is still being used

in int d and e so you can say these

functions are working simultaneously

so we are just checking is tall or not

okay

let's see before i open the serial

pointer

you can guess your values

right it's printing one because it has

returned true

so now let us take another value which

is less than

100 serial dot println

is tall

20. so now we should get

false

so it would be printing 1 0 1 0 because

1 is for

install 123 and 0 is for

install 20. so let us see that

right 1 0 1 0 one zero one zero one zero

okay so if you have to check height of

multiple people

instead of writing this code again and

again for that specific height

you can just call this function and

enter the height so you can see how much

work you have reduced for yourself

right by writing the functions so this

was all about

writing a custom function there is no

upper level to the complexity of the

code which you write in your functions

you can write endless number of lines in

this function

okay like i told you in the introductory

video there may be a thousands of lines

which are responsible for making

robot go forward so in that case we can

write

void move

robot forward and we can just define our

parameters here

and we can just write our statements

like this right

and this is our function this block of

code won't make your robot go forward

i'm just giving you an example of how do

we write functions

okay so whenever we call move robot

forward

in void setup or in void loop so the

compiler will take this function

and it will execute that alright so in

the next video we will take a deeper

look at

some of the inbuilt functions which the

arduino makers have made for us

so see you in the next video now in this

video we will talk about

digital input and output what that means

is we'll take a closer look at

the functions which are made by the

arduino makers to read or write

any sort of digital data all right that

data can be some sort of input given by

external sensors and it can be some sort

of output data which is given by arduino

to other peripherals or components right

so there are basically two functions

which are digital read

and digital right so let's take a look

at digital right

digital right is a function which we

have seen multiple times

before as well so can you recall what it

used to do it used to

write a state of low or high to a

digital pin

so we'll see digitalwrite is a function

where digitalwrite is the name of that

function

all right and it has two parameters

which are pin

and state where pin is the pin number

which we want to manipulate

and the state is the value of either

high or low

where high means five volts and low

means zero volts okay

just make sure whenever we use digital

write we have to declare

that pin as output using pin mode all

right and i have told you this earlier

as well

right next we will see digital read

as the name suggests it will read the

state of that pin

okay so here digital read is the name of

the function which we are calling

and pin number is the parameter which we

pass into it to read the state of that

particular pin

okay if it is high or low so we will now

see a combined example of using digital

read and digital write and how will we

do that we will turn on one led

if a switch is pressed okay so let's see

how we do that

so i have the circuit diagram here in

which i have used a regular led

with a resistance in series which you

can see and here i have used

a push button switch so before we move

further let us first look at

what a push button switch looks like

from inside then only you will be able

to understand it in a better manner

so here is a push button switch all

right which has four terminals out of

which these two terminals are internally

connected and these two terminals are

internally connected as well

okay so when we press the switch these

two terminals

get interconnected and these two

terminals get interconnected when it is

not pressed these two are

not interconnected okay so let's get

back to our example

okay so the code is we have started with

int button is equal to seven

as we want to read the state of that

button on a digital pin number

seven all right in white setup i have

declared pin mode led built in which is

the led connected to pin number 13

as output and using pin mode we have

declared the button as

input because button will be telling its

state to the arduino hence it is used as

input

okay serial dot begin 9600 as usual then

in void loop i have written

serial.println

digital read and bracket button so here

i am asking it to print the state of the

button

either it is pressed or not in the

circuit which we have used we will get

one on pressing the switch and we will

get zero when we do not press the switch

all right so let us see that works when

i'm pressing the switch

i'm getting one here when i'm releasing

the switch i'm getting zero here

look at the serial monitor here right

now i'm not pressing it so it's saying

zero

when i'm pressing it it's saying one

okay so most of you must have also

noticed the led which is connected on

pin number 13.

when i'm pressing the switch the led is

getting turned on and when i'm releasing

the switch

oops it's not getting turned off why

we'll see that in the moment probably

there is some error in the

code i've done this intentionally so

that you can pay attention to that

okay so here i have written if digital

read button is equal to high

then digital write led built in to high

when i press the switch

write a high state on pin number 13 but

i have not written what to do

if the button is not pressed so let us

do that now we will write

else digital right

led built in low

okay so now let us start this again

there was an error the closing bracket

to void loop was missing

so let us start it again all right

so when i press it the led turns on and

when i release it

the led turns off okay so you guys must

be wondering

what's the point of doing this we can

use a simple series connection

and we can turn on the led why are we

using arduino in that i absolutely agree

with you

you can do that very easily using a

series connection but what you have

learned here is

you have learned how to use the

functions like digital read and digital

write

you will be able to implement this

learning in further projects

the experiments which you do all right

so now let me just quickly explain you

the circuit which we have made here as

most of you must be facing

difficulty in that all right so here is

the switch

i showed you the diagram previously

right so these two terminals are

interconnected

automatically when i press the switch

this terminal will get connected to this

terminal

okay so i have taken a wire and

connected one terminal

to 5 volts okay and then i have taken a

resistor

and i have connected it to ground so

here we have made a series connection of

a switch and a resistor

like this and from this point as all

these points are interconnected we can

connect them anywhere

so at this point we're reading the

voltage which is present between

this and this point okay so as we want

to read the state we have connected it

to the pin number seven so when we press

the switch this

line will get connected to this line and

entire 5 volts will drop across

this resistance okay so hence the

arduino will read it as

high state and when the switch is

released this point will be connected to

ground via resistor so it will be read

as low

okay so i hope you understood the basic

idea

let me try to clarify it even more

so this is the equivalent circuit of the

circuit which you saw earlier

okay you can consider arduino's 5v pin

connected to

this switch this is a push button switch

right similarly these terminals are

connected

and when we press the switch these two

terminals will get interconnected

okay so in the series we have used a

resistance and we have connected one

point of that resistor

to ground okay and we are trying to read

voltage from this point can you see that

we have connected this point

to arduino's pin number seven all right

so this way we are able to read the

state of a switch

now what advantages can you have after

reading a state of a switch

you can trigger multiple actions like

running a motor

or sending some message right you can do

anything for that matter

so now you have learned about digital

input and output and in the next video

we'll look at other functions like

analog read and analog write

so see you in the next video in the

digital input output video we saw that

we can use a function called as digital

read to read the state of a pin

if it is high or if it is low that means

we can just read the binary situation

if it is on or either of that's all but

while making our projects

we may have situations in which we have

to read

not just those discrete values we may

also have to read the continuous

voltages so for that

we have analog read this function can be

used only on

the analog pins which are numbered a0 to

a5 right before seeing how it works

we'll have a basic idea of

analog information in the environment so

just look at this flowchart we have

the real world which is our environment

at the top we have some sensor

which is converting that physical

parameter into an analog signal

that physical parameter can be

temperature some distance

or humidity or anything for that matter

that analog signal

is then converted into digital signals

by

an analog to digital converter arduino

has a built-in

10 bit adc the short for analog to

digital converter is

adc so whenever i say adc you can

understand that i am saying analog to

digital converter so that digital signal

which is converted from

analog signal that is used by arduino to

make decisions

our arduino board is capable of

measuring voltage between 0 to

5 volts and this is the conversion scale

what i mean by that is since the

resolution

of adc on the arduino board is 10 bits

it can hold up to 1023 values okay

so if we compare that if the arduino

reads 0 volts so the corresponding adc

value will be

0 and if it reads 5 volts the

corresponding adc value will be 1023

and we can use unitary method to find

out values in between for

example you can tell me what will 3.3

volts

mean i hope i don't have to explain you

the unitary method right

this is the scale if zero volt means

zero and five volt means one zero two

three so one volt will mean

one zero two three divided by five so if

you know the value of one volt you can

find out value of

any voltage so now many of you must be

wondering from where this value of one

zero two three came from so i'll quickly

explain it to you we have a cupboard

here

which contains ten boxes and each box

can contain a value of either zero or

either

one okay so this is the cupboard and

these are the

boxes individual boxes to find the value

of the cupboard we take the value of

each box and we multiply it with the

multiplier the multiplier is this 2 to

the power 0 is

1 2 to the power 1 is 2 2 to the power 2

is

4 and similarly 2 to the power 9 is

512. so when we have values of all the

boxes

we take sum of all those values and we

get the value of that

entire cupboard so the maximum value

which can be held by a cupboard in which

all the boxes contain a value of one

will be one zero two three how this box

will evaluate to one

why because two to the power zero is one

and one multiplied by

1 is 1 okay so now the 2 to the power 1

is

2 and we multiply 1 by this so we get 2.

so we will be summing

all the values from here to here like 5

12 256

128 64 32 16

8 4 2 and 1 when you sum all these

values you will get 1 0 2 3 you can try

it on your calculator right now

so now let's take a look at analog read

function this function is simply used by

calling analog read

with the parameter of pin number where

pin number is a0 to

a5 so whenever you call this analog read

function it will return you the value at

red on that

pin so let's see how we use that so now

i have used

two one kilo ohm resistances in series

can you see that so now i have connected

it to

5 volts this point is connected to 5

volts and this point is

connected to ground so you can imagine a

series circuit

so now i want to read voltage across

this resistance since both the

resistances are equal

the 5 volt will split equally on both

the resistances

so we should be getting 2.5 volts let us

see that so in the code we have written

serial.begin

to start communication with the computer

and then we have written serial.println

bracket analog read a0 that means i want

to read the voltage

which is given at a0 so let's try this

code so we are getting

511 which is nearly 2.5 volts

we saw in that scale right so let's

change the resistance and see what value

do we get now

let's make this value as 2 kilo ohms

right so we got a change in value more

the value of resistance more the voltage

will drop across it

we can see the value of voltage across

this resistance is increasing if we make

it too high

it will increase it will also change if

we change the value of this resistance

let's say we make it 10. so now

the voltage across this resistance will

drop and hence we get a lower value

now let's see this with a light

dependent resistor this is a special

kind of resistance which changes

its resistance when light falls on it in

most of the light dependent resistance

the resistance will decrease

if the light on it increases okay so

let's try this

replace this resistance with

a light dependent resistor okay we'll

connect this in series

we'll take it here all right and we take

this wire now you see

this bar will represent the amount of

light falling on it right i can control

it like this

so right now here it is total darkness

and here it is very bright okay so when

it is dark the resistance of this

component is very high

okay so the voltage which drops across

this resistance will be very low

you can see the value is very low right

as soon as i increase the light on it

you will see the value in the serial

pointer is increasing

can you see that because the resistance

of this component is getting lower and

and more voltage is dropping across the

resistance

okay now this is the principle of analog

read now you can see how we can read the

value of analog sensors using

analog read all right so in the next

video we will look at the another

function which is known as

analog right so see you in the next

video in this video we'll take a look at

analog write function which is another

important built-in function

of arduino all right so to begin with

analog write i would firstly like to

tell you that it has no relation with

the analog pins or analog read function

it is absolutely a different thing what

exactly it is we will see

shortly so to use analog write function

we write analog write

bracket pin number on which we want to

use analog write

and then we specify a value which ranges

from 0 to 255.

we close the bracket and use a semicolon

right

the important thing which we need to

note is the pin numbers which we can use

here

are specific which are pin number 3 5

6 9 10 and 11 only okay

while all of these pins except pin

number five and six

support a frequency of 490 hertz and pin

number five and six support a frequency

of

980hz we don't need to worry about this

frequency right now

i'll explain as we progress so before we

dig deeper into this

we need to understand a few terms like

pwm

pulse width and frequency and even

before that we need to know what exactly

this analog write function does

the analog write function generates a

square wave of a specified

duty cycle on that specified pin the

major purpose of using analog write is

to control the brightness of led or to

control the speed of a motor

right the first thing which we need to

see now is a square wave what a square

wave is on the screen you can see

a square wave is coming this is a square

wave okay

although this is a varying square wave

now a square wave is nothing

but a signal which has only two discrete

values either on

or off as you can see here it is on

and here it is off and the time for

which it is on

and off is varying you can see here

right i can understand it must be

little difficult to comprehend but

please stick with me okay so the next

term is

pulse width the amount of time for which

a signal is on

is known as pulse width for example in

this wave

this is the pulse width denoted by this

arrow in this portion

this is the pulse width denoted by this

arrow in this portion

this is the pulse width noted by this

arrow

all right the next term is duty cycle

duty cycle is the fraction of period for

which the signal was

on right so we have five sections here

with zero percent duty cycle twenty five

percent due to cycle fifty percent duty

cycle seventy five percent duty cycle

and hundred percent duty cycle okay so

in this section

the voltage for entire time was zero

okay

so that means the duty cycle is zero

percent

in this section we have about one fourth

of the time

as on you can see that right for the one

fourth time it is on

and three fourth time it is off so that

means the duty cycle is

25 in this section we have about

half of the time as on time and half of

the time as of

time so here the duty cycle is 50

similarly here the on time is 3 4

hence the duty cycle is 75 and here

for the entire duration of time the

voltage was on hence

the duty cycle was 100 okay now

if we look in terms of arduino when we

call analog write

with a value of 0 it will give us 0

percent duty cycle

that means the signal will be off for

the whole time

if you write analog write 64 then it

will give us a duty cycle of 25 percent

if you write 191 it will give a value of

75 percent and 255 will give us a duty

cycle of 100

okay so now to summarize pulse width

modulation

or pwm is a technique for getting analog

results

with digital means digital control is

used to create a square wave which is a

signal

switch between on and off all right and

this

on and off cycle takes place really fast

and this on off pattern can simulate

voltages in between

full on and full off by changing the

portion of the time the signal spends

on versus the time that signal spins off

all right so next thing which we need to

look at

is the pwm frequency okay

let's see this is a wave which has a

duty cycle of

50 that means half of the time the

signal is on

and half of the time signal is off

changing the frequency of the signal

will not change the duty cycle of the

signal okay so let's say

we have a signal of 50 duty cycle here

and if we make the frequency to 400

so the waves will become closer that

means now it will turn

on two times and turn off two times

right you can see here

on and off earlier it was on one time

and off one time

okay but you see the duty cycle is still

50 you're getting my point so you see

the duty cycle of the signal has not

changed

because it was still on for the half of

the time and off for half of the time

even if i make it 600 it is still on for

the half of the time

and off for half of the time okay so i

hope it was clear to you and if in case

it was not clear to you

we'll take an example and blink the led

and change the brightness of the led

all right and we will also monitor it

along with a digital oscilloscope an

oscilloscope

is nothing but it is a device which is

used to analyze the signals okay so

let's see that so here what we have done

is we have taken an led

on pin number 10 and correspondingly we

have connected these wires to an

oscilloscope to see the signal so let us

see the

code first so you must have noticed that

we have not written anything in void

setup

and we don't have to use pin mode

whenever we want to use analog write

function

okay so now in void loop i have written

analog write

pin number 10 and a value of 50

okay and then i have given a delay of

one second then analog write 10 with the

value of 100 then 150 then 200 and 255

here we will get a duty cycle of 100

okay so now let's see how it looks like

pay attention to the wave which is

coming on the oscilloscope

and also note the brightness of this led

i'm starting the simulation

let's see can you see that the

brightness of led

is increasing gradually as the code

progresses and it gets backs to 50

and then it again increases also note

the pulses which are coming in the

oscilloscope so now we will see an

example in which we are changing the

brightness of led in steps of

five we will also look at the pwm wave

simultaneous

let's look at the code first we have

defined an led pin which is connected on

pin number ten in white setup we don't

have to do anything

in void loop we have written four which

is a for loop and we have defined a fade

value

in fade value is equal to 0 and you have

to do this till

the fade value is less than or equal to

255 okay

and then we are incrementing the value

of fade value by

5. this is an another compound operator

you can say it is similar to writing

fade value is equal to fade

value plus 5 all right

so now we have written analog write and

we have written led pin here which is

pin number 10

with the fade value okay

so how it will go it will write zero

here then after the delay of 30

milliseconds it will write five year

then after a delay of 30 milliseconds it

will write 10 here then 15 and 20

and 25 and so on till 255. once this

value

becomes 260 you know in the last

iteration the value will become 260

so this condition will become false and

it will exit this for loop and come

inside

this for loop in this for loop we have

used fade value starting from 255

and we have written a condition fade

value greater than equal to zero

that means you have to do this till the

value is greater than

or equal to zero okay then we have to

use fade value minus equal to five

and this is similar to writing yes you

guys did right it is similar to writing

okay so now it will start

at 255. after a delay of 30 milliseconds

it will write 250 and 245 then 240

and 235 and so on till 0. in the last

iteration

when the value is 0 the value will

become -5 and the condition will become

false so this loop will exit and it will

come back

into this for loop and this will repeat

endlessly till we turn off the arduino

let's start the simulation note the

brightness of the led and note the

signal which is coming in the

oscilloscope

let's see okay

it's interesting right the brightness of

leds increasing

from 0 to 55 and the pulse width is

changing when it is 0

you can see it is entirely off and when

the duty cycle becomes 100 it becomes

entirely on

the pulse width is changing here so i

hope you have understood this really

well

the last topic which we need to learn

about before starting our experiments

is the arduino libraries so libraries

are a collection of code that makes it

easier for you

to connect to a sensor display or a

module for example

there is a built-in library to control a

liquid crystal display

that library makes it easier for us to

talk to that display

right for example you can see that

library will control what character will

come at what position

apart from this library there are many

more libraries which are available for

download on internet

and there are also built-in libraries

for example

the built-in libraries are these

libraries which are already present in

arduino id i'll just name a few like ap

rom

is used to read and write elements from

the permanent storage

a gsm library is used to connect gsm or

gprs network with the gsm shield

the liquid crystal library which you

just saw controls the liquid crystal

display which is used for reading and

writing data on

sd cards a server library will be used

to control server motors similarly there

are many more libraries which are

already there on

arduino the code which is written inside

those libraries can be written by

someone else

or you can write the code on your own as

well once we have the library in our

arduino

id it's very simple to use that library

i'll just show you how

so this is our code let's say we have to

use liquid crystal library so we will

write hash

include liquid crystal dot

h okay whenever we use this library

we'll be able to use the functions which

are written inside the liquid crystal

library

okay similarly if we have to include

another library for sd cards we'll write

sd dot

h okay this will include the sd library

in our code

we'll be able to use all the functions

which are written in sd library

i would also like to tell you that the

functions which we were using like

digital write

were also declared in some library i

will just show you

how it was written so there's a built-in

code which is written inside

wiring underscore digital dot c which is

located at this location

see program files arduino hardware

arduino avr course

arduino and then finally the file now if

we see the declaration of

digitalwrite we will see that this is

how a digital write function is declared

in that library

okay you just see that void digitalwrite

pin number and value okay where pin is

the pin number and value is high or low

it accepts two arguments right we sorted

while calling this function

so this is how the digital write is

called we'll not get into

details of this function as it may be

very complicated for you to understand

okay similarly digital read has been

declared here this is a declaration of

digital read

similarly pin mode is also declared

right so i hope you were clear with

libraries

and i hope you understand how using

libraries saves a lot of our time

okay so in the next video we will see

how to add

additional libraries in our arduino ide

so see you in the

next video so now let's see how do we

install external libraries in our

arduino ide there are basically two

methods

one is through the library manager and

one is through

adding external zip files okay let's

look at

the library manager first we will go to

sketch

include libraries then manage libraries

it will open the library manager this is

the library manager

it will update all the libraries which

are already there

in their database and it will show us

the list of available libraries for us

you can see there are a lot of libraries

already there

right these are all the libraries which

are present

in their database right now so let's say

we need a library for dht 11

which is a sensor which captures

temperature and humidity of our

environment

so we will write dht11 here and it will

search all the libraries

which are available for dht 11 by

different authors

so let's say this is a very reliable

library by adafruit

which i've already installed okay so

just in case you have not installed it

already you will get

install here you can select the version

here which version you want to install

usually this is the latest one and then

you just click on install

and it will install the library in your

id okay

once it is installed we can use it in a

regular manner

hash include

dht dot h

okay if this dht library was not

installed in my id

it would not appear in this orange color

okay

let's take an arbitrary name include

ashish dot

h since there is no library named ashi

so this ashish is not coming in

orange color although this is not a very

hard and fast rule you might not get

orange color in some libraries but it is

a really

good indication that you're working in a

right direction

okay so now let us look at the other way

which is adding them

manually let's say again we want a

library

for our dht11 sensor we will write dht

11 library

for arduino usually

libraries are available on github you

may also find zip files on some other

websites

but github is usually preferred as you

would get the latest version of the

library from there so again adafruit has

hosted their library on github

so let's click on that and then we'll go

to clone or download

we'll click download zip

and it will start downloading it you

have to see where you have downloaded it

you have to go to sketch include library

then add

dot zip library in my case i downloaded

it

in my h drive so it is here we'll click

on this

and just click on open in my case it was

already installed so it gave me a

warning a library name dht sensor

library master already exists

okay but in your case it will say the

library has been successfully installed

so these are the basic two ways in which

we add libraries

at this point i can really say that you

have reached a milestone

and you are in a position to dig deeper

as you have so many tools under your

belt now

we have covered the foundations of

electronics then we covered

what is an arduino board and then we

discussed what is inside arduino

we covered the difference between the

microcontroller and microprocessor

then we saw the arduino ide how it works

and how we use it

we also saw an online simulator which

can be used if someone doesn't have an

arduino right now

then we saw how to use a breadboard then

some topics like

input output analog digital etc and then

we started

arduino programming and i tried to cover

all the essential topics which are

required

for you to start your own projects from

this point you can try making

various led patterns you can try to work

with

a seven segment display which can be

used to display different digits on it

then you can try to interface sensors

like ultrasonic sensor

or ir sensor and try to read their

values using the built-in functions

which we have studied already

then you can try to control the motion

and speed of a dc motor

then i recommend you to try using a

servo motor after this

you will be in a position to make robots

like a line falling reward

a robot which is capable of following

light lines over a dark background

or vice versa

you can also make obstacle of winning

robots

then you can make remote control cars

like this and once you get comfortable

with this

you can also make complicated robots

like a hexa port

like this which has several servo motors

used in it

right which is moving forward you can

also check out some posts at my

instagram

ashish underscore things and check out

some of my other projects as well

so i hope that you found this course

really useful to begin your journey with

arduino

thank you so much for your time and have

a nice day ahead