Arduino Tutorial #2 - Analog Inputs and Pulse Width Modulation (PWM) RGB LED Video Lecture | Drones for Beginners: How to make Arduino Drones - Electronics and Communication Engineering (ECE)

how's it going guys blood here and
welcome to the second Arduino tutorial
in which we are going to discuss reading
analog voltages and particularly from
this lm35 DZ temperature sensor we are
also going to discuss PWM and how to
fade in and out on RGB LED so red green
and blue LED for this particular
tutorial you're going to need your board
we're going to need some jumper wires
and LED you may use a single LED instead
of an RGB one if you don't have that you
can you're also going to need an analog
sensor of some sort it can be
temperature humidity anything you can
practice with you're going to need a
breadboard and some current limiting
resistors for your LEDs so stay tuned
and let's go into the first circuit all
right so before we hook it up what you
need to know is that the Arduino has the
Arena lumen particularly has six analog
to digital conversion pins and they're
located in this corner so as you can see
you have a 0 a 1 up to a 5 and you can
connect any analog voltage input to read
them on these pins so let's take a look
how we're going to connect the
temperature sensor to a0 alright so
first first circuit there is nothing
complicated to connect all you need to
do is to connect the a 0 pin to the
output pin of the temperature sensor as
well as the 5 volts and the ground so
let's take a look at what we need to do
to program the temperature reading so
the first thing that we're going to do
is create a setup function in which
we're going to define a serial
connection to our computer this is going
to be used in order to get the
temperature from the sensor onto our
screen so in the loop we're going to
define a sensor which is going to be an
analog read from the pin a 0 we are also
going to convert that to a voltage value
by
multiplying it by 5 volts and dividing
by 10 23 I'm going to discuss more in
detail where this 10 23 comes from and
how it's obtained but essentially it's a
10 bit conversion and 2 to the power of
10 equals 10 to the 24 that's where the
10 23 comes from so we're going to get
the temperature which is what we really
want and this is done by simply
multiplying the voltage by 100 and once
again this comes this comes from the
datasheet of the LM 35 G's ed sensor
which states that for each 10 millivolts
you have 1 degrees Celsius you can
obviously convert that to Fahrenheit if
you desire to do so before sending it
over serial so we're going to send that
and we're going to insert a half of a
second delay to make sure that we don't
have too much spam let's verify our
sketch everything seems to be fine and
let's upload that onto the Arduino so
let's take a look at what we've got all
right so now that our sketch is uploaded
on the sensors connected to the Arduino
now one thing that you're going to
notice is that the TX pin is going to
blink and this this is telling us that
there is a serial communication present
so the Arduino is sending a signal to
our computer which is what we define on
the program so let's take a look at what
we're getting on the actual screen
alright so if we go into the tools and
then to the serial monitor we are going
to see our temperature readings that
we're setting sending back to the
computer so as you can see right now
we're reading reading 24 degrees Celsius
25 and if I put my fingers onto the
sensor really it's difficult for me to
film both the screen and the sensor but
you can see the temperature rise as it
reads the temperature of my body and if
I let go it should steadily go down as
you can see 2028 slowly goes down to 27
so that's how you read in an
value of a sensor whether it be
temperature a gyroscope a an
accelerometer or a light sensor anything
else all right so for this circuit what
I'm using is a common anode LED what
that means is is that the common node
for all three LEDs is the 5 volts one so
as you can see I have it connected onto
the positive rail and I have current
limiting resistors which we've covered
in the previous tutorial for each LED
and after that there they are connected
to the pins 9 10 and 11 which have the
pwm sign in front of them you see on the
Arduino board itself so let's take a
look what it takes to program the
circuit in order to fake the LED all
right so the goal for this project is to
apply a different PWM signal in order to
fade the LED in and out and I'm using an
RGB LED so it'd be cool to make all
three colors cycle after one another so
we're going to start with LED blue and
that is connected to pin 9 for me LED
red which is connected to pin 10 LED
green is connected to pin 11 we have the
brightness value so let's set that to
zero and eight LED this is what we're
going to fade the led by so let's say
let's set that to five and current and
and this I'm using this value to track
which pin is currently being used so I
can toggle effectively so void setup
here as you remember we need to declare
each output that we're using so LED blue
is an output followed by green and red
there we go we can close the setup
function void loop what we're going to
have here is an analog right to the
current pen and we're going to write the
brightness value onto the spin so after
we have written a certain PWM value onto
the LED we are looking to increase this
brightness for the next step we're going
to do is brightness plus fade LED and if
our brightness is equal to zero so that
means this is once the LED had has gone
through a full cycle what we're going to
do is switch first of all we're going to
switch the LED directions so now it's
going instead of dimming down it's going
to
increase the brightness so it's going to
switch directions we're going to close
this function and if brightness equal
equal equal to 55 we are going to the
LED so we're also going to switch so
eight LED but in this case we need to
toggle the current pin because we want
to cycle between red green and blue
we're going to check that if current pen
is at its limit so at pin 11 is going to
become it's going to become nine
otherwise what we're going to do is
current and plus plus we're going to
increment so we're going from nine to
ten to eleven and once it's 11 we're
going back to nine so we're going to
close the else we're going to close our
F we're going to introduce a delay of 25
milliseconds we're going to close our
loop function and see if we got any
errors within this seems to be okay
let's upload the sketch on to the
Arduino and take a look at what we've
got alright so as you can see we are
applying a pulse width modulated signal
onto the LED and it goes from red
through green through blue and make sure
to check out the extended version of my
tutorials where I actually explain some
of the concepts behind these these
circuits and connections so like for
example I'm going to actually explain
what PWM does to the LED and why we are
seeing a different brightness on the LED
so thank you again for watching I hope
you learned something today and see you
onto the on the third tutorial and make
sure to comment subscribe and let me
know what you what you guys would like
to see in these tutorials thank you bye
you