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hello in this exercise we are going

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to use the same circuit that we

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used in the previous exercise so you

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can see I have a voltage divider

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connected the same way we connected it

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the other day and we are reading

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from five volts to zero volts using

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the

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zero analog connector

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and we have the LED

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connected to the arduino board the usual

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way

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but there is something different instead of

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connecting it to number thirteen we are

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connecting it to number eleven you can

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see if i zoom in that numbers

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eleven ten nine six five and three

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they all have a line in front

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of their number it means that these

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connectors are different

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and so these numbers can provide digital

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values the same way we have been

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doing during the previous days with the

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high and low digital values but these

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six connectors the ones with the line

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in front of the numbers these can

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also provide analog values

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so this means that if we send

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one volts two volts three volts we

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could send one and a half two

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and a half two point four zero

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point three three point six whatever we

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want and if this LED is connected

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to eleven for instance it means that

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we

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we'll be able to provide any voltage

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amount we want to control the intensity

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of the LED so we will be

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able to decide if it will shine

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brighter or less bright

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so let's have a look at the

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simulation I will show you the code

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later

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if we're reading zero using the

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zero connector eleven doesn't change it doesn't

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send anything to the LED so it

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won't shine

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if we move it a little bit

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higher it means we're reading a number

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higher than zero and as you can

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see the LED is shining just a

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little bit more

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now if we move it more we

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read a number even higher the LED

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will shine brighter and the higher the

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number we read the brighter it will

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shine this is the brightest value on

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five

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so it's the brightest back to zero

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off

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back to five so you can see

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the range of values we're reading and

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sending to the LED

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now let's stop the simulation

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and before we have a look at

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the code we need to take into

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account that a zero although it reads

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analog values the arduino board will work

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using integral numbers do you remember that

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the analog input reads numbers from zero

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to one hundred and two we studied

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it in

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the previous exercise means that we're going

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to use one thousand twenty four values

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this number zero is related to zero

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volts and number twenty three number one

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thousand twenty three is related to five

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volts for instance if we have five

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thousand and twelve that one in the

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middle then we will be reading two

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and a half volts it's the value

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in the middle

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so there's a proportional relationship between the

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number we use and the voltage were

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reading when we use these numbers as

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output values we're going to use a

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lower range of values we're going to

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use a range of two hundred and

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fifty six we will use numbers from

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zero to two hundred and fifty five

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so zero is real

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rated to zero volts two hundred and

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fifty five is related to five volts

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and the one in the middle which

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would be a one hundred and twenty

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eight that is related to two and

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a half volts so you see that

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there's a proportional relationship between the integral

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number and the voltage

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so it's the same idea as the

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first one although the range is just

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four times shorter

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so how will we program it well

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the first thing we need to do

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is create a variable in this case

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our variable is called input and we

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read the analog input with this block

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the one that's connected to a zero

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and we store it in the variable

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called input

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and then we're going to divide this

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variable by four because the range we're

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using for this output is four times

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shorter than the range where using to

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read the values and we use this

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range to send this value to eleven

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so it will send the value to

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the LED and the LED shines according

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to the value that we're sending

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so on zero it doesn't shine here

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in the middle it shines a little

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bit and if we move it all

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the way

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it's the brightest okay so this is

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the circuit this is the first thing

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you have to do just create the

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circuit but this is just the first

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step your exercise is going to be

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a little different

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your exercise is here it's rgb we're

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going to use a new component that

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is called the rgb LED and you

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can find it down here in the

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components library

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so it's an LED with four

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pins four connectors the first one is

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called a red connector one of them

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is called the blue connector and one

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of them is the green connector and

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this one here is just the cathode

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and it's connected to the ground through

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the protection resistor that we always have

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at two hundred and twenty

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don't forget that

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so it means that this LED will

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combine three colors so we will read

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three different values using a zero a

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one and a two

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okay can you see that we have

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three voltage dividers connected the way we

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connected just one before we will use

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these three variables instead of having input

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we will have input one input to

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input three for example

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so we will be reading three values

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the same way that we have read

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them before and we will send three

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different analog outputs the same way we

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sent them before one for the red

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one for the blue and one for

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the green

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so let's look at the simulation to

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understand it better if i move this

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first one the red control it means

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I'm sending five volts through the red

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wires

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and you can see the LED is

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red if i use the second one

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to the maximum value now I'm sending

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five volts to the blue wire

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and it's the same with the last

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one now I am going to send

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five volts through the green wire

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so the important thing is that we

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can combine for example green and blue

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and we'll get a new color it's

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almost turquoise

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what happens if we combine blue and

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red

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well you know we'll have purple

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so the idea is that every color

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can be produced using some combination of

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red green and blue and I'm not

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going to show you the code but

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it will be something that's repeated three

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times like the goal of the previous

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exercise so you have to use a

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variable read a number from the connectors

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a zero a one and a

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a two and storing the number in

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the variable then dividing the variable by

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four and sending it to the output

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we want eleven ten and nine if

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you know the connections for this one

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and the exercise should be pretty simple

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so try controlling the rgb LED using

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three voltage dividers

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good luck