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Hello! In this exercise we are going to use the same circuit we used in the

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previous exercise. You can see that we have the voltage divider connected the

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same way we connected it the previous day. We are reading from 5

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volts to 0 volts using the A0 analog connector and we have the LED connected

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to the Arduino board, the usual way, but there is something different. Instead of

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of connecting it to number 13, the LED is connected to number 11. Why number 11? You

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can see that numbers 11, 10, 9, 6, 5 and 3 have a line in front of the number. It means

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that they are different, these connectors are different. It means that they can provide

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also, they can provide, I mean, digital values, the same way we have been doing during the

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previous days, high and low digital values, but these six connectors, the one with the

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line in front of the number, can also provide analog values.

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It means that we can send one volts, two volts, three volts, one and a half, two and a half,

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2.40, 3.60, 3.75, whatever.

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And if this LED is connected to 11, for instance,

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it means that we will be able to provide, I don't know, maybe 240, 320.

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It means that we will be able to control the intensity of the LED.

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We will be able to decide if the LED will shine brighter or less bright.

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Okay?

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So, let's have a look at the simulation, I will show the code later to you.

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If we are reading 0 using the A0 connector, 11 doesn't send anything to the LED, it doesn't

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change.

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If we move a little bit higher, it means that we are reading a number higher than 0, as

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you can see the LED is shining a little bit.

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If we move it and we read a number even higher, the LED will shine brighter, and the higher

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the number we read, the brighter it will shine, okay?

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This is the brightest value.

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We go back to 0, 5, 0, 5.

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You can see the ranges, you can see the range of values we are reading and sending to the

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LED.

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Before we have a look at the code, we need to consider, we need to take into account that A0, although it reads analog values, the Arduino board will work using integer numbers.

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You remember that the analog input reads numbers from 0 to 1023.

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We studied it in the previous exercise.

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It means that we are going to use 1024 values.

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number 0 is related to 0 volts

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number 1023 is related to 5 volts

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and for instance if we have 5012

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the one in the middle, we will be reading

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or using, reading in this case

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2.5 volts, the value in the middle, ok?

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there is a proportional relationship between the number we use

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and the voltage we are reading

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when we use these numbers as

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output values, we are going to use

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a lower range of values. We are going to use a range of 256 values. We will use numbers

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from 0 to 255. 0 will be related to 0 volts, 255 will be related to 5 volts, and the one

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in the middle, for instance I think 128, will be related to 2.5. Do you understand the idea?

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There is a proportional relationship between the integer number and the voltage.

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But it's the same idea.

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Although the range is four times shorter, it's the same idea.

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So how can we program this circuit?

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Really, really easy.

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I want to show the code to you.

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The first thing we need to do is creating a variable.

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In this case, our variable is called input.

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We read the analog input with this block, leer pasador analogico,

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the one that is connected to a zero,

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and we store it in the variable called input.

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And then, what do we do? We divide this

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variable by 4. Why? Because of the range we are going to send,

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we are going to use as output, is 4 times shorter

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than the range we are using to read

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values. And we use this range to send this

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value to 11. 11 is here. It sends the value to the LED

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and the LED shines according to the value we are sending.

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Zero, it doesn't shine.

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Here in the middle, it shines just a little bit,

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and if we move here, it shines a lot, okay?

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So, this is the circuit.

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This is the first thing you have to do, create the circuit.

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But this is not the exercise.

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This is just the first step.

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Your exercise is going to be a little bit different.

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Your exercise is here.

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is the RGB, we are going to use a new component

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that is called the RGB LED, this here

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is an LED with

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four pins, four connectors. One of them

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is called the red connector, one of them is called the blue connector and one of them is called

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the green connector. And this one is the cathode and is connected

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to the ground through the protection resistor, the one

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we usually use with a value of 220 ohms, ok? Don't forget it.

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So, it means that this LED will combine three colors, ok?

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So, we will read three different values using A0, A1 and A2, ok?

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Can you see that we have three voltage dividers connected the way we connect them?

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We will use three variables instead of having input.

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We will have input 1, input 2 and input 3, for instance.

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We will read three values the same way we read them before, and we will send three different

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analog outputs the same way we have sent them before.

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One for the red, one for the blue, and one for the green.

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So let's have a look at the simulation.

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You will understand it better with the simulation.

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If I move this one, this is the red control.

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It means that I'm sending 5 volts, now I'm sending 5 volts through the red wires.

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If I connect, if I use the second one to the maximum value, now I'm sending 5 volts using

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the blue wire and it will happen something similar with this one.

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Now it means that I'm sending 5 volts through the green wire, ok?

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So the important thing is that we can combine, for instance, green and blue, and what happens

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if we combine green and blue, we have this one that is

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a different color. What happens if we combine blue

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and red? We have purple, okay? So the idea

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is that every color can be

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produced using a combination of red, green, and blue. And the way to

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I'm not going to show the code to you, but it's really simple. It's something like repeating

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three times the code of the previous exercise. Using a variable, reading

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it reading a number from the connector, A0, A1, and A2, storing the number in the variable,

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dividing the variable by 4, and sending it to the output we want, 11, 10, and 9, okay?

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So if you understand the first exercise, and if you have the connections for this one,

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the exercise is really, really simple.

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This is the exercise, controlling the LED RGB using three voltage dividers, okay?

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Good luck.