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In this video I'll introduce some new components 

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that will be used to construct your first circuit.

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Afterwards we will step into the Arduino development environment

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and learn some of it's basic features.

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Finally we will code our first microcontroller program and upload it to our Arduino.

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Let's get started.

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>> The first component that we should familiarize ourselves with is the solderless breadboard.

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This breadboard allows us to prototype or test our circuits

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simply by placing the leads or component ends inside these tiny holes called sockets.

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It's important to note that letters and numbers run along the perimeter of the breadboard.

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This is because the sockets in each numbered row are connected

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which means row 1A to row 1E, for example, 

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will receive the same current; however, the rows are not connected to each other.

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>> The next component is the resistor which has the primary puroposes

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of limiting current and dividing voltage.

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We use resistors because not all components accept the same level of voltage

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that the power source provides.

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When a steady voltage is applied to the leads of the resistor,

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the amount of current that allows to flow through it is determined by its resistance

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which is measured in ohms.

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So more ohms results to less current.

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In order to figure out how to calculate the amount of resistance in ohms

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that a resistor applies, we simply look at its color stripes 

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which wrap around the outer casing.

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The resistance value can be read by the first 3 stripes of color.

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Each color has a specified value from 0, being black, to 9, being white.

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You could find more information about these values from the link provided.

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There is also a fourth stripe that comes in either gold, silver, or just blank.

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This gives the tolerance levels of the resistor, i.e. how closely it matches its rated resistance.

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For now we can ignore the fourth stripe and set our focus on the first 3.

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>> The first stripe, which is the opposite of the tolerance stripe, is the first digit.

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This value can be 0 to 9.

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Similarly, the second stripe is the second digit which can also have a value of 0 to 9.

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But the third digit is where it becomes different.

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The third digit is the number of 0's that are added to the end of the first 2 digits.

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The formal name of this stripe is the multiplor.

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Take for example this resistor.

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We currently have an orange, orange, brown resistor.

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Orange's value is 3, and brown's value is 1.

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Therefore, we have a 3, 3, 0 or 330 ohm resistor.

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Remember the third stripe, which is brown, is telling us only the number of 0's to be added

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onto the first and second digits.

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>> Finally our last component is the light-emitting diode or LED for short.

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The LED is a little light that we may find in most of our electronics.

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In order for an LED to emit light, current must pass through a lead in a specific direction.

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But we will come back to this shortly.

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For now, notice how 1 lead is longer than the other.

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The longer lead is called the anode, and this is the positive terminal for the LED.

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The shorter lead, which is the negative terminal, is called the cathode.

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>> Now that we have a general understanding of our components,

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let's build our first circuit.

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When you begin building a circuit you should always unplug your Arduino from the computer.

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So according to our schematic, we know that the resistor should be between 

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the power source, i.e. one of the Arduino's digital pins, and the anode,

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the positive lead of the LED.

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While the cathode, negative lead, will be connected directly to ground,

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thus completing our circuit.

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Unlike the LED, the direction by which we place the resistor does not matter.

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Let's place one of the resistors leads in socket row 1A.

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Now let's place the other lead of the resistor in a separate circuit path.

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How about row 2A?

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>> Great. Halfway there. Let's move on to the LED.

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Per the schematic, our anode, the positive lead, must be connected to our resistor.

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This means that we should place the LEDs anode in a socket that is on the same 

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circuit path as 1 of the resistors leads.

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Let's do row 2E.

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Per our schematic, we know that the cathode will go directly into the Arduinos ground pin.

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So we can place the cathode into row 3E. 

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>> Great. The final part to our schematic is simply using these jumper cables

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to connect to our Arduino, thus completing the circuit.

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Let's start by making the connection from the cathode to the Arduinos ground.

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To do this, we simply plug the jumper cable into any of the sockets

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which share the same A to E row of the cathode.

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In this case we'll plug 1 end of the jumper cable directly into row 3A.

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The other plug will go into 1 of the grounded or GRD digital pins of the Arduino.

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As for the second cable, according to our schematic we will make a connection

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from our resistor to our power source which is 1 of the digital pins on the Arduino.

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We already know that 1 end of the resistor is connected to the LEDs anode.

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So this leaves us with only 1 option, row 1 sockets B through E.

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Let's give ourselves some room between our components.

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Let's plug 1 end of the jumper cable in row 1E.

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Finally, plug the other end of this jumper cable in digital pin 13.

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Remember this pin. It will be very important soon.

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>> Well the circuit looks pretty, but we want it to do something.

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Let's crack our knuckles and get down to business 

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writing our first microcontroller program.

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First plug the square USB end into the Arduino.

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In order to start writing our own program,

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we will need to access the Arduino integrated development environment,

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which I will refer to as the IDE.

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To do this click on the appliance menu at the bottom lefthand of the screen.

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Go to programming and select Arduino from this menu.

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If the Arduino software is not currently installed you can easily install it by

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opening a terminal and typing the following command:

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Sudo yum install arduino.

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You will need to restart the appliance when it completes.

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So once you launch the IDE, the first thing you should check

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is if the Arduino IDE is registering or seeing your Arduino device.

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You can do this by simply going to the tools menu, hover over serial port,

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and there should be at least 3 devices listed.

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If it is not checked already, do make sure you check the /dev/ttyacm0

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as this is where you Arduino is plugged into.

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>> When you first open the Arduino IDE a new project, which is called a Sketch,

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opens up automatically.

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This area will be used to place our coding.

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At the bottom of the screen there is a terminal window responsible for outputing information

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such as complilation response codes or syntax errors in your code.

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At the top of the screen just below the file menu, there are a series of icons 

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that we should be acquainted with.

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Starting from the far left, there is an icon that resembles a check.

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This button is called verify, and its responsible for compiling your code

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while validating the correctness of your program syntax.

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The button after verify, which resembles that of a sideways arrow pointing to the right,

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is the upload command.

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The upload command is resonsible for sending the programs compiled 1's and 0's

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over to your microcontroller for it to be saved on the board.

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Keep in mind that the verify button will not upload your code.

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The next 3 buttons are new, open, and save respectively.

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The final button to the far right of this menu is called the serial monitor,

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and it acts as a consult whereby programmers can configure the Arduino to read as the input

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or display as the output to and from the serial monitor.

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We'll come back to the serial monitor in another video.

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>> For now let's start writing our program.

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Now starting to write an Arduino program slightly differs from regular C programs.

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This is because an Arduino needs, at a bare minimum, 2 specific void funtions defined.

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Setup and loop.

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Arduino makes it very easy to get started by utilizing example code templates

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which come with the IDE.

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To load our bare minimum, simply go to the file menu, examples, choose number 1 basics,

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and click on bare minimum.

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A new sketch window should appear.

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Loading the templated code.

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Let's briefly go over these 2 functions.

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The setup function is similar to main as it is the first function to run,

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and it only runs once.

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Setup is used for defining which pins will be input or output.

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For example, this would be a great place to tell the Arduino that we want to output

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some electrical current over to pin number 13.

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Loop is a function that runs continuously on the microcontroller.

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Ever wonder why your alarm clock never stops?

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It's because most of the microcontrollers will loop through their program.

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In our current circuit this would be a great place to tell the Arduino that we want to make

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our light blink forever.

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So in pseudocode it would be something like turn light on, delay n seconds, turn light off,

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delay n seconds.

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>> Well instead of writing out that code we're just going to cheat. Just this time.

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This is actually already a code template for a blinking LED saved in our examples.

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To load it go to file, examples, choose number 1 basics, and choose blink.

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What happens here is that a new sketch window should appear with some code already inside.

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Inside of the setups body there is an Arduino helper function called pinMode.

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PinMode prepares the pin to be used.

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It accepts 2 parameters.

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First the IO pin number, which is the pin you want to utilize,

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and second, a value declaring whether the pin is used for input from the circuit

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constant value of INPUT in all capitals, or output to the circut,

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which is a constant value OUTPUT in all capitals.

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Inside of the loop there are 2 additional Arduino helper functions,

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digialWrite accepting 2 parameters and delay accepting 1 parameter.

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DigialWrite is used to interact with the pin that you configured using pinMode.

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>> The first argument is the pin number that you are interacting with.

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The second argument is a constant that is either high, meaning full voltage,

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or low, meaning no voltage.

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The second helper function is delay

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which will stop the code from running based on the amount of time in milliseconds.

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Remember 1 second is equal to 1,000 milliseconds.

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Based on our walkthrough we can deduce that if our circuit was set up correctly

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our LED should turn on and stay lit for 1 second and turn off and stay off for 1 second

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before turning it back on.

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This should repeat forever as it is currently in the loop function.

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Let's choose the upload to board button and find out.

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>> Great. So you might be wondering what's next.

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Well now that you have an understanding of everything that is needed to create

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an Arduino circuit, we can start applying knowledge gained from our lectures in CS50

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to sharpen our skills further.

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For example, what if I didn't want to use the Arduino loop function?

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What if instead I wanted to write my own type of loops and conditions

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or even create my own functions outside of the bare minimum?

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What if I wanted to play music or build a burglar alarm

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or even contact the internet with my Arduino?

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The answers to those questions are coming. So stick around.

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>> I'm Christoper Bartholomew. This is CS50.