{"id":40,"date":"2019-04-05T16:59:32","date_gmt":"2019-04-05T16:59:32","guid":{"rendered":"https:\/\/openlab.bmcc.cuny.edu\/mmp460\/?page_id=40"},"modified":"2020-10-11T20:31:19","modified_gmt":"2020-10-11T20:31:19","slug":"physical-computing","status":"publish","type":"page","link":"https:\/\/openlab.bmcc.cuny.edu\/mmp460-1100\/physical-computing\/","title":{"rendered":"Physical Computing"},"content":{"rendered":"

What is physical computing?<\/strong><\/h2>\n

Physical computing refers to the process of building physical interfaces that respond to the analog world. This is done by building circuits with micro controllers, wires, sensors, LEDs, motors etc. and controlling them with a piece of custom-made software (i.e: \u201cTurn the LED on when the number sent by the photocell sensor is less than 100\u201d). Physical computing is a great way of introducing or reinforcing programming concepts, and exploring how they can be applied to non-screenbased applications. But it has also been used beyond the educational realm \u2013 by artists<\/a>, to support ALS patients<\/a>, for immersive installations<\/a>, experimental music<\/a>, fashion<\/a>, and\u00a0to test water quality.<\/a><\/p>\n

While there are a lot of similarities between robotics and physical computing, the latter is focused on creating interfaces that explore the human body\u2019s relationship to the digital world (rather than building robots that can function without human or environmental input).<\/p>\n

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\u201cArduino with CdS & LED\u201d by yoggy0. License: CC BY 2.0<\/figcaption><\/figure>\n
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Using a Microcontroller<\/h1>\n<\/header>\n
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What\u2019s a Microcontroller?<\/h2>\n

A microcontroller is a small computer that can take in information from inputs such as sensors and switches and control outputs such as lights, motors and other computers. Microcontrollers are widely used in many different ways; DIY and robotics, art installations, industrial applications, and the internet of things.<\/p>\n

When you are using a microcontroller, or in our case a microcontroller platform, there are two components: hardware and software. The hardware includes the microcontoller and its input and output pins, and any input or output devices you want to attach to it. The software is programs you write that control the microcontroller and the devices you have attached to it.<\/p>\n

In this class we will be using the Arduino microcontroller platform. It was developed by a team of teachers to help their design students who were not engineers create physical interfaces.<\/p>\n

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The Arduino has an IDE, (integrated development environment), that is free and downloadable from the Arduino site (download it here<\/a>). This is a set of software that allows you to write code, then upload it directly to the Arduino.<\/p>\n

Arduino Uno<\/h3>\n

There are many different versions of the Arduino but we will be using just one, the Arduino Uno.<\/p>\n

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In order to program the Arduino, download the Arduino IDE and install it (detailed instructions on downloading and installing are here<\/a>). The laptops we have in our Maker Space already have the software installed. Connect the Arduino to the computer with a USB A-B cable. If you have a newer Macintosh laptop, you will have to use an USB-C to USB adapter.<\/p>\n<\/div>\n

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Parts of an Arduino Uno<\/h3>\n

Let\u2019s look a bit more closely to the parts of the Arduino. We\u2019ll look at the left side first.<\/p>\n

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Reset Button:<\/b> This button will restart the code currently uploaded on your Arduino. The reset button may be in a different location on your board than in this diagram, but it is the only button.<\/p>\n

USB Port:<\/b> The USB port takes a standard A-to-B USB cable, often seen on printers or other computer peripherals. The USB port serves two purposes: First, it is the cable connection to a computer which allows you to program the board. The USB cord will also provide power for the Arduino if you\u2019re not using the power port (described below).<\/p>\n

Voltage Regulator:<\/b> The voltage regulator converts power plugged into the power port (described below) into the 5 volts and 1 amp standard used by the Arduino. BE CAREFUL! This component gets very hot.<\/p>\n

Power Port:<\/b> The power port includes a barrel-style connector which allows for either power straight from a wall source or from a battery. This power is used instead of the USB cable. The Arduino can take a wide range of voltages (5V \u2013 20V) but will be damaged if power higher than that is connected.<\/p>\n

Now let\u2019s look at the rest of the board.<\/p>\n

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Built-in LEDs:<\/b> The LEDS indicate that there is power, and if your Arduino is sending or receiving data.<\/p>\n

Digital I\/O pins:<\/b> The holes on this side of the board are called the digital input\/output pins They are used to either sense the outside world (input) or control lights, sounds, or motors (output).<\/p>\n

TX\/RX pins:<\/b> Pin 0 and Pin 1 are special pins labeled TX and RX. They control how information is transmitted to and from a computer. It is best not to use them empty.<\/p>\n

ATmega328P, black chip:<\/b> The black chip in the middle of the board is an ATmega328P. This is the \u201cbrains\u201d of the Arduino: it interprets both the inputs \/ outputs and the programming code uploaded onto your Arduino.<\/p>\n

Power and ground pins:<\/b> All of the pins related to power are located here. You can use these pins to run power from your Arduino to your breadboard circuit.<\/p>\n

Analog pins:<\/b> These pins take sensor readings in a range of values (analog), rather than just sending whether something is just on or off (digital).<\/p>\n

Settings in the software<\/h3>\n

We have seen a bit about the parts of the Arduino and we have seen that we program it through the Arduino software. Before we start programming the Arduino, we have to set a couple of settings in the software to ensure that the Arduino can communicate with your computer.<\/p>\n

Load the Arduino software. Once it is loaded, go to the To do this, go to the Tools<\/b> menu, select Board<\/b>. From the fly out menu, select Arduino Uno\/Genuino<\/b>.<\/p>\n

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It is also necessary to specify a Serial Port for your Arduino to communicate with the computer. A Port is a channel of communication which connects your Arduino and the computer. On a Windows machine, go to the Tools Menu, select Port then select the COM port that is specified. It should look something like the screenshot below.<\/p>\n

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Once you have connected the Arduino to the computer and set the version and the port, you are ready to start programming the Arduino.<\/p>\n

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Programming the Arduino<\/h1>\n<\/header>\n
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As we have seen, the Arduino IDE<\/a> is free and can be downloaded from their site. Detailed instructions for installing and configuring the IDE can be found here<\/a>.<\/p>\n

What\u2019s an IDE?<\/h3>\n

An IDE, or integrated development environment, is a software application that allows you to write code and test that code out in the programming language the IDE supports.<\/p>\n

If you have experience programming, you may have used another IDE to write, test, debug, and turn your code into something the computer understands. If you haven\u2019t, the Arduino IDE is a good place to start, as it is relatively simple and easy to understand.<\/p>\n

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The Arduino team has designed an IDE for use with their devices that has the features you need. It has a built-in code editor, which is a program used to write the code files that you create when programming. You can test your code in the IDE and solve problems with the help of a message area that shows errors in your code and a console that provides more detail about the nature of these errors. It has buttons so you can check your code, save it, create a new code window, upload it to your Arduino and more.<\/p>\n

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The sketch<\/h3>\n

In the Arduino IDE, your program is called a sketch<\/b>. The sketch is the basic unit of Arduino programming. The Arduino IDE supplies example sketches, that cover many of the things you can do with an Arduino. Let\u2019s open, save, then upload a simple sketch called Blink.<\/p>\n

First, connect your computer to the Arduino with a USB A-B cable. Open up the Arduino IDE. When it is open, go to the File Menu > Examples > 01.Basics > Blink. This will open up the Blink Sketch<\/b>.<\/p>\n

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Let\u2019s take a look at the buttons in the IDE, at the top of the sketch. The verify button checks your code for errors, the Upload button sends your code to the Arduino, New creates a new code window, Open opens a previously saved sketch and Save saves your sketch.<\/p>\n

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Here\u2019s a screenshot of the Blink sketch, with the three main sections annotated.<\/p>\n

Comments<\/b> are used to write notes to anyone who might read your code. This might be you, when you return to a sketch you created earlier, or others who you are sharing your code with. Comments have no effect whatsoever on how the computer interprets the text and are only there to remind you or clue someone else in on what you intended to do, or how the program functions as a whole.<\/p>\n

The setup()<\/b> function is where you set initial conditions for your code. setup() happens only one time, when you run the code or turn on your Arduino.<\/p>\n

The loop()<\/b> function is where you put code that you want to run over and over again.This is generally where all of your code that creates functionality lives. We will see, for example in the Blink sketch, the code that turns the LED on and off is here.<\/p>\n

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Save and rename the sketch!<\/h3>\n

After you\u2019ve taken a look at the Blink Sketch, save it and give it a new name. File Menu > Save As > MyBlink for example. You don\u2019t want to write over the example files and also you want to make adjustments to the example file to understand how the code is working. Saving early and often is always a good practice.<\/p>\n

Verify and Upload<\/h3>\n

Let\u2019s verify the sketch, then upload to the Arduino. Click the Verify button to check your code. Even though this is an example sketch, it is good to get in the habit of checking your code. There will be a message in the bottom of the window that tells you a bit of information about your sketch. If there was a problem, it would also note it here. After verifying, you can upload your code, Make sure your Arduino is attached to the computer and that you have configured it properly. Then press the upload button. The LED on the Arduino near pin 13 should start blinking on and off.<\/p>\n

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setup() and loop(): the guts of the code<\/h3>\n

Now let\u2019s look a bit closer at setup() and loop(). We have seen that setup happens once and loop happens over and over again.<\/p>\n

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Inside of the setup()<\/code> function, there is a line of instructions to the Arduino. It tells the Arduino to set the pin on the Arduino that is attached to the built-in LED on the board to be an output. In other words, pinMode()<\/code> tells the Arduino to set LED_BUILTIN<\/code> (pin 13 on the Arduino Uno) to be an OUTPUT<\/code>.<\/p>\n

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If we look at loop()<\/code>, we see several more lines of instructions inside the function, These lines of code are what is turning the LED at pin 13 on and off. digitalWrite()<\/code> sets LED_BUILTIN<\/code> to HIGH<\/code>, turning on the LED. delay()<\/code> pauses the Arduino for 1000<\/code> milliseconds, or one second. The next line, digitalWrite()<\/code>, sets the LED_BUILTIN<\/code> LOW<\/code>, or turns off the LED. This is followed by another delay()<\/code>, which pauses the Arduino for 1000<\/code> or one second.<\/p>\n

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Try adjusting the amount of time that the LED is on and off. How do do that? Create a new pattern, perhaps a short time on, a long time off, a long time on. How would you do an SOS signal?<\/p>\n

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Building a circuit<\/h1>\n<\/header>\n
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The circuit is the basic building block for any electronics project. A circuit includes all of the electronic components required for a task as well as wires or another material which will let the electricity flow between the connected components. Electronic circuits describe a complete and closed loop.<\/p>\n

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There are two main parts that make up a circuit: conductive lines and components.What are\u00a0 components? LEDs, transistors, resistors, diodes, and all of the parts that control the flow of electricity or have another function in our circuit. Conductive lines are often metal threads or wires, as metal is a good conductor of electricity.<\/p>\n

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The Breadboard<\/h3>\n

Components are often attached to each other on a solderless breadboard<\/strong>. What\u2019s that?\u00a0 A solderless breadboard has rows and columns of metal strips encased in plastic with a grid of holes called tie-points on the top. It allows us to quickly build circuits without having to permanently connect the components (by soldering, for example). Here\u2019s an \u201cx-ray view\u201d of a breadboard.<\/p>\n

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There is a pattern to how the metal strips are arranged on a breadboard. There are long strips along the left and right of many breadboards that are used to attach power and ground in a circuit. These long columns are called busses. The power bus is marked with a red plus sign, the ground bus with a green, blue or black minus sign.<\/p>\n

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This drawing shows how components are attached on a breadboard; the leads of the components are in the same row of tie-points.<\/p>\n

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Connecting the breadboard to an Arduino<\/h3>\n

How do you connect a breadboard to an Arduino to build a circuit? Let\u2019s build a circuit that connects a breadboard with an LED and a resistor to an Arduino.<\/p>\n

You will need these parts:<\/p>\n