Pushbuttons and LEDs with Arduino. Using Digital (On/Off) Inputs and Outputs

what's up you guys welcome back to the channel in today's video we are going to build the Arduino beginner project called spaceship interface it's a cool name for a cool beginner project with some great electronics and programming Concepts so let's get right into it [Music] so this project builds right off the first Arduino tutorial video we just rolled out on the channel I'll leave a link to the playlist of the Arduino videos in the description of this video and a card to it somewhere in the top of the video right now as well the kit we're using in these initial few projects is the Arduino starter kit I got it from Amazon and I will put a link to it in the description section of this video if you'd like to get the same kit to follow along with all these projects exactly in the first video I show you how to get everything set up initially so we dive right into the concepts in this project assuming you've got the programming software on your computer and your board and breadboard all set up and ready to go so we built a very basic circuit in our first tutorial and to summarize it we provided a 5 volt power supply from our Arduino through a 220 Ohm resistor into a push button switch then through to an LED and finally back to ground via the Arduino board again check out the previous video if you need a deep dive into what's happening in this circuit and before we get into the spaceship interface it's time for a quick sciency lesson thing lesson thing so everything in an electrical circuit exists in either parallel or in series with the components around it things in series can be considered what a programmer would call an and command while everything stacks on top of each other while something in parallel can be viewed as an or command where there's basically a branch and you can do either option to look at the circuit we already built let's take a look at how we would add a second push button to this circuit once in series and once in parallel to add a second push button here we are adding it in series meaning that for the LED to get turned on AKA for electricity to get to the LED from our power supply we need this push button to be pressed and this push button to be pressed the conditions are additive and there is no other combination of these switches other than both being pressed that will lead to the LED lighting up however if we add a second push button to the Circuit here we we are now adding it in parallel to the first switch that means by pressing this switch or this switch we provide a valid flow path for electricity to make it to the LED both parallel and series circuits have different rules for calculating current resistance and voltage using Ohm's law but that's a discussion for a future lesson that's it for this quick sciencey lesson thing all right so this project is called the spaceship interface because the overall look and concept of the project is meant to replicate the special effects of a classic 70 eras sci-fi spaceship control board in the first configuration we build we're going to use three LEDs one that will be on the whole time our control button is not pressed and then when we press the control button the other two lights will alternate flashing between and the first light will turn off this will be our first project reading physical input signals into our Arduino board and controlling outputs based on those signals let's start by taking a look at what the code for this project object is going to look like so as always in an Arduino project often typically referred to as a sketch the two main areas for putting functional code are the setup area which executes once at the beginning of your code and the loop area where a code that you want to run continuously goes for this project we are also going to create a global variable before those two areas to keep track of the state of our control push button do this by creating a line of code where we Define a variable that'll be an integer using int give it a descriptive variable name in this case switch State and an optional but good step to add is give the variable an initial state in this case we'll use zero then in the setup region of your program Define which pins you're going to use for physical inputs and outputs in your build because the digital pins on arduinos can be used as inputs or outputs you need to tell your board which way you want to use them in this case we have one push button as an input in our project and we're going to control the state of three LEDs as outputs therefore we'll Define pin mode 2 as an input so we can hook our push button up to that pin and we'll make pin mode 3 4 and 5 all outputs to control our three LEDs if you build your programming first it's very important to make sure you keep your PIN definitions in mind as you build the physical circuit likewise if you build the physical circuit first it's very important to keep an eye on where you hooked everything up when you write your code so next let's take a look at what to put in the loop region of the sketch first thing we will do in every Loop is check the state of the push button switch we do this simply by setting our Global variable switch State equal to the status of the input on pin 2. this requires the simple command digital read followed by the pin you want to read from in this case pin 2. this means we can create a simple if else piece of code to determine what to do with our outputs based on the state of our push button now stored in the switch State variable first if the switch state is low meaning button not pressed we want the green light to turn on so we'll use the simple command digital right to tell our green light to turn on this requires giving digital right to arguments first we tell it what pin to write to in this case three for the green light then what value to write to that pin in this case hi to turn it on now use the same command line for Pins four and five but this time write a command low to turn off our two red lights while the button is not pressed this is everything we want to have happen while the button is not pressed now let's take a look at what to do if the button is pressed because with digital Boolean points the only two states are on or off so just else is all we need to say to put commands in for while the button is pressed so the first line is going to be the most direct and easy because all we're going to say is that we want the green led to turn off the whole time the button is pressed similar to before we're just writing a value of low to pin three now let's take a look at what we're going to do to command the red lights when the button is initially pressed we'll turn one light on and another light off while it's just two identical red lights which one we turn on and off doesn't really matter too much so I'll just say pin for off in pin 5 on initially then to incorporate alternating flashing lights put a delay into your code and hold those States for a defined duration the delay command uses units of milliseconds so we'll use 250 or one quarter of a second as a default value after the delay of 250 milliseconds we'll flip the states of pins four and five then add another 250 millisecond delay in total this reads as while the button is pressed and held in flip the states of my two red lights every quarter second back and forth this is the whole project so go ahead and verify it to make sure there's no errors with your build and then if you have your Arduino plugged in you can go ahead and upload the build to the controller you could also wait to upload until we built the circuit because as always we should build the circuit with the board disconnected from power now let's check out the physical circuit build for this project you'll need your Arduino board and your breadboard and a few jumper wires and in addition to those you'll need two red LED lights a green LED light a push button switch three 220 ohm resistors and one 10 kilo Ohm resistor start by putting 5 volt power and ground connections to one of your breadboard's power rails this gives that entire column of terminals power and ground properties respectively next run a jumper wire from the respective pins for your three LEDs to the long leg or anode of that led then connect the short leg also known as the cathode to one leg of a 220 ohm resistor and then connect the other leg of the resistor to ground for this circuit the pins that act as outputs will serve as the power supplies to the lights when they're commanded to be on AKA High next hook up the push button as follows on one leg of the push button switch provide a power feed then on the other side of that switch connect the leg to one leg of the 10 kilo Ohm resistor connect the other leg of that resistor to ground this resistor in this case is known as a pull down resistor because it'll Ensure sure that that leg of the switch reads Low when the push button is not pressed the final step in the push button circuit is placing a connection from Arduino pin 2 which is our input to the downstream leg of the switch now that's it for building this circuit and the time has now come to put it all together and enjoy the project if you haven't uploaded the project to your Arduino board yet go ahead plug it into your computer and upload now once the project is loaded and the board is powered on you should have your LEDs in their default states of green light on both red lights off now try pressing and holding the push button switches and you should start to see the red lights flashing and the green light go off there are a lot of great ways to expand and play around with this project for example one of my favorites is to make the three lights run in a sequential order while the button's not pressed and then do a pattern of blinks in increasing speed when you press the button to kind of simulate a launch sequence already with this simple build in this simple project there are so many variations and creative ways to make it your own and these base basic concepts we've learned here of digital inputs and outputs should get you thinking about what kind of real world applications can I take and use these sorts of projects for so that's as far as we'll be going today we covered a ton of content in this video hopefully nothing left you too confused or overwhelmed if you have any questions about anything you saw here today be sure to let me know about in the comments below and I'll get back to you as soon as I can all the viewers on the master attack in the Master Tech Community have been really amazing and been encouraging me to become a better engineer and continue trying new things if you guys want to help me do bigger and better robotics projects on the channel consider becoming a patreon supporter at the link in the comments below and everyone who hits that like button subscribes to the channel Rings the little notification Bell will get instant Good Vibes delivered directly to their doorstep for free thanks and until next time as always good luck with your projects and thanks for watching [Music]