How to Read Analog Input Signals Into An Arduino! Temperature Sensing 'Love-O-Meter' Project!

welcome back to the Master Tech and in today's video we're going to learn how to read from analog inputs with the Arduino by recreating the classic and only slightly cringy lovometer it's a funny name but it represents a cool beginner project using temperature sensing to light up an increasing number of LEDs based on heat [Music] so this project builds right off the first two Arduino tutorials we just did on the channel leave a link to the playlist in the description of this video and a card at the top of the window right now the kit we're using in these initial few projects is the official Arduino starter kit I got it from Amazon I'll put a link to it in the description if you'd like to get the same kit follow along exactly for this project I'm assuming you have the programming software installed and your Arduino and breadboard ready to go this will be our first project reading from a varying range sensor called an analog input so for this project in addition to your Arduino and a breadboard you'll need some jumper wires a TMP 36 temperature sensor four 220 ohm resistors and some LEDs before we dive into the physical circuit build we're going to take a look at a quick sciency lesson thing lesson thing so one of the very most common electrical components is a resistor virtually every electrical circuit that does anything useful or interesting needs a lot of these but if you know what resistor you need how do you know that you have the right resistor the numbers aren't exactly printed on them well the system is based on the total number of bands on the resistor they have either four five or six bands or strips of color on them let's start with the four band rules the first two bands are your tens place and your ones place each band has a value of zero to nine using an almost rainbow scale that you may just want to memorize and you can kind of think of it as the rainbow plus neutrals the third band is the multiplier which uses a very similar number code and can be thought of 10 to this power the fourth and final band on these is tolerance which has a few common ratings the rules for the Five band resistors are exactly the same except now you can have a three digit number so you have a hundreds place tens place in one's place and the multiplier intolerance bands stay with the same rule six band resistors have no difference in bands one through five but the sixth band is an additional temperature coefficient which just tells you how much change in resistance you should expect when the temperature changes there are other weird less common scenarios out there but this hits the most common ones quick sciency lesson thing alright so this project is called the love omitor and the Arduino beginner project manual because there was a corny old school line of arcade games where you would hold metal poles with your hands and a certain number of Lights would light up to say how romantic you were although most of the time it was actually just measuring how warm your hands are and this project we'll be taking that basic concept and remaking it with our Arduino although if you have cold hands our project won't condemn you to a life of loneliness being a computer nerd has a good chance of doing that on its own so in this video we're going to take a look at the physical build of the electrical components first and then the code for the project second let me know in the comments if you like this order or think code first is a better way of doing it so let's start this circuit build by choosing a digital pin for each LED in my build I'll use two three four and five normally skip zero and one because these pins also correlate with reading and writing through serial connections so if you have the space elsewhere it's better to use those hook the long leg AKA anode of each led up to the digital ping connection then put a 220 Ohm resistor from the short leg or cathode through to ground this is it for the Loops that we'll need to control our lights from our Arduino so now let's check out the temperature sensor Loop a quick online search for our tmp36 temperature sensor component will yield the spec sheet for it also known as a data sheet this will tell you a little bit about how the component works as well as its sensing range and how to wire it up for the tmp36 to follow along with my project have the flat side face the Arduino and rounded side away from it put voltage on the top pin ground on the bottom pin and a signal wire jumper from the middle pin back to channel a0 on the Arduino just understand the pins are not interchangeable so you do need to put positive voltage and ground on the proper pins or your sensor won't work then connect your power rail to the 5 volt and ground pins of the Arduino so this is actually it for the physical build we have a series of four LEDs here that we will turn on in order as the temperature sensor reads progressively hotter now let's take a look at what our Arduino program or sketch is going to look like start by defining a couple variables right at the top of your program first an integer called sensor pin will we will store which pin we have the temperature sensor hooked up to in this case a0 second create a float called Baseline temp that you'll Define to be approximately room temperature in this case I'm using 18.5 Celsius or 65 Fahrenheit and you can play around with this a bit later now in the setup Loop which runs once at the beginning of your program's initialization use the command serial begin followed by 9600. this 9600 is known as the baud rate and is how many bits of data are transferred between the Arduino and PLC per second this command is required if we want to see what the temperature sensor is reading while connected to our computer next set up a for Loop to tell all our LED pins in this case two through five that they'll be outputs and initially off a c plus for Loop requires an index or variable defined with an initial value in this case pin number equals two then the condition for how many times to iterate through the loop in this case as long as the pin number is still less than six and then what we want to do to the index variable after each iteration of the loop in this case add 1 to the pin number value shown by the plus plus command then inside this for Loop all we have to do is set the pin mode of each number to Output and then digital write each pin number and off or low command initially now let's take a look at what to put in our Loop area of the program which is the section that runs over and over again while our Arduino is powered start by reading the raw value from our sensor pin into an integer variable we'll call sensor valve using the command analog read and then give it the PIN to read from which we stored in the variable sensor pit to display what this raw value is on our computer use the command serial dot print and start by just giving it some text to tell us the value that we're seeing in this case it's the raw unscaled reading so we'll just say sensor value then add a second serial print command where we print the actual value add a delay of just one millisecond underneath the serial.print to make sure the speed at which the readings come in is manageable if you were to upload this project right now it wouldn't control your lights at all other than turning them off but if you open the serial monitor which is the magnifying glass over some dots icon in the top right window of your Arduino IDE you should see a constant stream of the text sensor value followed by the raw reading somewhere around 130 to 150 depending on how warm your room is now if you touch the temperature sensor or breathe some hot air onto it you should see the value go up this raw value is not in terms of units of voltage or degrees yet and to take a look at how to turn this raw value into useful system data let's jump back into our program we'll calculate the voltage and temperature the sensor is reading next Arduino analog input channels read a range of 0 to 5 volts over a raw signal value of 0 to 1024 which correlates to a 10 bit integer therefore to get voltage as a float variable divide our raw signal by 1024 and multiply by 5. then set up another two serial print commands to show voltage right next to the raw value lastly to get the actual temperature which is what we really want we want to check the TMP 36 data sheet it tells us it has a minimum temperature reading of negative 50 degrees Celsius at 0 volts and that for every 10 millivolts or 0.01 volts of signal increase that represents a real world 1 degree celsius increase of temperature this means to convert from volts to degrees Celsius subtract 0.5 from volts and then multiply by a hundred throw in two more serial prints so that we can get the temperature readings right next to voltage and raw and now let's take a look at how to actually use this value basically if we're chilling at around Baseline temperature we'll say within 1.5 degrees of Baseline let's have all our lights off we'll do this by writing digital write commands low to all of our LEDs now as temperature increases each 1.5 degrees Celsius span up from there let's turn on One LED at a time so for my program using a baseline of 18.5 we'll set up if else commands for each scenario above 20 will give us just the blue light above 21.5 will give us blue and green rain above 23 will add yellow in there and then above 24.5 we'll have all our lights on including red this gives us a pretty good sensing range but you can play around with these spans as much as you want change your Baseline temperature and choose temperatures that are fun for you now let's upload this program and see what we get your board will probably initially have no lights on or maybe just the blue since that's around the ambient room temperature and if you keep an eye on your serial monitor in your Arduino IDE you can see the temperature and how it's corresponding to the lights that are on try putting a finger on the sensor and you should see the temperatures start creeping up and lights turning on every time you hit that 1.5 degree increase now if you have clammy hands or you're just a cold fish and you can't get all the way up with a finger try lowering the Baseline temperature or breathing some hot air onto the sensor feel free to play around with this circuit and find creative new ways to use the LEDs to interact with our sense temperature and that's going to be as far as we build out this project today if you have any questions about anything you saw here today be sure to let me know about them in the comments below and I will get back to you as soon as I can if you guys want to help me do bigger and more complex projects in the future consider becoming a Super supporter of my Channel at my patreon link in the description of this video as well hit that like button subscribe button ring the notification button click any other buttons you can find and until next time good luck with your projects and thanks for watching [Music]