Arduino Capacitive Touch Sensing!

what's up you guys welcome back to the Master Tech and in today's video I'm going to show you how to use capacitive touch with Arduino [Music] so capacitive touch is a pretty cool Concept in electrical engineering and electronics and it's very similar to how a lot of smartphone and smart screen technology Works we've covered what capacitors do on the channel in past Arduino videos but just to recap a capacitor is an electrical component that stores a small amount of electrical charge that can be used to smooth out electrical signals and so capacitive touch with Arduino is actually saying you are being used as the capacitor so your body is storing a small amount of electrical charge and that's how capacitive touch works so in total the hardware that you'll need for this project is just two LEDs two 220 kilo ohm resistors one Mega ohm resistor about six or seven jumper wires A breadboard your Arduino and obviously a Serial cable to communicate with the computer now let's zoom in and take a look at the physical build for this project go ahead and start the physical build by connecting your Arduino ground pin to the ground rail on one power rail of your board next let's hook up the LEDs and we're going to put our 220 ohm resistors in line with the negative leg of both diodes remember that the negative leg on LEDs is typically the shorter leg now let's hook the power leg up the positive lead of both our LEDs to digital pins 12 and 13 on your Arduino board I'm using 12 and 13. you can use any digital pins that you want now let's hook up our capacitive sensor and for this just put your one Mega ohm resistor on the board connect one leg of the resistor to pin two of the Arduino board and the other leg to pin 4 of your Arduino board for these pins one is going to be the transmitter and one is going to be the receiver that we use to detect how long before the two stabilize then on the other side of the pin 2 leg of the resistor hook up your capacitive sensor wire and don't hook the other end of this to anything since this is what will be touching and making contact with when we look at the sketch of the project and that's it for the physical build you can hold off on plugging your board into the computer until we've written the code which we'll do in this next step alright so let's take a look at the programming for this project it's quite straightforward but let's go through it together to make sure everyone's on the same page the capacitive sensor library that we're going to use is free and open source but it's not included by default with the Arduino IDE so go to sketch go to include library and then go to manage libraries and just type in capacitive sensor okay and the one that we'll be using is by Paul Badger Paul stofgren it's uh it's recommended by the Arduino official Arduino beginner projects book and just install that there's a big button right there for install and then once you've done that you can go back into your code and you can use this pound sign include capacitivesensor.h and that's going to give you access to the capacitive sensor library then we need to set up an instance of capacitive sensor and say what two pins we want to use as our sensor and the first pin we put in is going to send the charge and the second pin we put in is going to sense the charge since we put our sensor pin on the same leg of the resistor as a pin two we are going to use pin 2 as our sensor and pin 4 as our sender if you were to move the capacitive sensor wire that we put on pin 2 over to pin 4 then you would want that to be second here then for now you can use the same two threshold lines that I have of 1400 and 300 if you want or you can hold off until we actually boot this project up and start seeing what the different values are for your sensor basically what I found is it's darn close to zero when not nothing is touching that wire if you let it lightly rest on your finger it can go anywhere between like 500 and 1000 and then when you squeeze it it's usually like fifteen hundred to two thousand so I found these to be good thresholds for light touch and then firm touch but feel free to play around with these as we get into the testing phase of this build now our two LEDs are on pin 12 and pin 13 so just set those up in the beginning as well and then in the setup loop we're just going to open the serial connection because we know we want to read what our sensor is reading and then we're going to set both of our LED pins up as outputs now in the loop section of the code we're going to use a long version of the sensor value variable that we're creating to sense what the capacitive sensor is detecting and this value is how many readings you want it to take 30 is a good intermediate because if you don't read enough then you're going to start getting wide variance in your sensor but if you read too many data points here you're going to start getting a really long lag so again feel free to experiment with this number but 30 is a really nice medium value for taking enough sense sensor value readings that you're going to get a fairly smooth reading but it's not going to slow your program down too much and then we're going to print to the serial window this sensor value and what we want to do now is control the LED pins based off of our sensor value so if it's greater than that first threshold let's turn our first LED pin on and that's what we're saying our firm pin uh our threshold our higher threshold was just threshold one and that's going to be our firm squeeze so we'll turn that first LED pin on if we break the threshold otherwise turn that LED pin off and then the same exact if else statement for LED pin 2 just now based off threshold 2 which is a lower threshold so that's our green light our light touch threshold and then put a small delay in here so that the program has a little time to actually respond and react this is just 10 milliseconds it's not a long delay and it just means your sensor has a reasonable amount of time to adjust to actual field data okay and so uh this is all you need you can find a link to this code in the description of the video below or you can go to file examples uh and then in the starter kit basic kit p13 touch sensor lamp is very close to this all you need to do is add threshold to an LED pin 2 to your program so that you get two sensors because that only has one uh LED in it by default go ahead and locate your Arduino board from the drop down hit upload as long as you don't get any errors saying that something was done wrong it'll say successful it'll show you how much the memory it used and now we can check out what's happening with our board so right away when you power it on you should notice that your communication lights start lighting up but your LEDs don't immediately turn on if you have an LED turned on right away then your thresholds you used in the code might be a little too low so you can tweak those but let's take a look at what happens when I lightly rest the PIN on my finger hopefully if you set the good thresholds up your green light should be on pretty consistently and your red light shouldn't come on until we go ahead and give it a good squeeze and when you give it a good squeeze what you should see on your serial monitor on your screen is that you start getting much higher values than when the wire is just resting on your finger this is because when you're squeezing it you're you're actually storing quite a bit more electricity because you're able to make a better connection but when it's just resting on your finger you have a light connection so you're not storing as much capacitive energy feel free to play around with the thresholds until you start getting really good numbers where you're able to make the both lights turn off when you're not making contact the green light on when you're making light contact and the red light on when you're making firm contact if you want try connecting this capacitive sensor pin to a piece of tin foil or any other surface and see how that changes the values you get through your capacitive sensor okay guys that is going to do it for 10 today's video on capacitive touch using Arduino if you have any questions about what you saw here or something you want to see in a Future video just let me know about in the comments below I'll get back to you as soon as I can and you might see that content in a future video all the hardware and the pieces that I used in this video can be found in the Arduino starter kit that I'll leave a link to in the description of this video if you need any of those pieces check it out if you love the content we're producing on the Channel please consider becoming a patreon Super supporter of the channel at the link below as well as always good luck with your projects thanks for watching until next time bye