How to Use Arduino Interrupts The Easy Way

Have you ever wanted to take advantage of Arduino hardware and software interrupts but didn't know how? In this tutorial, I'll show you the basics of using an Arduino's interrupts the easy way - quickly setting up the pins and handling events with just a few lines of code. Implementing software or hardware interrupts can open up a world of possibilities for your robotic creations - adding an extra layer of sophistication that takes your Arduino project to the next level. So dive in and let's discover how we can harness the power of Arduino interrupts for our own projects!
Arduino Interrupts Tutorial with Code ▶︎ racheldebarros.com/how-to-use...
Download TimerOne Library: playground.arduino.cc/Code/Ti...
Video Chapters:
0:00 Intro
1:04 Example Without Interrupts
7:26 Hardware Interrupts
20:00 Software Interrupts (with TimerOne library)
31:54 Wrap Up
Build & Code Along:
🛒 Arduino Uno or Clone: amzn.to/3MdxwRt
🛒 Breadboard: amzn.to/3MgbzkG
🛒 Jumper Wires: amzn.to/473kmON
🛒 LEDs: amzn.to/3FvqV0U
🛒 330 Ohm Resistors (or resistor kit): amzn.to/46TEZgm
🛒 Push Button: amzn.to/45IuETs
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#arduinotutorial #arduinointerrupts #arduino #interrupts

[@jdoedoenet]

You are one fantastic teacher! I am a former HP engineer (long ago!) and have finally reached a place in life where I can do this sort of thing just for fun. Your videos are immensely helpful and entertaining to boot. Absolute goldmine. Thanks for all that you do!

[@ZothiamaCF]

5 minutes in to the video and I've already clicked the subscribe and like buttons. This is how all tutorials should be made. You are a most awesome teacher.

[@Nemecys]

Exactly what this guy said - sooooooooooo beautifully explained :)

[@danielb8197]

ditto

[@user-xt8on4kf5o]

For real :)

[@ScreamingTurtleRacing]

Easily the best Arduino tutorials I’ve seen on KZbin. I came for the interrupts, but I will definitely be watching more. A refreshing change from the usual content. Thank you!

[@edgarbonet1]

Very nice tutorial! I would just suggest a few corrections: 1. The Arduino Uno has no software interrupts, although they can be simulated by writing to an interrupt pin configured as output. The timers are hardware devices, and the timer interrupts are hardware interrupts. 2. The first parameter of attachInterrupt() is an “external interrupt” number. This is not the same as an interrupt vector number. FWIW, external interrupt number 0 is interrupt vector 2 (see the ATmega328P datasheet). 3. Only variables shared between ISR and regular code need to be volatile. In the example you give, buttonState should be local to the ISR, and doesn't need to be volatile. 4. Using millis() within an ISR is perfectly fine. You should not, however, expect millis() to get updated within the ISR, as it gets “frozen” when the interrupt is triggered.

[@aardito215]

Great video, you explained this so well! I've spent hours looking at other videos on timers and interrupts which just confused me. I'm just getting back into Arduino programming after a 5-year break, and this was a huge help with the project I'm working on.

[@oscareriksson9414]

Really good, straight to the point and simple. Exactly what I need for my projects

[@kentharris7427]

I built a demonstration of a perpetual motion machine as my first project using an Arduino. "Perpetual Motion Machine?" The Arduino is very flexible and can even work with a power supply that is a half bridge rectifier. Looking forward to your next video.

[@shirleysharrock7204]

Your descriptions are clear and enjoyable to watch. I didn’t yawn at all and no urge to nap which is common with the monotone streams I have endured. Showing the pitfalls and showing the process . Thank you for your stream.

[@RachelDeBarrosLive]

I have also napped through many explanations 🤣

[@surenbono6063]

..i like the flow of this tuturial...its like a sketch itself...it delivers you from darkness to light...

[@jtodora]

EXCELLENT description of using interrupts. Very Good!!!

[@miachristensen5444]

This is so incredibly easy to understand and paced at such a great rate! Thanks for the amazing video! Can't wait to learn more from you =)

[@RachelDeBarrosLive]

Glad it was helpful! Let me know if you want me to cover any topics and I'll put it in rotation.

[@vladimirastrelin1719]

What an amazing lesson! Very clear ! Just a pure pleasure to listen, watch and follow your instructions. Thank you very much !

[@JumbleLane]

This is brilliant, for a 65 year old to finally understand how interupts work. Your upbeat way of describing how it works is just fantastic. I can now implement this in a few of my projects and also see if I can find information on doing a similar thing with the ESP32 to improve some of those projects. Thanks Rachel, I will certainly go through your videos and also subscribe. Regards, Geoff.

[@joemechanic2751]

I'm new to Arduino but not new to programming, so I'm glad I found this channel. Most other sites for Arduino channels for newbies assume you know zero about programming and are unwatchable.

[@acousvnt]

It's refreshing to hear code explained with such enthusiasm!

[@zuzukouzina-original]

You have a gift to explain it very clear and simple. Thank you 🙏🏼

[@PammyStevensonEquest]

Great video. Might be worth mentioning a while loop with small 1ms delay as a non interrupt solution on the way to the interrupt solution. Also an internal timer is a hardware interrupt, software interrupts are generated directly by the microprocessor when it needs system tasks done - memory management, errors, crashes, etc

[@KenanYusufTemel]

You are well prepared, so good at teaching and fun to watch. Thank you for making it possible to watch without getting bored.

[@grahamnichols1416]

Great video. Rachel's infectious enthusiasm had me hitting subscribe right away.

[@indikaudayasaranga988]

Your knowledge is excellent. Thank you for sharing. Big Hats off.

[@stevehamann9624]

I think the best explanation for interrups on youtube👍🏼

[@sanJorgeRM]

Very usefull explanations! Ty very much. Blessings from Spain 🇪🇸

[@Richardson_Valakyr]

Im learning english and also Arduino... i found both here you are amazing... Thanks!!!!

[@anthonysullivan851]

I have to confirm previous comments, you are a great teacher and the best and demonstrating Arduino IDE.

[@guidovlaere]

Thanks from the Netherlands 🇳🇱 for your super tutorial! Your videos are very helpfull! 😊

[@75mechanic]

Wow great video. Well presented. Easy to understand. Learning arduino and found this excellent.

[@bullitthead7853]

I'm new to arduino and programming. I thought that this video was fantastic, thank you. Liked and subscribed!

[@tonyparakka4038]

Thank you! So nicely explained!

[@nawnifari]

Cool.. arduino beginner should watch this.. I'm sharing it to classmate..

[@sennabullet]

Thank you for this video. I really appreciate your enthusiasm!

[@warsteelcalgarus5790]

This was awesome. Going to check out the rest of your Arduino vids. Thank you so much for posting this. Really appreciate it =)

[@RachelDeBarrosLive]

Thanks! Let me know if you'd like to see any specific topics.

[@ConzKlips]

interrupting my viewing to say this: Amazing, so clear and helping so much. Not even finished the video yet and its already heaps helpful, thanks!

[@RachelDeBarrosLive]

I'm glad to hear the vid is helping you out! Let me know if you'd like me to cover any other topics!

[@aaronfrye1195]

Thank you for this very inspiring and informative video.

[@onebeartoe]

This was really well explained!

[@nityamaheshwari8259]

i watch so may videos on google related to interrupt , but your lecture is amazing, i understand all the concept very clearythanku so much , for a grt video😁😁

[@RachelDeBarrosLive]

Glad you enjoyed it! Let me know if you want to see any other topics.

[@husky-nu3xk]

Best explanation ever. Thx Rachel

[@nexpro6985]

Pretty good explanation of ISR, thanks. Maybe the pin names should be constants not variables. They are not going to change. const int BLUE_LED = 11; LOW and HI are constants also hence uppercase.

[@ABaumstumpf]

"LOW and HI are constants also hence uppercase." Kinda,... not... they are defines.

[@hamradio3716]

Wow, what a great teacher. So enthusiastic!. Good examples. Now I can fix some broken ISRs that use sleep.

[@jstampfl]

Great video. Enjoyable and informative.

[@rhandynastor4866]

thanks for this. Very nice explanation

[@andybp840c]

I almost want to duplicate the previous comment excellent explanation so pleased I found this channel Thank you

[@SusanAmberBruce]

Very well explained and helps a lot of thanks.

[@autotuneengineering]

Great video!, thank you .

[@ms070965]

Very Well explained. Thx a lot

[@ChaplainDaveSparks]

I love this video for two different reasons: I haven’t programmed interrupts in ages. If I’m not mistaken, it was on a Z-80 back in the 80s. Rachel reminds me so much of someone we lost, also in the 80s: *_Karen Carpenter!_* Similar voice, facial expressions, and body language.

[@EditingApprentice]

Great video !!

[@rayleblanc7209]

I remote controlled a 10 HP Craftsman track drive snow blower using a 10 channel Flysky and mega 2560. I learned Arduino coding just to build the project. I use all 10 channels to operate the servos, motors and actuators. I was able to get everything to work without using any interrupts. I'm sure my code is far from perfect, but surprisingly I got everything to function.

[@MettaZen]

Good video :) You're clear in your explanations. Here are some video ideas. Id love to see a video about threading or on some more basic stuff like interpretation of the pinouts, how to look to get to know how a new component works (what things to look into)... Stuff that give users more independance

[@hanvanderveeken904]

love your energy and enthousiasm ;-)

[@zambonni]

You are my new favorite teacher

[@khanqaiserster]

You are a wonderful teacher of embedded systems. Your style is very nice otherwise it's a very dry subject

[@RachelDeBarrosLive]

I have fun doing these. Writing the code is like telling a story of what you want to see happen in order from beginning to end.

[@arliewinters2776]

Good Teacher ! Easy on the eyes too ☺

[@arliewinters2776]

My problem is, when I should be looking at the code, I'm looking elsewhere...!

[@mazharkhaliq1971]

Thank you, it is a well informed video 😊.

[@RachelDeBarrosLive]

You're welcome 😊

[@user-lk4bq5uk9v]

The world's best Queen teacher thanks

[@RachelDeBarrosLive]

Glad you enjoyed it! Let me know if there's any topics you'd like me to cover.

[@jaynewman6420]

I agree with the ones saying that you are a great instructor. I'm also retired, but I'm making and programming robots.

[@ProfessorOzone]

As I watched this video, I thought to myself, I know this person from somewhere, but from where? So I googled and OF COURSE, it was All Girls Garage! I'm a car guy too. I don't know how a marketing person gets into Arduino code, but I'm really glad you did because you explained it in a way I can understand. What I'm doing is simple and you explained very nicely how to do it simply. Thank you for this.

[@paulmcmahon7899]

Thank you for this. My project involves LaRa radios remotely located, so this is a big boost in being able to run the remote processes while waiting to receive a transmission. One difference from your video. When I run your sketch, exactly copied, RED flashes four times, the BLUE flashes, but twice, in opposite synch to RED. Then red flashes twice more, then blue-red twice, etc. I've played with the delay and the microseonds. Seems as though the ISR runs twice every 1/10 second. I'd like to test LoRa for data receipt in the interrupt and do pass the incoming data to the loop. It may not matter, but thought I'd ask since my results differ. Thank you again.

[@tenfriskydingos]

Awesome video thanks! Ive been having trouble reading the pulses from an old school rotary dialer using just debouncing, I think this will do the trick for me though!

[@rjm842]

Thank you for this very, very helpful tutorial! it wooooorrrrrrrkkkssssss :)

[@8867348]

Wow, you are so much fun. I don't know how far I will get with this arduino stuff. I'm 52 and originally just wanted to build an led cube but somehow got off into this coding. It's very interesting but having a difficult time retaining what I learn. I don't get to spend as much time on it as I would like to. You did a very good job explaining in your video and I completely understand but, 3 days from now I'll be like "how did that lady do that?". Lol, maybe I'm getting in over my head.

[@arliewinters2776]

I'm 64....Not as on-point as I used to be. I've found just reading about it is not enough for me.... "doing it" keeps it fresh in my mind.

[@uricohen5463]

I looooove the way you explain

[@RachelDeBarrosLive]

I have fun doing these and learn something new every time!

[@mmgc84]

Thanks for sharing

[@stephanc7192]

Great video

[@chronobot2001]

So pretty and smart. The video was excellent !!!! Thanks for doing it.

[@RachelDeBarrosLive]

Glad you liked it! Let me know if you'd like to see any other topics.

[@tb303wpf1]

Thank you so much for this video! I had buttons on pins that were not hardware interrupts and I woumd up modifying my code in some very creative ways to simulate hardware interrupts. It worked pretty good too. Lol. Now I will remove all of that erroneous code and move the buttons to the hardware pins. I feel like such an idiot. 🤣

[@paulalmquist5683]

When you refer to a function like setup or loop or any user defined function just say its name, "setup", "loop", or whatever it is called. Do not include "void", "int", or whatever it's return type is. The return type is part of the function declaration but is not part of the name. Good presentation. Nice to see someone that is obviously enthused about the topic.

[@speakertoanimals]

saying "void setup" adds clarity because the () are not spoken. IMO saying the return type is like prepending an honorific... like, "King Charles" instead of just "Charles."

[@rollyavecilla]

Thank you.

[@ilyass_bouarasse]

That's nice ❤

[@dougcox835]

I have multiple routines that are called from the main loop which are selected by a mode variable. The interrupt works to change that mode variable but it still has to return to the main loop in order to take the next action. I would love it to just break off from whatever it was doing and back to the main loop. At least the button push registers and can be depended on. I just have to wait for the current sub to finish. I could have each sub check for a change in mode and bail but that's messy because every routing would need the same treatment. If I want to do that I might as well have each routing check the button inside the loops.

[@vinxmod793]

Very Well Done Video

[@TheUnofficialMaker]

nicely presented.

[@KeffelewAssefa]

Thank you so much.

[@laidman2007]

Thank you!

[@antoniopavanetto9891]

Excellent indeed! I've suffered while you hot swap the connections.😅

[@georgejetson4378]

Great content and thank you for posting. I’m just getting started with Arduino so your posts are very timely but I’m wondering why you declared buttonState variable inside of loop. I was taught to only declare variables once otherwise the processor wastes resources. I think your code would still work if you declared before the loop. Do you agree?😊

[@vegansynths7757]

Thanks for this! With regard to the digitalPinToInterrupt, I wasn't sure if still need to use the proprietary pin designated by the board I have with this function? I.e. if the board I have has interrupt vector 0 on pin 2, can I use pin 10 and put digitalPinToInterrupt(10)?

[@NormanNodDunbar]

digitalPinToInterrupt will return an error (-1) if called with a pin which doesn't support hardware interrupts. Unfortunately attachInterrupt will silently fail to attach your function, and nothing will work. So no, you cannot use digitalPinToInterrupt(10). Cheers, Norm. (Author of Arduino Interrupts, published by Apress)

[@MikelGarin999]

Thank you! I didn't know TimerOne library and its ease use! I think i could use it on a 16 steps MIDI sequencer i have built! Can it be used in combination with hardware interruptions? I need two hardware interrupts to control the state os two buttons.

[@KennedyMbwambo]

nice tutorial

[@insoft_uk]

I would recommend when using such things as == LOW reverse it so LOW == as it prevents mistakes like single = getting missed as a “var = const” will compile yet “const = var” will fail and you will pickup on the missing =

[@hicl5450]

Thanks for the video. May I know for button interrupt, what if the button is kept to be pressed, is there any way to disable the interrupt and warn the user to release the button, then re-install the interrupt again?

[@williamburns7336]

I JUST FOUND YOU TODAY AND LOVED YOUR VIDEO. LEARNING CAN BE BORING, BUT NOT IN YOUR VIDEOS. I'M REQUESTING MORE CODING VIDEOS, YOU HAVE TWO, AND I SEE YOU PLAY THE VIOLIN , I HAVE ONE I HAVEN'T LEARNED TO PLAY YET. JUST A COUPLE OF SUGGESTIONS, THANK YOU WILLIAM

[@RachelDeBarrosLive]

Thanks so much for the suggestions! Yep - I have more coding videos coming - mostly Arduino and coding for robots/animatronics projects. I hope you pick up the violin soon!

[@BariumCobaltNitrog3n]

No need to shout.

[@bikkies]

This is really excellent. I have recently decided to do something with the Uno I bought mumblety years ago, and the billion others (also Nanos, Pro Micros, Megas and more) that I've hoarded over the last month. My electronics knowledge is rudimentary at best and, though I started my IT career 40*mumblety years ago as a programmer, I was never much good at coding. That's why I moved towards support, networking and my beloved UNIX. It's time for me to get back into writing crap code again and this is the sort of video I need to help me do that. Now all I need to do is find out how to make my Arduinos speak COMAL or Pascal. No? No :( bah.

[@kennysmart8273]

@ Rachel De Barros, how can I use this for multiple blinking lights, say like the strobe lights on an aircraft, if I wanted to put this on a model I need them to go on in one colour then off & onto another colour, there’s 3 colours I need to use red, white & green. The white light would be constantly on too. Any help or advice would be greatly appreciated.

[@valrach7303]

i am not a native english speaker.. i kind of have a hard time understanding various dialects..so, dear mam..THANK YOU!!! Its literally the first video I can understand 😭 I am missing out a lot in school due to mental health reasons and I try to relearn all the stuff so i wont fall behind

[@murugesh9338]

Your video is amazingly clear. thanks for the effort Rachel. Timers works in UNO but not in ESP boards. can you please suggest some library like the same that workks with esp32 boards?

[@ammarlokhandwala2858]

Hello there, I was just wondering if we can assign other pins appart from 2 and 3 in arduino uno for interrupt, if we are using digitalpintointerrupt function?

[@lagossmartmeterhackathonte8928]

You are awesome

[@AmosNistrian]

Good video. I think your next video should be interrupts based on serial read messages, like if that button was on a touch screen.

[@peterkowald7092]

So you asked has anyone ever written a multitasking function without using interrupts, and the answer is yes. I developed a cooperative multitasking core for any microcontroller after has a system that was doing a ton of work and struggling to get all done within a second. It took me a good while thinking about the problem before I developed the engine (it’s very very light weight and consumes only a few hundred bytes of memory. That same system doing all the same things (and now more) runs at around 15,500 cycles a second. I have now been using it for several years and use it on very project as it eliminated more code than it uses. In fact I even use it on top of RTOS because make coding do easy. So yo answer your question .. Yes I use it commercially so I won’t release it, sadly but I have a significant competitive edge killing systems with bigger, faster and more expensive microcontrollers. Nice bright video for beginners

[@davidnichols7401]

At 3:15 you asked if anyone had figured out how to do this without interrupts. Just build a state machine into the loop() code. Let's say you want to update the button every 50 mS. {20 times a second}. You have two tasks to accomplish (update the red LED and update the button), so loop() has to run every 25 mS. In setup(), add stored_millis = millis(); {along with all the other bits.}. Inside loop() write a while loop that reads the latest value of millis() and compares it to stored_millis(), If greater than 25 mS, break out of the while loop. Next, stored_millis = latest_millis; state_counter += 1; If state_counter is odd, call Update_Red() else call Update_Blue(). In Update_Red(): increment a variable red_counter. If red_counter == 10, {25*10 = 250mS}, change the state of the Red LED and reset red_counter to 0. In Update_Blue(), make the Blue LED state equal to the button state. easy peasy.

[@edgarbonet1]

Or just follow the “Blink Without Delay” Arduino tutorial.

[@zz3709]

Great explanation, how about serial receive interrupts?

[@columbiabuzz]

Thankyou darling: this the first time I've heard about Timer1. Many examples call to timer1 when there's no evidence where it came from. Obviously, it was in the library file, but I didn't know why everyone uses TimerOne the file name, but the code is calling Timer1. It must be imbedded in the library, but it wasn't obvious to me. First I heard about 3 timers also.

[@k9slover]

Good video, informative and well explained. I have subscribed.

[@jackkylejr.1112]

I have two water level switches on a aquaculture food system. The top switch tells when the thank is full and the water pump should turn off. And the bottom switch tells when the tank is empty and the pump should turn on. But I don't know how to code for to hardware switches that are in concert with each other???? Can arduino do this??

[@terrybest3036]

Question: Is the interrupt routine being called twice each press since you used "change"? The pin is pulled up, then you press the button so it goes low and the interrupt gets called. When you release the button, is that also another change to high so it gets called again?

[@jorgelima5695]

In the hardware interrupt example, the buttonState doesn't need to be global and doesn't need to be declared as volatile because the first thing the interrupt handler does is to assign it to the return value of digitalRead() and the variable is not accessed anywhere else in the program.

[@user-cg7vx7pt1p]

Linda e inteligente! Meu sonho de consumo!

[@clementyap1009]

Cool!

[@RachelDeBarrosLive]

🥳

[@ethzero]

13:00 Regarding where to put additional functions in code, it's true that for the Arduino IDE+Compiler top or bottom is fine. However, if you're using an ESP32+Arduino Framework+PlatformIO+VScode I've found that (probably) the compiler complains about "undeclared functions" if you put them at the end, i.e. you try to call on a named function before it's seen in the code. There might be an additional parameter or something that can be parsed to the compiler, but that beyond me.

[@spudnickuk]

I have not long understood about using Millis instead of delay I have a question to ask If I have power to the Arduino And have a code programed installed Can I use a button to activate the code Meaning the code is dormant untill I press a button What I'm doing at the moment is have two LEDs blink via the Millis timing But it runs all the time so I have a button that is used as a circuit breaker and so when I press it it makes the leds connect But I would like to understand is there a way how to use a button to run the code to activate the LEDs only when the button is pressed