How to use a Rotary Encoder with an Arduino - CODE EXPLAINED!

In this video we will have a look at rotary encoders and in particular go through a robust and reliable code for the Arduino.

The code in the video can be downloaded here:

Make sure that the pins used to connect the rotary encoder to support interrupts. See:

[colr]

I came here just to figure out how to hook up a Rotary Encoder, but I got so much more! Thank you for this excellent tutorial!

[mrdrgonzo]

Whoever worked out the coding for increasing and decreasing is a genius

[BenjaminParisi-ob]

I thought I had a pot, but instead I had a rotary encoder! You have unblocked my project with this helpful video. :) Thanks

[thomawhite]

I know this is a little late in the game, but I thought this may help someone. I loaded your code onto an ESP32 DevKit1C. Used pin 14 as A and 15 as B. Worked well except that: (1) the first turn of the knob did not register (counter did not change) and (2) after any change of direction, the first turn did not register. The code I downloaded from github has a few "static" declarations under the "read_encoder" function. The first is: "static uint8_t old_AB = 3; // Lookup table index 3". I changed "uint8_t old_AB = 3" to "uint8_t old_AB = 4" and the problem on my ESP32 is now solved. To the author. Thank you so much for a great piece of code. Brilliant!

[sophtware]

This is still by far the best code for handling rotary encoders that are a little noisy. This code works flawlessly every time I use it. Thanks for sharing and posting this video.

[jesenzeng]

thank you sir, Your video is the clearest one to explain the encoder state machine(the lookup table)，I modified the code a little bit, When a tick check failed because of a large number of noise.Assume the enc value has been added to 2. If next turn direction was CCW, the enc value would be changed like 2-->1-->0-->-1, The counter value won't change even enc value changed 4 times, Your code clears the enc value to zero only when it>3 or <-3, So the tick check will fail when enc value is not 0 due to last failed tick check, So I add a clear operation by adding a out time variable if there's no turnning action，After that the code works very nice, thanks again!

[valked]

Finally! Finally I found someone who clearly explain it! Thanks so much!

[trailranger]

Thanks for this video. I've been concentrating on becoming more fluent with encoders and steppers lately, and you've explained somethings that I haven't run across before. This is a very clear, concise and informational video. You have gained a subscriber 🙂

[brendanbarbour]

Hi Mo...that code is very responsive and reliable. I may need to adjust the multiplier value for the fast rotation, but that should be straightforward. I plan on using this as part of a precision AC current Trip. I'm using a Current Transformer to sense the current, which drives a Precision Rectifier and a comparator. I'm using an MCP4725 12-Bit DAC to set the reference for the Comparator. The falling-edge of the comparator output, triggers a D-FF which drives a DPDT relay to isolate the supply being monitored. Keep up the good work and thank you.

[tedwaetford]

I have a bunch of different encoders I am using to build a flight sim avionics panel. I was using some button box code I found on the internet, and the encoders were not behaving as expected. Specifically some of them only triggered every second click. Testing the encoders as you detail here, I found that some of them don't behave as the one in your example. A and B both alternate low, high, low... for subsequents rest positions. So using your LED test, at the rest positions, the lights go on, off, on... not just off. So I have a mixture of encoder types, X2 and X1 or X4, not sure which. Now I need to figure out how to adapt this code to cater for the different types. Be useful if these types were mentioned in this video. Great video, I am new to this stuff and your video was the most comprehensive explanation I have found for a newbie like me.

[stefanwinkler]

Excellent video Sir, very well explained, a real pleasure to watch. I will use your code for a stepper motor driven indexing head. However there is a tiny flaw: If you turn the knob really fast, you may end in a state where encval is +2 / -2 in the rest position and you need two clicks backward/forward to decrease/increase the counter by one. Just set old_AB = 3 after abs(encval) >= 4 to get bullet proof code 🙂

[requiemadreamc]

It works flawlessly. I tried different codes but they didn't work properly. Your code works perfect. Thanks :)

[PostalPete]

This is the only code that worked perfectly. All others I found on the internet for me only worked 80% correctly...

[ottosteehouder]

Very helpful, I nearly gave up on my encoder but this works remarkably well. I need an position on a positional axis and previous designs struggled with all kinds of misreading's.
Thank you for a very good explanation aswell.

[clarkso]

Great! You explained everything in detail. Thanks so much

[SamuelKreyenbuehl]

Thanks for sharing the information! ❤
Really helpful for my project I’m working on at the moment

[airdedman]

Great video, and very clear instructions. 😊

[MarioPToledo]

I dunno what to do! Im just using a rotary with the atmega328p chip, and then I make the pull up resistor circuit + filters but the values still bounce any time.

[FGRFPV]

Just wondering, maybe it's clearly stated and I'm just not getting it right now: What happens, if the user would change the direction mid-click? As in after 2 Statechanges he returns back to the starting point instead of completing the click? Thank you for the nice work, it helps a lot!

[PostalPete]

Interesting, I have a large rotary encoder on small PCB with 5 pins and with the LED test it behaves exactly as the one in this video. However, one of the mouse scroll wheel rotary encoders (Huano S-10 from Amazon) LED 1 lights up, then LED 2 (both are now lit), and then they both go out at the same time. In the other direction it's like: both are lit, LED 2 goes out, LED 1 goes out. Weird. I wonder if I can modify this code to work with this particular rotary encoder, as I am trying to save space in my project and not use one of the larger encoders.