The rotary encoder is an electro-mechanical switch. Its output signal can be used to determine the direction that its knob is being rotated. Not only that, but it is also capable of continuous rotation, unlike a regular potentiometer.

In this guide, learn to connect it to a micro:bit and program it using the MakeCode editor.

After completing this guide, you will understand the basics in using a rotary encoder. It has wide applications from robotics to computer input.
    • Let's take a closer look at the rotary encoder module. It has five pins:

      Encoder Pin 1 (CLK)

      Encoder Pin 2(DT)

      Switch (SW)

      3.3V  : This pin on the module is labelled '+'. We'll connect the VCC pin to 3.3V on the micro:bit

      GND: In electronics, we define a point in a circuit to be a kind of zero volts or 0V reference point, on which to base all other voltage measurements. This point is called  ground or GND.

    • Voltage is the difference in potential between two points. As it is difficult to talk about voltage without a reference point, we need another point to compare it to. 

    • Please use the M-F jumper wires included in the kit to connect this module to the breadboard.

    • First, open up MakeCode editor and start a new project. We will need to download the KY-040 package for the rotary encoder module to work.  So click on the 'Advanced' tab

    • Click on 'Extensions' tab

    • Type 'KY-040' in the search bar

    • Click on 'rotary-encoder-KY-040' library and it will be added to the MakeCode editor

  1. RotaryEncoder.onRotateEvent(RotationDirection.Left, function () {
    RotaryEncoder.onRotateEvent(RotationDirection.Right, function () {
    RotaryEncoder.init(Pins.P2, Pins.P1, Pins.P0)
    • Copy and paste this code into the Javascript interface.

  2. let Num = 0
    RotaryEncoder.onRotateEvent(RotationDirection.Right, function () {
        Num += 0 + 5
    RotaryEncoder.onRotateEvent(RotationDirection.Left, function () {
        Num += 0 - 5
    RotaryEncoder.init(Pins.P2, Pins.P1, Pins.P0)
    basic.forever(function () {
    • Replace the code with this in the Javascript interface

    • What happens:

      • Minus 5 from the variable, 'Num,' each time the rotary encoder is rotated left
      • Add 5 to the variable, 'Num' each time the rotary encoder is rotated right

    • Connect the micro:bit to your computer using a microUSB cable

    • Click on the 'Download' button in MakeCode editor

    • Open up Finder on the Mac OSX or if you are using Windows, open up Windows explorer. Find the downloaded hex file in your Downloads folder

    • Drag and drop this hex file to the MICRO:BIT drive

    • The micro:bit will flash as the code is being uploaded.Now, if you turn the rotary encoder knob, the number will change and display on the micro:bit's LED matrix!