If you ever wanted a key that works like keys on old cell phones, when you press a key and it cycles through a number of options in a sequence, then the cycling key is what you are looking for. It is a bit different than on cell phones of old, as it is a separate key, that works in combination of other keys: you press a key, then the cycle key, and the cycle key will replace the previously input symbol with another. Keep tapping the cycle key, and it will replace symbols with new ones, in a loop.

Using the plugin

To use the plugin, we need to include the header, and declare the behaviour used. Then, we need to place a cycle key or two on the keymap. And finally, we need to implement the cycleAction function that gets called each time the cycling key triggers.

#include <Kaleidoscope-Cycle.h>

// Somewhere in the keymap:

// later in the Sketch:
void cycleAction(Key previous_key, uint8_t cycle_count) {
  bool is_shifted = previous_key.getFlags() & SHIFT_HELD;
  if (previous_key.getKeyCode() == Key_A.getKeyCode() && is_shifted)
      cycleThrough (LSHIFT(Key_A), LSHIFT(Key_B), LSHIFT(Key_C));
  if (previous_key.getKeyCode() == Key_A.getKeyCode() && !is_shifted)
      cycleThrough (Key_A, Key_B, Key_C);


void setup() {

Keymap markup


The key code for the cycle key. There can be as many of this on the keymap, as many one wants, but they all behave the same. There is little point in having more than one on each side.

Plugin methods

The plugin provides a Cycle object, but to implement the actions, we need to define a function (cycleAction) outside of the object. A handler, of sorts. The object also provides a helper method to replace the previous symbol with another. The plugin also provides one macro that is particularly useful, and in most cases, should be used over the .replace() method explained below.


Cycles through all the possibilities given in keys (starting from the beginning once it reached the end). This should be used from the cycleAction function, once it is determined what sequence to cycle through.

To make the cycling loop complete, the first element of the keys list should be the one that - when followed by the Cycle key - triggers the action.


Deletes the previous symbol (by sending a Backspace), and inputs the new one. This is used by cycleThrough() above, behind the scenes.

The recommended method is to use the macro, but in special circumstances, this function can be of direct use as well.

Overrideable methods

cycleAction(previous_key, cycle_count)

The heart and soul of the plugin, that must be defined in the Sketch. It will be called whenever the cycling key triggers, and the two arguments are the last key pressed (not counting repeated taps of the cycling key itself), and the number of times the cycling key has been pressed.

It is up to us to decide what to do, and when. But the most common - and expected - action is to call cycleThrough() with a different sequence for each key we want to use together with the cycling key.


Further reading

Starting from the example is the recommended way of getting started with the plugin.