The Heatmap plugin provides a LED effect, that displays a heatmap on the keyboard. The LEDs under each key will have a color according to how much use they see. Fewer used keys will have deep blue colors, that gradually turns lighter, then green, to yellow, and finally red for the most used keys. The heatmap is not updated on every key press, but periodically. It’s precision is also an approximation, and not a hundred percent exact. Nevertheless, it is a reasonable estimate.

Using the plugin

The plugin comes with reasonable defaults pre-configured, all one needs to do is include the header, and make sure the plugin is in use:

#include <Kaleidoscope.h>
#include <Kaleidoscope-LEDControl.h>
#include <Kaleidoscope-Heatmap.h>

static const cRGB heat_colors[] PROGMEM = {
  {  0,   0,   0}, // black
  {255,  25,  25}, // blue
  { 25, 255,  25}, // green
  { 25,  25, 255}  // red


void setup() {
  Kaleidoscope.setup ();

  HeatmapEffect.heat_colors = heat_colors;
  HeatmapEffect.heat_colors_length = 4;

This sets up the heatmap to update every second (by default). It also registers a new LED effect, which means that if you have not set up any other effects, then Heatmap will likely be the default. You may not want that, so setting up at least one other LED effect, such as LEDOff is highly recommended.

Plugin methods

The plugin provides a HeatmapEffect object, which has the following methods and properties:


When called, immediately activates the Heatmap effect. Mostly useful in the setup() method of the Sketch, or in macros that are meant to switch to the heatmap effect, no matter where we are in the list.


The number of milliseconds to wait between updating the heatmap. Updating the heatmap incurs a significant performance penalty, and should not be done too often. Doing it too rarely, on the other hand, make it much less useful. One has to strike a reasonable balance.

Defaults to 1000.


A cRGB array describing the gradian of colors that will be used, from colder to hoter keys. E.g. with heat_colors = {{100, 0,  0}, {0, 100,  0}, {0,  0, 100}}, a key with a temperature of 0.8 (0=coldest, 1=hotest), will end up with a color {0, 40, 60}.

Defaults to {{0, 0, 0}, {25, 255, 25}, {25, 255, 255}, {25, 25, 255}} (black, green, yellow, red)


Length of the heat_colors array.

Defaults to 4


Further reading

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