Generative Music with a ROLI Lightpad Block

I was recently gifted a ROLI Lightpad M Block, which is programmable with a language called Littlefoot. You can control the display of 15×15 pixels and behavior for sending/receiving MIDI messages based on touch and/or time. There is a challenge though: your code size is capped to just a few KB and you only get three types – int, float, and bool. While it seems other types may be in the pipeline based on recorded talks about Littlefoot, right now there are no lists/arrays or other more complex types to work with.

So, what can we do within that? Well, using only 1.2KB (16% of the total allowed according to the editor), we can get this:

All of the generation is happening on the block, which is sending MIDI on/off messages to Izotope Iris2 to produce sound.

While the generative algorithm is extremely simply, doing random exploration of a major pentatonic scale within a confined pitch range, the parameters are controllable. This is what’s going on:

  • X-axis controls the tempo
  • Y-axis controls the volume
  • The light blue square marks the current tempo/volume settings. It will move towards a touch over time – it doesn’t jump there immediately, so transitions are smooth.
  • Pressing harder controls the pitch range being explored. The square turns dark blue when this happens. While it looks binary in terms of color, it responds to varied degrees of pressure in the pitch range.
  • Individual pixels light up to make sparkles when notes are played.

Here’s the code if you have a Lightpad Block and want to give it a go.


Random Pentatonic Music for the ROLI Lightpad Block
Donya Quick

1. Press the side button to start generating.
2. Push lightly and hold to move the generative parameters (they change gradually).
3. Push harder to lower the generative range (you'll see a color change).
4. To change the root of the scale, send MIDI note on from another device to the Lightpad.

<metadata description="Random Music Machine" details="Random Pentatonic Music" target="Lightpad" tags="Controller;MIDI"  canEmbedModes="false">

        <variable name="channel" displayName="MIDI Channel" type="int" min="1" max="16" value="1" displayMode="stepper" tooltip="The MIDI channel that values are sent on" />


int millis; // last time we generated something
int milliThresh; // timer setting that will change based on X position
float lastTouchX; // last X touch position
float lastTouchY; // last Y touch position
float centerX; // last center of the generative setting (may differ from last touch)
float centerY; // last center of the generative setting (may differ from last touch)
bool fillMiddle; // whether tof ill the middle of the generative setting indicator
int lastRandPitch; // last pitch played
bool play; // are we generating? Default is false
int root; // scale root - you can change it by sending MIDI note on events to the block
int range; // lower end of the range, which responds to Z-axis (pressure)
bool push; // whether the pressure is enough that the range should change

// API function called on start
void initialise()
    millis = getMillisecondCounter();
    for (int i = 0; i < 32; ++i)
        setLocalConfigActiveState (i, false, false);
    lastTouchX = 1;
    lastTouchY = 1;
    lastRandPitch = -1; // negative means no pitch

// What to do when the user pushes on the device
void handleTouch(int index, float x, float y, float z) {
    if (index==1) {
        centerX = x;
        centerY = y;
        if (abs(x-lastTouchX)<0.02)
            lastTouchX = x;
        else if (x > lastTouchX)
            lastTouchX += 0.02;
        else if (x < lastTouchX)
            lastTouchX -= 0.02;
        if (abs(y-lastTouchY)<0.02)
            lastTouchY = y;
        else if (y > lastTouchY)
            lastTouchY += 0.02;
        else if (y < lastTouchY)
            lastTouchY -= 0.02;
        if (z>=0.5) {
            range = -int(70*(z-0.5));
            push = true;
        } else {
            push = false;

// API function called at the onset of a touch series
void touchStart (int index, float x, float y, float z, float vz)
    if (index==1) {
        fillMiddle = true;

// API function called whenever the touch moves
void touchMove (int index, float x, float y, float z, float vz)
    if (index==1) {

// API function called whenever the touch series ends
void touchEnd (int index, float x, float y, float z, float vz)
    if (index==1) {
        fillMiddle = false;

// API function called on each update
void repaint()
    blendRect(0x20000000, 0, 0, 15, 15);
    milliThresh = 500-int(500*lastTouchX/2);
    if (millis<10) {
      millis = 10;  
    if(play) {

// what to draw each frame
void drawTouch() {
    if (lastTouchX >= 0 && lastTouchY >=0) {
        int x = int(lastTouchX*7);
        int y = int(lastTouchY*7);
        int x2 = int(centerX*7);
        int y2 = int(centerY*7);
        int edgeColor = 0x00FFFF;
        if (push)
            edgeColor = 0x0000FF;
        blendRect(0x40000000, x,y,2,2);
        if (fillMiddle)
            fillRect(0xFFFF00, x2,y2,2,2);

// given a random number, fit it to major pentatonic with a particular root
int fitMajorPenta(int root, int inValue) {
    int v = inValue%12;
    int retVal = inValue;
    if (v==(root+1)%12 || v==(root+3)%12 || v==(root+6)%12 || v==(root+8)%12 || v==(root+10)%12)
        retVal = retVal+1;
    v = retVal%12;
    if (v==(root+5)%12)
    if (v==(root+11)%12)
    return retVal;

// API function called when the side button is pushed
void handleButtonDown (int index) {
    play = !play;
    if (!play && lastRandPitch>=0) // if we stop playing and played a pitch...
        sendNoteOff(channel,lastRandPitch,0); // we better turn it off!

// API function called when the block receives a MIDI message from an external device
void handleMIDI(int b0, int b1, int b2) {
    int type = b0 & 0xF0;
    int chan = b0 & 0x0F;
    if (type==144) // note on check
        root = b1%12;

// Make it pretty when a note is generated by lighting up a pixel
void paintSpeckles() {
    int t = getMillisecondCounter(); // what time is it now?
    if (t - millis >= milliThresh) { // have we waited long enough to generate a new note?
        millis = t; // record the current time
        int color = getRandomInt(0xFFFFFF); // pick a random color
        fillPixel(color, getRandomInt(15), getRandomInt(15)); // light it up!
        if (lastRandPitch>=0) // did we play a pitch previously?
            sendNoteOff(channel,lastRandPitch,0); // if yes, then we need to turn it off
        lastRandPitch = fitMajorPenta(root, getRandomInt(30)+70+range); // calculate a new pitch
        int vol = 27+100-int(100*lastTouchY/2); // volume is based on Y axis
        sendNoteOn(channel,lastRandPitch,vol); // play the note

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