Patterns on LPX Novation

Use a Novation LPX controller to control MIDI devices.

Control the pad colours (normal colour and colour when the pad is pressed), individually or in groups.

Sections - Colour and Note

• Defined using sets of pads. Allows arbitrary, even discontinuous, sections
• All the pads in a section have the same properties (colours and MIDI note)
• No section can intersect with another, each pad is in at most one section
• There can be, at most, one section with no defined pads. It is the default for pads not included

Properties of a Section

• Main Colour: Each section has a main colour that is displayed when the pad is not pressed.
• Active Colour: Each section has an "active" colour. When any pad in the section is pressed (has issued an "on" but not an "off" MIDI signal) the section is the active colour.
• MIDI Note - the note to output

Two sections can have the same colours and or notes, but hey are still independant of each other.

Input

The definition of the sections is in a file that is the first argument: lpx_ctl <Section File>

It is a JSON file.

An array of JSON Objects. Each object, is a Section has the following properties:

• pads: Number[] (u8). 11 - 88. Pads in the section
• main_colour: [Number, Number, Number] ([usize;3]) RGB colour. Each in range 0-127
• active_colour: [Number, Number, Number] ([usize;3]) RGB colour. Each in range 0-127
• midi_note: The note to attach note-on and note-off MIDI events to.

Build

• Install Debian bookworm on a Raspberry Pi
• Install Rust
  • curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
• Clone this repository and its sub-module
  • git clone https://gitub.com/worik_gh/lpx_ctl --recursive
• Install Jackd2 and ALSA library develpment files
  • sudo apt install libasound2-dev libjack-jackd2-dev -y
    • Alsa is needed for lpx_ctl MIDI communication
    • Jackd is needed to run the example
• Build lpx_ctl
  • cargo build --release
• The example programmes use this MIDI sampler. This is a sub-module in lpx_ctl/example/sampler. So to use examples:

Examples

Drum Pad

This example sets up the LPX to act as ten drum pads.

It untilises two configuration files:

• examples/drum_layout.json configures lpx_ctl and defines the ten drum pads on the LPX, their main and active colours and the MIDI notes they emit
• examples/drum_samples.json configires midi_sample and associates MIDI notes with drum samples

Ensure jackd is running

In two terminals:

Change directory ot the examples/ directory. The drum samples are defined as patshs relative to the examples/ directory, so it must be the working directory

In one terminal start lpx_ctl

• ../target/release/lpx_ctl ./drum_layout.json

In the other terminal run the sample player

• sampler/target/release/midi_sample drum_samples.json