Custom-Note-LED-Input-Element-Callback-FastLED.ino

Custom-Note-LED-Input-Element-Callback-FastLED

This example demonstrates how to attach custom callbacks to Note or Control Change MIDI Input Elements.

Boards: 🛈

AVR, AVR USB, Nano 33 IoT, Teensy 3.x, ESP32

Connections

• Pin 2: The data pin of a Neopixel LED strip with (at least) 8 LEDs

Behavior

If a MIDI Note On event for note 0x3C (C4 or middle C) is sent, its velocity value sets the red value of the first LED, note 0x3D controls the green value of the first LED, note 0x3E controls the blue value of the first LED, note 0x3F controls the red value of the second LED, 0x40 controls the green value of the second LED, etc.

Mapping

Route the MIDI output of a MIDI keyboard to the Arduino's MIDI input. Then play some notes in the two octaves above middle C.
Alternatively, map it in you DAW, for example, in VirtualDJ:
<color notered="0x3C" notegreen="0x3D" noteblue="0x3E" ... />

Written by PieterP, 2020-03-12
https://github.com/tttapa/Control-Surface

 
#include <FastLED.h>
// Include FastLED before Control Surface
#include <Control_Surface.h> // Include the Control Surface library
 
// Instantiate a MIDI over USB interface.
USBMIDI_Interface midi;
 
// Custom MIDI Input Element to handle incoming note events and control the LEDs.
template <uint8_t RangeLen>
class CustomNoteLED : public MatchingMIDIInputElement<MIDIMessageType::NoteOn,
                                                      TwoByteRangeMIDIMatcher> {
 public:
  // Constructor
  CustomNoteLED(CRGB *ledcolors, MIDIAddress address)
    : MatchingMIDIInputElement<MIDIMessageType::NoteOn,
                               TwoByteRangeMIDIMatcher>({address, RangeLen}),
      ledcolors(ledcolors) {}
 
  // Called once upon initialization.
  void begin() override {}
 
  // Called when an incoming MIDI Note message matches this element's matcher
  // (i.e. it has the right MIDI address, channel and cable).
  // The match object that's passed as a parameter contains the velocity value
  // of the Note message that matched.
  void handleUpdate(typename TwoByteRangeMIDIMatcher::Result match) override {
    updateLED(match.index, match.value);
  }
 
  // Called each time a MIDI message is received and an LED has to be updated.
  void updateLED(uint8_t index, uint8_t value) {
    uint8_t ledIndex = index / 3;
    uint8_t colorIndex = index % 3; // 0 = R, 1 = G, 2 = B
    // Update the LED color
    ledcolors[ledIndex][colorIndex] = value;
    dirty = true;
  }
 
  // Check if the colors changed since the last time the dirty flag was cleared.
  bool getDirty() const { return dirty; }
  // Clear the dirty flag.
  void clearDirty() { dirty = false; }
 
 private:
  // Pointer to array of FastLED color values for the LEDs
  CRGB *ledcolors;
  // Should the LEDs be updated by FastLED?
  bool dirty = true;
};
 
// Define the array of leds.
Array<CRGB, 8> leds {};
// The data pin with the strip connected.
constexpr uint8_t ledpin = 2;
 
// Create a MIDI input element that listens to all notes in the range C4 - B5
// (the range starts at C4 and has a length equal to `leds.length * 3` == 24).
// Note C4 is the red channel of the first LED,
// Note C#4 is the green channel of the first LED,
// Note D4 is the blue channel of the first LED,
// Note D#4 is the red channel of the second LED, etc.
CustomNoteLED<leds.length * 3> midiled {leds.data, MIDI_Notes::C[4]};
 
void setup() {
  // See FastLED examples and documentation for more information.
  FastLED.addLeds<NEOPIXEL, ledpin>(leds.data, leds.length);
  FastLED.setCorrection(TypicalPixelString);
  FastLED.setBrightness(128);
  Control_Surface.begin();
}
 
void loop() {
  Control_Surface.loop();
  if (midiled.getDirty()) {
    FastLED.show();
    midiled.clearDirty();
  }
}