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

Custom-Note-LED-Input-Element-Callback

This example demonstrates how to attach custom actions to incoming Note or Control Change MIDI events.

Boards: 🛈

AVR, AVR USB, Due, Nano 33 IoT, Nano 33 BLE, UNO R4, Pi Pico, Teensy 3.x

Connections

• Pin 3 (PWM pin): An LED (with current-limiting resistor) to ground.

Behavior

If a MIDI Note On event for note 0x3C (C4 or middle C) is sent, the LED will light up at full brightness, if a Note Off event for that note is sent, the LED will light dimly.
(A Note On event with a velocity of zero also counts as a Note Off event.)

Mapping

Route the MIDI output of a MIDI keyboard to the Arduino's MIDI input. Then play a middle C on the keyboard.

Written by PieterP, 2020-03-10
https://github.com/tttapa/Control-Surface

 
#include <Control_Surface.h> // Include the Control Surface library
 
// Instantiate a MIDI over USB interface.
USBMIDI_Interface midi;
 
// MIDI Input Element that listens for MIDI Note events that turns on the LED at
// full brightness if the note value (velocity) is above the threshold,
// and turns on the LED at a lower brightness if the value is below the
// threshold.
 
class CustomNoteLED
  // First, inherit from the MatchingMIDIInputElement base class. Indicate that
  // you want to listen to MIDI Note events by specifying the MIDI message type,
  // and use a simple 2-byte message matcher, since MIDI Note events have two
  // data bytes.
  : public MatchingMIDIInputElement<MIDIMessageType::NoteOn,
                                    TwoByteMIDIMatcher> {
 public:
  // Constructor
  CustomNoteLED(pin_t ledPin, MIDIAddress address, uint8_t lowBrightness)
    : MatchingMIDIInputElement(address), ledPin(ledPin),
      lowBrightness(lowBrightness) {}
 
  // Called once upon initialization, set up the pin mode for the LED,
  // and output the initial value.
  void begin() override {
    ExtIO::pinMode(ledPin, OUTPUT);
    ExtIO::analogWrite(ledPin, lowBrightness);
  }
 
  // 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(TwoByteMIDIMatcher::Result match) override {
    if (match.value >= threshold)
      ExtIO::digitalWrite(ledPin, HIGH);
    else
      ExtIO::analogWrite(ledPin, lowBrightness);
  }
 
  // Called when the input element is reset (e.g. by an "All notes off" MIDI
  // event).
  void reset() override { ExtIO::analogWrite(ledPin, lowBrightness); }
 
 private:
  pin_t ledPin;
  uint8_t lowBrightness;
  const static uint8_t threshold = 0x01;
};
 
// Instantiate the LED that will light up when middle C is playing.
CustomNoteLED led {
  3,                             // Pin with the LED connected (PWM capable)
  {MIDI_Notes::C[4], Channel_1}, // Note C4 on MIDI channel 1
  10,                            // Intensity when off
};
 
void setup() {
  Control_Surface.begin(); // Initialize Control Surface
}
 
void loop() {
  Control_Surface.loop(); // Update the Control Surface
}