TODO

new version with less memory usage to avoid sound issues testing to switch waveform on the fly adding menu etc..

AccordinaMIDI

Journal de developpement ici
Dev Journal in french here

Presentation

This project is the last version (V5) of my Accordion Mechanical Keyboard

Powered by a teensy 4.1.

We use MIDI protocol and MOZZI library

Most of the code is a reuse of my previous version of Accordion Mechanical Keyboard

This version is very faster than the previous one thanks to the teensy.

I have tested it with 5 envelopes at the same time (work only with three with the arduino MEGA)

Goal

This project is a mechanical keyboard simulating a concertina keyboard.
Working both as a Synth and in MIDI.
Polyphonic (5 sound at a time now)

Electronic

TODO : Post a tutorial to make your own PCB
this project work with :

• 37 mechanical keyboards switchs (36 on the keyboard and one for the push/pull)
• 128*64 Oled screen
• Encoder
• jack 3.5 input
• micro usb input

Code

Menu

1. General
   • Octave (MIDI and Synth)
2. MIDI
   • Classic midi keyboard + 6 drones
   • Drum midi keyboard
3. Synth
   • Polyphonic keyboard + Envelope for drones (2 oscillators each)
   • Waveform for all oscillators
   • Waveform for all oscillators
   • Octave for all oscillators
   • Attack for all oscillators

Main.cpp

TODO : Translate all code in english and cleanup var names

MOZZI where the magic happen

I will not explain all mozzi stuff that you can find here https://sensorium.github.io/Mozzi/
MOZZI is working with tabs of oscillators value there is two functions

• UpdateAudio who manage sound output
• UpdateControl who manage control of the sound

Setup

#define POLYPHONY 4 // Number of sound that can be played at the same time (theme)

// Array of ADSR envelopes matching with 2 array of oscilators
ADSR <CONTROL_RATE, AUDIO_RATE> envelope[POLYPHONY]; 
Oscil<COS2048_NUM_CELLS, AUDIO_RATE> oscil1[POLYPHONY] = Oscil<COS2048_NUM_CELLS, AUDIO_RATE> (COS2048_DATA);
Oscil<COS2048_NUM_CELLS, AUDIO_RATE> oscil2[POLYPHONY] = Oscil<COS2048_NUM_CELLS, AUDIO_RATE> (COS2048_DATA);

// One ADSR envelope matching 2 oscillators for drones  
ADSR <CONTROL_RATE, AUDIO_RATE> envelopeBourdon; 
Oscil <COS2048_NUM_CELLS, AUDIO_RATE> bourdon1(COS2048_DATA);
Oscil <COS2048_NUM_CELLS, AUDIO_RATE> bourdon2(COS2048_DATA);

int notesPlaying[POLYPHONY]; // Tab to count how many notes are playing simultaneously

Update audio

Some magical byte shifting (MOZZI documentation is not clear about that but this look working)

int updateAudio(){
  long note = 0;
  for (byte i = 0; i < POLYPHONY; i++){
    long newNote = 0;
    // For each note we compute ( envelope x (oscil1 + oscil2))
    newNote = (long)envelope[i].next() * (oscil1[i].next()+oscil2[i].next());
    note = note + newNote;
  }
  // Magical byte shifting incoming !!!!
  note = note >> (POLYPHONY+7);
  return note;
  // Soon had to add drones
  // int16_t noteBourdon =  (int16_t)envelopeBourdon.next() * (bourdon1.next()+bourdon2.next()) >>8;
  // return (note + noteBourdon)>>2;
}

Update control

Used to manage envelope noteOn noteOff things.

void updateControl();

all that stuff is launched by audioHook(); in the main loop

MIDI another kind of magic

MIDI functions are very easy to understand.

This version of Teensy is recognized by windows as a MIDI device !

functions that emulate expected behaviors:

// Synth
static int noteSynthBourdon(uint8_t sens_soufflet, uint8_t index, Configuration conf);
static int noteSynth(uint8_t sens_soufflet, uint8_t index, Configuration conf);
// MIDI
static void noteMidiBourdon(uint8_t index, Configuration conf, int velocity);
static void noteMidi(uint8_t sens_soufflet, uint8_t index, Configuration conf, int velocity);
static void noteMidiDrum(uint8_t index, int velocity);

function to play notes

// Synth
static void noteOnSynth(int frequence, Configuration conf);
static void noteOffSynth(int frequence);
static void noteOnBourdonSynth(int frequence, Configuration conf);
// MIDI
static void noteOn(int noteToPlay, Configuration conf, int velocity, int index);
static void noteOff(int noteToShutdown, Configuration conf);

Display and Menu management

Display display = Display(I2C_ADDRESS); // Instanciate a Display object, used to display everything

display.maindisplay(0, mode, mode_midi, menuActiveItem, conf); // in setup to initialize display

static void menuSelector(Display d){
  encoder.tick();
  int newPosition = abs(encoder.getPosition());
  int state = digitalRead(buttonEncoder);
  if (encoderPosition != newPosition)
  {
    d.maindisplay(newPosition, mode, mode_midi, menuActiveItem, conf);// Update display when encoder is rotating
    encoderPosition = newPosition;
  }
  if(state == HIGH && state != stateButtonEncoder){
    menuActiveItem = menuSelectorSwitch(newPosition, menuActiveItem);
    d.maindisplay(newPosition, mode, mode_midi, menuActiveItem, conf);// Update display when encoder is clicked
  }
  stateButtonEncoder = state;
}

static int menuSelectorSwitch(int newPos, int menuActiveItem); // Automata that manage menuing

Presets

Configuration conf = newPresets[0];
// Configutation object are usefull to stock some informations and save and load presets
// Configuration(Name octave, tone shift, octaveOsc2, octaveOsc3, octaveOsc4, waveFormOsc1 ,waveFormOsc2 ,waveFormOsc3 ,waveFormOsc4 , attackTheme, attackDrones)
Configuration("Squ Tri",2,11, -1 ,-1 ,-2,-3 ,4,4,2,0 , 250, 250),

static void setPresets(int i){
  conf = newPresets[i]; // all data are stored in conf
  for(byte z = 0; z < POLYPHONY; z++){ // Setting good wave table for all synth
    oscil1[z].setTable(getWaveFromInt(conf.getOsc1()));
    oscil2[z].setTable(getWaveFromInt(conf.getOsc2()));
  }
  // Setting good wave table for drones
  bourdon1.setTable(getWaveFromInt(conf.getBrd1()));
  bourdon2.setTable(getWaveFromInt(conf.getBrd2()));
}

Concertina Library

Concertina library TODO rename the lib

• Configuration manager : goal is to manage presets TODO add reading/writing on the sd card.
• Display : Custom coded display menu
• MusicMath : Functions to compute some music stuff (tone shifting, octave shifting) TODO : Maybe add microtonal shifting
• Concertina.h : Definition of notes Name, Array of notes and pinout.

This project is working thanks to :
Camille MILLET, Tony JEGO, Yannick CHIRON, Nicolas HARRAND, Jean BANWARTH