NoteOff messages not always sent DIY MIDI keyboard with arduino uno

Other Hardware Audio
1

Dear readers,

I am trying to make an MIDI keyboard out of an old keyboard. This keyboard works with a matrix of pushbuttons. So I combined the keypad library and the midi library in order to send a note on when a key is pressed and note off when a key is released. (arduino->midi->midi-usb converter->computer) The following code sort of works but the note off message is not always sent. When I check the keystate with another code, pressed, hold, released and idle all work fine. I am not an programming expert and I know the code could be a lot shorter, any help on this part is also welcome but is not my main problem (unless it is my bad programming that causes the problem).

Thanks in advance.

 #include <Keypad.h>
 #include <MIDI.h>
 
 int velocity = 100;
 int note = 60;

const byte ROWS = 5;
const byte COLS = 6; 
//define the cymbols on the buttons of the keypads
char keys[ROWS][COLS] = {
  {'Y','0','0','0','0','0'}, 
  {'S','T','U','W','V','X'},
  {'M','N','O','Q','P','R'},
  {'G','H','I','K','J','L'},
  {'A','B','C','E','D','F'}
};
byte rowPins[ROWS] = {12, 11, 10, 9, 8}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {7, 6, 5, 4, 3, 2}; //connect to the column pinouts of the keypad

//initialize an instance of class NewKeypad
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

void setup() {
  MIDI.begin(8);

}

void loop() {
  char customKey = kpd.getKey();  
     // Fills kpd.key[ ] array with up-to 10 active keys.
    // Returns true if there are ANY active keys. 
 if (kpd.getKeys())
    {
        for (int i=0; i<LIST_MAX; i++)   // Scan the whole key list.
        {
          if (kpd.key[i].kchar == 'A'){
                       note=60;
        }
          if (kpd.key[i].kchar == 'B'){
                       note=61;
        }
          if (kpd.key[i].kchar == 'C'){
                       note=62;
        }
          if (kpd.key[i].kchar == 'D'){
                       note=63;
        }
          if (kpd.key[i].kchar == 'E'){
                       note=64;
        }
          if (kpd.key[i].kchar == 'F'){
                       note=65;
        }
          if (kpd.key[i].kchar == 'G'){
                       note=66;
        }
          if (kpd.key[i].kchar == 'H'){
                       note=67;
        }
          if (kpd.key[i].kchar == 'I'){
                       note=68;
        }
          if (kpd.key[i].kchar == 'J'){
                       note=69;
        }
          if (kpd.key[i].kchar == 'K'){
                       note=70;
        }
          if (kpd.key[i].kchar == 'L'){
                       note=71;
        }
          if (kpd.key[i].kchar == 'M'){
                       note=72;
        }
          if (kpd.key[i].kchar == 'N'){
                       note=73;
        }
          if (kpd.key[i].kchar == 'O'){
                       note=74;
        }
          if (kpd.key[i].kchar == 'P'){
                       note=75;
        }
          if (kpd.key[i].kchar == 'Q'){
                       note=76;
        }
          if (kpd.key[i].kchar == 'R'){
                       note=77;
        }
          if (kpd.key[i].kchar == 'S'){
                       note=78;
        }
          if (kpd.key[i].kchar == 'T'){
                       note=79;
        }
          if (kpd.key[i].kchar == 'U'){
                       note=80;
        }
          if (kpd.key[i].kchar == 'V'){
                       note=81;
        }
          if (kpd.key[i].kchar == 'W'){
                       note=82;
        }
          if (kpd.key[i].kchar == 'X'){
                       note=83;
        }
          if (kpd.key[i].kchar == 'Y'){
                       note=84;
          }
           
            if ( kpd.key[i].stateChanged )   // Only find keys that have changed state.
            {
                switch (kpd.key[i].kstate) {  // Report active key state : IDLE, PRESSED, HOLD, or RELEASED
                    case PRESSED:
                       MIDI.sendNoteOn(note, velocity, 8);//turn note on
                break;
                    case RELEASED:
                       MIDI.sendNoteOn(note, 0, 8);//turn note on
                }
                }
        }
    }
}
2

You are not sending note off message with your code, you are changing the velocity to "0".

MIDI.sendNoteOn(note, 0, 8);//turn note on

To send note off message you need to use "sendNoteOff"

3

you are changing the velocity to "0".

In MIDI that is a perfectly acceptable way of sending a note off command.

4

Yesterday i faced a similar problem. The only difference was that i was getting noteOn and noteOff two times for each key press. I fixed that by skipping the HOLD and IDLE state of the keys.

if ( kpd.key[i].stateChanged ) {
      if ( kpd.key[i].kstate == PRESSED || kpd.key[i].kstate == RELEASED ) {     //this line makes the program skip the HOLD and IDLE states of the keys
                switch (kpd.key[i].kstate) {
                    case PRESSED:
                       MIDI.sendNoteOn(note, velocity, 8);
                break;
                    case RELEASED:
                       MIDI.sendNoteOn(note, 0, 8);
              }
     }
}

You could also include the switch statement that maps the keys in that if {} statement.
But, maybe it was a bug in the library, you could try it again now and see if it works