// https://forum.arduino.cc/t/how-to-setup-array-structure-for-melody-sequences/1404240

// tone sequencer v1
// thisnote = row * column + column

#include <avr/pgmspace.h> // offload arrays from RAM to PROGMEM 

/*
  s or 6 = 1/16 (sixteenth)
  e or 8 =  1/8 (eighth)
  q or 4 =  1/4 (quarter)
  t or 3 =  1/3 (third)
  h or 2 =  1/2 (half)
  w or 1 =  1/1 (whole)
  r or 0 = rest
*/

unsigned long columnSpeed = 50; // milliseconds per element - speed control
byte tonePin = 3; // PWM pin

const char startup[] PROGMEM = { // single-dimension array of sequenced elements
  "GN4..q...."
  "FN4....qq."
  "EN4...q..q"
  "CN4.q....."
};

const char shutdown[] PROGMEM = {
  "GN4.....4."
  "FN4..44..."
  "EN4.4..4.."
  "CN4......4"
};

void setup() {
  pinMode(tonePin, OUTPUT);
}

void loop() {
  sequencer(startup, sizeof(startup));
  sequencer(shutdown, sizeof(shutdown));
}

void sequencer(char list[], int listLength) {
  for (int col = 0; col < listLength; col++) {
    for (int row = 0; row < ledCount; row++) {
      switch (pgm_read_byte(&list[row * listLength + col])) { // locate element with row and column
        case '*': digitalWrite(ledPin[row], HIGH); break; // turn LED ON
        case '.': digitalWrite(ledPin[row],  LOW); break; // turn LED OFF
        case '6':
        case 's': duration = 1000 / 16; break;
        case '4':
        case 'q': duration = 1000 / 4; break;
        case '8':
        case 'e': duration = 1000 / 8; break;
        case '3':
        case 't': duration = 1000 / 3; break;
        case '2':
        case 'h': duration = 1000 / 2; break;
        case '1':
        case 'w': duration = 1000 / 1; break;
        default: break;
      }
      tone (tonePin, note, duration)
      delay(duration * .8);
    }
    delay(columnSpeed); // regulate the speed of the sequence
  }
}