// tone sequencer version 1
// https://forum.arduino.cc/t/how-to-setup-array-structure-for-melody-sequences/1404240

// - char arrays are flat (one long string, no comma separators) 
// - thisnote = row * column + column
// - rows must be the same length

#include <avr/pgmspace.h> // offload arrays from RAM to PROGMEM 
bool firstTime = 1; // flag for printing Loop Time

// s or 6 = 1/16, e or 8 = 1/8, q or 4 =  1/4, t or 3 = 1/3, h or 2 = 1/2, w or 1 = 1/1, r = rest
unsigned long columnSpeed = 50; // milliseconds per element - speed control

const char startup[] PROGMEM = { // single-dimension array of sequenced elements
  ".q...." // G4 using q for quarter note
  "...qq." // F4
  "..q..q" // E4
  "q....." // C4
};

const char shutdown[] PROGMEM = {
  "....4." // G4 using 4 for quarter note
  ".44..." // F4
  "4..4.." // E4
  ".....4" // C4
};

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(columnSpeed); // regulate the speed of the sequence
  }
}