Development & Customization

Adding New Songs

Step 1: Add function declaration in pre_defined_songs.h

void play_my_song(void);

Step 2: Implement the song in pre_defined_songs.c

void play_my_song(void)
{
    const uint16_t notes[] = {C4, D4, E4, F4, G4, A4, B4, C5};
    const uint16_t durations[] = {Q, Q, Q, Q, Q, Q, Q, H};
    
    for (uint8_t i = 0; i < 8; i++)
        playNote(notes[i], durations[i]);
}

Step 3: Add command in main.c

else if (receivedChar == '3')
{
    printString("\r\nPlaying my custom song\r\n");
    play_my_song();
}

Note Frequency Calculation

Timer values are calculated as:

OCR = F_CPU / (2 × frequency × prescaler)
 
Example for C4 (261.63 Hz) with F_CPU=16MHz, prescaler=1:
OCR = 16000000 / (2 × 261.63 × 1) = 30578

Adding New Notes

Add to scale16.h:

#define NewNote  OCR_VALUE

Performance Improvements

Implement Non-blocking Playback

// Use timer interrupts instead of _delay_ms()
ISR(TIMER1_COMPA_vect) {
    // Toggle buzzer pin
}

Add Serial Buffer Queue

#define RX_BUFFER_SIZE 32
volatile char rx_buffer[RX_BUFFER_SIZE];
// Implement circular buffer in ISR

Troubleshooting

Problem	Solution
No sound	Check buzzer connection and resistor
Garbled serial	Verify baud rate (9600) and F_CPU
Wrong notes	Check F_CPU in CPU.h
No serial echo	Verify RX/TX cross connection