Implementation of pre-defined songs for musical organ. More...

#include "includes/CPU.h"
#include <avr/io.h>
#include <util/delay.h>
#include "includes/scale16.h"
#include "includes/organ.h"
#include "includes/pre_defined_songs.h"

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Macros
#define	_num_notes(x) sizeof(x) / sizeof(x[0])

Functions
void	play_twinkle_little_star ()
	Plays "Twinkle Twinkle Little Star" melody.

Detailed Description

Implementation of pre-defined songs for musical organ.

Author: Roybel Carbonell Camejo

Date: 2026-04-29

Version: 1.1

This file contains the actual implementations of all pre-programmed songs. Each song is defined as arrays of notes (frequencies) and durations (milliseconds), then played sequentially using playNote().

Implementation Details

All songs are blocking (playNote() waits for note to finish)
Note durations use constants Q (250ms) and H (500ms) from scale16.h
Songs are independent of main program's currentNoteLength setting
Each song uses its own fixed durations for consistent playback

Memory Usage Analysis

estrellita_notas: 42 notes × 2 bytes = 84 bytes
estrellita_duraciones: 42 notes × 2 bytes = 84 bytes
imperial_notas: 50 notes × 2 bytes = 100 bytes
imperial_duraciones: 50 notes × 2 bytes = 100 bytes
Total: ~368 bytes of flash memory (stored in .rodata)

Note: ATmega168 has 16KB flash, so memory usage is minimal

Warning: Modifying song arrays increases flash memory consumption

See also: pre_defined_songs.h Header file with function declarations; scale16.h Note definitions (C4, G4, Q, H, etc.); organ.h playNote() function implementation

Definition in file pre_defined_songs.c.

Macro Definition Documentation

◆ _num_notes

#define _num_notes ( x ) sizeof(x) / sizeof(x[0])

Examples: /home/luka/WORK/Programming/ARDUINO/AVR-Square-Wave-Organ/src/pre_defined_songs.c.

Function Documentation

◆ play_twinkle_little_star()

void play_twinkle_little_star ( )

Plays "Twinkle Twinkle Little Star" melody.

Implements the complete Twinkle Twinkle Little Star song using fixed note durations (Q=250ms for eighth notes, H=500ms for quarter notes). The song has 42 notes organized in 6 phrases of 7 notes each.

Song Structure (42 notes, 6 phrases)

* Phrase 1: C4  C4  G4  G4  A4  A4  G4  (Twinkle twinkle little star)
* Phrase 2: F4  F4  E4  E4  D4  D4  C4  (How I wonder what you are)
* Phrase 3: G4  G4  F4  F4  E4  E4  D4  (Up above the world so high)
* Phrase 4: G4  G4  F4  F4  E4  E4  D4  (Like a diamond in the sky)
* Phrase 5: C4  C4  G4  G4  A4  A4  G4  (Twinkle twinkle little star)
* Phrase 6: F4  F4  E4  E4  D4  D4  C4  (How I wonder what you are)
*

Rhythm Pattern

First 6 notes of each phrase: Q (250ms) - eighth notes
Last note of each phrase: H (500ms) - quarter note (held longer)
Creates a "swing" feel typical of children's songs

Note Frequency Analysis

Note	Frequency (Hz)	Period (μs)	Timer Value
C4	261.63	3822	1911
D4	293.66	3405	1702
E4	329.63	3033	1516
F4	349.23	2863	1431
G4	392.00	2551	1275
A4	440.00	2272	1136

@complexity O(n) where n = 42 notes @performance Takes ~10-15 seconds to complete (Q=250ms, H=500ms)

Bug:: None known for this implementation

See also: play_imperial_march() Another pre-defined song; playNote() Core function that generates tones

Note: This function is blocking - no other code executes during playback

Warning: Do not modify the arrays while the song is playing (not possible anyway)

Array of notes for Twinkle Twinkle Little Star

Contains 42 note frequency values in sequence. Values correspond to C4, G4, A4, F4, E4, D4 from scale16.h.

Note: Stored in flash memory (const qualifier in global scope)

See also: scale16.h for note definitions (C4, G4, A4, F4, E4, D4)

Array of durations for Twinkle Twinkle Little Star

Each duration corresponds to the note at the same index in estrellita_notas[]. Uses Q (250ms) for short notes and H (500ms) for notes that should be held longer.

Note: Pattern: 6 short notes + 1 long note repeated 6 times

See also: scale16.h for duration definitions (Q=250, H=500)

Play each note in sequence

Iterates through all 42 notes and plays each with its corresponding duration. The loop is blocking.

Invariant: i always ranges from 0 to 41 @ensures All 42 notes have been played

Definition at line 82 of file pre_defined_songs.c.

References A4, C4, D4, E4, F4, G4, H, playNote(), and Q.

Referenced by main().

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Macros

Functions