Organ tone generator interface. More...

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Functions
void	playNote (uint16_t half_us, uint16_t duration_ms)
	Play a musical tone.

void	rest (uint16_t duration_ms)

Detailed Description

Organ tone generator interface.

Author: Roybel Carbonell Camejo

Date: 2026-04-28

Definition in file organ.h.

Function Documentation

◆ playNote()

void playNote	(	uint16_t	half_us,
		uint16_t	duration_ms
	)

Play a musical tone.

Parameters

half_us	Half period in microseconds (1/(2*frequency))
duration_ms	Tone duration in milliseconds

Generates a square wave on the buzzer pin. Example: play_note(1136, 500) plays 440Hz for 500ms.

Warning: Blocking function - pauses execution during playback

Precondition: Buzzer pin must be configured as output

See also: pinDefines.h for buzzer pin configuration

Play a musical tone.

Parameters

[in]	half_us	Half period of the square wave in microseconds (1/(2*frequency))
[in]	duration_ms	Total note duration in milliseconds

This function generates a square wave on the buzzer pin to produce a musical tone. The tone is generated using the following formula:

Frequency (Hz) = 1,000,000 / (2 * half_us)
Total cycles = (frequency * duration_ms) / 1000

Algorithm:: The function toggles the buzzer pin between HIGH and LOW, with delays equal to the specified half period, thus generating a perfect square wave.

Example:: // Generate A4 (440 Hz) for 500 ms

// half_us = 1,000,000/(2*440) = 1136 us

play_note(1136, 500);

Note: The cycle calculation is performed as: cycles = (500000 / half_us) * duration_ms / 1000 This formula avoids integer overflow.

Warning: This function uses _delay_us() which is NOT accurate for delays > 768 us at 16 MHz. For half_us > 768, consider using hardware timers.; Delays are blocking; no other tasks can execute during note playback.

Precondition: The BUZZER_PIN must be configured as output on BUZZER_PORT before calling this function.

Postcondition: After playing the note, there is an additional 30ms delay to prevent "clicks" between notes.

See also: timer_generate_tone() For non-blocking implementation; play_song() For playing complete melodies

@bugs For very small half_us (< 10), the generated frequency may be inaccurate due to loop overhead.

Todo:

Implement hardware timer version for non-blocking playback

Add volume control using PWM modulation

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

Definition at line 66 of file organ.c.

References BUZZER_PIN, and BUZZER_PORT.

Referenced by main(), and play_twinkle_little_star().

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◆ rest()

void rest ( uint16_t duration_ms )

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

Definition at line 92 of file organ.c.

Referenced by main().

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Functions

Detailed Description

Function Documentation

◆ playNote()

◆ rest()