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RP2040-PWM Tone

Tone generation library for Raspberry Pi Pico. Plays melodies and chirping sounds via PWM through a buzzer or speaker.

Usage

#include "pwm-tone.h"   // Include the library

// Pin definitions
#define PIEZO_PIN       0 // The pin the buzzer or speaker is connected to.
                          // The other terminal of the buzzer is connected to ground.

// Create an instance of the tone generator
tonegenerator_t generator;

int main() {

    // Initialize the tone generator, assigning it the output pin
    tone_init(&generator, PIEZO_PIN);

    // Play a single tone for 200ms.
    tone(&generator, NOTE_A4, 200);

    // Wait while the tone plays
    while(generator.playing) { sleep_ms(2); }

    // Play a longer melody
    melody(&generator, HAPPY_BIRTHDAY, 0);
}

An example application is provided.

Available functions

void tone_init(tonegenerator_t* gen, uint8_t gpio);
void tone(tonegenerator_t* gen, int freq, uint16_t duration);
void melody(tonegenerator_t* gen, note_t *notes, int8_t repeat);

void set_tempo(uint16_t bpm);
void set_rest_duration(uint16_t duration);
void stop_tone(tonegenerator_t* gen);
void stop_melody(tonegenerator_t* gen);

Melody structure

Each data point defines a pitch (float, in Hz) and a duration (expressed in subdivisions of a whole note). This means that a duration of 16 (a sixteenth of a whole note) is half a duration of 8. Negative values represent dotted notation, so that -8 = 8 + (8/2) = 12. This data structure is inspired by the work at https://github.com/robsoncouto/arduino-songs/

    note_t HAPPY_BIRTHDAY[] = {
        {NOTE_C4, 4},
        {NOTE_C4, 8}, 
        {NOTE_D4, -4},
        {NOTE_C4, -4},
        {NOTE_F4, -4},
        {NOTE_E4, -2},
        {REST, 8},

        {MELODY_END, 0}, // Melody end code. Necessary to trigger repeats
    };

In addition to pitch definitions (G1 to F#9), a conversion array that maps midi note numbers to pitches is available:

float pitch = midi_to_pitch[midi_note_number];

A small number of original sound effects are included:

  • ALARM_1
  • ALARM_2
  • ALARM_3
  • CONFIRM
  • DANGER
  • VICTORY
  • DEFEAT
  • ERROR
  • REJECT
  • COIN
  • EXPLOSION
  • FANFARE
  • LASER
  • POWERUP
  • SWEEP
  • POSITIVE
  • NEGATIVE
  • RINGTONE_1
  • RINGTONE_2
  • RINGTONE_3

The library also includes a sample melody:

  • HAPPY_BIRTHDAY

Projects using this library

Version history

  • 2023.12.17 - v1.1.1 - Disable out of range notes; Code refactoring
  • 2023.12.16 - v1.1.0 - Added playing attribute; Changed struct to typedef
  • 2023.09.25 - v1.0.0 - First release