A library for playing tones and tone sequences, intended for the Arduboy game system
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README.md

The ArduboyTones Library

The ArduboyTones library is maintained in a git repository hosted on GitHub at:

https://github.com/MLXXXp/ArduboyTones

ArduboyTones is a library for playing tones and tone sequences, intended to be used with the Arduino based Arduboy miniature game system (but could be used with other Arduino boards).

Description

ArduboyTones is a small, efficient library which generates tones and tone sequences on a speaker attached to digital output pins. It is intended to be used by games and other sketches written for the Arduboy, so the pins (and timer) used are hard coded for the Arduboy, and thus aren't specified in any functions.

Like the Arduino built in tone() function, the tones are simple square waves generated by toggling a pin digitally high and low with a 50% duty cycle. Also like Arduino tone(), once started, interrupts are used so that the sound plays in the background while the real code continues to run.

ArduboyTones has equivalents to Arduino tone() and noTone() and additionally:

  • As well as a single tone, the tone() function can play two or three tones, in sequence, with a single call.
  • Includes functions to play a tone sequence of any length, specified by an array located in either program memory (PROGMEM) or RAM. The array can be optionally terminated with a repeat command so the sequence will repeat continuously unless stopped by using noTone() or a new tone or sequence is started.
  • Each tone can specify that it's to be played at either normal or a higher volume. High volume is accomplished by taking advantage of the speaker being wired across two pins and toggling each pin opposite to the other, which will generate twice the normal voltage across the speaker. For normal volume, one pin is toggled while the other is held low.
  • A function is available to set flags to ignore the individual volume setting in each tone, so that all tones will play at either normal or high volume.
  • Tone sequences can include intervals of silence (musical rests).
  • Includes a global mute capability by using a callback function, specified by the sketch, which indicates sound is to be muted. When muted, the sketch can continue to call functions to produce tones in the usual way but the speaker will remain silent. It is intended that the Arduboy2 Library's audio.enabled() function, or something similar, be used as this function.
  • A function is provided which will return true if tones are playing or false if the sequence has completed.

Note that even with all these features, ArduboyTones will use significantly less code space than using Arduino tone() functions.

Converting MIDI files

A separate command line utility program, midi2tones, is available. It will convert standard MIDI files to ArduboyTones format when the -o2 option is specified.

Installation

The library can be installed using the Arduino IDE library manager:

  • In the Arduino IDE select from the menus: Sketch > Include Library > Manage Libraries...
  • In the Library Manager Filter your search... field enter arduboytones.
  • Click somewhere within the ArduboyTones entry.
  • Click on the Install button.

For more library installation information see

Installing Additional Arduino Libraries - Using the Library Manager

Using the library

Setting up

Include the library using

#include <ArduboyTones.h>

You must then create an ArduboyTones object which specifies the callback function used for muting. The function is a required parameter. It must return a boolean (or bool) value which will be true if sound should be played, or false if all sounds should be muted. In this document the ArduboyTones object will be named sound. The audio.enabled() function of the Arduboy library will be used for the mute callback. The Arduboy object will be named arduboy.

So, to set things up we can use:

#include <Arduboy2.h>
#include <ArduboyTones.h>

Arduboy2 arduboy;
ArduboyTones sound(arduboy.audio.enabled);

Specifying tones

Each tone is specified by a frequency and duration pair, the same as with Arduino tone(). Like tone(), the frequency is specified in hertz (Hz, cycles per second). The duration is in milliseconds (actually very slightly shorter; see below).

There are some small differences between the Arduino tone() and the ArduboyTones frequency and duration parameters.

Frequency

  • ArduboyTones can only play frequencies between 16 Hz and 32767 Hz. Arduino tone() allows a greater range.
  • For efficiency, ArduboyTones uses a single clock prescaler value for the timer. The result is that very high frequencies may be a bit less accurate than what Arduino tone() would produce. It likely won't be noticeable for the range of frequencies that will mainly be used.
  • With ArduboyTones, you can use a frequency value of 0 to indicate silence (a musical rest) for the duration specified.
  • You can indicate that a tone should sound at a higher volume by adding the defined value TONE_HIGH_VOLUME to the desired frequency.

Duration

  • To make the code smaller and more efficient, durations are actually in 1024ths of a second instead of 1000ths (milliseconds). See the note near the end of this document for a detailed explanation.
  • With ArduboyTones, a tone's duration is specified as an unsigned int (16 bits) instead of an unsigned long (32 bits). This means the maximum duration allowed is 65535 (65 seconds). Like Arduino tone() a duration of 0 indicates forever, which can be stopped by noTone() or replaced by a new tone or sequence call.

Defines for musical notes

ArduboyTones includes file ArduboyTonesPitches.h which will automatically be included by ArduboyTones.h. ArduboyTonesPitches.h provides frequency values for musical notes based on A4 = 440 Hz.

The format is:

NOTE_<letter><optional S for sharp><octave number><optional H for high volume>

NOTE_REST is defined as 0 and can be used for a musical rest.

There are no flats. You have to use the sharp note equivalent.

Notes are define over the range of C0 (16 Hz) to B9 (15804 Hz)

Examples: NOTE_C3 NOTE_GS4 NOTE_B5H NOTE_DS6H

Functions

All functions are members of class ArduboyTones, so you must remember to reference each function with the object name. Example: sound.tone(1000, 500);


Play a tone forever or until interrupted:

void tone(frequency)

Play a single tone for the duration. Duration can be 0 (forever):

void tone(frequency, duration)

Play two tones in sequence:

void tone(freq1, dur1, freq2, dur2)

Play three tones in sequence:

void tone(freq1, dur1, freq2, dur2, freq3, dur3)


Play a tone sequence from frequency/duration pairs in an array in program memory:

void tones(arrayInProgram)

The array must end with a single value of either TONES_END, to end the sequence, or TONES_REPEAT to continuously repeat from beginning to end.

Example:

const uint16_t song1[] PROGMEM = {
  220,1000, 0,250, 440,500, 880,2000,
  TONES_END };

sound.tones(song1);

The same as tones() above except the frequency/duration pairs are in an array in RAM instead of in program memory:

void tonesInRAM(arrayInRAM)

Generally, the only reason to use tonesInRAM() instead of tones() would be if dynamically altering the contents of the array is required.

Example:

uint16_t song2[] = {
  NOTE_A3,1000, NOTE_REST,250, NOTE_A4,500, NOTE_A5,2000,
  TONES_REPEAT };

sound.tonesInRAM(song2);

Stop playing the tone or sequence:

void noTone()

If called when nothing is playing, it will do nothing.


Set the volume to always be normal, always high, or tone controlled:

void volumeMode(mode)

The following values for mode should be used:

  • VOLUME_IN_TONE - Each tone will play at the volume specified in the tone itself. This is the default.
  • VOLUME_ALWAYS_NORMAL - All tones will play at normal volume level regardless of what's specified in the tones.
  • VOLUME_ALWAYS_HIGH - All tones will play at high volume level regardless of what's specified in the tones.

Check if a tone or tone sequence is playing:

boolean playing()

Returns true if playing (even if sound is muted).


Notes and Hints

Example sketch

The ArduboyTones library contains an example sketch ArduboyTonesTest in the examples folder. It was primarily written to test the library but the code can be examined and uploaded for examples of using all the functions. It uses the Arduboy2 library, which must be installed to compile the sketch. ArduboyTonesTest can be loaded into the Arduino IDE using the menus:

File > Examples > ArduboyTones > ArduboyTonesTest

Frequencies and durations work the same everywhere

You can use rests and infinite durations in tone() functions the same as in sequence arrays. Most of the time this wouldn't be useful, however...

  • A rest would only be useful in the middle of a three tone tone() function, to play two tones with a rest between them. Or maybe on the end, if you were chaining tone() functions by using playing() to wait for each one to end, and then starting the next one immediately.
  • A duration of 0 (forever) is only useful on the last tone of a sequence, even in an array.
  • You can use TONES_REPEAT (and even TONES_END) in place of a frequency in a tone() function. In this case the mandatory duration value would be ignored. About the only place this might be useful would be using TONES_REPEAT at the end of a three tone tone() function, to play two tones repeatedly. For instance, two tones repeated could be used when a character starts walking and then noTone() could be called when the character stopped.

Something to consider for all of the above points, though:

Using a two or three tone array in program memory with tones() is likely more efficient than using a two or three tone tone() function. The two and three tone tone() functions were only added to make things easier and quick for sketches where code size isn't an issue.

Why durations aren't exactly in milliseconds

Ideally, to match Arduino tone(), durations should be given in 1000ths of a second (milliseconds). However, ArduboyTones treats durations as being in 1024ths of a second. Here's why:

To calculate internal timing values for a duration given in milliseconds, a divide by 500 on an unsigned long (32 bit) number is required, which is what Arduino tone() does. On an 8 bit processor without any native divide instructions, this is slow and takes a fair amount of code. On the other hand, a divide by 512 is easily and quickly accomplished by simply shifting the value right 9 bits. This is what ArduboyTones does, at the expense of durations being about 2.34% shorter than the same value would be with Arduino tone().

In most circumstances, the slightly shorter durations will likely be unnoticeable. If a duration needs to be precise, the required value can be calculated by multiplying the desired duration, in milliseconds, by 1.024.

Use with the Arduboy Development Kit (DevKit) version

ArduboyTones will work with the Arduboy DevKit. The DevKit is limited to controlling only one pin for the speaker, so all tones will sound at normal volume. The high volume setting in tones will be ignored, and calls to volumeMode() will have no effect.