Programming LRF Sounds



Let’s learn about the basics of programming your robot’s sound and speech with the Little Robot Friends Arduino Library. This is a really important feature because your robot has two main outputs: light and of course, sound!

How does your robot speak?

There is a ¼ watt, 8 ohm speaker on the center of your robot’s face circuit. Your robot doesn’t speak English like you and me, instead it speaks in a language called Beepboopbese. This language is composed of a series of sound and light patterns. You can program your robot’s sound and speech using code!

What is Sound? How do you program it?

A Sound, or LRFSound as written in code, is a combination of many parts including notes, octaves, intonations, durations, and pauses. All of these small components put together make sounds!

Let’s open up the Example Sketch: LRF_04-Sounds Sound Example

There are two ways to code a LRFSound.

1) Long Form

LRFSound mySound = {
  .note = LRFNote_A,
  .octave = LRFOctave_3,
  .intonation = LRFIntonation_Flat,
  .duration = LRFDuration_Long,
  .pause = LRFDuration_None

2. Short Form

LRFSound myOtherSound = { LRFNote_C, LRFOctave_4, LRFIntonation_Rising, LRFDuration_DoubleMedium, LRFDuration_None };

In your Short Form code, you might have noticed two LRFDurations. What does this mean? The first duration is the length of the note. The last duration is the pause in-between notes. That’s the difference!

Additionally, there are many different values in notes, octaves, intonations, durations, and pauses. For example, think about a piano - you can play a range of notes from A to G, and even sharp notes too. Same with your robot! We’ll be showing you a list of these values next!


To define a LRFSound code you must keep the attributes in order (note, octave, intonation, duration, pause).

List of Notes

Check out a list of notes that can be assigned onto your robot.

Constant Value
LRFNote_A A (55 hertz at octave #1)
LRFNote_AS A# (58hz)
LRFNote_B B (62hz)
LRFNote_C C (65hz)
LRFNote_CS C# (69hz)
LRFNote_D D (73hz)
LRFNote_DS D# (78hz)
LRFNote_E E (82hz)
LRFNote_F F (87hz)
LRFNote_FS F# (92hz)
LRFNote_G G (98hz)
LRFNote_GS G# (104hz)
LRFNote_Mute No Sound

What is an Octave?

An Octave, or LRFOctave as written in code, is what we use to make notes sound higher or lower. Oct is a prefix that means eight. Think of an octopus! How many tentacles do they have? Eight! You can apply one of eight different octaves to your sounds to make it sound high or low, but the base note will stay the same!

List of Octaves

Check out a list of octaves that can be assigned onto your robot.

Constant Value
LRFOctave_1 Lowest possible octave (some notes cannot be played)
LRFOctave_2 Lower octave
LRFOctave_3 Middle-low octave
LRFOctave_4 Middle octave
LRFOctave_5 Middle-high octave
LRFOctave_6 High octave
LRFOctave_7 Higher octave
LRFOctave_8 Highest possible octave

What is an Intonation?

An Intonation, or LRFIntonation as written in code, represents the inflection of a sound. Think about the way you talk. When you ask a question does it sound the same as when you make a statement? Probably not. That’s because you modulate your voice to make it sound questioning. It’s similar to the intonations we apply to our robot’s sound. This can make the robot sound expressive in many ways!

List of Intonations

Check out a list of intonations that can be assigned onto your robot.

Constant Value
LRFIntonation_Flat Flat tone (no change)
LRFIntonation_Rising Rising tone (happy or excited)
LRFIntonation_Falling Falling tone (sad or upset)
LRFIntonation_Peaking Peaking tone (rises, then returns to normal)
LRFIntonation_Dipping Dipping tone (falls, then returns to normal)

What is a Duration?

A Duration, or LRFDuration as written in code, represents time. Durations can be used in a few different situations. They can be used to determine the length of a note, the length in-between notes (or the pause), and also the amount of time a colour fades in and out. Most commonly, they’re used for programming sound, speech, and song.

List of Durations

Check out a list of durations that can be assigned onto your robot.

Constant Value
LRFDuration_None Oms (no duration)
LRFDuration_Short 50ms (1/16 note)
LRFDuration_DoubleShort 100ms (1/8 note)
LRFDuration_Medium 200 ms (1/4 note)
LRFDuration_DoubleMedium 400 ms (1/2 note)
LRFDuration_Long 800ms (whole note)
LRFDuration_DoubleLong 1600ms (double whole note)
LRFDuration_VeryLong 3200ms (quadruple whole note)

Program Your First Sound!

Now that you have a fundamental understanding of sound, let’s try to program your first sound on your robot from scratch.

Begin with the Setup and Loop sketch.

Setup Example

To begin, import your library at the top of the sketch. To learn more about how to read an Arduino Sketch and why this is important, go here.

#include <LittleRobotFriends.h>

Next, underneath #include you need to program your sound. You can name it whatever youd like, but in this case were calling it mySound. Set values for the note, octave, intonation, duration, and pause.

LRFSound mySound = {
  .note = LRFNote_A,
  .octave = LRFOctave_3,
  .intonation = LRFIntonation_Flat,
  .duration = LRFDuration_Long,
  .pause = LRFDuration_None

It’s time to declare your Event Handler. We’ll call it myTapHandler, but you can name it something different. Inside the curly brackets there is a saySound() function which plays your new sound.

We use the prefix lrf.speech in front of our saySound function because it is being called from the “eyes” section of our library. Think about the library in your neighbourhood. There are so many books! How do you find them all? The aisles and bookshelves are all labelled with genres and subgenres, which helps you find your books!

void myTapHandler(LRFEvent event)


Inside of void setup, you need to run your lrf.setup() function. We’re going to map the event to the event handler now. The function inside of the curly brackets has the event set to Tickle on your robot’s hair.

void setup()

  lrf.setEventHandler(LRFEvent_Tickle, myTapHandler);


Lastly, run your lrf.loop() function. We won’t be adding anything else here.

void loop()

Plug in your robot and upload the program.


Give your robot a tickle on the hair and you’ll hear the sound you just programmed! You won’t see any lights on your robot’s eyes, because we’re just focusing on sound in this lesson.

If you’re having trouble with your code, download it to see what went wrong.

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