Playing melodies with tone() in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Arduino sketch?

Consider the following Arduino code that plays a simple melody using tone(). What will be the behavior when this code runs on a board connected to a speaker on pin 8?

Arduino

const int speakerPin = 8;
int melody[] = {262, 294, 330, 349};
int noteDurations[] = {4, 4, 4, 4};

void setup() {
  for (int thisNote = 0; thisNote < 4; thisNote++) {
    int noteDuration = 1000 / noteDurations[thisNote];
    tone(speakerPin, melody[thisNote], noteDuration);
    delay(noteDuration * 1.3);
  }
}

void loop() {
  // no repeat
}

A The speaker plays a continuous tone at 262Hz without pauses.

B The speaker plays four notes (C4, D4, E4, F4) each for 250ms with short pauses, then stops.

C The code causes a compilation error due to missing semicolons.

D The speaker plays the notes but all at the same time, creating a chord.

💡 Hint

Think about how tone() and delay() work together to play notes sequentially.

The code plays each note in the melody array for a duration calculated from noteDurations. The delay after tone() ensures notes don't overlap. The loop runs once in setup, so the melody plays once and stops.

🧠 Conceptual

intermediate

Which statement about tone() is true?

Select the correct statement about the Arduino tone() function.

A tone() can play multiple tones simultaneously on different pins without interference.

B tone() automatically stops after 1 second if no duration is specified.

C tone() requires an external library to work.

D tone() stops any previous tone on the same pin when called again.

💡 Hint

Think about what happens if you call tone() twice on the same pin.

Calling tone() on a pin stops any tone currently playing on that pin before starting the new one. It does not support multiple simultaneous tones on the same pin.

🔧 Debug

advanced

Why does this melody play only one note?

This code is intended to play a melody of three notes, but only the last note sounds. What is the cause?

Arduino

const int speakerPin = 9;
int melody[] = {440, 494, 523};
int noteDurations[] = {500, 500, 500};

void setup() {
  for (int i = 0; i < 3; i++) {
    tone(speakerPin, melody[i]);
    delay(noteDurations[i]);
  }
}

void loop() {}

A The speakerPin is not set as output, so only the last note plays.

B The delay() function is too short to hear the notes properly.

C tone() without duration plays indefinitely until stopped, so only the last note remains audible.

D The melody array has invalid frequencies causing the first notes to be skipped.

💡 Hint

Check how tone() behaves when called without a duration parameter.

Calling tone() without a duration starts the tone and it plays until noTone() is called or another tone() call interrupts it. The delay pauses the program but does not stop the tone, so only the last tone remains playing.

📝 Syntax

advanced

Which option causes a compilation error?

Identify the code snippet that will cause a compilation error when trying to play a tone on pin 7.

A tone(7, 440 500); delay(500);

B tone(7, 440); delay(500); noTone(7);

C tone(7, 440, 500); delay(500); noTone(7);

D tone(7, 440, 500); delay(500);

💡 Hint

Look carefully at the parameters passed to tone().

Option A is missing a comma between frequency and duration parameters, causing a syntax error. The other options are syntactically correct.

🚀 Application

expert

How many notes are played by this code?

Given the code below, how many distinct notes will be played on the speaker connected to pin 10?

Arduino

const int speakerPin = 10;
int melody[] = {262, 294, 330, 349, 392};
int noteDurations[] = {4, 8, 4, 8, 4};

void setup() {
  int i = 0;
  while (i < 5) {
    int duration = 1000 / noteDurations[i];
    tone(speakerPin, melody[i], duration);
    delay(duration * 1.2);
    i++;
  }
}

void loop() {}

A 5 notes are played sequentially with varying durations.

B Only 4 notes are played because the last note is skipped.

C The code plays 5 notes but all with the same duration.

D No notes are played because tone() is called inside a while loop.

💡 Hint

Count how many times tone() is called and check the loop condition.

The while loop runs 5 times, playing each note in the melody array with durations calculated from noteDurations. All notes play sequentially.