noTone() to stop sound in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output on the buzzer?

Consider this Arduino code snippet. What will the buzzer do when this runs?

Arduino

tone(8, 1000); // Play 1000 Hz tone on pin 8
noTone(8); // Stop the tone immediately

A The buzzer never plays any sound.

B The buzzer plays a 1000 Hz tone briefly then stops immediately.

C The buzzer plays a 500 Hz tone instead of 1000 Hz.

D The buzzer plays a continuous 1000 Hz tone without stopping.

💡 Hint

noTone() stops any tone playing on the specified pin.

The tone() function starts playing a tone on pin 8 at 1000 Hz. The noTone() function immediately stops any tone on pin 8, so the buzzer only plays briefly.

🧠 Conceptual

intermediate

Why use noTone() in Arduino?

Which of these best explains why you would use noTone() in an Arduino sketch?

A To change the volume of the buzzer sound.

B To start playing a tone on a pin at a specific frequency.

C To stop a tone playing on a pin so the buzzer becomes silent.

D To make the buzzer beep faster.

💡 Hint

Think about what happens when you want silence after a sound.

noTone() stops the tone on the pin, making the buzzer silent. It does not start or change tones or volume.

🔧 Debug

advanced

Why does the buzzer keep playing?

This code is supposed to play a tone and then stop it after 2 seconds, but the buzzer keeps playing. What is the problem?

Arduino

tone(9, 440);
delay(2000);
noTone(9);

A tone(9, 0) does not stop the tone; noTone(9) should be used instead.

B delay(2000) is too short to stop the tone.

C tone() needs a third parameter to stop the tone.

D The buzzer is connected to the wrong pin.

💡 Hint

Check how to properly stop a tone playing on a pin.

Calling tone(pin, 0) does not stop the tone. The correct way to stop a tone is to call noTone(pin).

📝 Syntax

advanced

Identify the syntax error

Which option contains the correct syntax to stop a tone on pin 7?

A noTone(7);

B noTone 7;

C noTone(7)

D noTone7();

💡 Hint

Remember how functions are called in Arduino (C++).

The correct syntax is noTone(7); with parentheses and a semicolon. Options B, C, and D are missing parentheses or semicolon or have wrong syntax.

🚀 Application

expert

How many times does the buzzer beep?

What is the number of beeps heard from the buzzer after running this code?

Arduino

for (int i = 0; i < 3; i++) {
  tone(10, 1000);
  delay(200);
  noTone(10);
  delay(200);
}

A 6 beeps

B No beeps

C 1 beep

D 3 beeps

💡 Hint

Each loop iteration plays one beep then stops it.

The loop runs 3 times. Each time it plays a tone for 200 ms, then stops it and waits 200 ms. So, 3 beeps total.

Practice

1. What does the Arduino function noTone(pin) do?

easy

A. Changes the volume of the sound on the specified pin

B. Starts playing a tone on the specified pin

C. Stops any sound currently playing on the specified pin

D. Sets the pin as an output pin

Solution

1. Step 1: Understand the purpose of noTone()

   The function noTone(pin) is designed to stop any sound that is currently playing on the given pin.

2. Step 2: Differentiate from tone()

   Unlike tone(pin, frequency) which starts a sound, noTone(pin) stops it.

3. Final Answer:

   Stops any sound currently playing on the specified pin -> Option C

4. Quick Check:

   noTone() stops sound = A [OK]

Hint: Remember: noTone() always stops sound on the pin [OK]

Common Mistakes:

• Confusing noTone() with tone()
• Thinking noTone() changes volume
• Assuming noTone() starts sound

2. Which of the following is the correct syntax to stop a tone on pin 8?

easy

A. noTone8();

B. noTone();

C. noTone(pin=8);

D. noTone(8);

Solution

1. Step 1: Recall the function syntax

   The correct syntax for stopping a tone on a specific pin is noTone(pin); where pin is the pin number.

2. Step 2: Check each option

   noTone8(); uses invalid function name. noTone(pin=8); uses invalid named parameter syntax. noTone(); omits the pin number. noTone(8); is correct.

3. Final Answer:

   noTone(8); -> Option D

4. Quick Check:

   Correct syntax = B [OK]

Hint: Use noTone(pin) with pin number inside parentheses [OK]

Common Mistakes:

• Omitting the pin number
• Using incorrect function names
• Passing pin as named argument

3. What will be the output behavior of this Arduino code snippet?

tone(9, 1000);
delay(500);
noTone(9);
delay(500);

medium

A. A 1000 Hz tone plays continuously without stopping

B. A 1000 Hz tone plays for 500 ms, then stops

C. No sound plays at all

D. The tone plays for 1000 ms then stops automatically

Solution

1. Step 1: Analyze tone() and delay()

   The tone(9, 1000); starts a 1000 Hz sound on pin 9. The delay(500); pauses the program for 500 milliseconds while the tone plays.

2. Step 2: Analyze noTone() and second delay()

   The noTone(9); stops the sound on pin 9. The following delay(500); pauses for another 500 ms with no sound.

3. Final Answer:

   A 1000 Hz tone plays for 500 ms, then stops -> Option B

4. Quick Check:

   tone + delay + noTone = sound stops after 500 ms [OK]

Hint: noTone(pin) stops sound immediately after delay [OK]

Common Mistakes:

• Assuming tone stops automatically after delay
• Thinking noTone restarts sound
• Ignoring delay effects

4. Identify the error in this Arduino code snippet:

tone(7, 500);
noTone();
delay(1000);

medium

A. noTone() is missing the pin number argument

B. tone() frequency 500 is invalid

C. delay() cannot be used after noTone()

D. tone() must be called after noTone()

Solution

1. Step 1: Check noTone() usage

   The function noTone() requires the pin number to specify which pin to stop sound on. Here, it is called without any argument, which is incorrect.

2. Step 2: Verify other function calls

   The tone(7, 500); is valid, and delay(1000); is allowed after noTone(). The error is only the missing pin argument in noTone().

3. Final Answer:

   noTone() is missing the pin number argument -> Option A

4. Quick Check:

   noTone() needs pin argument = C [OK]

Hint: Always pass pin number to noTone() [OK]

Common Mistakes:

• Calling noTone() without pin
• Thinking delay() is disallowed after noTone()
• Misunderstanding tone() frequency limits

5. You want to play a 440 Hz tone on pin 6 for 2 seconds, then stop the sound immediately. Which code snippet correctly achieves this?

hard

A. tone(6, 440);
delay(2000);
noTone(6);

B. noTone(6);
tone(6, 440);
delay(2000);

C. tone(6, 440);
noTone(6);
delay(2000);

D. tone(6, 440, 2000);
noTone(6);

Solution

1. Step 1: Understand tone() with duration

   tone(6, 440, 2000); plays tone for 2 seconds automatically, so calling noTone(6); immediately after stops it early, which is unnecessary.

2. Step 2: Analyze each option's order

   tone(6, 440); delay(2000); noTone(6); plays tone on pin 6 at 440 Hz, waits 2 seconds, then stops the tone with noTone(6);. This correctly plays sound for 2 seconds then stops.

3. Step 3: Check incorrect options

   noTone(6); tone(6, 440); delay(2000); stops tone before playing it. tone(6, 440); noTone(6); delay(2000); stops tone immediately after starting, so no sound lasts. tone(6, 440, 2000); noTone(6); stops tone immediately after starting with duration, which is redundant.

4. Final Answer:

   tone(6, 440); delay(2000); noTone(6); -> Option A

5. Quick Check:

   Play tone, delay, then noTone = D [OK]

Hint: Play tone, delay for duration, then call noTone(pin) [OK]

Common Mistakes:

• Calling noTone() before delay
• Stopping tone immediately after starting
• Using tone() duration with noTone() redundantly