Mission 12 · Stage 2

Push Button Buzzer

if statement branches output

Play a buzzer tone when the button is pressed using an if statement.

Pin connections

Part 1		Part 2
Arduino pin 2	→	Button pin 1
Button pin 2	→	Arduino GND
Buzzer pin 1 (+)	→	Arduino pin 8
Buzzer pin 2 (-)	→	Arduino GND

See it

Let's make your code choose!

Press the button and the buzzer beeps. Let go and it stops — your code decides!

An "if" choice like this runs alarms, games, and robots every day.

The story

The problem

You want one thing to happen when the button is down, and another when it is up.

Think of it like

It's like saying "If it is raining, take an umbrella."

Meet the parts

It decides when the buzzer should beep.

Arduino

The brain

Loading part…

Press it to tell the brain to make sound.

Button

The button

Loading part…

It beeps when the brain says so.

Buzzer

The noise maker

Loading part…

How it works

Check button

This question is only true while you are holding the button down.

if (digitalRead(BUTTON_PIN) == LOW)

Play tone

Inside the if, the buzzer plays a beep at pitch 440.

tone(BUZZER_PIN, 440);

Otherwise stop

When you are not pressing, noTone keeps the buzzer quiet.

else { noTone(BUZZER_PIN); }

Then loop back to step 1

Build the circuit

Follow these steps in order. Match the wires to the colors shown.

1
Place Arduino
Place the Arduino (uno) on the breadboard.
Arduino placed — ready to build!
Loading part…
2
Place Button
Place the Button (btn1) on the breadboard.
Loading part…
3
Place Buzzer
Place the Buzzer (bz1) on the breadboard.
Loading part…
4
Connect Arduino pin 2 to Button (btn1) 1.l
Connect Arduino pin 2 to Button (btn1) 1.l.
5
Connect Button (btn1) 2.l to Arduino GND
Connect Button (btn1) 2.l to Arduino GND.
6
Connect Buzzer (bz1) 1 to Arduino pin 8
Connect Buzzer (bz1) 1 to Arduino pin 8.
7
Connect Buzzer (bz1) 2 to Arduino GND
Connect Buzzer (bz1) 2 to Arduino GND.

Try it

Press and hold — you should hear a steady beep.
Let go — silence! That is your "if" choice working.

Peek at code

Get input and output ready

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
}

The button is set to listen, and the buzzer pin is set to push sound out.

The if / else choice

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {
    tone(BUZZER_PIN, 440);
  } else {
    noTone(BUZZER_PIN);
  }
  delay(20);
}

One path plays a beep, the other stops it — that is an if/else choice.

Show full sketch (pushbutton-buzzer.ino)

const int BUTTON_PIN = 2;
const int BUZZER_PIN = 8;
void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
}
void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {
    tone(BUZZER_PIN, 440);
  } else {
    noTone(BUZZER_PIN);
  }
  delay(20);
}

Quick quiz

Q1. Where does work that repeats go?

A. loop() ✓
B. setup()
C. pinMode only

Why: Yes! loop() runs again and again.

Q2. What happens when the button is NOT pressed?

A. The else part runs noTone() and the buzzer is quiet ✓
B. setup() runs again
C. The beep plays forever

Why: Yes! The else part calls noTone() to stop the buzzer.

Code lab — try on your own

Make the beep higher — change tone(BUZZER_PIN, 440) to use 880.
Hint: It's inside the if, line 9.
Add a note (comment) above the if line: // buzzer when pressed
Hint: That's line 8.

Code walkthrough

A line-by-line tour of the sketch — the same steps as in Robot Gurukul Studio.

Program overview

Big idea

Every Arduino program has a top part, a setup() part that runs once, and a loop() part that runs again and again.

In this project

Hold the button and the buzzer plays a beep. Let go and it stops.

Tip

Read from the top to the bottom. Tap any word or line if you need help!

const int BUTTON_PIN = 2;
const int BUZZER_PIN = 8;

setup()

Big idea

setup() runs one time when the board turns on.

In this project

It gets the button ready to listen and pin 8 ready for the buzzer.

Why here

Things we do only once go inside setup().

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
}

loop()

Big idea

loop() runs again and again, forever.

In this project

It keeps asking "is the button pressed?" and beeps or stays quiet.

Why here

Things that repeat go inside loop().

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {
    tone(BUZZER_PIN, 440);
  } else {
    noTone(BUZZER_PIN);
  }
  delay(20);
}

Try this: Change a number inside loop(), then press Run to see what happens.

pinMode

Big idea

pinMode tells a pin if it will listen or push power out.

In this project

It makes pin 2 listen to the button and pin 8 push sound to the buzzer.

Why here

It goes in setup() because we only set it once.

  pinMode(BUTTON_PIN, INPUT_PULLUP);

digitalRead

Big idea

digitalRead checks if a pin is ON or OFF.

In this project

It checks if you are pressing the button.

Why here

It goes in loop() so we can react the moment you press.

  if (digitalRead(BUTTON_PIN) == LOW) {

tone

Big idea

tone makes a buzzer play a beep at a chosen pitch.

In this project

When you press, it plays a 440 note.

Why here

It goes in loop() so it can play when the button is held.

    tone(BUZZER_PIN, 440);

noTone

Big idea

noTone stops the buzzer so it goes quiet.

In this project

When you let go of the button, the beep stops.

Why here

It goes in loop() to turn the sound off when not pressing.

    noTone(BUZZER_PIN);

delay

Big idea

delay means wait. Nothing else happens while it waits.

In this project

A tiny wait makes the button read nice and steady.

Why here

Right after we check the button and play or stop the sound.

  delay(20);

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