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.. _ar_ac_buz:

3.1 Make the Buzzer Beep!
==========================

In this lesson, we will learn how to make a **buzzer** beep using the Raspberry Pi Pico 2. A buzzer is a digital output device, just like an LED, and it's very simple to control. We'll use an **active buzzer** for this project, which generates sound when it receives a signal.

**What is an Active Buzzer?**

An **active buzzer** has an internal oscillator that makes it easier to use. You only need to send a signal to the buzzer to make it beep—no complex frequency control is required. This is different from a **passive buzzer**, which requires an external signal to generate sound.

|img_buzzer|


**What You'll Need**

In this project, we need the following components. 

It's definitely convenient to buy a whole kit, here's the link: 

.. list-table::
    :widths: 20 20 20
    :header-rows: 1

    *   - Name	
        - ITEMS IN THIS KIT
        - LINK
    *   - Newton Lab Kit	
        - 450+
        - |link_newton_lab_kit|

You can also buy them separately from the links below.


.. list-table::
    :widths: 5 20 5 20
    :header-rows: 1

    *   - SN
        - COMPONENT	
        - QUANTITY
        - LINK

    *   - 1
        - :ref:`cpn_pico_2`
        - 1
        - |link_pico2_buy|
    *   - 2
        - Micro USB Cable
        - 1
        - 
    *   - 3
        - :ref:`cpn_breadboard`
        - 1
        - |link_breadboard_buy|
    *   - 4
        - :ref:`cpn_wire`
        - Several
        - |link_wires_buy|
    *   - 5
        - :ref:`cpn_transistor`
        - 1(S8050)
        - |link_transistor_buy|
    *   - 6
        - :ref:`cpn_resistor`
        - 1(1KΩ)
        - |link_resistor_buy|
    *   - 7
        - Active :ref:`cpn_buzzer`
        - 1
        - 


**Circuit Diagram**

|sch_buzzer|

In this circuit, the buzzer is powered through a transistor (**S8050** NPN). The transistor amplifies the current, making the buzzer sound louder than if it were connected directly to the Pico. 

Here's what happens:

* **GP15** outputs a high signal to control the transistor.
* When the transistor is activated, it allows current to flow through the buzzer, making it beep.

A **1kΩ resistor** is used to limit the current to protect the transistor.

**Wiring Diagram**

Make sure you are using the **active buzzer**. You can tell it's the correct one by looking for the sealed back (as opposed to the exposed PCB, which is a passive buzzer).

|img_buzzer|

|wiring_beep|


**Writing the Code**


.. note::

   * You can open the file ``3.1_beep.ino`` from ``newton-lab-kit/arduino/3.1_beep``. 
   * Or copy this code into **Arduino IDE**.
   * Select the **Raspberry Pi Pico 2** board and the correct port, then click "Upload".

.. code-block:: Arduino

    const int buzzerPin = 15;  // GPIO pin connected to the transistor base

    void setup() {
      pinMode(buzzerPin, OUTPUT);
    }

    void loop() {
      digitalWrite(buzzerPin, HIGH);  // Turn the buzzer on
      delay(1000);                    // Wait for 1 second
      digitalWrite(buzzerPin, LOW);   // Turn the buzzer off
      delay(1000);                    // Wait for 1 second
    }

After uploading the code:
The buzzer should beep for 1 second, then stay silent for 1 second, and repeat this pattern continuously.
If you do not hear the buzzer, check the wiring to ensure all connections are correct.
Make sure you are using an active buzzer.

**Understanding the Code**

#. Defining the Buzzer Pin:

   Assigns buzzerPin to GPIO 15, which controls the transistor and thus the buzzer.

   .. code-block:: Arduino

        const int buzzerPin = 15;  // GPIO pin connected to the transistor base

#. Setting Up the Pin Mode:

   Configures buzzerPin as an output.

   .. code-block:: Arduino

        void setup() {
          pinMode(buzzerPin, OUTPUT);
        }

#. Controlling the Buzzer: The ``loop()`` function repeats this process indefinitely, making the buzzer beep every second.


   * ``digitalWrite(buzzerPin, HIGH)``: Sets ``buzzerPin`` ``HIGH``, turning on the transistor, which allows current to flow through the buzzer, making it beep.
   * ``delay(1000)``: Pauses the program for 1000 milliseconds (1 second).
   * ``digitalWrite(buzzerPin, LOW)``: Sets ``buzzerPin`` ``LOW``, turning off the transistor, stopping the current flow, and silencing the buzzer.

   .. code-block:: Arduino

        void loop() {
          digitalWrite(buzzerPin, HIGH);  // Turn the buzzer on
          delay(1000);                    // Wait for 1 second
          digitalWrite(buzzerPin, LOW);   // Turn the buzzer off
          delay(1000);                    // Wait for 1 second
        }


**Further Exploration**

* Varying the Beep Duration:

  * Modify the ``delay()`` values to change how long the buzzer stays on and off.
  * Experiment with shorter or longer durations.

* Creating Patterns:

  * Create more complex patterns by adjusting the timing in the ``loop()`` function.
  * For example, create an SOS signal in Morse code.

* Using a Passive Buzzer:

  * Try using a passive buzzer and the ``tone()`` function to generate different frequencies.
  * Note that the wiring and code will be different for a passive buzzer.

**Conclusion**

In this lesson, you've learned how to make an active buzzer beep using the Raspberry Pi Pico and a transistor. By controlling the transistor with a GPIO pin, you can safely switch the buzzer on and off without overloading the Pico's GPIO pins. This basic concept can be expanded upon to create more complex sounds or to use buzzers in alarms, notifications, and interactive projects.