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.. _per_service_bell:

2.3 Service Bell
==========================

For this project we used a microswitch and an active buzzer to create a service bell. Tap the switch and the buzzer makes a sound.

Micro Switch is also a 3-pin device, the sequence of the 3 pins are C (common pin), NO (normally open) and NC (normally closed).

When the micro switch is not pressed, 1 (C) and 3 (NC) are connected together, when pressed 1 (C) and 2 (NO) are connected together.

|img_micro_switch|

* :ref:`cpn_bb`
* :ref:`cpn_led`
* :ref:`cpn_res`
* :ref:`cpn_limit_sw`
* :ref:`cpn_cap`
* :ref:`cpn_transistor`
* :ref:`cpn_buzzer`

**Wiring**

|service_bell0|

* By default, pins 1 and 3 of the Micro Switch are connected together and GP14 is low. When the Micro Switch is pressed, GP14 is high.
* GP15 outputs high to make the buzzer sound.

**Code**

.. note::

    * You can refer to the image below to write code by dragging and dropping. 
    * Import ``2.3_service_bell.png`` from the path of ``euler-kit\piper``. For detailed tutorials, please refer to :ref:`import_code_piper`.


|service_bell|

After connecting Pico, click the **Start** button and the code starts to run. Tap the switch and the buzzer makes a sound.

.. note::
    This project code is exactly the same as the previous project :ref:`per_button`.