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.. _2.1.3_js:

2.1.3 Touch Switch Module
=================================

Introduction
-------------------

In this project, you will learn about touch switch module. It can replace the traditional kinds of switch with these advantages: convenient operation, fine touch sense, precise control and least mechanical wear.


Required Components
------------------------------

In this project, we need the following components. 

.. image:: ../img/2.1.3component.png
    :width: 700
    :align: center

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
    *   - Raphael Kit
        - 337
        - |link_Raphael_kit|

You can also buy them separately from the links below.

.. list-table::
    :widths: 30 20
    :header-rows: 1

    *   - COMPONENT INTRODUCTION
        - PURCHASE LINK

    *   - :ref:`cpn_gpio_board`
        - |link_gpio_board_buy|
    *   - :ref:`cpn_breadboard`
        - |link_breadboard_buy|
    *   - :ref:`cpn_wires`
        - |link_wires_buy|
    *   - :ref:`cpn_resistor`
        - |link_resistor_buy|
    *   - :ref:`cpn_led`
        - |link_led_buy|
    *   - :ref:`cpn_touch_switch`
        - |link_touch_buy|

Schematic Diagram
-----------------

.. image:: ../img/2.1.3circuit.png
    :width: 500
    :align: center

**Experimental Procedures**
------------------------------

**Step 1:** Build the circuit.

.. image:: ../img/2.1.3fritzing.png
    :width: 700
    :align: center

**Step 2:** Go to the folder of the code.

.. raw:: html

   <run></run>

.. code-block::

    cd ~/raphael-kit/nodejs/

**Step 3:** Run the code.

.. raw:: html

   <run></run>

.. code-block::

    sudo node touch_switch.js

While the code is running, the red LED lights up; when you tap on the touch switch module, the yellow LED turns on. 

**Code**

.. code-block:: js

    const Gpio = require('pigpio').Gpio; 

    const led1 = new Gpio(22, {mode: Gpio.OUTPUT});
    const led2 = new Gpio(27, {mode: Gpio.OUTPUT});

    const touchSwitch = new Gpio(17, {
        mode: Gpio.INPUT,
        pullUpDown: Gpio.PUD_DOWN,     
        edge: Gpio.EITHER_EDGE        
    });

    touchSwitch.on('interrupt', (level) => {  
        led1.digitalWrite(level);   
        led2.digitalWrite(!level);       
    });   

**Code Explanation**

.. code-block:: js

    const Gpio = require('pigpio').Gpio; 

    const led1 = new Gpio(22, {mode: Gpio.OUTPUT});
    const led2 = new Gpio(27, {mode: Gpio.OUTPUT});

    const touchSwitch = new Gpio(17, {
        mode: Gpio.INPUT,
        pullUpDown: Gpio.PUD_DOWN,     
        edge: Gpio.EITHER_EDGE        
    });


Import the ``pigpio`` module and create three objects led1, led2, touchSwitch,
By reading the level of the touchSwitch IO port, the on and off of led1 and led2 are controlled.

.. code-block:: js

    touchSwitch.on('interrupt', (level) => {  
        led1.digitalWrite(level);   
        led2.digitalWrite(!level);       
    });   

When the level of the read touchSwitch IO port changes,
Write the same level to led1 and the opposite level to led2.


**Phenomenon Picture**
------------------------

.. image:: ../img/2.1.3touch_switch_module.JPG
    :width: 500
    :align: center