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.. _1.1.7_py:

1.1.7 I2C LCD1602
======================

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

LCD1602 is a character type liquid crystal display, which can display 32
(16*2) characters at the same time.

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

In this project, we need the following components. 

.. image:: ../img/list_i2c_lcd.png

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_i2c_lcd`
        - |link_i2clcd1602_buy|

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

============ ========
T-Board Name physical
SDA1         Pin 3
SCL1         Pin 5
============ ========

.. image:: ../img/schematic_i2c_lcd.png


Experimental Procedures
-----------------------------

**Step 1:** Build the circuit.

.. image:: ../img/image96.png


**Step 2**: Setup I2C (see :ref:`i2c_config`. If you have set I2C, skip this step.)

**Step 3:** Change directory.

.. raw:: html

   <run></run>

.. code-block::

    cd ~/raphael-kit/python/

**Step 4:** Run.

.. raw:: html

   <run></run>

.. code-block::

    sudo python3 1.1.7_Lcd1602.py

After the code runs, you can see ``Greetings!, From SunFounder`` displaying on the LCD.

.. note::

    * If you get the error ``FileNotFoundError: [Errno 2] No such file or directory: '/dev/i2c-1'``, you need to refer to :ref:`i2c_config` to enable the I2C.
    * If you get ``ModuleNotFoundError: No module named 'smbus2'`` error, please run ``sudo apt install python3-smbus2``.
    * If the error ``OSError: [Errno 121] Remote I/O error`` appears, it means the module is miswired or the module is broken.
    * If the code and wiring are fine, but the LCD still does not display content, you can turn the potentiometer on the back to increase the contrast.



**Code** 

.. note::

    You can **Modify/Reset/Copy/Run/Stop** the code below. But before that, you need to go to  source code path like ``raphael-kit/python``. After modifying the code, you can run it directly to see the effect.


.. raw:: html

    <run></run>

.. code-block:: python

    import LCD1602
    import time

    def setup():
        LCD1602.init(0x27, 1)   # init(slave address, background light)
        LCD1602.write(0, 0, 'Greetings!')
        LCD1602.write(1, 1, 'From SunFounder')
        time.sleep(2)

    def destroy():
        LCD1602.clear()

    if __name__ == "__main__":
        try:
            setup()
        except KeyboardInterrupt:
            destroy()



**Code Explanation**

.. code-block:: python

    import LCD1602

This file is an open source file for controlling I2C LCD1602. It allows us to easily use I2C LCD1602.

.. code-block:: python

    LCD1602.init(0x27, 1) 

The function initializes the I2C system with the designated device symbol. The first parameter is the address of the I2C device, which can be detected through the i2cdetect command (see Appendix for details). The address of I2C LCD1602 is generally 0x27.

.. code-block:: python

    LCD1602.write(0, 0, 'Greetings!')

Within this function, 'Greetings!! ' is the character to be printed on the Row 0+1, column 0+1 on LCD. 
Now you can see “Greetings!! From SunFounder” displayed on the LCD.

Phenomenon Picture
--------------------------

.. image:: ../img/image97.jpeg