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.. _2.2.10_c:

2.2.10 MFRC522 RFID Module
================================

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

Radio Frequency Identification (RFID) refers to technologies that use
wireless communication between an object (or tag) and interrogating
device (or reader) to automatically track and identify such objects.

Some of the most common applications for this technology include retail
supply chains, military supply chains, automated payment methods,
baggage tracking and management, document tracking and pharmaceutical
management, to name a few.

In this project, we will use RFID for reading and writing.

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

In this project, we need the following components. 

.. image:: ../img/list_2.2.7.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_mfrc522`
        - |link_mfrc522_rfid_buy|

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

.. image:: ../img/image331.png


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

**Step 1:** Build the circuit.

.. image:: ../img/image232.png


**Step 2:** Set up SPI (refer to :ref:`spi_configuration` for more details. If you have
set SPI, skip this step.)

**Step 3:** Go to the folder of the code.

.. raw:: html

   <run></run>

.. code-block:: 

    cd ~/raphael-kit/c/2.2.10/

**Step 4:** Compile the code.

.. raw:: html

   <run></run>

.. code-block:: 

    make read
    make write


**Step 5:** After running ``./write``, enter the information, such as the name of the person, and then put the tag or card on the MRC522 module and wait for the writing to be completed.

.. raw:: html

   <run></run>

.. code-block::

    sudo ./write

**Step 6:** Now run ``./read`` to read the information of the tag or card you have written.

.. raw:: html

   <run></run>

.. code-block:: 

    sudo ./read

.. note::

    If it does not work after running, or there is an error prompt: \"wiringPi.h: No such file or directory\", please refer to :ref:`install_wiringpi`.

**Code Explanation**

.. code-block:: c

    InitRc522();

This function is used to initialize the RFID RC522 module.

.. code-block:: c

    uint8_t read_card_data();

This function is used to read the data of the card, and if 
the read is successful, it will return "1".

.. code-block:: c

    uint8_t write_card_data(uint8_t *data);

This function is used to write the data of card and returns "1" if 
the write is successful. ``*data`` is the information that will be written 
to the card.

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

.. image:: ../img/image233.jpeg