SD Card
=========

The phyCORE-AM65x SOM brings out a 4-bit wide MMC data bus to the standard SDHC card slot at X13. Power to the card slot is supplied by inserting the appropriate card into the SD/MMC1 connector, which features card detection. This interface shares a bus with the WiFi module on the SOM, but is available on the development kit as an SD card interface for external media or as a bootable interface.

.. note:: In order to follow this guide, you will have to boot from the on-board eMMC. Follow this guide in order to flash :ref:`flashemmc-65`


.. image:: ../../images/phycore-am65x/pcm-067-sd-x13.webp
    :width: 800px
    :alt: phyCORE-AM65x microSD Card Connector

Requirements
-------------

* SDHC SD card, at least 8GB for PHYTEC's TISDK release image (Included in development kit)
* Linux Host PC or Virtual Machine (Ubuntu recommended) (Only for transferring media from Host)
* SD card reader (operational under Linux) (Only for transferring media from Host)

.. note:: When an external SD Card is inserted, it will be available as /dev/mmcblk1 in Linux.


Mounting the SD card
-----------------------

* Create a temporary directory and mount an SD card partition using the below commands:

  .. code-block:: none
    :caption: Target (Linux)

    mkdir /home/root/temp
    mount /dev/mmcblk1p1 /home/root/temp

Write to the SD Card
----------------------

* You can use basic Linux commands to create and write files to the SD card. Below is an example:

  .. code-block:: none
   :caption: Target (Linux)

   echo "Hello World" > test.txt
   cp test.txt /home/root/temp/

Read from the SD Card
----------------------------

* To read what was just written to the SD card in the previous example, use the following command:

  .. code-block:: none
    :caption: Target (Linux)

    cp /home/root/test.txt read.txt

* To check that the read file (read.txt) is the same as the one that was written (test.txt) you can use md5sum to compare and verify the data transfer was successful:

  .. code-block:: none
    :caption: Target (Linux)

    md5sum /home/root/test.txt && md5sum read.txt

* The above command will generate a long and seemingly random string of characters for both files. This long string is called a "hash" and it uniquely identifies the files. If the hash for both files match then you can be confident that both files (down to each bit) are identical.

  .. code-block:: none
    :caption: Expected Output

    root@am65xx-phycore-kit:~# md5sum /home/root/test.txt && md5sum read.txt
    e59ff97941044f85df5297e1c302d260  /home/root/test.txt
    e59ff97941044f85df5297e1c302d260  read.txt

Unmounting the SD Card
-----------------------

* Before unplugging the device from the development kit, make sure to unmount it in software. You can do this by running the following command:

  .. code-block:: none
    :caption: Target (Linux)

    umount /home/root/temp