eMMC

This guide will show how to mount, read from, and write to the phyCORE-i.MX7 onboard eMMC. In order to follow this guide your phyBOARD-i.MX7 development kit must be booting from SD Card.

Be careful with the fdisk command. You can accidentally delete the contents of other memory devices connected to the system.

Step-by-Step Guide

Viewing available eMMC partition information

• The eMMC corresponds to /dev/mmcblk2 in Linux when booting from SD Card. You can verify the eMMC partitions by using the following command:

  Target (Linux)

  fdisk -l

  CODE

• The fdisk command line utility will output disk partition information. Search through the list and verify the eMMC is listed. You should find an entry similar to the following:

  Expected Output

  Disk /dev/mmcblk2: 3.6 GiB, 3850371072 bytes, 7520256 sectors
  Units: sectors of 1 * 512 = 512 bytes
  Sector size (logical/physical): 512 bytes / 512 bytes
  I/O size (minimum/optimal): 512 bytes / 512 bytes
  Disklabel type: dos
  Disk identifier: 0x243d4084
  
  Device         Boot Start     End Sectors  Size Id Type
  /dev/mmcblk2p1       4096   20479   16384    8M 83 Linux
  /dev/mmcblk2p2      20480 7520255 7499776  3.6G 83 Linux

  CODE

Mounting the eMMC

• In order to read and write to the eMMC you will need to create a directory and then mount the partition you want to read from to that directory. Follow the steps below to mount partition 1 of the eMMC:

  Target (Linux)

  mkdir temp && mount /dev/mmcblk2p1 temp/

  CODE

• Check the contents of the eMMC by entering the following: 

  Target (Linux)

  ls temp

  CODE

Writing to the eMMC

• You can write to the eMMC by using the copy or move commands just like in Linux. To demonstrate, first create a test file.

  Target (Linux)

  echo "Hello World" > test.txt

  CODE

• Now copy this file to the mounted eMMC:

  Target (Linux)

  cp test.txt temp/

  CODE

• Verify that the file was written to the eMMC (test.txt should be listed in the output): 

  Target (Linux)

  ls temp

  CODE