Boot from microSD card

U-Boot is capable of starting a complete Yocto system from a microSD card. To boot a system from a microSD card, follow these steps:

1. Create a bootable microSD card from a Yocto image

2. Boot Yocto from the microSD card

1. Create a bootable microSD card from a Yocto image

Requirements:

The following procedure will destroy existing data in the microSD card.

To create a bootable microSD card from an existing Yocto image:

  1. Download the bootable Yocto image from this URL: ftp://ftp1.digi.com/support/digiembeddedyocto/2.2/r3/images/ccimx6sbc/x11/
  2. Extract the .sdcard file from the zip you downloaded into a folder of your choice.
  3. Insert the microSD card into your computer and check the node Linux assigns to it (/dev/[sdcard]) using dmesg:
    $ dmesg
[1413652.901270] sd 41:0:0:0: [sdc] 7744512 512-byte logical blocks: (3.96 GB/3.69 GiB)
[1413652.903140] sd 41:0:0:0: [sdc] No Caching mode page present
[1413652.903144] sd 41:0:0:0: [sdc] Assuming drive cache: write through
[1413652.905638] sd 41:0:0:0: [sdc] No Caching mode page present
[1413652.905642] sd 41:0:0:0: [sdc] Assuming drive cache: write through
[1413652.915154] sdc: sdc1

    Do not mount any partitions the card might contain (or unmount any partition if automatically mounted) as you will be writing to the entire block device.

    Using an incorrect device node in the next step might destroy all data on your computer hard drive.

  4. Raw write the image file to the microSD card with this command:
    $ sudo dd if=<path/filename.sdcard> of=/dev/<sdcard> bs=512 && sync

    In this example:

    • You must substitute <path/filename.sdcard> with the path and filename to the SD card image.
    • You must substitute <sdcard> with the device node Linux assigned to your microSD card.

The microSD card is now ready.

2. Boot Yocto from the microSD card

  1. Power off the device.
  2. Insert the microSD card into the microSD card holder (bottom side of the board).
  3. Change the boot source configuration to boot from the microSD card. To do so, set the boot mode micro-switches as follows:
    • SW3.1 OFF
    • SW3.2 ON

  4. Power on the device.

Digi Embedded Yocto now boots from the microSD card.