eMMC

Flashing the eMMC

By default, the phyCORE-AM62Ax development kit is configured to boot from an SD Card. This is generally one of the most convenient methods to boot your hardware throughout development because it allows for easy software updates and file transfers between your Host and target systems. In addition to creating a standard bootable SD card formatted with the phyCORE-AM62Ax Linux BSP, the following steps can be used to burn bootable software images to the onboard eMMC flash memory of the SOM, thus freeing up the SD Card slot on the carrier board.

The easiest way to access the SOM’s eMMC is to boot the SOM into Linux from an SD Card (you may already be doing this). The Linux instance running from the SD Card will need access to software binaries to flash to the eMMC; thus, we will also need to transfer those binaries to the SD Card so that they are present and accessible at runtime.

Note

When you boot into Linux from an SD Card, obviously all the required binaries for boot are all already present on the SD Card. But, the tricky part with copying the “in-use” software components, specifically the root filesystem of the SD Card, is that it is already actively mounted in memory while Linux is up and running. This makes copying the root filesystem to the eMMC complicated and prone to filesystem corruption/errors. For this reason, it is best to transfer the tarballed rootfs to the SD Card itself so that we have a inactive, unmounted copy of the root filesystem in userspace (it’s sort of like root filesystem “inception”, like that one confusing movie with Leonardo DiCaprio).

What You’ll Need

  • Ubuntu 22.04 LTS, 64-bit Host Machine or a Windows Machine

    • If using a virtual machine, VMWare Workstation, VMWare Player, and VirtualBox are all viable solutions.

  • SD Card Reader

  • 4GB micro-SD Card or larger (Included in development kit)

Preparing to Flash eMMC (Software)

  • Download the prebuilt SD card image (wic.xz) on your machine. Find the pre-build images on the Pre-Built Binaries guide.

Linux Machine

  • Power off the development kit and insert the micro-SD card from the development kit to your SD card reader.

    Target (Linux)
    poweroff

  • Transfer the SD card image onto the SD card.

    Host (Ubuntu)
    cd <image location>
sudo cp phytec-qt5demo-image-phyboard-lyra-am62axx-1.wic.xz /media/<user>/root
sudo umount /media/<user>/root

  • Safely eject the SD card from the Linux host machine.

  • Insert the micro-SD card into the development kit.

Windows Machine (SCP)

These instructions would work with a Linux machine as well via terminal.

  • With the develeopment kit booted into Linux, confirm the development kit’s ethernet IP address (DHCP). For more information on how to change the from a static IP address to a DHCP address, see the Ethernet interface guide.

    Target (Linux)
    ip addr

  • Open the Command Prompt tool on Windows and navigate to the directory where the SD card image and bootloader files are located.

    Host (Windows)
    cd <insert-path-to-files>

  • Transfer the files to the development kit’s root directory.

    Host (Windows)
    scp phytec-qt5demo-image-phyboard-lyra-am62axx-1.wic.xz root@<insert-IP-address>:~

Preparing to Flash eMMC (Hardware)

  • With the development kit powered off, verify that the boot switches are set to boot from SD card, not eMMC.

    See the table on Booting Essentials page to confirm SD card boot switches.

Starting with a Clean eMMC

  • Check the eMMC for existing filesystem partitions

Note

The eMMC is /dev/mmcblk0 and the SD Card is /dev/mmcblk1.

Target (Linux)
fdisk -l /dev/mmcblk0

You should see something like the following:

Example Output
root@phyboard-lyra-am62axx-2:~# fdisk -l /dev/mmcblk0
Disk /dev/mmcblk0: 14.69 GiB, 15758000128 bytes, 30777344 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: 0x327de2fa

Device         Boot  Start     End Sectors   Size Id Type
/dev/mmcblk0p1 *      2048  273063  271016 132.3M  c W95 FAT32 (LBA)
/dev/mmcblk0p2      274432 5799513 5525082   2.6G 83 Linux

  • In the above example output, we see that /dev/mmcblk0 has a two partitions on it. For the sake of this guide, we are going to first delete any and all existing partitions so that we can start from a clean eMMC flash device. We can do this using an fdisk interactive session.

    Target (Linux)
    umount /dev/mmcblk0*
fdisk /dev/mmcblk0

# Use the following command sequence for reference once in the fdisk interactive session.
d # delete partition (you will need to repeat this for every partition present)
w # write the changes to the disk

Flash the eMMC

  • Now we can flash the eMMC using the SD card binary you previously downloaded.

    Target (Linux)
    xzcat -dc phytec-qt5demo-image-phyboard-lyra-am62axx-2.wic.xz | dd of=/dev/mmcblk0 bs=4M conv=fsync

  • Now when you run the following ‘fdisk’* command the eMMC should be partitioned into two parts.

    Target (Linux)
    fdisk -l /dev/mmcblk0
    Expected Output
    root@phyboard-lyra-am62axx-1:~# fdisk -l /dev/mmcblk0
Disk /dev/mmcblk0: 15 GB, 15913189376 bytes, 31080448 sectors
242816 cylinders, 4 heads, 32 sectors/track
Units: sectors of 1 * 512 = 512 bytes

Device       Boot StartCHS    EndCHS        StartLBA     EndLBA    Sectors  Size Id Type
/dev/mmcblk0p1 *  16,0,1      1023,3,32         2048     264191     262144  128M  c Win95 FAT32 (LBA)
/dev/mmcblk0p2    1023,3,32   1023,3,32       264192    2121229    1857038  906M 83 Linux

  • Now we must also flash the bootloader to the eMMC.

    Target (Linux)
    echo 0 > /sys/class/block/mmcblk0boot0/force_ro

dd if=/boot/tiboot3.bin of=/dev/mmcblk0boot0 count=1024 conv=fsync
dd if=/boot/tispl.bin of=/dev/mmcblk0boot0 seek=1024 count=3072 conv=fsync
dd if=/boot/u-boot.img of=/dev/mmcblk0boot0 seek=5120 count=3072 conv=fsync

  • The following must be run once per eMMC device in order for it to allow the bootROM to load the bootloaders from it. Once done for a given phyCORE-AM62Ax SOM, you won’t ever have to do this again for the life of that device.

    Target (Linux)
    mmc bootpart enable 1 1 /dev/mmcblk0
mmc bootbus set single_backward x1 x8 /dev/mmcblk0
mmc hwreset enable /dev/mmcblk0

  • Power off the development kit and configure the hardware to boot from the onboard eMMC flash. See the section “Booting from eMMC” for more information on that.

Booting from eMMC

The phyCORE-AM62Ax development kit is configured to boot from an SD Card slot by default. This guide will serve to provide basic steps for booting from the SOM’s onboard eMMC flash memory after it has been flashed.

Boot Switch Settings

  • S7 should be ON

eMMC Boot Switch phyBOARD-AM62Ax boot switches

Note

Be mindful of the switch orientation!