In the following scenarios, you can use U-Boot instead of a Linux software update package to program the firmware in your device:

  • You only want to update one partition with the artifact generated by a Digi Embedded Yocto project.

  • You don’t have any firmware programmed in your device (except the bootloader).

  • Your bootloader is corrupt and does not boot. In this case, first see Recover your device.

If none of these scenarios apply, Digi recommends updating the firmware from Linux. See Program firmware from Linux

Update firmware from TFTP

U-Boot bootloader allows you to update the firmware of your device over Ethernet. U-Boot uses the TFTP protocol to get the firmware images from a TFTP server running on your computer and programs them onto the eMMC of the device.

This update process requires a TFTP server running on your computer with a configured exposed folder. If you don’t have a running TFTP server, follow the installation instructions in Install Digi Embedded Yocto. The devices look for the firmware files in this folder when performing the update.

Once you have the TFTP server running on your computer, you can start the update process:

  1. Get the Yocto firmware images:

    • <u-boot-file>.bin for your hardware variant. See Hardware variants.

    • <boot-file>.boot.vfat

    • <recovery-file>.recovery.vfat

    • <rootfs-file>.rootfs.ext4

    1. After building the Yocto firmware, you can find the image files inside the project directory at:

      <project_folder>/tmp/deploy/images/<platform>

    2. You can download Digi provided pre-built images from:

  2. Copy the images in your TFTP server’s exposed folder (typically /tftpboot).

  3. Connect the board to your host computer. See Step 2 - Set up the hardware for instructions.

  4. Open a serial connection to the serial port to which the device is connected. Use the following settings:

    • Port: Serial port where your ConnectCore board is attached

    • Baud rate: 115200

    • Data Bits: 8

    • Parity: None

    • Stop Bits: 1

    • Flow control: None

  5. Reset the device (press the Reset button on the board) and immediately press a key in the serial terminal to stop the auto-boot process. You will be stopped at the U-Boot bootloader prompt:

    U-Boot SPL dub-2020.04-r2.2 (Jan 18 2021 - 15:54:36 +0000)
DDRINFO: start DRAM init
DDRINFO: DRAM rate 3000MTS
DDRINFO:ddrphy calibration done
DDRINFO: ddrmix config done
Normal Boot
Trying to boot from BOOTROM
image offset 0x0, pagesize 0x200, ivt offset 0x0


U-Boot dub-2020.04-r2.2 (Jan 18 2021 - 15:54:36 +0000)

CPU:   i.MX8MNano Quad rev1.0 1400 MHz (running at 1200 MHz)
CPU:   Industrial temperature grade (-40C to 105C) at 36C
Reset cause: POR
DRAM:  1 GiB
MCA:   HW_VER=1  FW_VER=1.01
MMC:   FSL_SDHC: 1, FSL_SDHC: 0
In:    serial
Out:   serial
Err:   serial
Model: Digi ConnectCore 8M Nano Development Kit
ConnectCore 8M Nano SOM variant 0x01: 1 GiB LPDDR4, Wi-Fi, Bluetooth, MCA, Crypto-auth
  Board version 3, ID undefined
Boot:  MMC2

 BuildInfo:
  - ATF 9447098
  - U-Boot dub-2020.04-r2.2

flash target is MMC:0
Net:   eth0: ethernet@30be0000
Fastboot: Normal
Normal Boot
Hit any key to stop autoboot:  0
{pu}

  6. Configure the network settings of the device by doing one of the following:

    • Get a dynamic IP address from a DHCP server by running the following commands:

      => setenv autoload no
=> dhcp

    • Configure a static IP address, where a.b.c.d is the IP address of your device:

      => setenv ipaddr a.b.c.d

  7. Configure the IP address of the machine where the TFTP server is running and save the configuration as follows, where w.x.y.z is your machine IP address where the TFTP server is running:

    => setenv serverip w.x.y.z
=> saveenv

  8. Update the U-Boot image (optional):

    1. Execute the following command to update the U-Boot image:

      => update uboot tftp <u-boot-file>.bin

    2. Reset the board to boot into the recently updated U-Boot, and press any key to stop the autoboot process.

    3. Reset the U-Boot environment to default values (this will not reset protected variables like the MAC address). To do so, issue this command:

      => env default -a

    4. Configure the network and TFTP settings on your device again and save the configuration.

  9. Configure the partition of the eMMC for holding Yocto images by running these commands:

    => setenv mmcdev 0
=> run partition_mmc_linux

  10. Update the boot image by executing this command:

    => update linux tftp <boot-file>.boot.vfat

  11. Update the root file system image by issuing this command:

    => update rootfs tftp <rootfs-file>.rootfs.ext4

  12. Update the recovery image by executing this command:

    => update recovery tftp <recovery-file>.recovery.vfat

  13. You can format the update partition or directly boot the new firmware:

    • To format the update partition, run the following commands. They boot in recovery mode to format the partition and then boots the device normally with the new firmware:

      => setenv recovery_command wipe_update
=> saveenv
=> run recoverycmd

    • If the update partition is already formatted or you want to preserve its contents, boot the device with the firmware you have just programmed:

      => boot

Update firmware from microSD

If you don’t have a TFTP server, you can still program Yocto in your device using a microSD card. The microSD card must be FAT formatted.

Your microSD card must have at least 2 GB of capacity.

To program Yocto from the microSD card:

  1. Power off the device.

  2. Change the boot source configuration to boot from the internal eMMC.

    • S1.1: OFF

    • S1.2: OFF

    • S1.3: OFF

    • S1:4: N/A

      eMMC boot

  3. Get the Yocto firmware images:

    • <u-boot-file>.bin for your hardware variant. See Hardware variants.

    • <boot-file>.boot.vfat

    • <recovery-file>.recovery.vfat

    • <rootfs-file>.rootfs.ext4

    1. After building the Yocto firmware, you can find the image files inside the project directory at:

      <project_folder>/tmp/deploy/images/<platform>

    2. You can download Digi provided pre-built images from:

  4. Place the images in the root of the FAT formatted microSD card.

  5. Connect the board to your host computer. See Step 2 - Set up the hardware for instructions.

  6. Open a serial connection to the serial port the device is connected to. Use the following settings:

    • Port: Serial port where the device is attached

    • Baud rate: 115200

    • Data Bits: 8

    • Parity: None

    • Stop Bits: 1

    • Flow control: None

  7. Reset the device (press the Reset button on the board) and immediately press a key in the serial terminal to stop the auto-boot process. You will be stopped at the U-Boot bootloader prompt:

    U-Boot SPL dub-2020.04-r2.2 (Jan 18 2021 - 15:54:36 +0000)
DDRINFO: start DRAM init
DDRINFO: DRAM rate 3000MTS
DDRINFO:ddrphy calibration done
DDRINFO: ddrmix config done
Normal Boot
Trying to boot from BOOTROM
image offset 0x0, pagesize 0x200, ivt offset 0x0


U-Boot dub-2020.04-r2.2 (Jan 18 2021 - 15:54:36 +0000)

CPU:   i.MX8MNano Quad rev1.0 1400 MHz (running at 1200 MHz)
CPU:   Industrial temperature grade (-40C to 105C) at 36C
Reset cause: POR
DRAM:  1 GiB
MCA:   HW_VER=1  FW_VER=1.01
MMC:   FSL_SDHC: 1, FSL_SDHC: 0
In:    serial
Out:   serial
Err:   serial
Model: Digi ConnectCore 8M Nano Development Kit
ConnectCore 8M Nano SOM variant 0x01: 1 GiB LPDDR4, Wi-Fi, Bluetooth, MCA, Crypto-auth
  Board version 3, ID undefined
Boot:  MMC2

 BuildInfo:
  - ATF 9447098
  - U-Boot dub-2020.04-r2.2

flash target is MMC:0
Net:   eth0: ethernet@30be0000
Fastboot: Normal
Normal Boot
Hit any key to stop autoboot:  0
{pu}

  8. Optional. Update the U-Boot image:

    1. Execute the following command to update the U-Boot image:

      => update uboot mmc 1 fat <u-boot-file>.bin

    2. Reset the board to boot into the recently updated U-Boot, and press any key to stop the auto-boot process.

    3. Reset the U-Boot environment to default values (this will not reset protected variables like the MAC address). To do so, issue this command:

      => env default -a

    4. Save the U-Boot environment to apply the default configuration.

      => saveenv

  9. Configure the partition table of eMMC to hold Yocto images. To do so, execute these commands:

    => setenv mmcdev 0
=> run partition_mmc_linux

  10. Update the boot image by executing this command:

    => update linux mmc 1 fat <boot-file>.boot.vfat

  11. Wait until the process ends, then update the root file system image by issuing this command:

    => update rootfs mmc 1 fat <rootfs-file>.rootfs.ext4

  12. Wait until the process ends, then update the recovery image by executing this command:

    => update recovery mmc 1 fat <recovery-file>.recovery.vfat

  13. Change the default boot command in U-Boot to boot from the eMMC by issuing these commands:

    => setenv bootcmd dboot linux mmc
=> saveenv

  14. You can format the update partition or directly boot the new firmware:

    • To format the update partition, run the following commands. They boots in recovery mode to format the partition and then boots the device normally with the new firmware:

      => setenv recovery_command wipe_update
=> saveenv
=> run recoverycmd

    • If the update partition is already formatted or you want to preserve its contents, boot the device with the firmware you have just programmed:

      => boot