This topic explains how to boot Digi Embedded Yocto images without updating the firmware on the internal NAND. This is helpful during the development phase, as it preserves the original firmware on the SOM.
Open a serial connection
You must open a serial connection to communicate with your device.
Open a serial connection using any terminal program such as Tera Term, Minicom, Coolterm, or HyperTerminal. This documentation demonstrates using Minicom to work with the device command line.
Use the following settings:
Serial port where the device is connected
Reset the device by pressing the reset button on the board. Then immediately press any key in the serial terminal to stop the auto-boot process. The U-Boot bootloader prompt displays:
NOTICE: CPU: STM32MP157CAC Rev.Z NOTICE: Model: Digi International ConnectCore MP15 Development Kit NOTICE: BL2: v2.6-stm32mp1-r1.0(release):dub-2021.10-r1.1 NOTICE: BL2: Built : 13:07:24, Nov 4 2022 NOTICE: BL2: Booting BL32 optee optee: OP-TEE: revision 3.16 (9f1b4813) U-Boot dub-2021.10-r1.1 (Nov 04 2022 - 13:58:26 +0100) CPU: STM32MP157CAC Rev.Z DRAM: 512 MiB optee optee: OP-TEE: revision 3.16 (9f1b4813) Clocks: - MPU : 650 MHz - MCU : 208.878 MHz - AXI : 266.500 MHz - PER : 24 MHz - DDR : 533 MHz WDT: Started with servicing (32s timeout) NAND: 512 MiB MMC: STM32 SD/MMC: 1 In: serial Out: serial Err: serial Model: Digi International ConnectCore MP15 Development Kit ConnectCore MP15 SOM variant 0x01: 512 MiB DDR3, Wi-Fi, Bluetooth Board version 1 Boot: NAND Net: eth0: ethernet@5800a000 Hit any key to stop autoboot: 0 =>
Boot the system from network
This shows how to transfer the images to the target via TFTP or NFS, and mount an NFS root file system.
|This requires that you set up your PC workstation as explained in Set up native Linux PC.|
1. Prepare the device artifacts
Get the Digi Embedded Yocto firmware images to boot from network:
The kernel file:
The device tree:
Any device tree overlays files that apply to your hardware:
<device-tree-overlay-file>.dtbo(see Pre-compiled device tree overlays).
The compressed root file system:
After building the Digi Embedded Yocto firmware, you can find the image files inside the project directory at:
You can download Digi provided pre-built images from:
For ConnectCore MP15 Development Kit: Wayland images
Untar the root file system tarball (
*.rootfs.tar.bz2) in the NFS exported directory of your development workstation. See Set up native Linux PC.
$ sudo tar xvfp image.rootfs.tar.bz2 -C /exports/nfsroot-ccmp15_dvk
Copy the kernel
*.binfile to the TFTP exported directory of your development workstation.
$ sudo cp <kernel-file>.bin /tftpboot
Copy the device tree
*.dtbfile to the TFTP exported directory of your development workstation.
$ sudo cp <device-tree-file>.dtb /tftpboot
(Optional) Copy any device tree overlay
*.dtbofiles that apply to your variant to the TFTP exported directory of your development workstation.
$ sudo cp <device-tree-overlay-file>.dtbo /tftpboot
2. Configure your device’s network settings
Get a dynamic IP for your target:
=> setenv autoload no => dhcp
or you can set a static IP:
=> setenv ipaddr 192.168.115.222
Configure the IP of the development workstation with TFTP and NFS servers installed. See Set up native Linux PC:
=> setenv serverip 192.168.115.1
3. Boot from network
Boot from TFTP+NFS
Set the directory with the rootfs to mount. This directory is the one exported via NFS in your development workstation. See Set up an NFS server.
=> setenv rootpath /exports/nfsroot-ccmp15_dvk
Specify the device tree (
*.dtb) file name. This is the name of the
*.dtbfile you copied to the TFTP exported directory of your development workstation.
=> setenv fdt_file <device-tree-file>.dtb
(Optional) Use a comma-separated list to specify the device tree overlay (
*.dtbo) files you want to apply. These are the names of the
*.dtbofiles you copied to the TFTP exported directory of your development workstation.
=> setenv overlays <overlay1>.dtbo,<overlay2>.dtbo
Establish the kernel file (
*.bin) name. This is the name of the
*.binfile you copied to the TFTP exported directory of your development workstation.
=> setenv zimage <kernel-file>.bin
Save the changes.
Boot from TFTP.
=> dboot linux tftp
You can make these changes persistent by writing the following command:
=> setenv bootcmd 'dboot linux tftp' => saveenv
The target now loads the kernel and device tree from the TFTP server and the root file system from the NFS server.
Boot entirely from NFS
To avoid using TFTP for kernel and device tree files and boot everything from NFS, copy the kernel
*.bin and device tree
*.dtb files to the NFS-exported directory of your development workstation (instead of to the TFTP directory).
See Set up an NFS server.
=> dboot linux nfs