ElimOS Buildroot external tree for Impetus SoM and Initium EVK

This repository is a Buildroot BR2_EXTERNAL tree dedicated to supporting the Elimo Engineering Impetus SoM and Initium EVK platforms.

Available configurations

This BR2_EXTERNAL tree provides 3 example Buildroot configurations:

1. elimo_initium_defconfig, which is a minimal configuration to support the Initium EVK board based on the Impetus SoM. It builds the U-Boot bootloader, Linux kernel and a minimal user-space composed of just Busybox and a few utilities.

2. elimo_playtus_defconfig, which is a configuration to build the Initium demo as shown in our stands at various industry events It builds the U-Boot bootloader, Linux kernel, and a richer user-space that includes OpenTyrian and prboom (a Doom emulator).

3. elimo_beechat_defconfig, support for the custom carrier board for the Beechat portable mesh hotspot

Getting started

Pre-requisites

In order to use Buildroot, you need to have a Linux distribution installed on your workstation. Any reasonably recent Linux distribution (Ubuntu, Debian, Fedora, Redhat, OpenSuse, etc.) will work fine.

Then, you need to install a small set of packages, as described in the Buildroot manual System requirements section.

For Debian/Ubuntu distributions, the following command allows to install the necessary packages:

$ sudo apt install debianutils sed make binutils build-essential gcc g++ bash patch gzip bzip2 perl tar cpio unzip rsync file bc git gcc-multilib g++-multilib python3-dev libssl-dev

There are also optional dependencies if you want to use Buildroot features like interface configuration, legal information or documentation. Please see the corresponding manual section.

Getting the code

This tree brings in the required version of buildroot as a submodule, so you do not need to clone buildroot separately.

Now, clone the matching branch of the BR2_EXTERNAL tree:

$ git clone --recurse-submodules git@github.com:elimo-engineering/elimos.git

or, if you want to use the https protocol:

$ git clone --recurse-submodules https://github.com/elimo-engineering/elimos.git

Configure and build

From the root of the repo, configure the system you want to build by using one of the 3 defconfigs provided in this BR2_EXTERNAL tree. For example:

$ make -C buildroot BR2_EXTERNAL=.. elimo_initium_defconfig

We are passing two informations to make:

1. The path to BR2_EXTERNAL tree, relative to the buildroot submodule directory. This is only needed once per repo, as the value of BR2_EXTERNAL is stored on disk.

2. The name of the Buildroot configuration we want to build.

If you want to further customize the Buildroot configuration, you can now run make menuconfig or make nconfig, but for your first build, we recommend you to keep the configuration unchanged so that you can verify that everything is working for you.

Start the build:

$ make -C buildroot

This will automaticaly download and build the entire Linux system for your Impetus platform: cross-compilation toolchain, firmware, bootloader, Linux kernel, root filesystem. It might take between 30 and 60 minutes depending on the configuration you have chosen and how powerful your machine is.

Flashing and booting the system

The Buildroot configurations generate a ready-to-use SD card image, available as buildroot/output/images/sdcard.img. Flash this image on a SD card:

$ dd if=buildroot/output/images/sdcard.img of=/dev/sdX bs=1M

(Note: this assumes your SD card appears as /dev/sdX on your system.)

Then (assuming you are using the Initium, custom carrier boards will vary):

1. Switch the POWER SW switch to OFF

2. Insert the microSD card on the Impetus SoM

3. Configure the UART SELECT switch to 0

4. Plug a USB-C cable in the USB-C connector of the Initium and run your serial communication program on /dev/ttyUSB0.

5. Switch the POWER SW switch to ON.

6. The system will start, with the console on UART. You can log-in as root with no password. If you have an LCD, you can plug in a keyboad on a USB-A connector and log in on the LCD

Going further

• Testing display support
• Using WiFi
• Using Bluetooth
• Using Audio
• Using Camera
• Using Qt5 demos
• Using OP-TEE

References

• Buildroot
• Buildroot reference manual
• Buildroot system development training course, with freely available training materials

Support

You can contact Elimo at info@elimo.io for commercial support on using Buildroot on Impetus SoM platforms.