External buildroot tree for stm32f769 discovery board

This repository provides an external buildroot tree to be used with at least buildroot 2021.02 for the stm32f769 discovery board from STMicroelectronics.

It builds a minimal operating system for the target:

• Das U-Boot bootloader.
• Minimal Linux kernel.
• Very small userspace (minimal busybox).

The current configuration is built using a prebuilt toolchain from Bootlin to accelerate the build.

How to build

First install Buildroot's required dependencies. See: The buildroot user manual, chapter 2: System requirements. Also install openocd, it is required for the flashing script (see below).

Then set up the required source code:

mkdir STM32F769DISCO && cd STM32F769DISCO
wget 'https://buildroot.org/downloads/buildroot-2021.02.7.tar.gz'
tar -xf buildroot-2021.02.7.tar.gz
mv buildroot-2021.02.7 buildroot
git clone 'https://git.lumina-sensum.com/git/LuminaSensum/buildroot-stm32f769-disco.git'
export BR2_EXTERNAL="$PWD/buildroot-stm32f769-disco"

Build the image:

cd buildroot
make O=output_build stm32f769-disco_defconfig
cd output_build
make
cd ../..

Flashing

To flash the bootloader, run the provided flash.sh script which is located in the external tree:

buildroot-stm32f769-disco/board/stm32f769-disco/flash.sh buildroot/output_build

Installing the operating system

During build, buildroot creates the sdcard.img file inside the images directory, which you can then simply burn onto a micro sd card using dd:

sudo dd if=buildroot-stm32f769-disco/output_build/images/sdcard.img of=/dev/sdX

• Notes:
  • This will destroy any data stored on the micro sd card!
  • Replace sdX with the correct device node name for your micro sd card!