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Microchip AT91 Buildroot External

This buildroot external includes Microchip packages, patches, setup, and configuration to work with Microchip provided software that is not included in mainline buildroot. This includes creating demo root filesystems. This project provides an extension to buildroot to support these customizations outside of the standard buildroot tree.

Install System Dependencies

The external is tested on Ubuntu 18.04 LTS. The following system build dependencies are required.

sudo apt-get install subversion build-essential bison flex gettext \
libncurses5-dev texinfo autoconf automake libtool mercurial git-core \
gperf gawk expat curl cvs libexpat-dev bzr unzip bc python-dev \
wget cpio rsync xxd

In some cases, buildroot will notify that additional host dependencies are required. It will let you know what those are.

Buildroot Dependencies

This buildroot external requires the specific buildroot-at91 version 2021.02-at91. It is not designed to work with another version of buildroot-at91.


Clone, configure, and build. When building, use the appropriate defconfig in the buildroot-external-microchip/configs directory for your board.

git clone -b 2021.02-at91
git clone -b 2021.02-at91
cd buildroot-at91
BR2_EXTERNAL=../buildroot-external-microchip/ make sama5d4_xplained_graphics_defconfig

The resulting bootloader, kernel, and root filesystem will be put in the 'output/images' directory. There is also a complete sdcard.img.

Optionally Configure Packages and Kernel

Userspace packages and the Linux kernel, for example, can be optionally selected and configured using buildroot.

To configure userspace packages and build:

make menuconfig

To configure the kernel and build:

make linux-menuconfig

Create a list of software licenses used:

make legal-info

Create an SD Card

A SD card image is generated in the file sdcard.img. The first partition of this image contains a FAT filesystem with at91bootstrap, u-boot, a u-boot env, ITB file, which contains kernel and device tree. The second partition contains the root filesystem. This image can be written directly to an SD card.

You need at least a 1GB SD card. All the data on the SD card will be lost. Find the device node name for your card. To copy the image on the SD card:

cd output/images
sudo dd if=sdcard.img of=/dev/sdX bs=1M

Another method, which is cross platform, to write the SD card image is to use Etcher.

For more information on how these components are generated and what makes up a bootable SD card, see SDCardBootNotice.

Configuring the LCD Display

U-boot will automatically detect your connected display and load the corresponding DT-overlay for your screen. For more information, adjustments of this behavior, check the information on at91Wiki.

Kernel and Device Tree Blob packaging

Linux Kernel and the Device Tree Blob will be included in a single file named FIT Image (*.itb files). U-boot needs to boot a FIT Image, unlike before, when it was loading two separate files (zImage and dtb). For more information, check the information on at91Wiki.


For more information on using and updating buildroot, see the buildroot documentation.


This project is licensed under the GPLv2 or later with exceptions. See the COPYING file for more information. Buildroot is licensed under the GPLv2 or later with exceptions. See the COPYING file in that project for more information.