AT91Bootstrap is the 2nd level bootloader for Microchip microprocessors (aka AT91). It providing a set of algorithms to manage the hardware initialization such as clock speed configuration, PIO settings, DRAM initialization, to download your main application from specified boot media: NAND FLASH, serial FLASH (both AT25-compatible of DataFlash), serial EEPROM, SD Card, etc. to main memory and to start it.

Refer to the GNU ARM Toolchain section below for toolchain recommendations.

A toolchain such as GNU Tools for Arm Embedded Processors shall be provided. Get one from e.g. https://developer.arm.com/open-source/gnu-toolchain/gnu-rm. Run the installation wizard and specify a destination folder whose full path is free from any whitespace. Further instructions below are written as if the toolchain had been installed to C:\opt\gnu_tools_arm\7-2018-q2.

Building AT91Bootstrap requires a POSIX environment. Several tools are available on the market to provide such an environment. In these instructions we rely on Minimal SYStem 2 (MSYS2). Get MSYS2 from http://www.msys2.org. Install it. The installation wizard ask for the installation folder, and suggests to keep its full path short. Further instructions below are written as if MSYS2 had been installed to C:\opt\msys.

MSYS2 notably provides a minimal Bourne Shell, named mintty. Launch mintty in the "MSYS2 MSYS" configuration: either search for the "MSYS2 MSYS" shortcut in the Program menu, or invoke the Run dialog ('Windows' and 'R' key combination) and enter the following command at the Open prompt:

C:\opt\msys\msys2_shell.cmd -msys

In this terminal, whose prompt is suffixed with "MSYS", request the package manager to update both its database and the packages already installed:

$ pacman -Syuu

Still at the "MSYS" prompt, install additional packages that we will need later on when building AT91Bootstrap:

$ pacman -S bc gawk gcc git make python2 tar
$ cd /usr/bin
$ ln -s python2.exe python.exe && ln -s python2-config python-config

Finally, close the "MSYS2 MSYS" terminal window.

Launch mintty in the "MSYS2 MinGW 64-bit" configuration: either search for the "MSYS2 MinGW 64-bit" shortcut in the Program menu, or invoke the Run dialog ('Windows' and 'R' key combination) and enter the following command at the Open prompt:

C:\opt\msys\msys2_shell.cmd -mingw64

In this terminal, whose prompt is suffixed with "MINGW64", configure environment variables:

$ export CROSS_COMPILE="arm-none-eabi-"
$ export PATH=/c/opt/gnu_tools_arm/7-2018-q2/bin:$PATH

Still at the "MINGW64" prompt, proceed with instructions given in the Compile AT91Bootstrap section below.

AT91Bootstrap has been compiled and tested under Linux using the following GNU ARM Toolchain:

• gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
• gcc version 4.7.3 (Sourcery CodeBench Lite 2013.05-24)
• gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)
• gcc version 4.8.3 (Sourcery CodeBench Lite 2014.05-29)
• gcc version 4.9.3 (Linaro GCC 2014.11)
• gcc version 5.1.1 (Linaro GCC 5.1-2015.08)
• gcc version 7.2.1 (Linaro GCC 7.2-2017.11)
• gcc version 7.3.1 (Linaro GCC 7.2-2018.05)
• gcc version 8.2.0 (Ubuntu 8.2.0-7ubuntu1)

WARNING: check KNOWN_ISSUES for issues with older gcc versions. We recommend using a toolchain newer than 6.0.

Let's use at91sam9x5ek as an example.

$ cd <project directory>
$ make mrproper
$ make at91sam9x5ekdf_uboot_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

$ cd <project directory>
$ make mrproper
$ make at91sam9x5ekdf_linux_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

$ cd <project directory>
$ make mrproper
$ make at91sam9x5ekdf_linux_dt_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

Let's use at91sam9m10g45ek as an example.

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eknf_uboot_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eknf_linux_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eknf_linux_dt_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

Let's use at91sam9m10g45ek as an example,

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eksd_uboot_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eksd_linux_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

$ cd <project directory>
$ make mrproper
$ make at91sam9m10g45eksd_linux_dt_defconfig
$ make

If the building process is successful, the final .bin image can be found under binaries/

If you plan to release the project, you can use the command as below

$ cd <project directory>
$ make tarball

If the command is successful, the .tar.gz tar package can be found under the project top directory.

Booting from the external NOR flash is supported in ROM code v2.1 for SAMA5D3x. Bootstrap relocates the binary to the internal SRAM and run.

Using SAM-BA to program the binary to the NOR flash is a little different from other booting mode. Namely, there is no 'Send Boot File' command for NOR flash.

You should use 'Send File' command to send the binary file the same like for a normal file, with 'Address' selected to 0.

If the system board that you have is not listed, then you will need to port AT91Bootstrap to your hardware platform. To do this, follow these steps:

1. Create a new directory to hold your board specific code under contrib/board/ directory. Add any files you need.
In your board directory, you will need at least the "board.mk", a ".c", ".h", "Config.in.board", and "Config.in.boardname".
2. Create the necessary default configuration files such as "df_uboot_defconfig" in your new board directory.
3. Add(source) your board's "Config.in.board" in "contrib/board/Config.in.board" file.
4. Add(source) your board's "Config.in.boardname" in the "contrib/board/Config.in.boardname" file.
5. Add your board's ".h" in the "contrib/include/contrib_board.h" file.
6. Run "make df_uboot_defconfig" with your new name.
7. Type "make", and you should get the final .bin image can be found under the binaries/ directory.

To contribute to AT91Bootstrap you should submit the patches for review to the github pull-request facility directly or the forum. And don't forget to Cc the maintainers.

AT91 Forum:

http://www.at91.com/discussions/

Maintainers:

Eugen Hristev eugen.hristev@microchip.com

Nicolas Ferre nicolas.ferre@microchip.com

When creating patches insert the [at91bootstrap] tag in the subject, for example use something like:

git format-patch -s --subject-prefix='at91bootstrap][PATCH' <origin>

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