STM32 MCU boards

This is a quick instruction for setup STM32 MCU boards.

Supported devices

U-Boot supports the following STMP32 MCU SoCs:

• STM32F429

• STM32F469

• STM32F746

• STM32F769

• STM32H743

• STM32H750

SoCs information:

STM32F4 series are Cortex-M4 MCU. STM32F7 and STM32H7 series are Cortex-M7 MCU.

• STM32F4 series: https://www.st.com/en/microcontrollers-microprocessors/stm32f4-series.html

• STM32F7 series: https://www.st.com/en/microcontrollers-microprocessors/stm32f7-series.html

• STM32H7 series: https://www.st.com/en/microcontrollers-microprocessors/stm32h7-series.html

Currently the following boards are supported:

• stm32f429-discovery

• stm32f469-discovery

• stm32746g-evaluation

• stm32f746-discovery

• stm32f769-discovery

• stm32h743i-discovery

• stm32h743i-evaluation

• stm32h750i-art-pi

Boot Sequences

For STM32F7 series, 2 boot configurations are supported with and without SPL

FSBL	SSBL	OS
First Stage Bootloader	Second Stage Bootloader	Linux Kernel
embedded Flash	DDR

The boot chain with SPL

defconfig_file :

• stm32746g-eval_spl_defconfig

• stm32f746-disco_spl_defconfig

• stm32f769-disco_spl_defconfig

FSBL	SSBL	OS
U-Boot SPL	U-Boot	Linux

The boot chain without SPL

defconfig_file :

• stm32f429-discovery_defconfig

• stm32f429-evaluation_defconfig

• stm32f469-discovery_defconfig

• stm32746g-eval_defconfig

• stm32f746-disco_defconfig

• stm32f769-disco_defconfig

• stm32h743-disco_defconfig

• stm32h743-eval_defconfig

• stm32h750-art-pi_defconfig

FSBL	OS
U-Boot	Linux

Build Procedure

1. Install the required tools for U-Boot

   • install package needed in U-Boot makefile (libssl-dev, swig, libpython-dev…)

   • install ARMv7 toolchain for 32bit Cortex-A (from Linaro, from SDK for STM32MP15x, or any crosstoolchains from your distribution) (you can use any gcc cross compiler compatible with U-Boot)

2. Set the cross compiler:

   # export CROSS_COMPILE=/path/to/toolchain/arm-linux-gnueabi-
   

3. Select the output directory (optional):

   # export KBUILD_OUTPUT=/path/to/output
   

   for example: use one output directory for each configuration:

   # export KBUILD_OUTPUT=stm32f4
   # export KBUILD_OUTPUT=stm32f7
   # export KBUILD_OUTPUT=stm32h7
   

   you can build outside of code directory:

   # export KBUILD_OUTPUT=../build/stm32f4
   

4. Configure U-Boot:

   # make <defconfig_file>
   

   For example with <defconfig_file>:

   • For stm32f429 discovery board : stm32f429-discovery_defconfig

   • For stm32f769 discovery board with SPL: stm32f769-disco_spl_defconfig

   • For stm32f769 discovery board without SPL: stm32f769-disco_defconfig

5. Configure the device-tree and build the U-Boot image:

   # make DEVICE_TREE=<name> all
   

   Examples:

1. boot with SPL on stm32f746 discovery board:

   # export KBUILD_OUTPUT=stm32f746-disco
   # make stm32f746-disco_spl_defconfig
   # make all
   

2. boot without SPL on stm32f746 discovery board:

   # export KBUILD_OUTPUT=stm32f746-disco
   # make stm32f746-disco_defconfig
   # make all
   

3. boot on stm32h743 discovery board:

   # export KBUILD_OUTPUT=stm32h743-disco
   # make stm32h743-disco_defconfig
   # make all
   

4. boot on stm32h743 evaluation board:

   # export KBUILD_OUTPUT=stm32h743-disco
   # make stm32h743-eval_defconfig
   # make all
   

6. U-Boot Output files

   So in the output directory (selected by KBUILD_OUTPUT), you can found the needed U-Boot files, for example:

   - stm32f746-disco_defconfig = **u-boot-dtb.bin** and **u-boot.dtb**
   
     - FSBL = u-boot-dtb.bin
   
   - stm32f746-disco_spl_defconfig = **u-boot-dtb.bin**, **u-boot.dtb** and **u-boot-with-spl.bin**
   
     - FSBL + SSBL = u-boot-with-spl.bin
     - SSBL = u-boot-dtb.bin
   

7. Flash U-Boot files

Plug STM32 MCUs board using the USB ST-Link connector, hence it will expose the flash area as a mass-storage. In this mass-storage you will find the following files:

• DETAILS.TXT: give the bootrom version and build

• MBED.HTM: shortcul to the hardware board description web page from st.com.

Copy/paste the u-boot.bin or u-boot-with-spl.bin (in case of bootchain with SPL) to this mass-storage. The “COM” LED will blink alternatively red and green during the flash process. When done the board will reboot automatically.

In case of boot with SPL, by default SPL will try to load either a Linux kernel (falcon mode) or, if the key “c” is maintained pressed, the main U-Boot.