STM32

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TL;DR [Too Long; Didn't Read]

You can download THIS Quickstart script to guide you through the process.

Introduction

This is starting page for Linux on STMicroelectronics STM32 microcontrollers family. These pages are not meant to replace official STMicroelectronics support.

Supported Boards

STM32F429i-Discovery

The STM32F429 Discovery kit has the following features:

  • STM32F429 MCU (ARM Cortex-M4 up to 180MHz, 2MB internal flash, 256KB internal RAM)
  • 8MB SDRAM
  • USB OTG Full-Speed
  • 2.4" LCD
  • MEMS motion sensor
  • STLink/V2 (debugging)
  • Extension headers

STM32F469i-Discovery

The STM32F469 Discovery kit has the following features:

  • STM32F469 MCU (ARM Cortex-M4 up to 180MHz, 2MB internal flash, 256KB internal RAM)
  • 16MB SDRAM
  • 16MB QSPI NOR
  • USB OTG Full-Speed
  • 4" DSI LCD
  • SD-Card
  • MEMS motion sensor & microphones
  • STLink/V2-1 (debugging + UART(ACM profile))
  • Extension headers (Arduino compatible)

Toolchains

You will need 2 separate toolchains, one for building the Kernel and Bootloader and the other for building userspace.

Kernel/Bootloader Toolchain

Baremetal Toolchain

Version known to work here.

Userspace uClibc Toolchain

OSELAS Toolchain

Pengutronix provides OSELAS (arm-cortexm3-uclinuxeabi-gcc-4.7.2) toolchain for Cortex-M MCUs.

Alternative Toolchains

Buildroot

Alternatively you can use Kamil Lulko's Buildroot fork which generates a uClibc toolchain.

The fork also builds a Kernel and U-boot; however, since many STM32 boards are low on resources some prefer to use AFBoot-STM32 (see below) to save space. In which case it's better to build Kernel, Bootloader and Buildroot as separate entities.

Bootloaders

AFBoot-STM32

AFBoot-STM32 has been developed by Andreas Färber and is available on his GitHub page.

The main advantage of this bootloader is its size (less than 2KB). Indeed, the STM32F429 only has 2MB internal flash for Bootloader, Kernel, Rootfs and DTB.

A fork compatible with mainline Kernel (from v4.2-rc1) is available here.

The following commands cover the later version.

git clone https://github.com/mcoquelin-stm32/afboot-stm32.git
cd afboot-stm32
make stm32f429i-disco
make flash_stm32f429i-disco

Note: The last command uses OpenOCD to flash the bootloader onto the board, so it needs to be installed (not just built in a src directory) for this to work.

U-Boot

U-Boot STM32 port to mainline has been done by Kamil Lulko. The port is based on U-Boot fork from Emcraft, distributed on their GitHub page

git clone git://git.denx.de/u-boot.git
cd u-boot
make ARCH=arm CROSS_COMPILE=arm-none-eabi- stm32f429-discovery_defconfig
make ARCH=arm CROSS_COMPILE=arm-none-eabi-

Note that mainline Kernel requires some patches on top to work with U-Boot port, these patches are available on Kamil GitHub.

Linux Kernel

Mainline Kernel

STM32F429 Discovery board basic support has been merged in Kernel v4.2-rc1.

STM32F469 Discovery board needs the following changes at the time of writing

 --- a/arch/arm/boot/dts/stm32f429-disco.dts
 +++ b/arch/arm/boot/dts/stm32f429-disco.dts
 @@ -58,7 +58,8 @@
 -               reg = <0x90000000 0x800000>;
 +               reg = <0x00000000 0x800000>;
         };
 
         aliases {
 -               serial0 = &usart1;
 +               serial0 = &usart3;
         };
  };

 @@ -70,6 +72,7 @@
         clock-frequency = <8000000>;
  };

 -&usart1 {
 +&usart3 {
         status = "okay";
  };
 --- a/arch/arm/configs/stm32_defconfig
 +++ b/arch/arm/configs/stm32_defconfig
 @@ -21,7 +21,7 @@ CONFIG_EMBEDDED=y
  CONFIG_ARM_SINGLE_ARMV7M=y
  CONFIG_ARCH_STM32=y
  CONFIG_SET_MEM_PARAM=y
 -CONFIG_DRAM_BASE=0x90000000
 +CONFIG_DRAM_BASE=0x00000000

STM32 maintainer git repository is hosted on kernel.org.

Steps to build mainline kernel for STM32f429i-Discovery board:

git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
cd linux
make ARCH=arm CROSS_COMPILE=arm-none-eabi- stm32_defconfig
make ARCH=arm CROSS_COMPILE=arm-none-eabi-

Produced files are xipImage to be written at address 0x08008000, and arch/arm/boot/dts/stm32f429-disco.dtb DTB file to be written at address 0x08004000.

stm32_defconfig file generates binaries compatible with afboot-stm32 fork.

Emcraft Kernel

Emcraft shares its kernel based on uClinux Kernel v2.6.33 on his GitHub page.

Andreas Färber's Kernel

For ARM TechSymposium Europe 2014 Andreas Färber presented a 3.19-rcX based kernel for the STM32F429I-DISCO at the openSUSE booth. Most of this work was superseded by Maxime; some drivers remain to be forward-ported.

User Space

Busybox

Below link is a prebuilt minimal Busybox to be used as a Ramdisk:

File:Stm32 mini rootfs.cpio.bz2

Buildroot

A fork of Buildroot has been done by Kamil Lulko to add STM32 support.

The git repo is available here.

It builds Kernel, U-Boot and RootFS (busybox).

Debug

OpenOCD in combination with GDB can be used to debug through the STLink interface.

In one terminal:

 openocd -f board/stm32f469discovery.cfg

Then, in a separate terminal:

 cd <afboot_dir> && make debug_stm32f469i-disco

Flash Tools

OpenOCD

OpenOCD can be used to write binaries to internal flash.

Be aware that OpenOCD needs to be installed (not just built in a src directory) for this to work.

git clone git://git.code.sf.net/p/openocd/code openocd
cd openocd
git submodule init && git submodule update && ./bootstrap && ./configure --enable-stlink  && make && sudo make install

Usage example

openocd -f  board/stm32f429discovery.cfg \
 -c "init" \ 
 -c "reset init" \
 -c "flash probe 0" \
 -c "flash info 0" \
 -c "flash write_image erase arch/arm/boot/dts/stm32f429-disco.dtb 0x08004000" \
 -c "flash write_image erase arch/arm/boot/xipImage 0x08008000" \
 -c "reset run" \
 -c "shutdown"

Texane

STlink tool from Texane can be found here.

Once built, you'll need to copy the udev rule for your STLink device to /etc and reload udev

 cp 49-stlinkv*.rules /etc/udev/rules.d
 udevadm control --reload-rules
 udevadm trigger

Usage example

st-flash --reset write arch/arm/boot/dts/stm32f429-disco.dtb 0x08004000
st-flash --reset write arch/arm/boot/xipImage 0x08008000