sleuek/korchega

Kocherga Bootloader Build from zero

Branches

There is :

• main : with STM32F4 code
• STM32F4: with STM32F4 code
• STM32L496: with STM32L496 code

Start of tutorial

You need the korchega-demo directory to continue.

You can download it : here the link is provided by Pavel Kirienko

Before all (Arthur)

ARM GCC

Download the specific toolchain for ARM GCC 7.3 here : https://majenko.co.uk/downloads/arm-gcc-731-compiler-2018-q2

or here : https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads

You have to choose your OS.

Setup the path

Make a place to install it to

mkdir /usr/local/gcc_arm

Move the unzipped stuff there.

mv ~/Downloads/gcc-arm-none-eabi-4_7-2013q3 /usr/local/gcc_arm/

Check out all the purdy binaries, you'll need to build firmware.

ls /usr/local/gcc_arm/gcc-arm-none-eabi-7-2018-q2-update/bin/

Peep your current PATH

echo $PATH

/usr/local/heroku/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:<BLA BLA BLA>

Change your PATH by appending the "bin" folder of the folder

NOTE: You should also add this line to ~/.bashrc or ~/.bash_profile (in your home directory) so you don't have to remember to do this every time you want to compile firmware.

export PATH="$PATH:/usr/local/gcc_arm/gcc-arm-none-eabi-7-2018-q2-update/bin/"

Check to ensure the gcc-arm firmware compiler is available (so make clean dependents all will work.)

arm-none-eabi-gcc --version

Building

In order to build the bootloader, execute make RELEASE=1. Omit setting the RELEASE variable to build the debug version (it won't fit into the bootloader area).

cd build/
ls -la

You should have :

bootloader.bin
bootloader.elf
kocherga_demo.map
lst
obj

Once the release version of the bootloader is built, its binary (.bin) will have to be manually copied into the firmware source root directory. This is arranged this way to ensure that once a working version of bootloader is finished and tested, it will stay frozen in this exact configuration until updated explicitly. The bootloader has to be robust and is not expected to change frequently.

MCU Usage

Timers

The following list documents the current usage of hardware timers. All timers are clocked at 180 MHz. Note that ChibiOS 16.1 does not recognize that; please read this post for details: http://www.chibios.com/forum/viewtopic.php?f=35&t=3870.

Timer	Resolution	Usage
TIM1	16	Not used
TIM2	32	RTOS System Timer (tickless)
TIM3	16	RGB LED PWM
TIM4	16	Not used
TIM5	32	Not used
TIM6	16	Not used
TIM7	16	Not used
TIM8	16	Not used
TIM9	16	Not used
TIM10	16	Not used
TIM11	16	Not used
TIM12	16	Not used
TIM13	16	Not used
TIM14	16	Not used

Watchdog

Release builds of the bootloader initialize the watchdog with a large timeout. This is needed to prevent broken firmwares from bricking the device.

Debug builds to not initialize the watchdog in order to not interfere with debugging.

RCC

The RCC CSR register contains reset cause flags. If either of the watchdog timers is known to have caused the last reset, the bootloader will inject a 10 second timeout before booting the application, allowing external systems or the user to intervene and replace the bad firmware. The reset cause flags are cleared by the bootloader.