UART Bootloader for STM32F4 MCU

This is a simple UART bootloader written for STM32f4 MCUs based on the libopencm3 library.

Building

clone this repo, build and setup the submodules and run make.

git clone git@github.com:mdnr/stm32f4-uart-bootloader.git --recurse-submodules --shallow-submodules
cd stm32f4-uart-bootloader
make -C src/shared/opencm3/ TARGETS=stm32/f4
cp configs/FreeRTOSConfig.h src/app/freertos/include/
make

The versioning of the build output is done automatically based on the latest tag and commit hash. (tag format must be v<MAJOR>.<MINOR>, e.g. v0.1)

Memory layout

Currently the flash memory of the MCU is divided as below:

****************************************
0x0800000: Flash base  / Bootloader start
Bootloader: 16KB
****************************************
0x0804000: Bootloader end / Parameters start
Parameters: 8KB (Config and application settings based on user's needs)
----------------------------------------
0x8002000: Parameters end / Diagnostic area start
Doggy litter box: 8KB  (Watchdog register dump area)
****************************************
0x0808000: Application start
Aplication Vector table
----------------------------------------
Firmware info (Version, size, etc)
----------------------------------------
Application code
****************************************

The root directory Makefile takes care of compiling both binaries for bootloader and application and flashing them in the corresponding addresses.

• make all: compile both application and bootloader binaries
• make app: compile application binary
• make bl: compile bootloader binary
• make flash: flash both application and bootloader to MCU
• make flash-bl: flash bootloader only without touching the application
• make flash-app: flash application only without touching the bootloader

Also there are 2 debug targets (make fw-debug and make bl-debug) for debugging the bootlaoder and application remotely on the target.

Using the bootloader

Run the python script from the root directory to connect to the serial port using a usb-serial converter

./bootloader.py

Specify the port connected to the MCU board (e.g. /dev/ttyUSB0) and choose one of the actions listed:

1. Read parameters: Read current parameters stored in the MCU's parameter section
2. Update parameters: Write new parameters to the flash without touching application code
3. Read firmware info: Read firmware verison, size, etc.
4. Reset the core: Send reboot command ans start bootloader process.
5. Lock serial line: Lock the UART line in case it's used by the application
6. UnLock serial line: Release the UART lock
7. Read diagnostics: Read the dumped diagnostic data from corresponding section
8. Abort: Quit the bootlaoder

TODO

• Adding GSM layer to support OTA update
• Rewriting bootloader.py in C perhaps and adding proper UI to it
• Adding Encryption