stm32-modbus-bootloader

Simple Modbus RTU bootloader for STM32F103 (blue pill).

The code is somewhat messy but good enough for POC.

Inspired by this series of articles by SLR:

• Bootloader Basics – Part 1
• Simple STM32F103 Bootloader Implementation – Bootloader Development Tutorial Part 2
• STM32F1 Firmware Update using Custom Bootloader – Bootloader Development Tutorial Part 3

Structure

• stm32f103-bootloader -- bootloader
• stm32f103-app -- example application (blink LED)

Protocol

You can use it with mbloader. There's an explanation of the protocol.

License

• FreeMODBUS -- BSD-3-Clause
• STM32 LL -- BSD-3-Clause
• CMSIS -- Apache-2.0

Import

STM32CubeIDE -> File -> Import -> Existing Projects into Workspace -> Select root directory

How it works

1. After reset, the MCU waits 5 seconds for the command to start programming. This is indicated by a rapidly blinking LED.
2. If the MCU received the command, programming sequence will be executed.
3. If the MCU didn't receive the command, it will jump to the app.

Usage

You can use it with the mbloader.

There's an example app. Check the linker file and the system_stm32f1xx.c file (USER_VECT_TAB_ADDRESS and VECT_TAB_OFFSET).

Bootloader occupies the first 16 KB of flash.