Dual Bootloader with FDCAN Firmware Update and CRC Validation on STM32G0B1CCT6

[AKG123]

I am working on a custom dual-boot bootloader for the STM32G0B1CCT6 with the following features:

• Bootloader located at 0x08000000 (about 20 KB flash).

• Two application firmware slots:

  • App1 at 0x08005000 (22 KB)

  • App2 at 0x0800A800 (22 KB)

• On reset, the bootloader checks the CRC of App1 and App2 firmware:

  • If App1 is valid, it jumps to App1.

  • Else if App2 is valid, it jumps to App2.

  • Else it stays in bootloader mode.

• Firmware updates are sent via FDCAN as .bin files (no special commands, just the binary data).

• The bootloader receives the firmware, writes it to the free app slot, verifies CRC:

  • If CRC passes, it overwrites the old firmware and jumps to the new app.

  • If CRC fails, it keeps the old firmware and stays in bootloader mode.

• I want to support multiple firmware updates this way reliably.

I have basic HAL code generated from CubeMX for FDCAN and CRC peripherals.

My questions:

1. Is my memory layout and CRC validation approach suitable for STM32G0B1CCT6 with 64KB flash?

2. How can I best implement the FDCAN reception to reliably receive large .bin files chunked over CAN FD?

3. Are there any reference projects or examples from ST that implement similar dual-bootloader with CRC check and FDCAN update?

4. Any tips on safely erasing and writing flash while receiving firmware over FDCAN?

5. How do I store and update CRC metadata securely in flash?

6. How to properly jump from bootloader to application and manage vector tables?

[Abdul-khalil]

Problem Statement:

I am developing a custom bootloader for the STM32G0B1CCT6 microcontroller that supports the following functionality:

1. Dual Boot Mode:

   • The bootloader is programmed via ST-LINK V2.

   • The application firmware is uploaded later via FDCAN in .bin format.

2. CRC Validation:

   • On every power-up or reset, the bootloader checks the CRC of the existing application firmware.

   • If the firmware is valid (CRC matches), the bootloader jumps to the application.

   • If the firmware is invalid (CRC mismatch or corrupted), the bootloader remains active and does not jump.

3. Firmware Update via FDCAN:

   • The bootloader receives the new .bin file via FDCAN (without waiting for any specific command/message).

   • After receiving the complete firmware, it calculates the CRC and verifies it.

   • If the new firmware is valid, the bootloader erases the previous one and flashes the new firmware.

   • If the new firmware is invalid, the old firmware remains untouched and continues to run.

4. Repeatable Process:

   • I should be able to update the firmware multiple times via FDCAN.

   • Each time, CRC is verified before replacing the existing firmware.

Goal:
To ensure reliable firmware updates via FDCAN, with automatic CRC verification and fallback to the previous valid firmware if the update fails or is corrupted.

[Saket_Om]

Hello @AKG123 

Please refer to the open bootloader example below.

STM32CubeG4/Projects/NUCLEO-G491RE/Applications/OpenBootloader at master · STMicroelectronics/STM32CubeG4 · GitHub

[AKG123]

Thank you for the reference.

I did check the example at:
STM32CubeG4/Projects/NUCLEO-G491RE/Applications/OpenBootloader,
but I was not able to fully understand it.

If there is any specific example for FDCAN or CAN-based bootloader (especially for STM32G0 series) available on GitHub or any official ST repo, could you please share the link? That would be very helpful.

[Saket_Om]

Hello @AKG123 

There is a CAN bootloader driver, it can be useful for your application.

stm32-mw-openbl/Modules/CAN/openbl_can_cmd.c at main · STMicroelectronics/stm32-mw-openbl · GitHub

[Abdul-khalil]

Thank you for sharing the FD-CAN bootloader driver.

Could you please guide me on how to identify which files from the repository are essential for implementing the FD-CAN bootloader in my project?

I want to make sure I only include the necessary files and avoid any extra code that I might not need.

Also, is there a recommended way to integrate these files step-by-step for someone new to this FD-CAN bootloader implementation?

Thanks in advance for your help!

[Saket_Om]

Hello @Abdul-khalil 

Below you find an example using open bootloader with FDCAN interface driver. 

STM32CubeH7RS/Projects/STM32H7S78-DK/Applications/OpenBootloader at main · STMicroelectronics/STM32CubeH7RS · GitHub

[Abdul-khalil]

Hello @Saket_Om 

Thanks for sharing the OpenBootloader example for FDCAN from the STM32CubeH7RS repository.

I have the following questions regarding integrating this into my own project using only the FDCAN interface:

My Requirements:

1. I only want to use the FDCAN bootloader part (no USB, UART, SPI, etc.).

2. I’m working on a different MCU (e.g., STM32G0B1CCT6) and I will configure my project using STM32CubeMX.                                                                                                                                                        Questions:

1. Which exact files from the example project should I copy into my CubeMX-generated project if I only want FDCAN support?

   • For example, from:
     STM32CubeH7RS/Projects/STM32H7S78-DK/Applications/OpenBootloader

2. Can I remove all other interface files like openbl_uart.c, openbl_usb.c, etc., and only keep FDCAN-related files?

3. Should I:

   • (A) Start with a clean CubeMX project for my MCU and then copy only required FDCAN bootloader source files,

   • OR

   • (B) Modify the full OpenBootloader example and strip out the unused parts?

4. Which files are the bootloader core files, and which are the user application files?

Goal

I want to make a minimal, clean bootloader that works only with FDCAN and ValueCAN4 (Vehicle Spy 3) for firmware update.

Please guide me with a recommended file structure or integration steps for my use case.

Thanks! 

[Saket_Om]

Hello @Abdul-khalil 

You can start by CubeMX project and then add file related to Bootloader. You can start by cleaning the bootloader project to determine which files should be copied. 

[Abdul-khalil]

Hello @Saket_Om 

Thank you for your response.

I visited the GitHub repository, but I noticed that there are many files spread across different folders, and the FDCAN command files, handler files, and interface files are located in separate directories.

I’m finding it a bit difficult to understand which specific files are required to implement the FD-CAN bootloader in my project.

Could you please just list the exact files I need to copy and use for a basic FD-CAN bootloader setup?

It would be a big help in getting started without confusion.

Thank you