USB Firmware Update using MCUBoot on RA6M3 Custom Board (R7FA6M3AF3CFB)

Hello Team,

I am using a RA6M3 custom board with MCU R7FA6M3AF3CFB, working with e2 studio IDE and FSP version 4.2.0.

I am new to implementing firmware updates using the MCUBoot bootloader over USB (not over-the-air). I referred to the example project ra_mcuboot_ra6m3 and added the PCDC USB stack in the FSP configuration. I also updated the device number and pin configurations according to my custom board.

I’m not sure if I am proceeding in the correct direction. From the resources and AI tools I’ve consulted, I’ve learned that:

• Renesas does not officially support USB DFU by default.

• However, it is possible to use the MCUBoot example and integrate the PCDC stack manually to enable USB-based firmware updates.

• In this case, the firmware update logic must be implemented manually to handle USB data reception and flash programming.

I would appreciate it if you could confirm if this approach is valid, and what additional steps or best practices I should follow to complete the implementation.

Task	Required?	Details
Add USB PCDC to application	️	Use r_usb_pcdc stack and match settings to your board
Handle USB receive	️	Implement usb_event_callback() or polling for data
Store firmware to flash	️	Use r_flash_hp or r_flash_lp
Trigger MCUboot swap	️	Mark image for update using bootutil APIs
USB DFU class		Not supported by default in Renesas FSP

Feature	Support
Use ra_mcuboot_ra6m3 as base	Yes
Add PCDC USB stack	Yes
Native USB DFU support	No (must implement manually)
USB firmware update over CDC	Supported (with custom logic)
Bootloader USB handling	Not directly unless you modify bootloader

The above information was suggested by an AI tool while I was researching how to implement a working firmware update process.

Thank you,

Manthan