Custom RA4M1 Board Based on Arduino UNO R4 Minima – Bootloader

Development Tools Arduino Command Line Tools
1

Hi,

I am developing a custom board based on the Renesas RA4M1 microcontroller, designed to be functionally equivalent to the Arduino UNO R4 Minima.

I would like to achieve full compatibility with the Arduino IDE, allowing users to program the board exactly as they would with an official UNO R4 Minima. To do that, I would like to know:

1. Bootloader – How can I obtain or build the official UNO R4 Minima bootloader for the RA4M1 so that my custom board can be recognized and programmed via the Arduino IDE?

* Is the bootloader open source or available for licensed use?
* What is the recommended process for flashing it onto a new RA4M1 chip?

2

Hi @nbabu_2023. Cool project!

It is here:

It is available under the "MIT" open source license.

3

Hi! Thanks for the link.
I'm new to bootloaders and to the RA4M1, so could you please explain step-by-step how to actually bootload my UNO R4 Minima using the files from that GitHub repository?

Specifically, I’m unsure about:

  • How to build the bootloader from the GitHub source

  • Which tools I need (e2 studio? Flash Programmer?)

  • How to put the board into bootloader/DFU mode

  • Which file I’m supposed to flash (.hex or .bin?)

  • How to flash it correctly onto the RA4M1

A simple, beginner-friendly walkthrough of the entire bootloading process would be very helpful.
Thanks!

4

Hello there. I was able to follow this document right here and flash the bootloader. The relevant parts for you are “bootloaders/UNO_R4“ and “How to load bootloader (UNO R4 Minima)”. The rfp-cli can be found in Renesas website. It works great and it’s super-fast. That said, they require a registration and they want quite some of your data - probably because of export controls. With the above, you will be able to burn the Arduino Bootloader for RA4M1 and use bossac.