Burning Bootloader onto UNO R4 using an UNO R3

[virtual_boi]

As the topic name entails, I have a blank MCU on an arduino uno r4 minima and I was hoping I could burn a bootloader to it using my older uno r3. I wanted to see if anyone has tired doing this before and had success. I couldn't find anything online explicitly explaining how to do it. I'll give it a try tonight and update this post if I figure it out.

Any information would be a big help, thanks all!

PS: I saw that someone tried to do the reverse operation here:

Burn Bootloader from UNO4 to UNO3

Hello, I bought a UNO4 card to check if my current installation was the problem. It turns out that it's my old UNO3 board that seems to be KO. I would like to do a "burn bootloader" from my UNO4 to the UNO3 because it is impossible to burn or upload a program on the UNO3 board. I saw from this link (https://support.arduino.cc/hc/en-us/articles/4841602539164-Burn-the-bootloader-on-UNO-Mega-and-classic-Nano-using-another-Arduino) that the UNO4 should not be used. But I don't know if it's a mi…

[virtual_boi]

Although the link above is relevant, I meant to link this:

Burn Bootloader from UNO4 to UNO3

Hi @t0mt0m. Yes, you can use the UNO R4 WiFi or UNO R4 Minima board as a programmer to burn the bootloader to the UNO R3 board. The procedure is slightly different from how it would be when using an UNO R3 or other AVR board as the programmer. I'll provide instructions for doing it: ⓘ In the instructions below, the board used as an "Arduino as ISP" is referred to as the "programmer board". The board the bootloader is being burned on is referred to as the "target board". A. Prepare "Arduino …

[Delta_G]

No. Burning the bootloader on the Renesas chip requires the Renesas Flash Programmer which only runs on your computer.

It's the same with the R3. In that link they're sending the bootloader from the PC. The R4 is just replacing the programmer.

On the R4 you don't need a separate programmer. So there would be nothing for an R3 to contribute. You just connect the USB directly to the PC and burn your bootloader.

[ptillisch]

There are instructions for flashing the bootloader to the UNO R4 Minima here:

https://github.com/arduino/ArduinoCore-renesas/tree/main/bootloaders/UNO_R4#rocket-how-to-load-bootloader-uno-r4-minima

They are pretty minimal. If you have any questions or problems while following them we can provide assistance.

You can download the dfu_minima.hex file here:

https://github.com/arduino/ArduinoCore-renesas/blob/1.0.5/bootloaders/UNO_R4/dfu_minima.hex

@virtual_boi

I have a blank MCU on an arduino uno r4 minima

I'm just curious, is that because you had to replace the original chip on your board?

[virtual_boi]

thanks, ill take a look at that too.

Long story short, I have a bunch of blank Renesas MCUs (same one thats on the R4) that I am using for a school project. I made some custom PCBs but when I went to test them, they didn't show up as a COM port. As a way to see if the chips were empty/cooked, I stole the MCU off of my R4 minima and put it on my custom PCB, it worked perfectly. Now I'm left with chips that wont show up as a COM port even when theyre placed on the original UNO R4 PCB... I suspect I need to use a J-Link device to flash the chips using the renesas flash programmer... Issue is, I dont have a J-Link and theyre expensive

[ptillisch]

Thanks for the clarification. Very cool!

@virtual_boi

I suspect I need to use a J-Link device to flash the chips using the renesas flash programmer... Issue is, I dont have a J-Link and theyre expensive

I am not very knowledgeable on the subject, but I think you can put the chip into DFU mode and then flash the firmware directly via the USB interface without any need for additional hardware such as a J-Link.