Burning question:

So, I'm trying to burn the Arduino Leo bootloader onto a ATmega32U4 that's on 3.3V and the internal 8MHz clock. Do I have to modify and rebuild the bootloader to set the fuses correctly, and can this be done with AVR Studio?

All of the references on doing this are dated. The folder structure for the Arduino IDE has changed. I've done it in the past with 5V 16MHz 32U4s using an Arduino as ISP, but never with the AVRISP mkII on the Arduino IDE.

On the good side, I do have it up and running Atmel Studio.


EDIT: Sorry for double posting, I posted in electronics before I noticed there was an Arduino specific section.

  • LilyPad Arduino USB uses the ATmega32U4 on +3.3V and 8MHz oscillator. So, you can use the LilyPad USB bootloader. That worked for me without any modifications to the bootloader. – Nick Alexeev Sep 2 '15 at 17:52
  • Thank you! Though I've been trying to do this with an AVRISP mkII as ISP in the Arduino IDE, but for some reason I get this error message: "avrdude: usbdev_open(): did not find any USB device "usb"" – BlackJester Sep 4 '15 at 5:28

If you have an appropriate crystal attached then you can do this in the Arduino IDE. Select your board and programmer in the IDE menu, connect the programmer to the board, and choose Burn Bootloader from the menu. This will both burn the prebuilt bootloader image and set the fuses in a single operation.

Note that you cannot use USB on the '32U4 if you are running off either a ceramic resonator or the internal oscillator, and so you should not attempt to use the Leonardo bootloader in either case.

  • Why can't the USB be used with the internal RC? Datasheet says that it's possible. I'm not doubting you, I'm just wondering the reason. – BlackJester Sep 4 '15 at 5:33
  • It is possible to use low speed USB if you have a way of keeping the oscillator calibrated. It is not accurate enough for high speed USB even if calibrated. – Ignacio Vazquez-Abrams Sep 4 '15 at 5:35

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