I am in a situation where it is useful if I can upload a bootloader into an ATmega32U4 using another Arduino like this, for ex:https://www.arduino.cc/en/Tutorial/ArduinoToBreadboard. I have a different circuit though.

Is there a reason to believe that this can't be adapted to ATmega32U4?

Are there any important differences between the ATmega328P and ATmega32U4, that I have to take into account for this to work?

  • Which Arduino board are you using as the programmer?
    – per1234
    Commented Aug 20, 2017 at 2:08
  • I entend to use arduino uno Commented Aug 20, 2017 at 4:10

1 Answer 1


The only difference you have to take into account is that if you're using an ATmega32U4 board such as Leonardo the SPI pins are not broken out to the pin headers along the edge of the board as is the case with the Uno shown in the tutorial you linked. Instead you should connect the programmer board to the ICSP header pins on your ATmega32U4 board, where the SPI pins are broken out:

  • MISO: ICSP-1
  • MOSI: ICSP-4
  • SCK: ICSP-3

So this means you can't follow the wiring shown on the tutorial exactly but it should be very easy to adapt that tutorial to your needs.

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