Can't Upload to 32u4 After Bootloader

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I have an ATmega32u4 running at 3.3V with an 8MHz resonator. I used an Arduino Uno (running the ArduinoISP sketch) to flash the Arduino Leonardo bootloader onto it successfully, but unfortunately after doing this I can't seem to upload code to it. When I try uploading the blink sketch it just goes through the "PORTS {} / {} => {}" scan in Arduino IDE but never finds my board, even though I press the reset button during that search. I've also tried burning the Adafruit 32u4 Feather bootloader to it as well since their board runs on 3.3V/8MHz, but no luck loading code after the bootloader.

 

Any ideas?

 

 

EDIT: I think I might know what the problem is, but would like to confirm: This is a custom PCB and I connected the VBUS pin to 3.3V. Should this go to the V_USB 5V instead?

Last Edited: Sat. Sep 30, 2017 - 09:08 PM
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I'm also trying to do something similar. the Leonardo bootloader is set for a 16Mhz xtal and 5v operation.

My limited understanding is that you will need to put a 16Mhz xtal on there to talk to the chip, then flash a different bootloader that can deal with the 8Mhz clock, then switch the xtal back to 8Mhz?

That sounds more complicated than it should be. I'm about to post a question asking the best path to convert a 5v to 3.3v board, hoping to find the answer

The 3.3v leonardo pro-micro configuration from Sparkfun may be a suitable candidate.

Last Edited: Sat. Jan 27, 2018 - 10:52 PM