ATmegaa32U4 USB with internal RC clock

[branjb]

I am trying to achieve the exact same thing as the OP, but even with the provided bootloader, am unable to get the board show up as a USB device. Burning the bootloader using Arduino IDE works and after the process has completed, the LED_BUILTIN starts to blink, which afaik should indicate that the bootloader is running. Any ideas what might be the issue? Any tips on how to debug this?

Here is the entry from boards.txt I'm using:

micro_int.name=Standalone Micro
micro_int.vid.0=0x03eb
micro_int.pid.0=0x204a

micro_int.upload.tool=avrdude
micro_int.upload.protocol=avr109
micro_int.upload.maximum_size=28672
micro_int.upload.maximum_data_size=2560
micro_int.upload.speed=57600
micro_int.upload.disable_flushing=true
micro_int.upload.use_1200bps_touch=true
micro_int.upload.wait_for_upload_port=true

micro_int.bootloader.tool=avrdude
micro_int.bootloader.low_fuses=0xe2
micro_int.bootloader.high_fuses=0xd8
micro_int.bootloader.extended_fuses=0xfb
micro_int.bootloader.file=caterina-internal/Caterina-eevblog2.hex
micro_int.bootloader.unlock_bits=0x3F
micro_int.bootloader.lock_bits=0x2F

micro_int.build.mcu=atmega32u4
micro_int.build.f_cpu=8000000L
micro_int.build.vid=0x03eb
micro_int.build.pid=0x204a
micro_int.build.usb_product="Standalone Micro"
micro_int.build.board=AVR_LILYPAD_USB
micro_int.build.core=arduino
micro_int.build.variant=leonardo
micro_int.build.extra_flags={build.usb_flags}

I made a board with a 32u4 using USB in crystal less mode.  There documentation is @ https://github.com/lostangles/LoraWAN-Stick, maybe something there can help you.

[elysion]

Thanks! I'll take a look .

[Harmony]

How could I use the "Caterina.hex" file?