Custom standalone atmega32u4 pcb showing up as unknown device

Thread Starter


Joined Aug 8, 2020
Hi there, I am having issues with a standalone atmega32u4 project i've been working on and was hoping someone would be able to help :)

I have designed a pcb that uses the atmega32u4 to recreate the arduino leonardo. I have been able to successfully burn the Arduino bootloader onto the chip using the pcb but when I get round to plugging it into the computer through a usb type c connector, the device shows up in device manager as 'Unknown USB device' instead of a COM port. This is my second version of the board- the first version used a usb type c breakout board and was consequently far easier to solder- the first board worked perfectly. Since then I haven't made any significant changes to the schematic besides adding the usb type C connector in the place of the type c connector breakout board.

I have soldered 4 boards now, all having the same issue, so I don't think it is my soldering incompetence causing the issue.

I have attached a png of my schematic and error message as well as my gerber files. I hope someone would be able to point out any mistakes I have made or give me some pointers as to how to fix the issue.

Many thanks