I'm working on a controller for a USB-C keyboard. I understand USB is a very complicated protocol, and USB-C even more so, however luckily enough there's a ton of open-source projects that aim to accomplish similar goals so I've been basing my controller off of that. I've mostly been following this guide.

I thought it was finally finished, but upon connecting the controller to my computer via USB, it's not detected by Device Manager.

Here's my schematic. Basically everything I've done here is the same or very similar to other projects.

controller schematic

I had a fair amount of issues soldering it all together as the components are SMD, however it all looked good in the end. I suppose I could've fried the AT90USB1286, but I assume that's unlikely.

Here's some pics of the actual board, sorry for the potato quality.

image of mcu

image of usb

Can someone recommend some next steps to troubleshoot this? I understand this is somewhat advanced and I am somewhat of a beginner, but I'm just trying to create something I'd use and am enjoying it.

  • \$\begingroup\$ If someone that reasonably knows what they’re doing can’t find a problem, I’d appreciate that mentioned as then I’ll just reorder the parts and try again. \$\endgroup\$
    – ashpil
    Commented Nov 13, 2019 at 2:42
  • 1
    \$\begingroup\$ Should the 5k1 resistors on CC pins be grounded? They are not connected to anything at the moment. The ESD protection device is not grounded either, so it won't protect the DP/DN pins. \$\endgroup\$
    – Justme
    Commented Nov 13, 2019 at 5:43
  • \$\begingroup\$ @Justme that might be just it! You're right, they're supposed to be grounded, no idea how I missed that. I'll try to fix that and report back with my findings. \$\endgroup\$
    – ashpil
    Commented Nov 13, 2019 at 17:23
  • 1
    \$\begingroup\$ @Justme Yooooo it works! Connected ground to the 5k1 resistor trace with some solder, and it’s detected by windows. Thank you so much! \$\endgroup\$
    – ashpil
    Commented Nov 13, 2019 at 21:11
  • \$\begingroup\$ I also would strongly advise to use more soldering (rosin-cased) flux to make soldering spots more round and avoid potential hair-like shorts. \$\endgroup\$ Commented Nov 19, 2019 at 3:29

1 Answer 1


There is a schematic error where 5k1 resistors and ESD protector are disconnected from GND so the device is not detected.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.