I have made my own version of the Leonardo, and I am having USB issues. Plugging it in to a windows computer - nothing happens! If I hold down reset, I get the "device not recognized error", but if I don't hold down reset, Windows acts like nothing is there.

Schematic: (http://i.imgur.com/V76C6GS.png) enter image description here

Fuses Extended: FB (If I program it as CB, then press read again, it comes out as FB?) High: D8 Low: FF

Using Caterina-Leonardo.hex, uploaded with AVR ISP MKII

The board itself is working, if I compile a blink sketch and flash it directly it works great. It's just that when I plug it into a computer, nothing happens.

Any ideas?

  • \$\begingroup\$ This is going to be a dumb question, based on my ignorance of the platform, but are you certain that image provides USB connectivity? \$\endgroup\$ – Ignacio Vazquez-Abrams Aug 6 '13 at 0:56
  • \$\begingroup\$ I'm not too familiar with the Leonardo, but I'm under the impression that the bootloader makes the chip act as a virtual COM port, which allows you to upload code like a normal Arduino. \$\endgroup\$ – user2461391 Aug 6 '13 at 0:59
  • \$\begingroup\$ You should always have a pullup to VDD on the reset line. A common value is usually 4.7k or 10k. \$\endgroup\$ – DeathBySnuSnu Aug 6 '13 at 2:04

UCAP does not look right, it should not be connected to VCC, but to a capacitor to GND.

edit: I was rather tired when answering this yesterday, so I omitted the fact that I built my own Leonardo-style design recently, and correctly connecting UCAP made a big difference in getting USB working.

  • \$\begingroup\$ Thank you! As a quick fix I ripped off the UCAP pin. Now it shows up as "unknown device", which is progress! \$\endgroup\$ – user2461391 Aug 6 '13 at 2:21
  • \$\begingroup\$ Last update - turns out that UCAP pin with capacitor is absolutely critical to operation. Since disconnecting it wasn't enough, I wired in the 1uF cap to ground and now it works perfectly! \$\endgroup\$ – user2461391 Aug 6 '13 at 13:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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