Fried USB interface?

I have a Duemilanove and it seems like the USB interface has gone bad. My computer no longer detects the board and the FTDI chip gets hot almost immediately when I connect it to the computer. Any suggestions on what to try in order to be sure it's not a software problem? This worked as it is for a long time and just suddenly stopped working the other day.

Thanks!

Well if you remove the AVR processor chip from the board and the your PC still doesn't detect the USB being plugged in then there is sure to be a hardware problem. You might try and measure the +5vdc when plugged in to see what value it is.

Lefty

I don't see how a hot FTDI chip can be a software problem, unfortunately. Most likely the chip is bad.

Did you short out the 3.3V output? Or connect it to 5V or Vin, etc.? That could damage the FTDI chip as the 3.3V output comes from it.

One thing I remember now is that I overloaded the the 5v power supply I was using to run the board a while back and caused the whole project to fade into a weird state (assumed to be an under-voltage but could have been anything). That was a couple weeks ago and I don't think I've tried the USB port until now. Dang. :-[

So just to clarify: the FTDI chip is not normally very warm. And it being noticeably hot is a dead giveaway of failure. Yes?

I'm going to try pulling the AVR chip out anyway just to be sure. :wink:

So just to clarify: the FTDI chip is not normally very warm. And it being noticeably hot is a dead giveaway of failure. Yes?

Pretty much yes. It could also be hot, however, if its 3.3V output is being asked to source a lot of current.

I don't see how overloading the 5V supply would have caused damage to the FTDI, though.