Sat May 19 00:21:15 EDT 2012

USB on scope

Looking on scope, I see only one of the lines (D-) move between 0-3V,
the other (D+) stays at 0.  Here[1] is mentioned that there is single
ended signalling, but only for initial conditions.  Doesn't look

However, if something that lowlevel is wrong, why does reception work?
PIC does get bytes in just fine.

Ordering new chips so I can see if a fresh chip has the same behaviour.

Could also be output config.

EDIT: Looks like I was just seeing the single-ended signalling.
Setting a 1->0 trigger on D+ does show some 12Mbps symmetric waveforms
after a while.

[1] http://www.beyondlogic.org/usbnutshell/usb2.shtml#Electrical