[Noisebridge-discuss] arduino+wave shield+external power supply issue

[Michael Shiloh]

a friend has been developing a project using a wave shield. (some of you 
may have met him: he's visited noisebridge and found great help, which 
we both appreciate.)

he's been using usb power while developing, but now it's time to switch 
to external power.

as soon as he plugs in his 12VDC external power supply, the program 
stops working as it should have.

if we re-attach the usb cable to get debugging messages, we get 
gibberish, as if the baud rate is off. the length of the messages and 
the timing is about right though.

any ideas? i've never used the waveshield before but i can't believe it 
cares about the input power to arduino. by my quick glance it has its 
own regulator, but i didn't actually find the schematic (a pointer to 
this would be most helpful).

by the way, taylor would love to pay someone to help him with this. it's 
due on tuesday. i would guess 1-4 hours today and/or tomorrow would be 
very helpful. he's copied on this letter.

michael