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

Jonathan Foote jtfoote at ieee.org
Sun May 16 18:12:45 UTC 2010


You've put a scope on all the power lines right? Linear regulators can
oscillate under rare conditions. And check the Arduino 5V regulator is
rated for the extra current draw of the waveshield (which can be
non-trivial given the 3.3 regulator).


On Sun, May 16, 2010 at 10:20 AM, Michael Shiloh
<michaelshiloh1010 at gmail.com> wrote:
> 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
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