If your application has a GSM cellular shield, are you planning on having
it be mobile? in which case, the wall wart method will only serve you
sitting in one place, and not on the go.
As far as the Arduino power selection, it depends on the model board you
have. The newer Uno boards i know for sure select the power source
automatically, and don't skip a beat when, for example, a USB cable is
powering it and you plug a battery into the barrel jack and then remove the
USB cable (and vice versa). (Older boards may have a movable jumper to
select USB or External power.)
I see on the sparkfun site that the shield itself has a dedicated voltage
regulator (SPX29302). Before considering an additional regulator, take a
look to see if this regulator simply takes the Vin from whatever battery
and modifies it. (Schematic:
this is the case, then maybe all you need is a battery with enough mAH to
supply the peak loads.
On Tue, Dec 13, 2011 at 10:19 AM, Guan Yang <g...
> On Tuesday, December 13, 2011 at 10:15 , c f wrote:
> > If you are powering the GSM module from the arduino's onboard regulator
> chip, it probably can't actually source 2A. In that case, you would need to
> make sure that the GSM module does not share a "V_in" with the arduino
> (even though they do still need to share a ground wire), and that it is
> powered by another, dedicated voltage regulator that can supply enough
> current. Many voltage regulator chips are available that you could hook up
> to a wall supply to power the GSM module.
> What exactly happens if you take an Arduino (without any shields) and plug
> in both a 9V wall wart and a USB cable? Are the 5V from USB and the 5V side
> of the regular just tied together? Is there a switch ensuring that only one
> power source is used?
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