[Lab] Arduino CapSense library + Shiftbrites + interference

[Adam Hill]

Hi Andrew,

I suspect that your EMI thesis is the correct one. I see that on the CapSense
arduino page <http://www.arduino.cc/playground/Main/CapSense>, it notes that
"At its most sensitive, the sensor will start to sense a hand or body inches
away from the sensor" so I'm sure the array's are sufficiently noisy for the
sensor to notice, especially when they're shifting! You could try wrapping
the cables in tinfoil but other than that I can't think of any good solution
except to put the setup into some kind of Faraday
box<http://en.wikipedia.org/wiki/Faraday_cage>
.

BTW, care to share a few pics of the setup?

-a

On Wed, Apr 13, 2011 at 11:07 AM, Andrew O'Malley <aomalley at gmail.com>wrote:

> Hi everyone,
>
> I have a pretty specific situation here that I'd love to hear your thoughts
> on:
>
> I have four panels of 5x6 Shiftbrite arrays, attached to plastic
> supports.  In front of each panel I'm placing an acylic sheet for
> diffusion, and on this sheet are several wires attached to an Arduino
> running the CapSense library.
>
> I can get useable data from the capsense arrangement running by
> itself, but when placed (3") in front of the shiftbrite arrary, the
> capsense values become extremely unstable (huge fluctuations making
> the data unuseable) when the Shiftbrites are receiving data.  The
> capsense circuit and the shiftbrite circuit are electrically isolated,
> as the capsense circuit is running from its own battery while the
> shiftbrite circuit is plugged in via a power supply; so I don't think
> it's noise from the power supply.  Is it possible that the array of
> Shiftbrites are giving off significant EMI while shifting data?
>
> If this is the case, anyone have any suggestions for add-on shielding
> for the shiftbrite array/cables?
>
> Thanks for your time and attention!
>
> Andrew
>
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