We found the 220k-680k Ohm (1M Ohm reference) range to be appropriate for sleep, but when our subject is awake and aroused, it varies between the 10k-56k (40K Ohm reference) range and the 56k-220k Ohm (287K Ohm reference) range.
We are still having a lot of issues with this GSR board flatlining and giving invalid output when the slightest pressure is put on the Shimmer. When the Shimmer unit and the GSR top are screwed together, a light push flatlines everything and it sticks at the flatline. When we unscrew the two and let them rest apart, we get the proper resistance, but when we put them together, everything flatlines. We validated this claim using 300K Ohm resistors to see that it initially gives around 290K Ohm reading, which is appropriate, but when we screw the two together, it jumps up, saturates, and just flat lines at a very large resistance value. Anyone else having this problem that can offer advice? On Mon, Apr 2, 2012 at 12:34 PM, Raffaele Gravina < [email protected]> wrote: > Dear all, > > which is the best value for the active resistor you have found out during > your experiment? I'm just approaching the GSR, I tried with the default > value (40KOhms) and I always got (I placed the two electrodes to the index > and middle fingers) RAW ADC values close to 4095. > > Thanks, > > raffaele > > > 2012/4/2 mike healy <[email protected]> > >> Hi, >> >> When using ShimmerConnect you should see two GSR values in the "Control" >> window, i.e. "GsrRaw" and "GsrResistance". The second value gives the GSR >> in ohms. >> >> See the attached document for the method used to get the ohms values from >> the raw ADC and range values. >> >> An implementation of this can be seen in the Gsr.calcResistance() >> function here: >> http://code.google.com/p/tinyos-main/source/browse/trunk/tos/platforms/shimmer/chips/gsr/GsrP.nc >> or in the ShimmerConnect source code (which is available to Shimmer >> customers on request). >> >> Mike >> >> >> >> On Mon, Apr 2, 2012 at 2:09 AM, Sensors Capstone 2012 < >> [email protected]> wrote: >> >>> Using ShimmerConnect with the Shimmer GSR unit, we get outputs between >>> 1000 and 3000. These appear to be an output of an ADC. We have tried >>> searching all shimmer documentation, but cannot find how to convert these >>> back into ohm, depending on which GSR range we are in {0, 1, 2, or 3}. >>> >>> Can anyone shed some light on how to convert the values back into ohm? >>> >>> >>> Thank You, >>> SC >>> >>> _______________________________________________ >>> Shimmer-users mailing list >>> [email protected] >>> https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users >>> >>> >> >> _______________________________________________ >> Shimmer-users mailing list >> [email protected] >> https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users >> >> >
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